Publications by authors named "Soo Choon Tan"

38 Publications

Influence of Polymorphisms on the Clinical Outcomes of Opioiddependent Patients on Methadone Maintenance Therapy.

J Pharm Bioallied Sci 2020 Nov 5;12(Suppl 2):S787-S803. Epub 2020 Nov 5.

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), Kelantan, Malaysia.

Introduction: Dopamine receptor D2 (DRD2) is one of the dopamine receptors that have been studied in relation to opioid dependence. It is possible, therefore, that gene () polymorphisms influence treatment outcomes of patients with opioid dependence. The objective of this study was to investigate the influence of polymorphisms on the clinical outcomes of opioid-dependent patients on methadone maintenance therapy (MMT).

Materials And Methods: Patients with opioid dependence ( = 148) were recruited from MMT clinics. Pain sensitivity, severity of the opiate withdrawal syndrome, and sleep quality were assessed using cold pressor test (CPT), Subjective Opiate Withdrawal Scale (SOWS-M), and Pittsburgh Sleep Quality Index (PSQI)-Malay, respectively. Deoxyribonucleic acid (DNA) was extracted from whole blood, and then was used for genotyping of Val96Ala, Leu141Leu, Val154Ile, Pro310Ser, Ser311Cys, A, -141C , and -241 polymorphisms.

Results: Among 148 patients, 8.1% ( = 12), 60.8% ( = 90), 27.7% ( = 41), and 29.1% ( = 43) had at least one risk allele for Ser311Cys, A, -141C and polymorphisms, respectively. There were no significant differences in pain responses (pain threshold, tolerance, and intensity), SOWS, and PSQI scores between polymorphisms.

Conclusion: The common polymorphisms are not associated with pain sensitivity, severity of the opiate withdrawal syndrome, and sleep quality in patients with opioid dependence on MMT. However, this may be unique for Malays. Additional research should focus on investigating these findings in larger samples and different ethnicity.
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http://dx.doi.org/10.4103/jpbs.JPBS_248_19DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8021064PMC
November 2020

Development of an ELISA for detection of mitragynine and its metabolites in human urine.

Anal Biochem 2020 06 14;599:113733. Epub 2020 Apr 14.

Institute for Research in Molecular Medicine (INFORMM), Main Campus, Universiti Sains Malaysia, 11800, Penang, Malaysia.

An enzyme-linked immunosorbent assay for detection of mitragynine, other closely related Kratom alkaloids and metabolites was developed using polyclonal antibodies. Mitragynine was conjugated to a carrier protein, cationized-bovine serum albumin using Mannich reaction. The synthesized antigen was injected into rabbits to elicit specific polyclonal antibodies against mitragynine. An enzyme conjugate was synthesized for evaluating its performance with the antibodies produced. The assay had an IC of 7.3 ng/mL with a limit of detection of 15 ng/mL for mitragynine. Antibody produced have high affinity for mitragynine (100%), other closely related Kratom alkaloids such as paynantheine (54%), speciociliatine (63%), 7α-hydroxy-7H-mitragynine (83%) and cross-reacted with metabolites 9-O-demethyl mitragynine (79%), 16-carboxy mitragynine (103%), 9-O-demethyl mitragynine sulfate (263%), 9-O-demethyl mitragynine glucuronide (60%), 16-carboxy mitragynine glucuronide (60%), 9-O-demethyl-16-carboxy mitragynine sulfate (270%) and 17-O-demethyl-16,17-dihydro mitragynine glucuronide (34%). It showed cross-reactivity less than 0.01% to reserpine, codeine, morphine, caffeine, methadone, amphetamine, and cocaine. Ten-fold dilution urine was used in the assay to reduce the matrix effects. The recovery ranged from 83% to 112% with variation coefficients in intraday and interday less than 8% and 6%, respectively. The ELISA turned out to be a convenient tool to diagnose mitragynine, other closely related Kratom alkaloids and metabolites in human urine samples.
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http://dx.doi.org/10.1016/j.ab.2020.113733DOI Listing
June 2020

BZD9L1 sirtuin inhibitor as a potential adjuvant for sensitization of colorectal cancer cells to 5-fluorouracil.

Ther Adv Med Oncol 2019 27;11:1758835919878977. Epub 2019 Sep 27.

Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800, Malaysia.

Background: This study aims to investigate the combination effect of a novel sirtuin inhibitor (BZD9L1) with 5-fluorouracil (5-FU) and to determine its molecular mechanism of action in colorectal cancer (CRC).

Methods: BZD9L1 and 5-FU either as single treatment or in combination were tested against CRC cells to evaluate synergism in cytotoxicity, senescence and formation of micronucleus, cell cycle and apoptosis, as well as the regulation of related molecular players. The effects of combined treatments at different doses on stress and apoptosis, migration, invasion and cell death mechanism were evaluated through two-dimensional and three-dimensional cultures. studies include investigation on the combination effects of BZD9L1 and 5-FU on colorectal tumour xenograft growth and an evaluation of tumour proliferation and apoptosis using immunohistochemistry.

Results: Combination treatments exerted synergistic reduction on cell viability on HCT 116 cells but not on HT-29 cells. Combined treatments reduced survival, induced cell cycle arrest, apoptosis, senescence and micronucleation in HCT 116 cells through modulation of multiple responsible molecular players and apoptosis pathways, with no effect in epithelial mesenchymal transition (EMT). Combination treatments regulated SIRT1 and SIRT2 protein expression levels differently and changed SIRT2 protein localization. Combined treatment reduced growth, migration, invasion and viability of HCT 116 spheroids through apoptosis, when compared with the single treatment. In addition, combined treatment was found to reduce tumour growth through reduction of tumour proliferation and necrosis compared with the vehicle control group. This highlights the potential therapeutic effects of BZD9L1 and 5-FU towards CRC.

Conclusion: This study may pave the way for use of BZD9L1 as an adjuvant to 5-FU in improving the therapeutic efficacy for the treatment of colorectal cancer.
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http://dx.doi.org/10.1177/1758835919878977DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6767736PMC
September 2019

Anticancer activities of a benzimidazole compound through sirtuin inhibition in colorectal cancer.

Future Med Chem 2018 Sep 1;10(17):2039-2057. Epub 2018 Aug 1.

Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800, Malaysia.

Aim: This study aims to investigate the mode of action of a novel sirtuin inhibitor (BZD9L1) and its associated molecular pathways in colorectal cancer (CRC) cells.

Materials & Methods: BZD9L1 was tested against metastatic CRC cell lines to evaluate cytotoxicity, cell cycle and apoptosis, senescence, apoptosis related genes and protein expressions, as well as effect against major cancer signaling pathways.

Results & Conclusion: BZD9L1 reduced the viability, cell migration and colony forming ability of both HCT 116 and HT-29 metastatic CRC cell lines through apoptosis. BZD9L1 regulated major cancer pathways differently in CRC with different mutation profiles. BZD9L1 exhibited anticancer activities as a cytotoxic drug in CRC and as a promising therapeutic strategy in CRC treatment.
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http://dx.doi.org/10.4155/fmc-2018-0052DOI Listing
September 2018

Relationship between Serum Methadone Concentration and Cold Pressor Pain Sensitivity in Patients Undergoing Methadone Maintenance Therapy.

Iran J Pharm Res 2018 ;17(Suppl):8-16

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), Kelantan, Malaysia.

Hyperalgesia is a common clinical phenomenon among opioid dependent patients on methadone maintenance therapy (MMT) and it may be associated with undertreated pain and/or therapeutic failure. This study aimed to investigate association between serum methadone concentration (SMC) and cold pressor pain responses. Cold pressor pain responses in 147 opioid dependent patients on MMT were assessed using cold pressor test (CPT) at 0 h and at 2, 4, 8, 12, and 24 h after the dose intake. Blood samples were collected at 24 h after the dose. Serum methadone concentrations were measured using the Methadone ELISA kit and classified into two categories: < 400 ng/mL and ≥ 400 ng/mL. Eighty-eight patients (59.9%) had trough concentrations of < 400 ng/mL and 40.1% had trough concentrations of ≥ 400 ng/mL. There were significant effects of SMC on the cold pressor pain threshold ( = 0.019). Patients with concentrations < 400 ng/mL had significantly higher (almost 60% higher) cold pressor pain threshold (adjusted mean (95% CI) = 30.15 (24.29, 36.01) s) compared to those with concentrations of ≥ 400 ng/mL (18.93 (11.77, 26.08) seconds). There was also a 20% difference in pain tolerance, and 6% difference in cold pressor pain intensity score, neither of which were significant statistically ( > 0.05). Our results suggest an association of trough methadone concentration with the cold pressor pain threshold among opioid dependent patients on MMT. It would be useful to study the mechanisms underlying this association to help managing pain in such a population.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5958320PMC
January 2018

Isolation and characterization of a novel anti-salbutamol chicken scFv for human doping urinalysis.

Anal Biochem 2018 08 23;555:81-93. Epub 2018 Jun 23.

Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), 11800, Minden, Penang, Malaysia. Electronic address:

Anti-salbutamol antibodies remain as important tools for the detection of salbutamol abuse in athletic doping. This study evaluated the feasibility and efficiency of the chicken (Gallus gallus domesticus) as an immunization host to generate anti-salbutamol scFv antibodies by phage display. A phage display antibody library was constructed from a single chicken immunized against salbutamol-KLH conjugate. After a stringent biopanning strategy, a novel scFv clone which was inhibited by free salbutamol recorded the highest affinity. This scFv was expressed as soluble and functional protein in Escherichia coli T7 SHuffle Express B (DE3) strain. Cross-reactivity studies of the scFv towards other relevant β2-agonists revealed that the scFv cross-reacted significantly towards clenbuterol. The determined IC of the scFv towards the two β2-agonists were; IC salbutamol = ∼0.310 μg/ml, IC clenbuterol = ∼0.076 μg/ml. The generated scFv demonstrated poor stability based on accelerated stability studies. The scFv was used to develop an competitive indirect ELISA (LOD = 0.125 μg/ml) for detection of parent salbutamol in spiked human urine (n = 18) with ∼83.4% reliability at the cut-off of 1 μg/ml currently implemented by WADA and may be of potential use in human doping urinalysis.
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http://dx.doi.org/10.1016/j.ab.2018.05.009DOI Listing
August 2018

Process intensification of core streptavidin production through high-cell-density cultivation of recombinant E. coli and a temperature-based refolding method.

J Biotechnol 2018 Jun 19;276-277:34-41. Epub 2018 Apr 19.

Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Minden, 11800, Penang, Malaysia. Electronic address:

An intensified process was developed that enables high level production of recombinant core streptavidin (cSAV), a non-glycosylated tetrameric protein utilised in a wide range of applications. A pH-stat fed-batch feeding strategy was employed to achieve high-cell-density and improve volumetric yield of cSAV which was expressed as inclusion bodies (IBs). The effect of induction at different cell densities (OD 20, 60 and 100) on volumetric and specific yield were then studied. Highest volumetric yield of cSAV (1550 mg L) was obtained from induction at OD 100 without significant reductions in specific yield. To recover active cSAV from IBs, the possibility of refolding using a temperature-based refolding method was investigated. Refolded cSAV obtained from temperature-based refolding were then compared against cSAV refolded with conventional dialysis and dilution methods using quantitative and qualitative metrics. The temperature-based refolding method was found to improve the yield of cSAV by 6-18% in comparison to conventional methods without compromising quality. Intensification was achieved by reductions in process volumes and a more concentrated product stream. Using the newly developed process, the volumetric yield of cSAV IBs was improved by thirty-six fold in comparison to low-cell-density shake flask cultivation, and 33% of cSAV can be recovered from IBs at 90% purity.
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http://dx.doi.org/10.1016/j.jbiotec.2018.04.012DOI Listing
June 2018

Method validation in quantitative analysis of phase I and phase II metabolites of mitragynine in human urine using liquid chromatography-tandem mass spectrometry.

Anal Biochem 2018 02 14;543:146-161. Epub 2017 Dec 14.

Institute for Research in Molecular Medicine (INFORMM), Main Campus, Universiti Sains Malaysia, 11800, Penang, Malaysia. Electronic address:

A method using solid phase extraction and liquid chromatography-tandem mass spectrometry to quantitatively detect mitragynine, 16-carboxy mitragynine, and 9-O-demethyl mitragynine in human urine samples was developed and validated. The relevant metabolites were identified using multiple reaction monitoring in positive ionization mode using nalorphine as an internal standard. The method was validated for accuracy, precision, recovery, linearity, and lower limit of quantitation. The intra- and inter-day accuracy and precision were found in the range of 83.6-117.5% with coefficient of variation less than 13%. The percentage of recovery for mitragynine, 16-carboxy mitragynine, and 9-O-demethyl mitragynine was within the range of 80.1-118.9%. The lower limit of quantification was 1 ng/mL for mitragynine, 2 ng/mL for 16-carboxy mitragynine, and 50 ng/mL for 9-O-demethyl mitragynine. The developed method was reproducible, high precision and accuracy with good linearity and recovery for mitragynine, 16-carboxy mitragynine, and 9-O-demethyl mitragynine in human urine.
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http://dx.doi.org/10.1016/j.ab.2017.12.021DOI Listing
February 2018

Contrasting sirtuin and poly(ADP-ribose)polymerase activities of selected 2,4,6-trisubstituted benzimidazoles.

Chem Biol Drug Des 2018 01 9;91(1):213-219. Epub 2017 Aug 9.

Department of Chemistry, University of Malaya, Kuala Lumpur, Malaysia.

Both sirtuin and poly(ADP-ribose)polymerase (PARP) family of enzymes utilize NAD as co-substrate. Inhibitors of sirtuins and PARPs are important tools in drug discovery as they are reported to be linked to multiple diseases such as cancer. New potent sirtuin inhibitors (2,4,6-trisubstituted benzimidazole) were discovered from reported PARP inhibitor scaffold. Interestingly, the synthesized compounds have contrasting sirtuin and PARP-1 inhibitory activities. We showed that modification on benzimidazoles may alter their selectivity toward sirtuin or PARP-1 enzymes. This offers an opportunity for further discovery and development of new promising sirtuin inhibitors. Molecular docking studies were carried out to aid the rationalization of these observations. Preliminary antiproliferative studies of selected compounds against nasopharyngeal cancer cells also showed relatively promising results.
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http://dx.doi.org/10.1111/cbdd.13072DOI Listing
January 2018

Insights into the chicken IgY with emphasis on the generation and applications of chicken recombinant monoclonal antibodies.

J Immunol Methods 2017 08 11;447:71-85. Epub 2017 May 11.

Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), 11800 Minden, Penang, Malaysia. Electronic address:

The advantages of chicken (Gallus gallus domesticus) antibodies as immunodiagnostic and immunotherapeutic biomolecules has only been recently recognized. Even so, chicken antibodies remain less-well characterized than their mammalian counterparts. This review aims at providing a current overview of the structure, function, development and generation of chicken antibodies. Additionally, brief but comprehensive insights into current knowledge pertaining to the immunogenetic framework and diversity-generation of the chicken immunoglobulin repertoire which have contributed to the establishment of recombinant chicken mAb-generating methods are discussed. Focus is provided on the current methods used to generate antibodies from chickens with added emphasis on the generation of recombinant chicken mAbs and its derivative formats. The advantages and limitations of established protocols for the generation of chicken mAbs are highlighted. The various applications of recombinant chicken mAbs and its derivative formats in immunodiagnostics and immunotherapy are further detailed.
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http://dx.doi.org/10.1016/j.jim.2017.05.001DOI Listing
August 2017

ABCB1 Polymorphisms and Cold Pressor Pain Responses: Opioid-Dependent Patients on Methadone Maintenance Therapy.

Nurs Res 2017 Mar/Apr;66(2):134-144

Zalina Zahari, MSc, is Pharmacist, Department of Pharmacy, Hospital Universiti Sains Malaysia, and Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Chee Siong Lee, MMed, is Emergency Medicine Specialist, Department of Emergency Medicine, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Muslih Abdulkarim Ibrahim, PhD, is Senior Lecturer, Department of Pharmacology and Toxicology, College of Pharmacy, Hawler Medical University, Hawler, Iraq. Nurfadhlina Musa, MSc, is Senior Research Officer, Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Mohd Azhar Mohd Yasin, MMed, is Psychiatrist, Department of Psychiatry, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Mohd Azhar Mohd Yasin, MMed, is Psychiatrist, Department of Psychiatry, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Yeong Yeh Lee, PhD, is Professor, School of Medical Sciences, Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Soo Choon Tan, PhD, is Professor, Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. Nasir Mohamad, PhD, is Professor, Faculty of Medicine and Health Sciences, Universiti Sultan Zainal Abidin, Kuala Terengganu, Terengganu, Malaysia. Rusli Ismail, PhD, is Professor, Centre of Excellence for Research in AIDS (CERiA), University of Malaya, Kuala Lumpur, Malaysia.

Background: Methadone is a substrate of the P-glycoprotein efflux transporter, which is encoded by ABCB1 (MDR1), and thus, ABCB1 polymorphisms may influence the transport of methadone at the blood-brain barrier, affecting its adverse effects.

Objectives: This study investigated the association between ABCB1 polymorphisms and cold pressor pain responses among opioid-dependent patients on methadone maintenance therapy (MMT).

Methods: Malay male opioid-dependent patients receiving MMT (n = 148) were recruited. Cold pressor pain responses (pain threshold, pain tolerance, and pain intensity) were measured at 0, 2, 4, 8, 12, and 24 hours post-methadone dose. DNA was extracted from whole blood and genotyped for ABCB1 polymorphisms including 1236C>T (rs1128503), 2677G>T/A (rs2032582), and 3435C>T (rs1045642) using the allelic discrimination real-time polymerase chain reaction. Repeated-measure analysis of variance between-group analysis was used to compare the three cold pressor pain responses and ABCB1 polymorphisms (1236C>T, 2677G>T/A, and 3435C>T) according to genotypes and allelic additive models, genotype dominant and recessive models, haplotypes, and diplotypes.

Results: Patients with 2677 GG or 2677G allele had the lowest pain threshold compared with 2677G>T/A genotypes or alleles (p = .007 and .002, respectively). Haplotype analysis showed a significant association between ABCB1 haplotypes and pain threshold (p = .02). Patients with 2677G allele had the lowest pain tolerance compared to those with 2677T and 2677A alleles (2677G < 2677T < 2677A allele carriers; p = .05). In terms of pain intensity scores, patients with 2677 GG or 2677G allele had the highest scores compared to other 2677G>T/A genotypes or alleles (p = .04 and .008, respectively). Haplotype analysis revealed a significant difference between patients with CGC haplotype and those without this haplotype (p = .02).

Discussion: To the best of our knowledge, this study provides the first evidence that ABCB1 polymorphisms are associated with cold pressor pain responses among Malay male patients with opioid dependence on MMT. The results may provide an initial prediction on heightened pain sensitivity or hyperalgesia for individuals who are carriers of the ABCB1 polymorphisms.
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http://dx.doi.org/10.1097/NNR.0000000000000204DOI Listing
May 2017

Exploring CYP2B6 activity by measuring the presence ofnevirapine hydroxy metabolites in plasma.

Turk J Med Sci 2016 Dec 20;46(6):1875-1881. Epub 2016 Dec 20.

Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia.

Background/aim: Nevirapine is a reverse-transcriptase inhibitor widely used in combination therapy to treat HIV infection. Nevirapine is extensively metabolized in the liver and CYP2B6 is mainly responsible for oxidation of 3-hydroxynevirapine (3-OH NVP). This study aims to explore CYP2B6 activity by measuring 2-hydroxynevirapine (2-OH NVP) and 3-OH NVP in plasma and to identify factors associated with nevirapine pharmacokinetic parameters.

Materials And Methods: A total of 112 patients were recruited and treated with nevirapine-based antiretroviral therapy. Plasma nevirapine and metabolite concentrations were assayed using high-performance liquid chromatography via liquid-liquid extraction.

Results: Thirty-nine (34.8%) of the patients had no 3-OH NVP detected in their plasma while 2-OH NVP was detected in all patients. Metabolite concentrations were low compared to nevirapine. Positive correlations were observed between nevirapine and its metabolites, 2-OH NVP (P < 0.01) and 3-OH NVP (P = 0.012). Nevirapine concentration was decreased when concomitantly administered with methadone. Univariate analysis showed that ALT level, AST level, and detection of 3-OH NVP were associated with nevirapine pharmacokinetic parameters.

Conclusion: The variability of nevirapine pharmacokinetic parameters was caused by liver enzymes and the presence of 3-OH NVP metabolites. The presence of 3-OH NVP can probably be used to distinguished CYP2B6 activity and efficacy of nevirapine in patients with HIV infection.
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http://dx.doi.org/10.3906/sag-1503-116DOI Listing
December 2016

Sleep quality in opioid-naive and opioid-dependent patientson methadone maintenance therapy in Malaysia.

Turk J Med Sci 2016 Dec 20;46(6):1743-1748. Epub 2016 Dec 20.

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia.

Background/aim: Sleep disturbances may contribute to poor treatment outcomes in opioid-dependent patients. The extent to which the sleep profiles of opioid-dependent patients differ from those of the general Malaysian population is not documented. This study compared opioid-naive subjects and opioid-dependent patients on methadone maintenance therapy (MMT) in terms of their sleep quality.

Materials And Methods: Participants comprised Malay male opioid-naive subjects (n = 159) and opioid-dependent patients (n = 160) from MMT clinics in Kelantan, Malaysia, between March and October 2013. Sleep quality was evaluated using the translated and validated Malay version of the Pittsburgh Sleep Quality Index (PSQI).

Results: The opioid-dependent patients exhibited higher global PSQI scores [adjusted mean (95% CI) = 5.46 (5.02, 5.90)] than the opioid-naive group [4.71 (4.26, 5.15)] [F (1, 313) = 4.77, P = 0.030].

Conclusion: This study confirmed the poorer sleep quality among opioid-dependent patients on MMT, as manifested by their higher global PSQI scores. The sleep complaints in this patient population are a factor to consider and, when necessary, sleep evaluation and treatment should be undertaken to improve MMT patients' quality of sleep and overall treatment outcome.
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http://dx.doi.org/10.3906/sag-1507-132DOI Listing
December 2016

Relationship Between ABCB1 Polymorphisms and Cold Pain Sensitivity Among Healthy Opioid-naive Malay Males.

Pain Pract 2017 09 22;17(7):930-940. Epub 2017 Feb 22.

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Kelantan, Malaysia.

Background: Endogenous and exogenous opioids are substrates of the permeability glycoprotein (P-gp) efflux transporter, which is encoded by the ABCB1 (MDR1) gene. Genetic polymorphisms of ABCB1 may contribute to interindividual differences in pain modulation and analgesic responses. We investigated the relationship between ABCB1 polymorphisms and cold pain sensitivity among healthy males.

Methods: Cold pain responses, including pain threshold and pain tolerance, were measured using the cold-pressor test (CPT). DNA was extracted from whole blood and genotyped for ABCB1 polymorphisms, including c.1236C>T (rs1128503), c.2677G>T/A (rs2032582), and c.3435C>T (rs1045642), using the allelic discrimination real-time polymerase chain reaction.

Results: A total of 152 participants were recruited in this observational study. Frequencies of mutated allele for c.1236C>T, c.2677G>T/A, and c.3435C>T polymorphisms were 56.6%, 49.7%, and 43.4%, respectively. Our results revealed an association of the CGC/CGC diplotype (c.1236C>T, c.2677G>T/A, and c.3435C>T) with cold pain sensitivity. Participants with the CGC/CGC diplotype had 90% and 72% higher cold pain thresholds (87.62 seconds vs. 46.19 seconds, P = 0.010) and cold pain tolerances (97.24 seconds vs. 56.54 seconds, P = 0.021), respectively, when compared with those without the diplotype.

Conclusion: The CGC/CGC diplotype of ABCB1 polymorphisms was associated with variability in cold pain threshold and pain tolerance in healthy males.
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http://dx.doi.org/10.1111/papr.12546DOI Listing
September 2017

Ethyl nitrobenzoate: A novel scaffold for cholinesterase inhibition.

Bioorg Chem 2017 02 11;70:27-33. Epub 2016 Nov 11.

Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Minden, 11800 Penang, Malaysia.

A series of novel cholinesterase inhibitors containing nitrobenzoate core structure were synthesized by a facile and efficient method. The structure of the novel compounds were fully characterized and confirmed by analytical as well as spectroscopic methods. Compound indicated as 2f was found to possess the best cholinesterase inhibitory activities of all the evaluated compounds. Results suggest that 2f is a selective acetylcholinesterase inhibitor, although it also inhibits butyrylcholinesterase at higher concentration. Kinetics inhibition result suggest that 2f is a mixed-mode inhibitor of acetylcholinesterase. In addition, it was found to have low cytotoxicity. Molecular docking on compound 2f was carried out to rationalize the observed in vitro enzymatic assay results. Most importantly, the potential of nitrobenzoate derivatives as cholinesterase inhibitor was shown through this study. In summary, we discovered nitrobenzoates as a new scaffold that may eventually yield useful compounds in treatment of Alzheimer's disease.
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http://dx.doi.org/10.1016/j.bioorg.2016.11.005DOI Listing
February 2017

Relationship between CYP2B6*6 and cold pressor pain sensitivity in opioid dependent patients on methadone maintenance therapy (MMT).

Drug Alcohol Depend 2016 Aug 6;165:143-50. Epub 2016 Jun 6.

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), Kelantan, Malaysia; Centre of Excellence for Research in AIDS (CERiA), University of Malaya, Kuala Lumpur, Malaysia.

Background: CYP2B6 polymorphisms contribute to inter-individual variations in pharmacokinetics of methadone. Increased pain sensitivity is frequently reported by opioid dependent patients on methadone maintenance therapy (MMT). It is possible, therefore, that genetic polymorphisms in CYP2B6, which affects the metabolism of methadone, influence pain sensitivity among patients on MMT. This study investigated CYP2B6 polymorphisms and pain sensitivity in this group.

Methods: The cold pressor pain responses of 148 opioid dependent patients receiving MMT were evaluated using the cold pressor test (CPT). DNA was extracted from whole blood and subjected to polymerase chain reaction (PCR)-genotyping.

Results: Of the 148 subjects, 77 (52.0%) were carriers of CYP2B6*6 allele. CYP2B6*6 allele carriers had shorter cold pain threshold and pain tolerance times than non-carriers of CYP2B6*6 allele (21.05s vs 33.69s, p=0.036 and 27.15s vs 44.51s, p=0.020, respectively). Pain intensity scores of the CYP2B6*6 allele carriers was 67.55, whereas that of the CYP2B6*6 allele non-carriers was 64.86 (p=0.352).

Conclusion: Our study indicates that the CYP2B6*6 allele is associated with a lower pain threshold and lower pain tolerance among males with opioid dependence on MMT. The CYP2B6*6 allele may provide a mechanistic explanation for clinical observations of heightened pain sensitivity among opioid dependent patients receiving MMT.
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http://dx.doi.org/10.1016/j.drugalcdep.2016.05.028DOI Listing
August 2016

Relationship between ABCB1 polymorphisms and serum methadone concentration in patients undergoing methadone maintenance therapy (MMT).

Am J Drug Alcohol Abuse 2016 09 10;42(5):587-596. Epub 2016 Jun 10.

b Pharmacogenetics and Novel Therapeutics Cluster , Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM) , Kelantan , Malaysia.

Background: Methadone is a substrate of the permeability glycoprotein (P-gp) efflux transporter, which is encoded by the ABCB1 (MDR1) gene. Large interindividual variability in serum methadone levels for therapeutic response has been reported. Genetic variations in ABCB1 gene may be responsible for the variability in observed methadone concentrations.

Objective: This study investigated the associations of ABCB1 polymorphisms and serum methadone concentration over the 24-hour dosing interval in opioid-dependent patients on methadone maintenance therapy (MMT).

Methods: One hundred and forty-eight male opioid-dependent patients receiving MMT were recruited. Genomic deoxyribonucleic acid (DNA) was extracted from whole blood and genotyped for ABCB1 polymorphisms [i.e. 1236C>T (dbSNP rs1128503), 2677G>T/A (dbSNP rs2032582), and 3435C>T (dbSNP rs1045642)] using the allelic discrimination real-time polymerase chain reaction (PCR). Blood samples were collected at 0, 0.5, 1, 2, 4, 8, 12, and 24 hours after the dose. Serum methadone concentrations were measured using the Methadone ELISA Kit.

Results: Our results revealed an association of CGC/TTT diplotype (1236C>T, 2677G>T/A, and 3435C>T) with dose-adjusted serum methadone concentration over the 24-hour dosing interval. Patients with CGC/TTT diplotype had 32.9% higher dose-adjusted serum methadone concentration over the 24-hour dosing interval when compared with those without the diplotype [mean (SD) = 8.12 (0.84) and 6.11 (0.41) ng ml mg, respectively; p = 0.033].

Conclusion: There was an association between the CGC/TTT diplotype of ABCB1 polymorphisms and serum methadone concentration over the 24-hour dosing interval among patients on MMT. Genotyping of ABCB1 among opioid-dependent patients on MMT may help individualize and optimize methadone substitution treatment.
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http://dx.doi.org/10.3109/00952990.2016.1172078DOI Listing
September 2016

Chiral liquid chromatography-mass spectrometry (LC-MS/MS) method development for the detection of salbutamol in urine samples.

J Chromatogr B Analyt Technol Biomed Life Sci 2016 Jul 13;1025:83-91. Epub 2016 May 13.

Usains Biomics Laboratory Testing Services Sdn. Bhd., Universiti Sains Malaysia, Suite 016 Ground Floor, Eureka Complex, 11800 USM Minden, Penang, Malaysia; Institute for Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 USM Minden, Penang, Malaysia. Electronic address:

A sequential solid-phase extraction (SPE) method was developed and validated using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the detection and quantification of salbutamol enantiomers in porcine urine. Porcine urine samples were hydrolysed with β-glucuronidase/arylsulfatase from Helix pomatia and then subjected to a double solid-phase extraction (SPE) first using the Abs-Elut Nexus SPE and then followed by the Bond Elut Phenylboronic Acid (PBA) SPE. The salbutamol enantiomers were separated using the Astec CHIROBIOTIC™ T HPLC column (3.0mm×100mm; 5μm) maintained at 15°C with a 15min isocratic run at a flow rate of 0.4mL/min. The mobile phase constituted of 5mM ammonium formate in methanol. Salbutamol and salbutamol-tert-butyl-d9 (internal standard, IS) was monitored and quantified with the multiple reaction monitoring (MRM) mode. The method showed good linearity for the range of 0.1-10ng/mL with limit of quantification at 0.3ng/mL. Analysis of the QC samples showed intra- and inter-assay precisions to be less than 5.04%, and recovery ranging from 83.82 to 102.33%.
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http://dx.doi.org/10.1016/j.jchromb.2016.05.015DOI Listing
July 2016

Comparison of Pain Tolerance between Opioid Dependent Patients on Methadone Maintenance Therapy (MMT) and Opioid Naive Individuals.

J Pharm Pharm Sci 2016 ;19(1):127-36

Department of Pharmacy, Hospital Universiti Sains Malaysia, Kelantan, Malaysia. Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), Kelantan, Malaysia.

Purpose: This study compared pain sensitivity among opioid dependent patients on methadone maintenance therapy (MMT) and opioid naive subjects.

Methods: The three hundred participants comprised 152 opioid naive subjects and 148 opioid dependent patients. Opioid naive subjects had not taken any opioids including morphine and methadone to their best knowledge and were presumed so after two consecutive negative urine screenings for drugs. All opioid dependent patients were stabilized in treatment, defined as having been enrolled in the program for more than one month with no change of methadone dosage over the past one month. Excluded from the study were individuals with chronic or ongoing acute pain and individuals with a history of analgesics ingestion within 3 d before the cold pressor test (CPT). Pain tolerance to CPT was evaluated at 0 h, and at 2, 4, 8, 12, and 24 h post-methadone dose.

Results: Patients exhibited a significantly shorter mean pain tolerance time of 34.17 s (95% CI 24.86, 43.49) versus 61.36 (52.23, 70.48) [p < 0.001] compared with opioid naive subjects. Time-dependent mean pain tolerance was also significantly different when naive subjects were compared to patients (p = 0.016).

Conclusions: This study revealed hyperalgesia amongst patients on MMT, as manifested by their quicker hand withdrawal. The complaints of pain in this population should not be underestimated and the pain should be evaluated seriously and managed aggressively.
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http://dx.doi.org/10.18433/J3NS49DOI Listing
February 2017

The AC/AG Diplotype for the 118A>G and IVS2 + 691G>C Polymorphisms of OPRM1 Gene is Associated with Sleep Quality Among Opioid-Dependent Patients on Methadone Maintenance Therapy.

Pain Ther 2016 Jun 20;5(1):43-54. Epub 2016 Jan 20.

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), Kota Bharu, Kelantan, Malaysia.

Introduction: Methadone is a full agonist of the opioid receptor mu 1 which is encoded by the OPRM1 gene. Sleep disorders were frequently reported by opioid-dependent patients during methadone maintenance therapy (MMT). It is possible, therefore, that genetic polymorphisms in OPRM1 influence sleep quality among patients on MMT. This study investigated the association of OPRM1 polymorphisms with sleep quality among opioid-dependent patients on MMT.

Methods: The sleep quality of 165 male opioid-dependent patients receiving MMT was evaluated using the Pittsburgh Sleep Quality Index (PSQI). DNA was extracted from whole blood and subjected to polymerase chain reaction (PCR) genotyping.

Results: Patients with IVS2 + 691 CC genotype had higher PSQI scores [mean (SD) = 5.73 (2.89)] compared to those without the IVS2 + 691 CC genotype (IVS2 + 691 GG/GC genotype) [4.92 (2.31)], but the difference did not reach statistical significance (p = 0.081). Patients with combined 118 AA genotype and IVS2 + 691 GC genotype (AC/AG diplotype) had significantly lower PSQI scores [mean (SD) = 4.25 (2.27)] compared to those without the diplotype [5.68 (2.77)] (p = 0.018).

Conclusion: Our study indicates that the AC/AG diplotype for the 118A>G and IVS2 + 691G>C polymorphisms of OPRM1 gene is associated with better sleep quality among males with opioid dependence on MMT.
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http://dx.doi.org/10.1007/s40122-016-0044-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4912965PMC
June 2016

The Opposing Roles of IVS2+691 CC Genotype and AC/AG Diplotype of 118A>G and IVS2+691G>C of OPRM1 Polymorphisms in Cold Pain Tolerance Among Opioid-Dependent Malay Males on Methadone Therapy.

Pain Ther 2015 Dec 18;4(2):179-96. Epub 2015 Nov 18.

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia (USM), Kota Bharu, Kelantan, Malaysia.

Introduction: We recently reported that a majority of opioid-dependent Malay males on methadone therapy are cold pain sensitive. It is postulated that common OPRM1 polymorphisms may be responsible. This study investigated the association between 118A>G (dbSNP rs1799971) and IVS2+691G>C (dbSNP rs2075572) variants on cold pain responses among opioid-dependent Malay males on methadone maintenance therapy.

Methods: Cold pain responses including pain threshold, pain tolerance, and pain intensity were measured using the cold pressor test. DNA was extracted from the venous blood before polymerase chain reaction genotyping. Repeated measures analysis of variance was used to compare the cold pain responses and OPRM1 polymorphisms (118A>G and IVS2+691G>C) using models including genotype dominant and recessive models, allelic additive models, and analysis of haplotypes and diplotypes.

Results: A total of 148 participants were recruited. With the recessive model, those with IVS2+691 homozygous CC genotype had a shorter cold pain tolerance time than those without CC genotype (i.e., GG/GC genotype; 29.81 vs. 43.08 s, respectively, P = 0.048). On the other hand, with diplotype analysis, participants with combined homozygous 118 AA genotype and heterozygous IVS2+691 GC genotype (i.e., AC/AG diplotype) had a longer cold pain tolerance time than those without this diplotype (49.34 vs. 31.48 s, respectively, P = 0.043). Cold pain threshold was not associated with any of the 118A>G and IVS2+691G>C variations despite being analyzed using various models (all P > 0.05).

Conclusion: The IVS2+691 CC genotype and AC/AG diplotype of 118A>G and IVS2+691G>C seem to have opposing roles in pain tolerance among opioid-dependent Malay males on methadone therapy. Haplotypes of OPRM1 may be associated with altered binding affinity.
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http://dx.doi.org/10.1007/s40122-015-0041-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4676768PMC
December 2015

High allele frequency of CYP2C9*3 (rs1057910) in a Negrito's subtribe population in Malaysia; Aboriginal people of Jahai.

Ann Hum Biol 2016 Sep 24;43(5):445-50. Epub 2015 Sep 24.

a Department of Paediatrics , School of Medical Sciences, Universiti Sains Malaysia , Health Campus, Kubang Kerian , Kelantan , Malaysia .

Background: CYP2C9 gene polymorphisms modulate inter-individual variations in the human body's responses to various endogenous and exogenous drug substrates. To date, little is known about the CYP2C9 gene polymorphisms among the aboriginal populations of the world, including those in Malaysia.

Aim: To characterise and compare the CYP2C9 polymorphisms (CYP2C9*2, CYP2C9*3, CYP2C9*4 and CYP2C9*5) between one of Malaysia's aboriginal populations, Jahai, with the national major ethnic, Malay. To also compare the allele frequencies from these two populations with available data of other aboriginal populations around the world.

Subjects And Methods: The extracted DNA of 155 Jahais and 183 Malays was genotyped for CYP2C9 polymorphisms using a nested multiplex allele-specific polymerase chain reaction technique. The results were confirmed by DNA direct sequencing.

Results: Genotyping results revealed that CYP2C9*2, CYP2C9*4 and CYP2C9*5 were absent in Jahais, while only the latter two were absent in Malays. The CYP2C9*3 allelic frequency in Jahais was 36.2%, making them the most frequent carriers of the allele thus far reported in any ethnic group from Southeast Asia.

Conclusions: The high frequency of CYP2C9*3 and the absence of CYP2C9*2 in Jahais suggest that genetic drift may be occurring in this ethnic group. This is the first study to determine the CYP2C9 polymorphisms in an aboriginal population in Malaysia.
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http://dx.doi.org/10.3109/03014460.2015.1068372DOI Listing
September 2016

Relationship between cold pressor pain-sensitivity and sleep quality in opioid-dependent males on methadone treatment.

PeerJ 2015 9;3:e839. Epub 2015 Apr 9.

Pharmacogenetics and Novel Therapeutics Cluster, Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia , Kubang Kerian, Kelantan , Malaysia ; Centre of Excellence for Research in AIDS (CERiA), University of Malaya , Kuala Lumpur , Malaysia.

Aim. Poor sleep quality due to pain has been reported among opioid-dependent male patients on methadone maintenance therapy (MMT) but objective pain data are lacking. This study aimed to investigate the rate of pain-sensitivity using cold pressor test (CPT) and the relationship between pain-sensitivity and sleep quality in this population. Methods. A total of 168 male participants were included into the study. Objective pain-tolerance was evaluated at 0 h and at 24 h after the first CPT. Malay version of the Pittsburgh Sleep Quality Index (PSQI) and the subjective opiate withdrawal scale (SOWS) questionnaires were administered to evaluate the quality of sleep and withdrawal symptoms, respectively. Results. The mean age of study participants was 37.22 (SD 6.20) years old. Mean daily methadone dose was 76.64 (SD 37.63) mg/day, mean global PSQI score was 5.47 (SD 2.74) and mean averaged SOWS score was 5.43 (SD 6.91). The averaged pain-tolerance time ranged from 7 to 300 s with a mean time of 32.16 (SE 2.72) s, slightly below the cut-off score of 37.53 s. More specifically, 78.6% (n = 132) of participants were identified as pain-sensitive (averaged pain-tolerance time ≤37.53 s), and 36 (21.4%) participants were pain-tolerant (averaged pain-tolerance time >37.53 s). The pain-sensitive group reported poorer sleep quality with mean (SD) PSQI of 5.78 (2.80) compared with the pain-tolerant group with mean (SD) PSQI of 4.31 (2.18) (p = 0.005). With analysis of covariance, pain-sensitive group was found to have higher global PSQI scores (adjusted mean 5.76, 95% CI 5.29; 6.22) than pain-tolerant participants (adjusted mean 4.42, 95% CI 3.52; 5.32) (p = 0.010). Conclusions. Majority of opioid-dependent male patients on methadone treatment are pain-sensitive with CPT. Poor sleep quality is associated with cold pressor pain-sensitivity. Pain and sleep complaints in this male population should not be overlooked.
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http://dx.doi.org/10.7717/peerj.839DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4393806PMC
April 2015

Understanding the physicochemical properties of mitragynine, a principal alkaloid of Mitragyna speciosa, for preclinical evaluation.

Molecules 2015 Mar 18;20(3):4915-27. Epub 2015 Mar 18.

Centre for Drug Research, Universiti Sains Malaysia, Penang 11800, Malaysia.

Varied pharmacological responses have been reported for mitragynine in the literature, but no supportive scientific explanations have been given for this. These studies have been undertaken without a sufficient understanding of the physicochemical properties of mitragynine. In this work a UV spectrophotometer approach and HPLC-UV method were employed to ascertain the physicochemical properties of mitragynine. The pKa of mitragynine measured by conventional UV (8.11 ± 0.11) was in agreement with the microplate reader determination (8.08 ± 0.04). Mitragynine is a lipophilic alkaloid, as indicated by a logP value of 1.73. Mitragynine had poor solubility in water and basic media, and conversely in acidic environments, but it is acid labile. In an in vitro dissolution the total drug release was higher for the simulated gastric fluid but was prolonged and incomplete for the simulated intestinal fluid. The hydrophobicity, poor water solubility, high variability of drug release in simulated biological fluids and acid degradable characteristics of mitragynine probably explain the large variability of its pharmacological responses reported in the literature. The determined physicochemical properties of mitragynine will provide a basis for developing a suitable formulation to further improve its solubility, stability and oral absorption for better assessment of this compound in preclinical studies.
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http://dx.doi.org/10.3390/molecules20034915DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6272646PMC
March 2015

Optimization of palm oil physical refining process for reduction of 3-monochloropropane-1,2-diol (3-MCPD) ester formation.

J Agric Food Chem 2013 Apr 18;61(13):3341-9. Epub 2013 Mar 18.

Department of Food Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.

The reduction of 3-monochloropropane-1,2-diol (3-MCPD) ester formation in refined palm oil was achieved by incorporation of additional processing steps in the physical refining process to remove chloroester precursors prior to the deodorization step. The modified refining process was optimized for the least 3-MCPD ester formation and acceptable refined palm oil quality using response surface methodology (RSM) with five processing parameters: water dosage, phosphoric acid dosage, degumming temperature, activated clay dosage, and deodorization temperature. The removal of chloroester precursors was largely accomplished by increasing the water dosage, while the reduction of 3-MCPD esters was a compromise in oxidative stability and color of the refined palm oil because some factors such as acid dosage, degumming temperature, and deodorization temperature showed contradictory effects. The optimization resulted in 87.2% reduction of 3-MCPD esters from 2.9 mg/kg in the conventional refining process to 0.4 mg/kg, with color and oil stability index values of 2.4 R and 14.3 h, respectively.
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http://dx.doi.org/10.1021/jf4009185DOI Listing
April 2013

3-{5-Eth-oxy-carbonyl-1-[3-(2-oxopyrrol-idin-1-yl)prop-yl]-1H-benzimidazol-2-yl}benzoic acid.

Acta Crystallogr Sect E Struct Rep Online 2013 Feb 31;69(Pt 2):o304. Epub 2013 Jan 31.

Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia.

In the title compound, C(24)H(25)N(3)O(5), the eth-oxy group is disordered over two orientations in a 0.853 (14):0.147 (14) ratio. The benzimadazole ring system (r.m.s. deviation = 0.016 Å) makes a dihedral angle of 35.47 (7)° with the attached benzene ring. The pyrrolidine ring adopts an envelope conformation with a methyl-ene C atom as the flap. In the crystal, inversion dimers linked by pairs of O-H⋯N hydrogen bonds generate R(2) (2)(16) loops. C-H⋯O inter-actions link the dimers into a three-dimensional network.
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http://dx.doi.org/10.1107/S1600536813001116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3569823PMC
February 2013

In-vitro inhibitory effect of Tualang honey on cytochrome P450 2C8 activity.

J Pharm Pharmacol 2012 Dec 8;64(12):1761-9. Epub 2012 Jun 8.

Pharmacogenetics & Novel Therapeutics Cluster, Institute for Research in Molecular Medicine, Universiti Sains Malaysia, Penang, Malaysia.

Objectives: To investigate the effect of Tualang honey on cytochrome P450 2C8 (CYP2C8) activity in vitro using an amodiaquine N-desethylase assay.

Methods: CYP2C8 and NADPH cytochrome P450 reductase was cotransformed, expressed and harvested. The incubation assay contained expressed proteins, MgCl(2), NADP, glucose 6-phosphate, glucose-6-phosphate dehydrogenase, potassium phosphate buffer, and amodiaquine. The rate of conversion of amodiaquine to desethylamodiaquine, the metabolite, was determined using a high performance liquid chromatography (HPLC) method. The inhibition parameters, IC50 (concentration of inhibitor causing 50% inhibition of original enzyme activity) and apparent inhibition constant (K(i) ) values were determined.

Key Findings: The recombinant proteins were successfully expressed and used to investigate the effect of Tualang honey on CYP2C8 activity. The activity was measured by the rate of metabolism of amodiaquine to desethylamodiaquine determined using a successfully developed HPLC method. Kinetic parameters as determined by nonlinear least-squares regression and evaluated with Aikeike's goodness of fit criteria revealed that Tualang honey competitively inhibited CYP2C8 activity in a dose-dependent manner. Maximum inhibition of 80% occurred at 0.01% honey. The IC50 and K(i) values were (10.0 ± 3.0) × 10(-3) % and (5.1 ± 0.5) × 10(-3) % w/v, respectively.

Conclusions: This study has provided evidence for the in vitro inhibition of CYP2C8-mediated amodiaquine N-desethylase activity by Tualang honey. It revealed that honey, through this inhibition, may have the potential to cause in-vivo drug-food interaction with drugs metabolized by CYP2C8.
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http://dx.doi.org/10.1111/j.2042-7158.2012.01551.xDOI Listing
December 2012

Potent α-glucosidase and α-amylase inhibitory activities of standardized 50% ethanolic extracts and sinensetin from Orthosiphon stamineus Benth as anti-diabetic mechanism.

BMC Complement Altern Med 2012 Oct 8;12:176. Epub 2012 Oct 8.

School of Pharmaceutical Sciences, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia.

Background: In the present study, we tested a 50% ethanolic extract of Orthosiphon stamineus plants and its isolated bioactive compound with respect to their α-glucosidase and α-amylase inhibitory activities.

Methods: Bioactive flavonoid sinensetin was isolated from 50% ethanolic extract of Orthosiphon stamineus. The structure of this pure compound was determined on the NMR data and the α-glucosidase and α-amylase inhibitory activities of isolated sinensetin and 50% ethanolic extract of Orthosiphon stamineus were evaluated.

Results: In vitro studies of a 50% ethanolic extract of O. stamineus and the isolated sinensetin compound showed inhibitory activity on α-glucosidase (IC50: 4.63 and 0.66 mg/ml, respectively) and α-amylase (IC50: 36.70 mg/ml and 1.13 mg/ml, respectively). Inhibition of these enzymes provides a strong biochemical basis for the management of type 2 diabetes via the control of glucose absorption.

Conclusion: Alpha-glucosidase and α-amylase inhibition could the mechanisms through which the 50% ethanolic extract of O. stamineus and sinensetin exert their antidiabetic activity, indicating that it could have potential use in the management of non-insulin-dependent diabetes.
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http://dx.doi.org/10.1186/1472-6882-12-176DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3533584PMC
October 2012

A rapid and cost effective method in purifying small RNA.

World J Microbiol Biotechnol 2012 Jan 3;28(1):105-11. Epub 2011 Jun 3.

Infectious Disease Cluster, Advanced Medical & Dental Institute, Universiti Sains Malaysia, 13200, Kepala Batas, Penang, Malaysia.

Purification of RNA fragments from a complex mixture is a very common technique, and requires consideration of the time, cost, purity and yield of the purified RNA fragments. This study describes the fastest method of purifying small RNA with the lowest cost possible, without compromizing the yield and purity. The technique describes the purification of small RNA from polyacrylamide gel, resulting in a good yield of small RNA with minimum experimental steps in avoiding degradation of the RNA, obviating the use of ethidium bromide and phenol-chloroform extraction, as well as siliconized glass wools to remove the polyacrylamide gel particles. The purified small RNA is suitable for a wide variety of applications such as ligation, end labelling with radio isotope, RT-PCR (Reverse Transcriptase-PCR), Northern blotting, experimental RNomics study and also Systematic Evolution of Ligands by Exponential Enrichment (SELEX).
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http://dx.doi.org/10.1007/s11274-011-0797-0DOI Listing
January 2012

Assays for aptamer-based platforms.

Biosens Bioelectron 2012 Apr 25;34(1):1-11. Epub 2012 Jan 25.

Infectious Disease Cluster, Advanced Medical & Dental Institute (AMDI), Universiti Sains Malaysia, 13200 Kepala Batas, Penang, Malaysia.

Aptamers are single stranded DNA or RNA oligonucleotides that have high affinity and specificity towards a wide range of target molecules. Aptamers have low molecular weight, amenable to chemical modifications and exhibit stability undeterred by repetitive denaturation and renaturation. Owing to these indispensable advantages, aptamers have been implemented as molecular recognition element as alternative to antibodies in various assays for diagnostics. By amalgamating with a number of methods that can provide information on the aptamer-target complex formation, aptamers have become the elemental tool for numerous biosensor developments. In this review, administration of aptamers in applications involving assays of fluorescence, electrochemistry, nano-label and nano-constructs are discussed. Although detection strategies are different for various aptamer-based assays, the core of the design strategies is similar towards reporting the presence of specific target binding to the corresponding aptamers. It is prognosticated that aptamers will find even broader applications with the development of new methods of transducing aptamer target binding.
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http://dx.doi.org/10.1016/j.bios.2012.01.002DOI Listing
April 2012