Publications by authors named "Vichai Reutrakul"

99 Publications

Emerging 2D/0D g-CN/SnO S-scheme photocatalyst: New generation architectural structure of heterojunctions toward visible-light-driven NO degradation.

Environ Pollut 2021 Oct 5;286:117510. Epub 2021 Jun 5.

Ho Chi Minh City University of Technology (HUTECH), 475A Dien Bien Phu Street, Binh Thanh District, Ho Chi Minh City, 700000, Viet Nam. Electronic address:

Enhancing and investigating the photocatalytic activity over composites for new models remains a challenge. Here, an emerging S-scheme photocatalyst composed of 2D/0D g-CN nanosheets-assisted SnO nanoparticles (g-CN/SnO) is successfully synthesized and used for degrading nitrogen oxide (NO), which causes negative impacts on the environment. A wide range of characterization techniques confirms the successful synthesis of SnO nanoparticles, g-CN nanosheets, and 2D/0D g-CN/SnO S-scheme photocatalysts via hydrothermal and annealing processes. Besides, the visible-light response is confirmed by optical analysis. The S-scheme charge transfer was elucidated by Density-Functional Theory (DFT) calculation, trapping experiments, and electron spin resonance (ESR). We found that intrinsic oxygen vacancies of SnO nanoparticles and S-scheme charge transfer addressed the limitation of other heterojunction types. It is notable that compared pure SnO nanoparticles and g-CN, g-CN/SnO offered the best photocatalytic NO degradation and photostability under visible light with the removal of more than 40% NO at 500 ppb throughout the experiment. Benefiting from the unique structural features, the new generation architectural structure of S-scheme heterojunction exhibited potential photocatalytic activity and it would simultaneously act more promising for environmental treatment in the coming years.
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http://dx.doi.org/10.1016/j.envpol.2021.117510DOI Listing
October 2021

Gambogic Acid Inhibits Wnt/β-catenin Signaling and Induces ER Stress-Mediated Apoptosis in Human Cholangiocarcinoma.

Asian Pac J Cancer Prev 2021 Jun 1;22(6):1913-1920. Epub 2021 Jun 1.

Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Objective: Gambogic acid (GA) has been reported to induce apoptosis in cholangiocarcinoma (CCA) cell lines. However, the molecular mechanisms underlying its anti-cancer activity remain poorly understood. This study was aimed to investigate GA's effect on human CCA cell lines, KKU-M213 and HuCCA-1, and its associated mechanisms on Wnt/β-catenin signaling pathway.

Methods: Cell viability, apoptosis, and cell cycle analysis were conducted by MTT and flow cytometry. The effect of GA mediated Wnt/β-catenin and ER stress were determined by luciferase-reporter assay, qRT-PCR, and western blot analysis.

Results: GA exhibited potent cytotoxicity in CCA cells which was associated with significantly inhibited cell proliferation, promoted G1 arrest, and activated caspase 3 mediated-apoptosis. GA attenuated β-catenin transcriptional levels, decreased β-catenin protein, and suppressed the expression of c-Myc, a downstream target gene of Wnt/β-catenin signaling. GA activated genes involved in ER stress mechanism in KKU-M213 and enhanced CCA's sensitivity to gemcitabine.

Conclusion: Our findings reveal that the molecular mechanism underpinning anti-cancer effect of GA is partially mediated through the inhibition of Wnt/β-catenin signaling pathway and induction of ER stress induced-apoptosis. GA may serve as a promising therapeutic modality for amelioration of gemcitabine-induced toxicity in CCA.
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http://dx.doi.org/10.31557/APJCP.2021.22.6.1913DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8418851PMC
June 2021

Mass spectral analysis of secondary metabolites from Zingiber montanum rhizome extract using UHPLC-HR-ESI-QTOF-MS/MS.

Phytochem Anal 2021 May 30. Epub 2021 May 30.

Department of Pharmacognosy and Center of Innovative Pharmacy for Pharmaceutical and Herbal Product Development, Faculty of Pharmacy, Mahidol University, Bangkok, Thailand.

Introduction: Zingiber montanum (J.Koenig) Link ex A.Dietr. is a popular medicinal plant in Thailand. Its rhizomes have been used as an ingredient in various Thai traditional medicine formulas. While many reports have focused on the chemical constituents and biological activities of this plant, a comprehensive study on secondary metabolite profiling using tandem mass spectrometry has, to this point, never been documented.

Objective: To analyze the chemical constituents in Z. montanum rhizomes using ultra-high performance liquid chromatography coupled with ultra-high-resolution electrospray ionization quadrupole time-of-flight tandem mass spectrometry (UHPLC-HR-ESI-QTOF-MS/MS) analyses and to utilize the characteristic fragmentation patterns of these compounds to facilitate their identification.

Methodology: UHPLC-HR-ESI-QTOF-MS/MS in positive ion mode was used for chemical identification of secondary metabolites from the ethanolic extract of the plant material. MS/MS data of some known reference compounds, together with detailed fragmentation pattern information of several compounds obtained from the crude extract, were used to elucidate their chemical structures.

Results: In this work, one benzaldehyde, ten phenylbutenoid monomers, six curcuminoids, and nine phenylbutenoid dimers were assigned based on their characteristic fragment ions. Among these compounds, 2-(3,4-dimethoxystyryl)oxirane was tentatively suggested as a potential new compound. Several characteristic fragment ions from these compounds were assigned and the relative ion abundance of these was also used to differentiate the chemical structures of compounds having the same molecular mass.

Conclusions: The results will benefit future high-throughput screening of bioactive compounds and method development for the quality control of raw materials and herbal drugs derived from Z. montanum rhizome extracts.
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http://dx.doi.org/10.1002/pca.3068DOI Listing
May 2021

Bioactive tetrahydrofuran lignans from roots, stems, leaves and twigs of Anogeissus rivularis.

Fitoterapia 2021 Jun 22;151:104885. Epub 2021 Mar 22.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand. Electronic address:

Four previously undescribed tetrahydrofuran lignans, named anorisols A-D (1-4) and fourteen known compounds (5-18) were isolated from the roots, stems, leaves and twigs of Anogeissus rivularis. The chemical structures were elucidated on the basis of their spectroscopic data and by comparison with the literature data. The absolute configurations of 1-4 were established by comparison of the experimental ECD spectra with the calculated ECD spectra. Some isolated compounds were evaluated for their cytotoxic activity as well as anti-HIV-1 activity employing reverse transcriptase (RT) and syncytium reduction assays using the MC99 virus in 1A2 cell line systems. Compound 6 displayed the most potent activity in syncytium inhibition assay with effective concentration at 50% (EC) value of 13.3 μM (SI >3.0). In the reverse transcriptase assay, compound 1 exhibited moderate activity with IC value of 213.9 μM.
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http://dx.doi.org/10.1016/j.fitote.2021.104885DOI Listing
June 2021

UPLC-ESI-MRM/MS for Absolute Quantification and MS/MS Structural Elucidation of Six Specialized Pyranonaphthoquinone Metabolites From .

Front Plant Sci 2020 11;11:602993. Epub 2021 Jan 11.

Metabolomics and Systems Biology, Department of Biochemistry, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.

Pyranonaphthoquinones (PNQs) are important structural scaffolds found in numerous natural products. Research interest in these specialized metabolites lies in their natural occurrence and therapeutic activities. Nonetheless, research progress has thus far been hindered by the lack of analytical standards and analytical methods for both qualitative and quantitative analysis. We report here that various parts of are rich sources of PNQs. We developed an ultraperformance liquid chromatography-electrospray ionization multiple reaction monitoring/mass spectrometry method to quantitatively determine six PNQs from leaves, root, bark, wood, and heartwood. The addition of standards in combination with a stable isotope of salicylic acid-D was used to overcome the matrix effect with average recovery of 82% ± 1% ( = 15). The highest concentration of the total PNQs was found in the root (11,902 μg/g dry weight), whereas the lowest concentration was found in the leaves (28 μg/g dry weight). Except for the root, PNQ-332 was found to be the major compound in all parts of , accounting for ∼48% of the total PNQs quantified in this study. However, PNQ-318A was the most abundant PNQ in the root sample, accounting for 27% of the total PNQs. Finally, we provide novel MS/MS spectra of the PNQs at different collision induction energies: 10, 20, and 40 eV (POS and NEG). For structural elucidation purposes, we propose complete MS/MS fragmentation pathways of PNQs using MS/MS spectra at collision energies of 20 and 40 eV. The MS/MS spectra along with our discussion on structural elucidation of these PNQs should be very useful to the natural products community to further exploring PNQs in and various other sources.
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http://dx.doi.org/10.3389/fpls.2020.602993DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7830255PMC
January 2021

Inhibitory effect of isomorellin on cholangiocarcinoma cells via suppression of NF-κB translocation, the phosphorylated p38 MAPK pathway and MMP-2 and uPA expression.

Exp Ther Med 2021 Feb 17;21(2):151. Epub 2020 Dec 17.

Faculty of Public Health, Kasetsart University Chalermphrakiat Sakon Nakhon Province Campus, Sakon Nakhon 47000, Thailand.

Evidence indicates that most cancer deaths are caused by tumor invasion and metastasis. Cholangiocarcinoma (CCA) is a tumor of the bile duct epithelium characterized by slow growth, rapid metastasis and poor prognosis. Caged xanthones are extracted from gamboge, a dry resin exuded by . These compounds have been reported to be cytotoxic to several types of cancer cells, without affecting normal cells. The aim of the present study was to determine the effect of isomorellin on the inhibition of CCA cell (KKU-100) viability, migration, invasion and the expression of invasion-regulated proteins. Cytotoxicity of isomorellin was evaluated using a sulforhodamine B assay. The anti-migratory and anti-invasive effects of isomorellin on KKU-100 cells were assessed using wound healing and chamber invasion assays, respectively. Furthermore, the activities of matrix metalloproteinases (MMPs)-2 and -9, and urokinase-type plasminogen activator (uPA) were also investigated. The expression levels of proteins regulating invasion were determined via western blot analysis. The cell viability of KKU-100 cells was decreased following treatment with isomorellin in a dose-dependent manner, with IC50 values at 24, 48 and 72 h of 3.46±0.19, 3.78±0.02 and 4.01±0.01 µM, respectively. Wound healing and chamber invasion assays indicated that isomorellin significantly inhibited KKU-100 cell migration and invasion in a dose-dependent manner. In addition, isomorellin significantly inhibited cancer cell migration and invasion abilities via focal adhesion kinase (FAK), protein kinase C (PKC), the phosphorylated (p)-p38 mitogen-activated protein kinase (MAPK) pathway, and nuclear factor (NF)-κB expression and translocation to the nucleus, thus resulting in downregulation of MMP-2, uPA and cyclooxygenase-2 (COX-2) expression. Therefore, inhibition of MMP-2, uPA and COX-2 expression may result in decreased CCA cell invasion ability. These data demonstrated for the first time that the suppression of KKU-100 cell viability, invasion and migration, and downregulation of NF-κB, MMP-2, uPA and the p-p38 MAPK pathway, may result in isomorellin-mediated anti-invasiveness.
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http://dx.doi.org/10.3892/etm.2020.9583DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7792505PMC
February 2021

Boesenmaxane Diterpenoids from .

J Nat Prod 2021 02 29;84(2):518-526. Epub 2020 Dec 29.

The Forest Herbarium, National Parks, Wildlife and Plant Conservation Department, Ministry of Natural Resources and Environment, Bangkok 10900, Thailand.

Three new diterpenoids, boesenmaxanes A-C (-), with an unprecedented core skeleton consisting of an unusual C-C bond between C-12 and an -cyclic methylene C-13, were isolated from the rhizome extracts of . The structures were elucidated by analysis of spectroscopic and X-ray diffraction data. Electronic circular dichroism spectra were used to determine the absolute configuration. All the isolates were evaluated for their cytotoxic effects, anti-HIV activity, and antimicrobial activity. Boesenmaxanes A and C ( and ) showed significant inhibitory activity in the syncytium reduction assay, with EC values of 55.2 and 27.5 μM, respectively.
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http://dx.doi.org/10.1021/acs.jnatprod.0c00629DOI Listing
February 2021

Cytotoxic compounds from the leaves and stems of the endemic Thai plant .

Pharm Biol 2020 Dec;58(1):490-497

Department of National Parks, Wildlife and Plant Conservation, Ministry of Natural Resources and Environment, The Forest Herbarium, Bangkok, Thailand.

Weeras., Chalermglin & R.M.K. Saunders (Annonaceae) is a plant endemic to Thailand. Its constituents and their biological activities are unknown. Isolation and identification of the compounds in the leaves and stems of and determination of their cytotoxicity. Methanol extracts of the leaves and stems of were separated by chromatography, and spectroscopic methods were used to determine the structures of the components. The cytotoxicity of the extracts and pure compounds was evaluated using the sulforhodamine B assay with several cell lines. The cells were treated with the compounds at concentrations of 0.16-20 µg/mL for 48 or 72 h. The investigation of the extracts of leaves and stems resulted in the isolation of a new lignan, mitrephoran, and 15 known compounds. Among these compounds, 2-(3,4-dimethoxyphenyl)-6-(3,5-dimethoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane, ciliaric acid, 6-methoxymarcanine A, and stepharanine were isolated from this genus for the first time. The alkaloids liriodenine and oxoputerine exhibited strong cytotoxicity against all tested cells (IC values of 6.59-11.02 µM). In contrast, magnone A, 3',4--dimethylcedrusin, and 6-methoxymarcanine A inhibited the growth of some of the tested cells (IC values of 2.03-19.73 µM). Magnone A and 6-methoxymarcanine A showed low toxicity for Hek 293 cells (IC >20 µM). is a source of cytotoxic lignans and alkaloids. Among the cytotoxic compounds, magnone A and 6-methoxymarcanine A are potentially useful lead compounds for the further development of anticancer agents because of their selective inhibitory effects on cancer cell lines.
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http://dx.doi.org/10.1080/13880209.2020.1765813DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7336994PMC
December 2020

Alkanethiol-Mediated Cyclization of -Alkynylisocyanobenzenes: Synthesis of Bis-Thiolated Indole Derivatives.

J Org Chem 2020 May 15;85(10):6338-6351. Epub 2020 Apr 15.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.

Reactions of -alkynylisocyanobenzenes with a variety of alkanethiols (Alk-SH) provide the corresponding bis-thiolated indole derivatives. The advantages of the reaction include metal-free, room-temperature, mild reaction conditions and broad functional group compatibility. The reaction proceeds via nucleophilic addition of an alkanethiol to an isonitrile moiety, 5- cyclization, followed by nucleophilic addition of an alkanethiol to a 3-alkylidene indole intermediate. Density functional calculations on the electronic structures and relative free energies of 5- and 6- cyclization pathways support that the 5- cyclization is preferable.
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http://dx.doi.org/10.1021/acs.joc.0c00003DOI Listing
May 2020

Pyranonaphthoquinone and anthraquinone derivatives from Ventilago harmandiana and their potent anti-inflammatory activity.

Phytochemistry 2020 Jan 24;169:112182. Epub 2019 Oct 24.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand. Electronic address:

The chemical study on the heartwoods extract of Ventilago harmandiana (Rhamnaceae) resulted in the isolation of ten previously undescribed pyranonaphthoquinones (ventilanones A-J), an undescribed anthraquinone (ventilanone K), together with eight known anthraquinone derivatives. Their structures were elucidated by extensive analysis of their spectroscopic data. The absolute configuration of ventilanone A was established from single crystal X-ray crystallographic analysis of its p-bromobenzenesulfonate ester derivative using Cu Kα radiation. The absolute configurations of the other related compounds were identified by comparison of their ECD data with those of ventilanone A and related known compounds. Cytotoxic and anti-inflammatory activities of some of the isolated compounds were evaluated. Ventilanone A and ventilanone C exhibited moderate cytotoxicity against P-388 cell line. Ventilanone D exhibited significant anti-inflammatory activity while ventilanone A and ventilanone C showed moderate activity.
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http://dx.doi.org/10.1016/j.phytochem.2019.112182DOI Listing
January 2020

Synthesis of Indolo- and Benzothieno[2,3-]quinolines by a Cascade Cyclization of -Alkynylisocyanobenzene Derivatives.

J Org Chem 2019 12 14;84(23):15131-15144. Epub 2019 Nov 14.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science , Mahidol University , Rama 6 Road , Bangkok 10400 , Thailand.

A new synthetic approach for the synthesis of indolo[2,3-]quinolines and benzothieno[2,3-]quinolines has been developed by employing the freshly prepared -alkynylisocyanobenzenes derived from -alkynylformamide derivatives as substrates. The synthetic transformations involved chloride-ion-triggered 6- cyclization of -alkynylisocyanobenzenes to generate 2-chloroquinolines in situ, which further cyclized intramolecularly with nitrogen or sulfur atom via a cascade process to provide the corresponding indolo[2,3-]quinolines and benzothieno[2,3-]quinolines, respectively, in moderate to excellent yields.
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http://dx.doi.org/10.1021/acs.joc.9b02081DOI Listing
December 2019

Anti-HIV-1 activities of constituents from the rhizomes of Boesenbergia thorelii.

Fitoterapia 2019 Nov 23;139:104388. Epub 2019 Oct 23.

Department of Chemistry, Center of Excellence for Innovation in Chemistry, Faculty of Science, Prince of Songkla University, Songkhla 90112, Thailand; Medical Science Research and Innovation Institute, Prince of Songkla University, Songkhla 90112, Thailand.

A new lignan, thoreliin A (1), and a new bisnorlignan, thoreliin B (2), were isolated from a MeOH extract of the rhizomes of Boesenbergia thorelii. In addition, the known bisnorlignans 3 and 4, neolignan 5, phenylpropanoids 6-15, as well as benzenoids 18-21 were also obtained from the same source. The structures were elucidated based on their spectroscopic data. By single crystal X-ray analysis, the relative stereochemistry of 1 was confirmed. All isolated compounds were evaluated for anti-HIV-1 activities. Among them, thoreliin A (1) exhibited anti-HIV-1 activities on both HIV-1 reverse transcriptase (41.43% inhibition at 200 μg/mL) and syncytium reduction assays (EC 20.6 μM, SI 3.7), while compounds 3-6, 9 and 11-21 showed anti-HIV-1 activity only in the anti-syncytium assay (EC 6.6-454.1 μM, SI >1.32-7.75).
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http://dx.doi.org/10.1016/j.fitote.2019.104388DOI Listing
November 2019

Cytotoxic polyoxygenated cyclohexene derivatives from the aerial parts of Uvaria cherrevensis.

Fitoterapia 2019 Sep 28;137:104182. Epub 2019 May 28.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Bangkok 10400, Thailand. Electronic address:

Three previously undescribed polyoxygenated cyclohexene derivatives named cherrevenol M (1), cherrevenol N (2), and cherrevenone (3), together with nine related known analogues 4-12 were isolated from the ethyl acetate fraction partitioned from the methanol extract of the aerial parts of Uvaria cherrevensis (Annonaceae). The determination of the structures and their relative configurations of the isolated compounds were established by spectroscopic techniques, electronic circular dichroism (ECD) analysis as well as comparison with the literature data. For cherrevenone (3), the relative and absolute configurations were also confirmed by using X-ray diffraction and ECD techniques, respectively. Compounds isolated except for compounds 8 and 10 were evaluated for their cytotoxic activity and cherrevenone (3) showed moderate cytotoxic activity against all cancerous cell lines except for ASK cell line with ED values ranging from 1.04 ± 0.13 to 10.09 ± 4.31 μM.
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http://dx.doi.org/10.1016/j.fitote.2019.104182DOI Listing
September 2019

Antimicrobial activity of rhodomyrtone isolated from (Aiton) Hassk.

Nat Prod Res 2020 Sep 2;34(17):2518-2523. Epub 2019 Jan 2.

Institute of Biotechnology, Vietnam Academy of Science and Technology, Hanoi, Vietnam.

Rhodomyrtone was isolated from the leaves of (Aiton) Hassk grown in Vietnam using chromatographic methods. Its chemical structure was confirmed by means of spectroscopic data analysis. The pH drop measurement, enzyme activity assays and fluorescence stain were used to examine rhodomyrtone anticaries activity. It was found that rhodomyrtone suppressed acid production by , a major cariogenic agent in human by inhibiting enzyme activities responsible for acid production and tolerance, including membrane bound enzymes F-ATPase and phosphotransferase system (PTS), as well as glycolysis enzymes glyceraldehyphosphate dehydrogenase (GAPDH) and pyruvate kinase (PK) in cytoplasm with the IC values of 24 μM, 19 μM, 23 μM and 28 μM, respectively. Moreover, 50 μM rhodomyrtone reduced biofilm biomass formed by up to 59% ( < 0.05). Fluorescent images indicated that cells on the biofilms were significantly killed. Thus, rhodomyrtone is a new and potential anticaries agent against .
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http://dx.doi.org/10.1080/14786419.2018.1540479DOI Listing
September 2020

Sulfinates and thiocyanates triggered 6-endo cyclization of o-alkynylisocyanobenzenes.

Org Biomol Chem 2018 11;16(44):8553-8558

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.

Diverse 2-sulfonyl- and 2-thiocyanato-3-substituted quinolines were synthesized from o-alkynylisocyanobenzenes by nucleophilic addition of the respective sulfinate sodium salts and ammonium thiocyanate to the isocyanide moiety followed by cyclization. The salient features of the methodology include metal-free, ambient temperature and mild reaction conditions, ease of reagent handling, and broad functional group tolerance.
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http://dx.doi.org/10.1039/c8ob02338gDOI Listing
November 2018

Synthesis of 3-substituted quinolin-2(1H)-ones via the cyclization of o-alkynylisocyanobenzenes.

Org Biomol Chem 2018 10;16(38):7050-7054

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.

A facile synthesis of various functionalized 3-substituted quinolin-2(1H)-ones through Ag(i) nitrate-catalyzed cyclization of o-alkynylisocyanobenzenes is described. The reaction allows rapid and convenient access to 3-substituted quinolin-2(1H)-one scaffolds in moderate to good yields.
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http://dx.doi.org/10.1039/c8ob01882kDOI Listing
October 2018

Bioinspired Asymmetric Synthesis of (-)-Gymnothelignan V.

J Org Chem 2018 04 12;83(7):4173-4179. Epub 2018 Mar 12.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science , Mahidol University , Rama 6 Road , Bangkok 10400 , Thailand.

A bioinspired asymmetric total synthesis of a structurally unique subtype of lignan, namely, (-)-gymnothelignan V, was achieved. The key synthetic sequences involved reduction of the eupomatilone skeleton leading to (-)-gymnothelignan J followed by the formation of the corresponding oxocarbenium ion and stereoselective intramolecular Friedel-Crafts reaction. Our synthetic approach provides the information to support the plausible biosynthetic pathway of this structurally unusual lignan. On a similar basis, other structurally related natural and non-natural gymnothelignans including (-)-gymnothelignan D, 6,9-bis- epi-gymnothelignan V, and 5- epi-gymnothelignans D and J were readily prepared.
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http://dx.doi.org/10.1021/acs.joc.8b00164DOI Listing
April 2018

Anti-HIV and cytotoxic biphenyls, benzophenones and xanthones from stems, leaves and twigs of Garcinia speciosa.

Phytochemistry 2018 Mar 2;147:68-79. Epub 2018 Jan 2.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand. Electronic address:

Eleven previously undescribed compounds, including four benzophenones (garciosones A-D), four xanthones (garciosones E-H) and three biphenyls (garciosines A-C), along with eighteen known compounds were isolated from the stems, leaves and twigs of Garcinia speciosa Wall. (Clusiaceae). Their structures were established by extensive spectroscopic analysis. For garciosines A-C, the structures were confirmed by single crystal X-ray diffraction analysis. Most of the isolated compounds were evaluated for their cytotoxic activity and anti-HIV-1 activity using the syncytium inhibition assay and HIV-1 reverse transcriptase (RT) assay. The known compounds, 4,6,3',4'-tetrahydroxy-2-methoxybenzophenone and macluraxanthone, displayed significant cytotoxic activity with the ED in the range of 1.85-11.76 μM. 1,5-Dihydroxyxanthone exhibited the most potent anti-HIV activity against syncytium formation with EC < 17.13 μM (SI > 25.28) and 2-(3,3-dimethylallyl)-1,3,7-trihydroxyxanthone was the most active compound in the HIV-1 reverse transcriptase assay with IC value of 58.24 μM. Structure-activity relationship of some isolated compounds were also discussed.
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http://dx.doi.org/10.1016/j.phytochem.2017.12.013DOI Listing
March 2018

Synergistic Effect of Forbesione From Garcinia hanburyi in Combination with 5-Fluorouracil on Cholangiocarcinoma

Asian Pac J Cancer Prev 2017 Dec 29;18(12):3343-3351. Epub 2017 Dec 29.

Department of Microbiology, Khon Kaen University, Khon Kaen 40002, Thailand.

Background: Chemotherapy for advanced cholangiocarcinoma (CCA) is largely ineffective; thus innovative combinations of chemotherapeutic agents and natural compounds represent a promising strategy. This study aimed to investigate the synergistic effects of forbesione combined with 5-fluorouracil (5-FU) in hamster cholangiocarcinoma (Ham-1) cells both in vitro and in vivo. The anti-tumor effects of 5-FU combined with forbesione in vitro were determined using the Sulforhodamine B (SRB) assay and the effects in vivo were assessed in transplanted Ham-1 allograph models. Using ethidium bromide/acridine orange (EB/AO) staining, the morphological changes of apoptotic cells was investigated. The expressions of apoptosis-related molecules after combined treatment with forbesione and 5-FU were determined using real-time RT-PCR and western blot analysis. Forbesione or 5-FU alone inhibited proliferation of Ham-1 cells in a dose-dependent manner and their combination showed a synergistic proliferation inhibitory effect in vitro. In vivo studies, forbesione in combination with 5-FU exhibited greater inhibition of the tumor in the hamster model compared with treatment using either drug alone. Forbesione combined with 5-FU exerted stronger apoptotic induction in Ham-1 cells than did single drug treatment. The combination of drugs strongly suppressed the expression of B-cell lymphoma 2 (Bcl-2) and procaspase-3 while enhancing the expression of p53, Bcl-2-associated X protein (Bax), apoptotic protease activating factor-1 (Apaf-1), caspase-9 and caspase-3, compared with single drug treatments. These results explained the decreased expression of cytokeratin 19 (CK19) positive cells and proliferation cell nuclear antigen (PCNA) positive cells in Ham-1 cell tumor tissues of the treated hamsters. There was no apparent systemic toxicity observed in the treated animals compared with the control groups. Forbesione combined with 5-FU strongly induced apoptosis in Ham-1 cells. The growth inhibitory effect of combined treatment using these two drugs was much greater than treatment with either drug alone, both in vitro and in vivo.
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http://dx.doi.org/10.22034/APJCP.2017.18.12.3343DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5980893PMC
December 2017

Oxidative Difluoromethylation of Tetrahydroisoquinolines Using TMSCFSPh: Synthesis of Fluorinated Pyrrolo[2,1-a]isoquinolines and Benzo[a]quinolizidines.

J Org Chem 2018 01 5;83(2):765-782. Epub 2018 Jan 5.

Center of Excellence for Innovation in Chemistry (PERCH-CIC) and Department of Chemistry, Faculty of Science, Mahidol University , Rama VI Road, Bangkok 10400, Thailand.

An efficient C1-difluoromethylation of tetrahydroisoquinolenes was achieved using TMSCFSPh as a difluoromethylating agent and 2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (TEMPOBF) as an oxidant. The process provides an access to a variety of C1-difluoro(phenylsulfanyl)methylated tetrahydroisoquinoline adducts in good yields. These adducts were employed as key precursors for preparing fluorinated pyrrolo[2,1-a]isoquinoline and benzo[a]quinolizidines.
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http://dx.doi.org/10.1021/acs.joc.7b02783DOI Listing
January 2018

Antibiofilm activity of α-mangostin extracted from Garcinia mangostana L. against Staphylococcus aureus.

Asian Pac J Trop Med 2017 Dec 31;10(12):1154-1160. Epub 2017 Oct 31.

Department of Pharmacy and Pharmacology, University of Bath, Claverton Down Bath, BA2 7AY, Bath, UK. Electronic address:

Objective: To isolate α-mangostin (AMG) from the peels of mangosteen (Garcinia mangostana L.), grown in Vietnam, and to investigate antibiofilm activity of this compound against three Staphylococcus aureus (S. aureus) strains, one of which was methicillin-resistant S. aureus (MRSA) and the other two strains were methicillin-sensitive S. aureus (MSSA).

Methods: AMG in n-hexane fraction was isolated on a silica gel column and chemically analyzed by HPLC and NMR. The antibiofilm activity of this compound was investigated by using a 96-well plate model for the formation of biofilms. Biofilm biomass was quantified using crystal violet. The viability of cells was observed under confocal microscopy using LIVE/DEAD BacLight stains. Biofilm composition was determined using specific chemical and enzyme tests for polysaccharide, protein and DNA. Membrane-damaging activity was assayed by measuring the hemolysis of human red blood cells in presence of AMG.

Results: The results indicated that the isolated AMG, with a purity that exceeded 98%, had minimal inhibitory concentrations in the range of 4.6-9.2 μmol/L for the three strains tested. Interestingly, the MSSA strains were more sensitive to AMG than the MRSA strain. Minimal bactericidal concentrations were 2-fold higher than the minimal inhibitory concentration values for the three strains, indicating that AMG was a bactericidal compound. AMG also prevented biofilm formation effectively, albeit that again the MRSA strain was the most resistant. Interestingly, biofilms of the MRSA strain contained protein as a main component of the extracellular matrix, whereas this was polysaccharide in the MSSA strains. This might relate to the resistance of the MRSA 252 strain to AMG. Assays using human red blood cells indicated that AMG caused significant membrane damage with 50% of cell lysis occurred at concentration of about 36 μmol/L.

Conclusions: Our results provide evidence that the isolated AMG has inhibitory activity against biofilm formation by S. aureus, including MRSA. Thus, isolated AMG proposes a high potential to develop a novel phytopharmaceutical for the treatment of MRSA.
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http://dx.doi.org/10.1016/j.apjtm.2017.10.022DOI Listing
December 2017

Polycyclic polyprenylated acylphloroglucinols and biphenyl derivatives from the roots of Garcinia nuntasaenii Ngerns. & Suddee.

Phytochemistry 2018 Feb 22;146:63-74. Epub 2017 Dec 22.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand. Electronic address:

Seven previously undescribed compounds, including three polycyclic polyprenylated acylphloroglucinols (garcinuntins A-C), three biphenyl derivatives (garcinuntabiphenyls A-C) and a lanostane triterpene (garcinuntine), along with thirteen known compounds were isolated from the root of Garcinia nuntasaenii Ngerns. & Suddee. Their structures were elucidated on the basis of spectroscopic techniques. For garcinuntins A-C, the absolute configurations were confirmed by the combination of single X-ray crystallography and ECD calculations. Anti-HIV activity using anti-HIV-1 reverse transcriptase and syncytium inhibition assays, and cytotoxic activity against a panel of cultured mammalian cancer cell lines of isolated compounds were investigated.
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http://dx.doi.org/10.1016/j.phytochem.2017.12.001DOI Listing
February 2018

Synthesis of C-Symmetric gem-Difluoromethylenated Angular Triquinanes.

J Org Chem 2018 01 21;83(1):388-402. Epub 2017 Dec 21.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University , Rama VI Road, Bangkok 10400, Thailand.

A synthesis of symmetrical gem-difluoromethylenated angular triquinanes is described. The synthetic strategy involved sequential fluoride-catalyzed nucleophilic addition of PhSCFSiMe (1) to 2,2-diallylated or 2,2-dipropargylated indane-1,3-diones 2 followed by stereoselective radical cyclization of the resulting adducts 3 to provide the cyclized gem-difluoromethylenated diquinanes 4 as a mixture of stereoisomers. Repeated addition of 1 to 4 followed by cyclization resulted in the stereoselective synthesis of the desired C-symmetric gem-difluoromethylenated angular triquinanes 6 in good yields with high stereoselectivity.
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http://dx.doi.org/10.1021/acs.joc.7b02777DOI Listing
January 2018

TBAI/TBHP-Mediated Cascade Cyclization toward Sulfonylated Indeno[1,2-c]quinolines.

Org Lett 2017 12 27;19(24):6546-6549. Epub 2017 Nov 27.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University , Rama 6 Road, Bangkok 10400, Thailand.

Treatment of ortho-amino-substituted aryldiyne derivatives with sulfonyl hydrazides in the presence of tetrabutylammonium iodide (TBAI) and tert-butyl hydroperoxide (TBHP) led to a cascade cyclization reaction to yield sulfonylated indeno[1,2-c]quinolines in moderate to good yields. The features of the methodology include metal-free reaction, the ease of reagent handling, and a broad functional group tolerance.
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http://dx.doi.org/10.1021/acs.orglett.7b03246DOI Listing
December 2017

Asymmetric synthesis of ent-fragransin C.

Org Biomol Chem 2017 May;15(18):3985-3994

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama VI Road, Bangkok 10400, Thailand.

The first asymmetric synthesis of ent-fragransin C was reported. The key step involves an intramolecular C-O bond formation (furan ring formation) via chemoselective generation of the benzylic carbocation leading to the 2,3-anti-3,4-syn-4,5-anti-tetrahydrofuran moiety as a single diastereomer in good yield. Our synthesis confirms that ent-fragransin C possesses 2R,3R,4S,5S configurations.
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http://dx.doi.org/10.1039/c7ob00749cDOI Listing
May 2017

Synthesis of N-alkyl-3-sulfonylindoles and N-alkyl-3-sulfanylindoles by cascade annulation of 2-alkynyl-N,N-dialkylanilines.

Org Biomol Chem 2017 May;15(17):3662-3669

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.

An efficient and metal-free approach to N-alkyl-3-sulfonylindoles and N-alkyl-3-sulfanylindoles from 2-alkynyl-N,N-dialkylanilines has been developed. In the presence of iodine and tert-butylhydroperoxide (TBHP), a variety of 2-alkynyl-N,N-dialkylanilines underwent a cascade radical annulation to yield 3-arylsulfonylindoles. In contrast, 3-arylsulfanylindoles were conveniently prepared by iodine mediated electrophilic annulation reactions. The present protocol uses the economical and environmentally friendly I-TBHP or I system, and potentially bioactive N-alkyl-3-sulfonylindoles and N-alkyl-3-sulfanylindoles with various functional groups were successfully synthesized in moderate to good yields.
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http://dx.doi.org/10.1039/c7ob00366hDOI Listing
May 2017

Antitumor effect of forbesione isolated from on cholangiocarcinoma and .

Oncol Lett 2016 Dec 18;12(6):4685-4698. Epub 2016 Oct 18.

Center of Excellence for Innovation in Chemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.

Cholangiocarcinoma (CCA) is a malignancy with no effective therapy and poor prognosis. Forbesione, a caged xanthone isolated from , has been reported to inhibit proliferation and to induce apoptosis in human CCA cell lines. The present study aimed to further explore the potential anticancer properties of forbesione by testing its effects against the hamster CCA cell line Ham-1 and . It was observed that forbesione inhibited the growth of Ham-1 cells and suppressed Ham-1 growth as allograft in hamsters by inducing cell cycle arrest at the S phase. This was mediated by decreasing the protein expression of cyclin E, cyclin A and cyclin-dependent kinase 2. In addition, increased expression of p21 and p27 was detected, which could possibly explain the reduced expression of proliferating cell nuclear antigen and of the bile duct cell marker cytokeratin 19 observed in forbesione-treated Ham-1 cells and in tumor tissues of forbesione-treated hamsters. Furthermore, forbesione induced apoptosis through multiple pathways. The death receptor pathway was activated by increased expression of Fas, Fas-associated death domain and activated caspase-3, along with decreased expression of procaspase-8 and procaspase-3. The mitochondrial pathway was driven by increased expression of B-cell lymphoma (Bcl)-2-like protein 4, activated caspase-9 and inhibitor of κB-α, along with decreased expression of Bcl-2, survivin, procaspase-9 and nuclear factor-κB/p65. The endoplasmic reticulum pathway was stimulated by increased expression of activated caspase-12 and decreased expression of procaspase-12. No side effects or toxicity were observed in forbesione-treated hamsters. Thus, forbesione is a potential drug candidate for cancer therapy that deserves further investigation.
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http://dx.doi.org/10.3892/ol.2016.5284DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5228296PMC
December 2016

Cytotoxic lanostanes from fruits of Garcinia wallichii Choisy (Guttiferae).

Bioorg Med Chem Lett 2016 12 15;26(23):5773-5779. Epub 2016 Oct 15.

Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand. Electronic address:

Five new lanostanes, wallichinanes A-E (1-5) together with a known lanostane derivative 6 were isolated from the cytotoxic hexanes extract of fruits of Garcinia wallichii Choisy (Guttiferae). The structures of the isolated compounds were established by analysis of spectroscopic data, X-ray diffraction technique as well as comparison with the literature data. The cytotoxicity of all isolated compounds against a panel of cultured cancer cell lines was evaluated. Compound 4 exhibited good cytotoxicity with ED values ranging from 3.91 to 7.63μM.
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http://dx.doi.org/10.1016/j.bmcl.2016.10.045DOI Listing
December 2016

5-Acetyl goniothalamin suppresses proliferation of breast cancer cells via Wnt/β-catenin signaling.

Eur J Pharmacol 2016 Nov 16;791:455-464. Epub 2016 Sep 16.

Department of Physiology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand; Chakri Naruebodindra Medical Institute, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand. Electronic address:

Styryl lactones are plant-derived compounds from genus Goniothalamus with promising anti-proliferation and anticancer properties. However, the exact mechanism and the target for their activities remained unclear. In the present study, we investigated the effect of 5-acetyl goniothalamin (5GTN) from Goniothalamus marcanii on Wnt/β-catenin signaling pathway which is a key regulator in controlling cell proliferation in breast cancer cells (MCF-7 and MDA-MB-231). 5GTN, a naturally occurring derivative of goniothalamin (GTN) mediated the toxicity to MCF-7 and MDA-MB-231 cells in a dose- and time- related manner, and was more potent than that of GTN. 5GTN strongly inhibited cell proliferation and markedly suppressed transcriptional activity induced by β-catenin in luciferase reporter gene assay. In consistent with this view, the expression of Wnt/β-catenin signaling target genes including c-Myc, cyclin D1 and Axin2 in MCF-7 and MDA-MB-231 cells were suppressed after treatment with 5GTN. It was concomitant with cell cycle arrest at G phase and cell apoptosis in MCF-7 cells. In addition, 5GTN enhanced glycogen synthase kinase (GSK-3β) activity and therefore reduced the expression of active form of β-catenin protein in MCF-7 and MDA-MB-231 cells. Taken together, 5GTN exhibited a promising anticancer effect against breast cancer cells through an inhibition of Wnt/β-catenin signaling. This pathway may be served as a potential chemotherapeutic target for breast cancer by 5GTN.
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http://dx.doi.org/10.1016/j.ejphar.2016.09.024DOI Listing
November 2016

A New Neolignan, and the Cytotoxic and Anti-HIV-1 Activities of Constituents from the Roots of Dasymaschalon sootepense.

Nat Prod Commun 2016 Jun;11(6):809-13

Bioassay-guided isolation from the ethyl acetate extract of Dasymaschalon sootepense roots led to the isolation of twelve compounds including a new dihydrobenzo-furan neolignan, (+)-(2S,3S)-2,3-dihydro-2-(3,4-dimethoxyphenyl)-3-methylbenzofuran-5-carbaldehyde (5), and eleven known compounds (1-4, and 6-12). The chemical structures and stereochemistry of all the isolated compounds were established by spectroscopic techniques. The known compounds 4 and 6 have been fully characterized spectroscopically, including their absolute configurations. Cytotoxic and anti-HIV-1 reverse transcriptase (RT) activities of compounds 1-3, 5 and 8-12 were determined. Among compounds screened, compounds 2, 3 and 10 displayed weak cytotoxic activity with ED50 values ranging from 9.6-47.5 μM and only compound 2 was found weakly active against HIV-1 RT with an IC50 value of 323.2 μM.
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June 2016
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