Publications by authors named "Anderson Rodrigo Moraes de Oliveira"

46 Publications

In vitro enantioselective inhibition of the main human CYP450 enzymes involved in drug metabolism by the chiral pesticide tebuconazole.

Toxicol Lett 2021 Aug 15;351:1-9. Epub 2021 Aug 15.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil; National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Unesp, Institute of Chemistry, P.O. Box 355, 14800-900, Araraquara, SP, Brazil. Electronic address:

Tebuconazole (TEB) is a chiral triazole fungicide worldwide employed to control plant pathogens and preserve wood. People can be exposed to TEB either through diet and occupational contamination. This work investigates the in vitro inhibitory potential of rac-TEB, S-(+)-TEB, and R-(-)-TEB over the main cytochrome P450 enzymes (CYP450) using human liver microsomes to predict TEB in vivo inhibition potential. The IC values showed that in vitro inhibition was enantioselective for CYP2C9, CYP2C19, and CYP2D6, but not for CYP3A4/5. Despite enantioselectivity, rac-TEB and its single enantiomers were always classified in the same category. The inhibition mechanisms and constants were determined for rac-TEB and it has shown to be a mixed inhibitor of CYP3A4/5 (K = 1.3 ± 0.3 μM, αK = 3.2 ± 0.5 μM; K = 0.6 ± 0.3 μM, αK = 1.3 ± 0.3 μM) and CYP2C9 (K = 0.7 ± 0.1 μM, αK = 2.7 ± 0.5 μM), and a competitive inhibitor of CYP2D6 (K = 11.9 ± 0.7 μM) and CYP2C19 (K = 0.23 ± 0.02 μM), respectively, suggesting that in some cases, rac-TEB has a higher or comparable inhibitory potential than well-known strong inhibitors of CYP450 enzymes, especially for CYP2C9 and CYP2C19. In vitro-in vivo extrapolations (IVIVE) were conducted based on the results and data available in the literature about TEB absorption and metabolism. R values were estimated based on the Food and Drug Administration guideline and suggested that in a chronic oral exposure scenario considering the acceptable daily intake dose proposed by the European Food and Safety Authority, the hypothesis of rac-TEB to inhibit the activities of CYP3A4/5, CYP2C9, and CYP2C19 in vivo and cause pesticide-drug interactions cannot be disregarded.
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http://dx.doi.org/10.1016/j.toxlet.2021.08.006DOI Listing
August 2021

Enantioselective inhibition of human CYP2C19 by the chiral pesticide ethofumesate: Prediction of pesticide-drug interactions in humans.

Chem Biol Interact 2021 Aug 17;345:109552. Epub 2021 Jun 17.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil; National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Unesp, Institute of Chemistry, P.O. Box 355, 14800-900, Araraquara, SP, Brazil. Electronic address:

Ethofumesate is a chiral herbicide that may display enantioselective behavior in humans. For this reason, the enantioselective potential of ethofumesate and its main metabolite ethofumesate-2-hydroxy to cause pesticide-drug interactions on cytochrome P450 forms (CYPs) has been evaluated by using human liver microsomes. Among the evaluated CYPs, CYP2C19 had its activity decreased by the ethofumesate racemic mixture (rac-ETO), (+)-ethofumesate ((+)-ETO), and (-)-ethofumesate ((-)-ETO). CYP2C19 inhibition was not time-dependent, but a strong inhibition potential was observed for rac-ETO (IC = 5 ± 1 μmol L), (+)-ETO (IC = 1.6 ± 0.4 μmol L), and (-)-ETO (IC = 1.8 ± 0.4 μmol L). The reversible inhibition mechanism was competitive, and the inhibition constant (K) values for rac-ETO (2.6 ± 0.4 μmol L), (+)-ETO (1.5 ± 0.2 μmol L), and (-)-ETO (0.7 ± 0.1 μmol L) were comparable to the K values of strong CYP2C19 inhibitors. Inhibition of CYP2C19 by ethofumesate was enantioselective, being almost twice higher for (-)-ETO than for (+)-ETO, which indicates that this enantiomer may be a more potent inhibitor of this CYP form. For an in vitro-in vivo correlation, the Food and Drug Administration's (FDA) guideline on the assessment of drug-drug interactions used in the early stages of drug development was used. The FDA's R values were estimated on the basis of the obtained ethofumesate K and distribution volume, metabolism, unbound plasma fraction, gastrointestinal and dermal absorption data available in the literature. The correlation revealed that ethofumesate probably inhibits CYP2C19 in vivo for both chronic (oral) and occupational (dermal) exposure scenarios.
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http://dx.doi.org/10.1016/j.cbi.2021.109552DOI Listing
August 2021

An appraisal of experimental designs: Application to enantioselective capillary electromigration techniques.

Electrophoresis 2021 Sep 15;42(17-18):1726-1743. Epub 2021 Feb 15.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Sao Paulo, 14040-901, Brazil.

Enantioresolution processes are vital tools for investigating the enantioselectivities of chiral compounds. An analyst resolves to optimize enantioresolution conditions once they are determined. Generally, optimization is conducted by a one-factor-at-a-time (OFAT) approach. Although this approach may determine an adequate condition for the method, it does not often allow the estimation of the real optimum condition. Experimental designs are conducive for the optimization of enantioresolution methods via capillary electromigration techniques (CETs). They can efficiently extract information from the behavior of a method and enable the estimation of the real optimum condition. Furthermore, the application of the analytical quality by design (AQbD) approach to the development of CET-based enantioselective methods is a trend. This article (i) offers an overview of the application of experimental designs to the development of enantioselective methods from 2015 to mid-2020, (ii) reveals the experimental designs that are presently employed in CET-based enantioresolutions, and (iii) offers a critical point of view on how the different experimental designs can aid the optimization of enantioresolution processes by considering the method parameters.
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http://dx.doi.org/10.1002/elps.202000334DOI Listing
September 2021

Risk assessment of the chiral pesticide fenamiphos in a human model: Cytochrome P450 phenotyping and inhibition studies.

Food Chem Toxicol 2020 Dec 27;146:111826. Epub 2020 Oct 27.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil; National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Unesp, Institute of Chemistry, P.O. Box 355, 14800-900, Araraquara, SP, Brazil. Electronic address:

Fenamiphos (FS) is a chiral organophosphate pesticide that is used to control nematodes in several crops. Enantioselective differences may be observed in FS activity, bioaccumulation, metabolism, and toxicity. Humans may be exposed to FS through occupational and chronic (food, water, and environmental) exposure. FS may cause undesirable CYP450 pesticide-drug interactions, which may impact human health. Here, the CYP450 isoforms involved in enantioselective FS metabolism were identified, and CYP450 inhibition by rac-FS, (+)-FS, and (-)-FS was evaluated to obtain reliable information on enantioselective FS risk assessment in humans. CYP3A4 and CYP2E1 metabolized FS enantiomers, and CYP2B6 may participate in rac-FS metabolism. In addition, rac-FS, (+)-FS, and (-)-FS were reversible competitive CYP1A2, CYP2C19, and CYP3A4/5 inhibitors. High stereoselective inhibition potential was verified; rac-FS and (-)-FS strongly inhibited and (+)-FS moderately inhibited CYP1A2. Stereoselective differences were also detected for CYP2C19 and CYP3A4/5, which were strongly inhibited by rac-FS, (+)-FS, and (-)-FS. Our results indicated a high potential for CYP450 drug-pesticide interactions, which may affect human health. The lack of stereoselective research on the effect of chiral pesticides on the activity of CYP450 isoforms highlights the importance of assessing the risks of such pesticides in humans.
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http://dx.doi.org/10.1016/j.fct.2020.111826DOI Listing
December 2020

A fast-multiclass method for the determination of 21 endocrine disruptors in human urine by using vortex-assisted dispersive liquid-liquid microextraction (VADLLME) and LC-MS/MS.

Environ Res 2020 10 11;189:109883. Epub 2020 Jul 11.

Departamento de Análises Clínicas, Toxicológicas e Bromatológicas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14040-903, Ribeirão Preto, SP, Brazil. Electronic address:

Simplicity, speed, and reduced cost are essential demands for routine analysis in human biomonitoring studies. Moreover, the availability of higher volumes of human specimens is becoming more restrictive due to ethical controls and to the costs associated with sample transportation and storage. Thus, analytical methods requiring much lower sample volumes associated with simultaneous detection capability (multiclass analysis) are with a very high claim. In this sense, the present approach aimed at the development of a method for preconcentration and simultaneous determination of four classes of endocrine disruptors (seven bisphenols, seven parabens, five benzophenones, and two antimicrobials) in the urine. The approach is based on vortex-assisted dispersive liquid-liquid microextraction (VADLLME) and high-performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). After optimization of the significant parameters of VADLLME extraction, the proposed procedure showed to be simple, fast, sensitive, requiring only 1.0 mL of urine, 400 μL of organic solvents with a total stirring time of 20 s. Moreover, a variation of inter-day and between-day runs were lower than 10.0% and 11.0%, respectively. Finally, the proposed method was successfully applied to the analysis of 50 urine samples of Brazilian pregnant women to establish reference ranges.
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http://dx.doi.org/10.1016/j.envres.2020.109883DOI Listing
October 2020

Enantioselective in vitro metabolism and in vitro-in vivo correlation of the herbicide ethofumesate in a human model.

J Pharm Biomed Anal 2020 Aug 5;187:113349. Epub 2020 May 5.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil; National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Unesp, Institute of Chemistry, P.O. Box 355, 14800-900, Araraquara, SP, Brazil. Electronic address:

Ethofumesate (ETO) is a chiral herbicide that is marketed as a racemic mixture in the European Union and the United States. The growing consumption of pesticides in the world, along with their presence in water and food, has increased human exposure to these chemicals. Another issue concerning these compounds is that each enantiomer of a chiral pesticide may interact with biomolecules differently. For this reason, this study aimed to investigate the in vitro metabolism of ethofumesate (the racemic mixture as well as the isolated enantiomers) by human liver microsomes (HLM) and to explore the in vitro-in vivo correlation. Before the kinetics was determined, the method was fully validated by evaluating its selectivity, linearity, precision, accuracy, carryover, and stability. All the evaluated parameters agreed with the European Medicines Agency guideline. The enzyme kinetic parameters and the in vitro-in vivo correlation demonstrated that there was no enantioselective difference for the metabolism and bioavailable fraction of each enantiomer. The enzyme kinetics was biphasic; the K values were 15, 5.8, and 5.6 for rac-ETO, (+)-ETO, and (-)-ETO, respectively. The total in vitro intrinsic clearance was 0.10 mg mL min mg for rac-ETO and its enantiomers. The enantiomer (-)-ETO was only metabolized by CYP2C19, while (+)-ETO was metabolized by both CYP2C19 and CYP3A4. CYP2C19 polymorphism and/or inhibition may represent a risk for humans exposed to this pesticide.
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http://dx.doi.org/10.1016/j.jpba.2020.113349DOI Listing
August 2020

Prediction of seriniquinone-drug interactions by in vitro inhibition of human cytochrome P450 enzymes.

Toxicol In Vitro 2020 Jun 3;65:104820. Epub 2020 Mar 3.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil; National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Unesp, Institute of Chemistry, P.O. Box 355, 14800-900 Araraquara, SP, Brazil.

Seriniquinone is a secondary metabolite isolated from a rare marine bacterium of the genus Serinicoccus. This natural quinone is highlighted for its selective cytotoxic activity toward melanoma cancer cells, in which rapid metastatic properties are still a challenge for clinical treatment of malignant melanoma. The progress of seriniquinone as a promising bioactive molecule for drug development requires the assessment of its clinical interaction potential with other drugs. This study aimed to investigate the in vitro inhibitory effects of seriniquinone on the main human CYP450 isoforms involved in drug metabolism. The results showed strong inhibition of CYP1A2, CYP2E1 and CYP3A, with IC values up to 1.4 μM, and moderate inhibition of CYP2C19, with IC value >15 μM. Detailed experiments performed with human liver microsomes showed that the inhibition of CYP450 isoforms can be explained by competitive and non-competitive inhibition mechanisms. In addition, seriniquinone demonstrated to be an irreversible and time-dependent inhibitor of CYP1A2 and CYP3A. The low inhibition constants values obtained experimentally suggest that concomitant intake of seriniquinone with drug metabolized by these isoforms should be carefully monitored for adverse effects or therapeutic failure.
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http://dx.doi.org/10.1016/j.tiv.2020.104820DOI Listing
June 2020

Yangambin and Epi-yangambin Isomers: New Purification Method from Ocotea fasciculata and First Cytotoxic Aspects Focusing on In Vivo Safety.

Planta Med 2020 Apr 3;86(6):415-424. Epub 2020 Mar 3.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.

presents yangambin (YAN) and its isomer epi-yangambin (EPI-YAN) as major lignans, which are employed as the plant markers for quality control purposes and as potential pharmacological compounds. However, a gap between the pure isomers and safety and efficacy protocols is faced by the scientific community. In this context, this work aimed to report (i) a new and advantageous purifying process in a semi-preparative scale for YAN and EPI-YAN isolation from , and (ii) an cytotoxicity study to estimate, for the first time, the LD values of the isolated epimers, as well as the influence of albumin concentration in cell culture medium. The best condition for epimers isolation was achieved in normal-phase liquid chromatography. The lignan fraction (LF), previously obtained from the plant ethanolic extract, was purified yielding 17% and 29% of YAN and EPI-YAN, respectively. The study demonstrated that YAN and EPI-YAN were safe, and only at the highest concentration studied, a decrease on cell viability was observed. The estimated LD value was higher than 1612 mg/kg for both epimers. The LF, on the other hand, demonstrated an estimated LD of 422 mg/kg. Lignan cytotoxicity studies also evidenced that the higher cell viability was related to the higher concentration of fetal bovine serum as a source of albumin in medium. This is the first time the LD and safety of the isolated epimers were estimated, opening up great perspectives of success in studies.
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http://dx.doi.org/10.1055/a-1118-3828DOI Listing
April 2020

In vitro inhibition of human CYP2D6 by the chiral pesticide fipronil and its metabolite fipronil sulfone: Prediction of pesticide-drug interactions.

Toxicol Lett 2019 Oct 3;313:196-204. Epub 2019 Jul 3.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil; National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Unesp, Institute of Chemistry, P.O. Box 355, 14800-900, Araraquara, SP, Brazil. Electronic address:

Fipronil is a chiral insecticide employed worldwide in crops, control of public hygiene and control of veterinary pests. Humans can be exposed to fipronil through occupational, food, and environmental contamination. Therefore, the risk assessment of fipronil in humans is important to protect human health. Fipronil sulfone is the major metabolite formed during fipronil metabolism by humans. Since the CYP450 enzymes are the main ones involved in drug metabolism, the evaluation of their inhibition by fipronil and its main metabolite is important to predict drug-pesticide interactions. The aim of this work was to investigate the inhibition effects of rac-fipronil, S-fipronil, R-fipronil and fipronil sulfone on the main human CYP450 isoforms. The results showed that CYP2D6 is the only CYP450 isoform inhibited by these xenobiotics. In addition, no enantioselective differences were observed in the inhibition of CYP450 isoforms by fipronil and its individuals' enantiomers. Rac-fipronil, S-fipronil and R-fipronil are moderate CYP2D6 inhibitors showing a competitive inhibition profile. On the other hand, the metabolite fipronil sulfone showed to be a strong inhibitor of CYP2D6 also by competitive inhibition. These results highlight the importance of metabolite evaluation on pesticide safety since the metabolism of fipronil into fipronil sulfone increases the risk of pesticide-drug interactions for drugs metabolized by CYP2D6.
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http://dx.doi.org/10.1016/j.toxlet.2019.07.005DOI Listing
October 2019

In vitro enantioselective study of the toxicokinetic effects of chiral fungicide tebuconazole in human liver microsomes.

Ecotoxicol Environ Saf 2019 Oct 5;181:96-105. Epub 2019 Jun 5.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil. Electronic address:

Tebuconazole (TEB) is a chiral triazole fungicide that is globally marketed and used as a racemic mixture to control plant pathogens. Due to its use as a racemic mixture, TEB may exhibit enantioselective toxicokinetics toward nontarget organisms, including humans. Therefore, the in vitro enantioselective metabolism of TEB by cytochrome P450 enzymes (CYP450) was studied using human liver microsomes, and the in vivo toxicokinetic parameters were predicted. A new enantioselective, reversed-phase LC-MS/MS method was developed and validated to analyze the enantiomers of TEB and its main metabolite, 1-hydroxytebuconazole (TEBOH). In vitro metabolic parameters were obtained, and in vitro-in vivo extrapolations were performed. Michaelis-Menten and atypical biphasic kinetic profiles were observed with a total intrinsic clearance ranging from 53 to 19 mL min mg. The in vitro-in vivo extrapolation results showed that TEB first passage effect by the liver seems to be negligible, with hepatic clearance and extraction ratios ranging from 0.53 to 5.0 mL min kg and 2.7-25%, respectively. Preferential metabolism of (+)-TEB to rac-TEB and (-)-TEB was observed, with preferential production of (+)-TEBOH. Furthermore, reaction phenotyping studies revealed that, despite the low hepatic clearance in the first pass metabolism of TEB, multiple human CYP450 isoforms were involved in TEB metabolism when TEBOH enantiomers were generated, mainly CYP3A4 and CYP2C9, which makes TEB accumulation in the human body more difficult due to multiple metabolic pathways.
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http://dx.doi.org/10.1016/j.ecoenv.2019.05.071DOI Listing
October 2019

Evaluation of the enantioselective in vitro metabolism of the chiral pesticide fipronil employing a human model: Risk assessment through in vitro-in vivo correlation and prediction of toxicokinetic parameters.

Food Chem Toxicol 2019 Jan 30;123:225-232. Epub 2018 Oct 30.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil. Electronic address:

The chiral pesticide fipronil is employed as a racemic mixture to control pests. Although there are no enantioselective differences in the fipronil enantiomer activities toward target organisms, fipronil enantiomers may exhibit enantioselective differences in their bioaccumulation, toxicity, and metabolism toward non-target organisms, including humans. The present work aims to provide significant reliable enantioselective information concerning fipronil risk assessment in humans. For that, the in vitro metabolism of rac-fipronil, S-fipronil, and R-fipronil by human liver microsomes was evaluated, the in vivo enantioselective toxicokinetic parameters were predicted and the main CYP450 isoforms involved in the enantioselective metabolism were determined. The obtained results demonstrated that fipronil may undergo a clearance by the liver and it is exclusively metabolized by the CYP3A4 isoform. Although no significative stereoselective differences were observed, the results provide reliable information on fipronil risk assessment for humans.
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http://dx.doi.org/10.1016/j.fct.2018.10.060DOI Listing
January 2019

Characterization of Casearin X Metabolism by Rat and Human Liver Microsomes.

Planta Med 2019 Mar 29;85(4):282-291. Epub 2018 Oct 29.

Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.

Casearin X (CAS X) is the major clerodane diterpene isolated from the leaves of and has been extensively studied due to its powerful cytotoxic activity at low concentrations. Promising results for antitumor action have also been described when CAS X was administered intraperitoneally in mice. Conversely, loss of activity was observed when orally administered. Since the advancement of natural products as drug candidates requires satisfactory bioavailability for their pharmacological effect, this work aimed to characterize the CAS X metabolism by employing an microsomal model for the prediction of preclinical pharmacokinetic data. Rat and human liver microsomes were used to assess species differences. A high-performance liquid chromatography with diode-array detection (HPLC-DAD) method for the quantification of CAS X in microsomes was developed and validated according to European Medicines Agency guidelines. CAS X was demonstrated to be a substrate for carboxylesterases via hydrolysis reaction, with a Michaelis-Menten kinetic profile. The enzyme kinetic parameters were determined, and the intrinsic clearance was 1.7-fold higher in humans than in rats. The hepatic clearance was estimated by - extrapolation, resulting in more than 90% of the hepatic blood flow for both species. A qualitative study was also carried out for the metabolite identification by mass spectrometry and indicated the formation of the inactive metabolite CAS X dialdehyde. These findings demonstrate that CAS X is susceptible to first-pass metabolism and is a substrate for specific carboxylesterases expressed in liver, which may contribute to a reduction in antitumor activity when administered by the oral route.
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http://dx.doi.org/10.1055/a-0765-9523DOI Listing
March 2019

Paenibacillus polymyxa Associated with the Stingless Bee Melipona scutellaris Produces Antimicrobial Compounds against Entomopathogens.

J Chem Ecol 2018 Dec 23;44(12):1158-1169. Epub 2018 Oct 23.

Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Avenida do Café, s/n, Ribeirão Preto, SP, 14040-903, Brazil.

Social insects are frequently observed in symbiotic association with bacteria that produce antimicrobial natural products as a defense mechanism. There is a lack of studies on the microbiota associated with stingless bees and their antimicrobial compounds. To the best of our knowledge, this study is the first to report the isolation of Paenibacillus polymyxa ALLI-03-01 from the larval food of the stingless bee Melipona scutellaris. The bacterial strain was cultured under different conditions and produced (L)-(-)-3-phenyllactic acid and fusaricidins, which were active against entomopathogenic fungi and Paenibacillus larvae. Our results indicate that such natural products could be related to colony protection, suggesting a defense symbiosis between P. polymyxa ALLI-03-01 and Melipona scutellaris.
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http://dx.doi.org/10.1007/s10886-018-1028-zDOI Listing
December 2018

A fast and simple air-assisted liquid-liquid microextraction procedure for the simultaneous determination of bisphenols, parabens, benzophenones, triclosan, and triclocarban in human urine by liquid chromatography-tandem mass spectrometry.

Talanta 2018 Jun 13;183:94-101. Epub 2018 Feb 13.

Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14049-903 Ribeirão Preto, SP, Brazil. Electronic address:

The increasing awareness and public concern with hazard exposure to endocrine-disrupting chemicals calls for methods capable to handle numerous samples in short analysis time. In this present study, a novel method combining air-assisted liquid-liquid microextraction and liquid chromatography coupled to mass spectrometry was developed and validated for the extraction, preconcentration, and determination of 7 bisphenols (bisphenol A, bisphenol S, bisphenol AP, bisphenol P, bisphenol F, bisphenol AF, bisphenol Z), 7 parabens (methyl-, ethyl-, propyl-, butyl-, benzyl-paraben, methyl-protocatechuic acid, and ethyl-protocatechuic acid), 5 benzophenones (benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-8, and 4-hydroxybenzophenone), and two antimicrobials (triclosan and triclocarban) in human urine samples. Type and volume of solvent, extraction time (cycles), pH sample, ionic strength, agitation, and needle dimensions were evaluated. The matrix-matched calibration curves of all analytes were linear with correlation coefficients higher than 0.99 in the range level of 1.0-20.0 ng mL. The relative standard deviation, precision, at three concentrations (1.0, 10.0 and 20.0 ng mL) was lower than 15% with accuracy ranging from 90% to 114%. The biomonitoring capability of the new proposed method was confirmed with the analysis of 50 human urine samples randomly collected from Brazilian children. High urinary concentrations of several EDCs associated with usage of personal care products were found.
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http://dx.doi.org/10.1016/j.talanta.2018.02.052DOI Listing
June 2018

Drug-resistant epilepsy and topiramate: Plasma concentration and frequency of epileptic seizures.

Clin Exp Pharmacol Physiol 2018 07 25;45(7):652-658. Epub 2018 Mar 25.

School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil.

Topiramate (TPM) is a second-generation antiepileptic drug (AED), acting on drug-resistant epilepsy. The aim of the study was to evaluate the influence of the dose, use of other AEDs on TPM plasma concentration (C ), and frequency of epileptic seizures. A cross-sectional analytical study was developed with patients aged 18-60 years, for diagnosis of drug-resistant epilepsy, using TPM in monotherapy or associated with other AEDs. The following variables were analyzed: age, frequency of epileptic seizures, pharmacotherapeutic regimen with its respective doses, adherence to medication treatment, and adverse events score. Thirty-seven patients were included, 83.8% of the patients presented C below the therapeutic range. Multiple linear regression estimated that the increase of 1.0 mg/kg/d promoted an increase of 0.68 μg/mL in TPMC , while the use of inducers predicted a reduction of 2.97 μg/mL (P < .001). Multiple Poisson regression predicts that an increase of 1.0 μg/mL in TPMC decreased the patient's chance of presenting seizures, and patients using AED inducers were about ten times more likely to present seizures than those who do not use (P < .001). In addition, for patients using AED inducers with C below the therapeutic range, the mean number of seizures per month was greater than those with C within the therapeutic range. The prescribed dose and the use of AED inducers influence C of TPM, likewise the low C of first-line AEDs and of the adjuvant in the treatment, TPM, as well as low TPM dose seem to affect the control of epileptic seizures.
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http://dx.doi.org/10.1111/1440-1681.12923DOI Listing
July 2018

Metabolism studies of chiral pesticides: A critical review.

J Pharm Biomed Anal 2018 Jan 11;147:89-109. Epub 2017 Aug 11.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil. Electronic address:

The consumption of pesticides worldwide has been growing in recent decades, and consequently the exposure of humans and other animals to them as well. However, even though it is known that chiral pesticides can behave stereoselectively, the knowledge about the risks to human health and the environment is scarce. Among the pesticides registered to date, approximately 30% have at least one center of asymmetry, and just 7% of them are currently marketed as a pure stereoisomer or as an enriched mixture of the active stereoisomer. There are several in vitro, in vivo, and in silico models available to evaluate the enantioselective metabolism of chiral pesticides aiming ecotoxicological and risk assessment. Therefore, this paper intends to provide a critical view of the metabolism of chiral pesticides in non-target species, including humans, and discuss their implications, as well as, conduct a review of the analytical techniques employed for in vitro and in vivo metabolism studies of chiral pesticides.
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http://dx.doi.org/10.1016/j.jpba.2017.08.011DOI Listing
January 2018

In Vitro Metabolism of Artepillin C by Rat and Human Liver Microsomes.

Planta Med 2017 May 10;83(8):737-745. Epub 2017 Jan 10.

Departamento de Química, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.

Artepillin C, a natural product present in the Brazilian green propolis, has several biological properties. Among these properties, the antitumor action of this product is noteworthy and makes it a promising drug candidate for the treatment of several types of cancer. This paper describes the metabolism of Artepillin C in rat and human liver microsomes. The rat model suggested a sigmoidal profile for the metabolism, adapted to the Hill's kinetic model. The enzymatic kinetic parameters were as follows: maximal velocity = 0.757 ± 0.021 µmol/mg protein/min, Hill coefficient = 10.90 ± 2.80, and substrate concentration at which half-maximal velocity of a Hill enzyme is achieved = 33.35 ± 0.55 µM. Based on these results, the calculated intrinsic clearance for Artepillin C was 16.63 ± 1.52 µL/min/mg protein. The metabolism assay conducted on the human model did not fit any enzymatic kinetic model. Two novel metabolites were formed in both mammal microsomal models and their chemical structures were elucidated for the first time. The main human cytochrome P450 isoforms involved in Artepillin C metabolism had been identified, and the results suggest a majority contribution of CYP2E1 and CYP2C9 in the formation of the two metabolites.
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http://dx.doi.org/10.1055/s-0042-124359DOI Listing
May 2017

Determination of Levetiracetam in Human Plasma by Dispersive Liquid-Liquid Microextraction Followed by Gas Chromatography-Mass Spectrometry.

J Anal Methods Chem 2016 17;2016:5976324. Epub 2016 Oct 17.

Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, 14040-903 Ribeirão Preto, SP, Brazil.

Levetiracetam (LEV) is an antiepileptic drug that is clinically effective in generalized and partial epilepsy syndromes. The use of this drug has been increasing in clinical practice and intra- or -interindividual variability has been exhibited for special population. For this reason, bioanalytical methods are required for drug monitoring in biological matrices. So this work presents a dispersive liquid-liquid microextraction method followed by gas chromatography-mass spectrometry (DLLME-GC-MS) for LEV quantification in human plasma. However, due to the matrix complexity a previous purification step is required. Unlike other pretreatment techniques presented in the literature, for the first time, a procedure employing ultrafiltration tubes Amicon® (10 kDa porous size) without organic solvent consumption was developed. GC-MS analyses were carried out using a linear temperature program, capillary fused silica column, and helium as the carrier gas. DLLME optimized parameters were type and volume of extraction and dispersing solvents, salt addition, and vortex agitation time. Under chosen parameters (extraction solvent: chloroform, 130 L; dispersing solvent: isopropyl alcohol, 400 L; no salt addition and no vortex agitation time), the method was completely validated and all parameters were in agreement with the literature recommendations. LEV was quantified in patient's plasma sample using less than 550 L of organic solvent.
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http://dx.doi.org/10.1155/2016/5976324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5086507PMC
October 2016

In Vitro Metabolism Evaluation of the Ergot Alkaloid Dihydroergotamine: Application of Microsomal and Biomimetic Oxidative Model.

Planta Med 2016 Oct 2;82(15):1368-1373. Epub 2016 Aug 2.

Núcleo de Pesquisa em Produtos Naturais e Sintéticos (NPPNS), Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil.

Dihydroergotamine is a semisynthetic natural product derived from ergotamine, an ergot alkaloid. It is used to treat migraines, a neurological disease characterized by recurrent moderate to severe headaches. In this work, the metabolism of dihydroergotamine was evaluated in a biomimetic phase I reaction, aiming to verify all possible formed metabolites. Dihydroergotamine was submitted to an metabolism assay using rat liver microsomes, and the metabolites were analyzed by HPLC-MS/MS. The biomimetic reactions were performed with Jacobsen catalyst for scaling up production of oxidized metabolites. Two hydroxylated metabolites were isolated and characterized by MS/MS and H NMR analysis.
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http://dx.doi.org/10.1055/s-0042-111732DOI Listing
October 2016

In-line coupling of an achiral-chiral column to investigate the enantioselective in vitro metabolism of the pesticide Fenamiphos by human liver microsomes.

J Chromatogr A 2016 Oct 16;1467:326-334. Epub 2016 Aug 16.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil. Electronic address:

The distinct activity and toxicity of enantiomers has increased concern about the use of chiral pesticides. The chiral pesticide Fenamiphos (FS) is employed as a racemic mixture to control nematode pests. Although recent studies revealed that FS enantiomers possess different toxicity, the toxicokinetics and liver metabolism of these enantiomers in humans remain unclear. This study characterizes the in vitro metabolism of rac-FS, (+)-FS, and (-)-FS by human liver microsomes and predicts some toxicokinetic parameters. First, a new enantioselective HPLC method was developed to analyze FS and its metabolites [fenamiphos sulfoxide (FSO) and fenamiphos sulfone (FSO)]. Chiral separation of the stereoisomers was accomplished in an in-line coupled achiral-chiral column (Lichrosorb Si60 - Chiralpak AS-H); hexane: ethanol: methanol (85:12:3, v/v/v) was used as mobile phase at a flow rate of 1.2mLmin. Then, the HPLC method was fully validated. All the evaluated parameters agreed with the European Medicines Agency guideline. Finally, the enantioselective kinetic parameters were determined for CYP450 enzymes. The predicted toxicokinetic parameters showed that the liver exclusively eliminated FS without stereoselectivity.
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http://dx.doi.org/10.1016/j.chroma.2016.08.039DOI Listing
October 2016

A three phase hollow fiber liquid-phase microextraction for quantification of lamotrigine in plasma of epileptic patients by capillary electrophoresis.

Electrophoresis 2016 10 22;37(20):2678-2684. Epub 2016 Sep 22.

Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, São Paulo, Brazil.

A three phase hollow fiber liquid-phase microextraction technique combined with capillary electrophoresis was developed to quantify lamotrigine (LTG) in plasma samples. The analyte was extracted from 4.0 mL of a basic donor phase (composed of 0.5 mL of plasma and 3.5 mL of sodium phosphate solution pH 9.0) through a supported liquid membrane composed of 1-octanol immobilized in the pores of the hollow fiber, and to an acidic acceptor phase (hydrochloric acid solution pH 4.0) placed in the lumen of the fiber. The extraction was carried out for 30 min at 500 rpm. The eletrophoretic analysis was carried out in 130 mmol/L MES buffer, pH 5.0 with a constant voltage of +15 kV and 20°C. Sample injections were performed for 10 s, at a pressure of 0.5 psi. The detection was performed at 214 nm for both LTG and the internal standard lidocaine. Under the optimized conditions, the method showed a limit of quantification of 1.0 μg/mL and was linear over the plasmatic concentration range of 1.0-20.0 μg/mL. Finally, the validated method was applied for the quantification of LTG in plasma samples of epileptic patients.
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http://dx.doi.org/10.1002/elps.201600137DOI Listing
October 2016

In vitro enantioselective human liver microsomal metabolism and prediction of in vivo pharmacokinetic parameters of tetrabenazine by DLLME-CE.

J Pharm Biomed Anal 2016 Sep 20;128:528-537. Epub 2016 Jun 20.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto, SP, Brazil. Electronic address:

A new capillary electrophoresis method for the enantioselective analysis of cis- and trans- dihydrotetrabenazine (diHTBZ) after in vitro metabolism by human liver microsomes (HLMs) was developed. The chiral electrophoretic separations were performed by using tris-phosphate buffer (pH 2.5) containing 1% (w/v) carboxymethyl-β-CD as background electrolyte with an applied voltage of +15kV and capillary temperature kept at 15°C. Dispersive liquid-liquid microextraction was employed to extract the analytes from HLMs. Dichloromethane was used as extraction solvent (75μL) and acetone as disperser solvent (150μL). The method was validated according to official guidelines and showed to be linear over the concentration range of 0.29-19.57μmolL(-1) (r=0.9955) for each metabolite enantiomer. Within- and between-day precision and accuracy evaluated by relative standard deviation and relative error were lower than 15% for all enantiomers. The stability assay showed that the analytes kept stable under handling, storage and in metabolism conditions. After method validation, an enantioselective in vitro metabolism and in vivo pharmacokinetic prediction was carried out. This study showed a stereoselective metabolism and the observed kinetic profile indicated a substrate inhibition behavior. DiHTBZ enantiomers were catalyzed mainly by CYP2C19 and the predicted clearance suggests that liver metabolism is the main route for TBZ elimination which supports the literature data.
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http://dx.doi.org/10.1016/j.jpba.2016.06.028DOI Listing
September 2016

A fast method for bisphenol A and six analogues (S, F, Z, P, AF, AP) determination in urine samples based on dispersive liquid-liquid microextraction and liquid chromatography-tandem mass spectrometry.

Talanta 2016 07 31;154:511-9. Epub 2016 Mar 31.

Laboratório de Toxicologia e Essencialidade de Metais, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, 14049-903 Ribeirão Preto, SP, Brazil. Electronic address:

In this study, a novel method combining dispersive liquid-liquid microextraction (DLLME) and fast liquid chromatography coupled to mass spectrometry (LC-MS/MS) was developed and validated for the extraction and determination of bisphenol A (BPA) and six bisphenol analogues, namely bisphenol S (BPS), bisphenol F (BPF), bisphenol P (BPP), bisphenol Z (BPZ), bisphenol AP (BPAP) and bisphenol AF (BPAF) in human urine samples. Type and volume of extraction and disperser solvents, pH sample, ionic strength, and agitation were evaluated. The matrix-matched calibration curves of all analytes were linear with correlation coefficients higher than 0.99 in the range level of 0.5-20.0ngmL(-1). The relative standard deviation (RSD), precision, at three concentrations (1.0, 8.0 and 15.0ngmL(-1)) was lower than 15% with accuracy ranging from 90 to 112%. The biomonitoring capability of the new method was confirmed with the analysis of 50 human urine samples randomly collected from Brazilians. BPA was detected in 92% of the analyzed samples at concentrations ranging
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http://dx.doi.org/10.1016/j.talanta.2016.03.098DOI Listing
July 2016

Evaluation of the Intestinal Absorption Mechanism of Casearin X in Caco-2 Cells with Modified Carboxylesterase Activity.

J Nat Prod 2016 Apr 18;79(4):1084-90. Epub 2016 Mar 18.

Institute for Pharma Technology, School of Life Sciences, University of Applied Sciences Northwestern Switzerland , 4132 Muttenz, Switzerland.

The clerodane diterpene casearin X (1), isolated from the leaves of Casearia sylvestris, is a potential new drug candidate due to its potent in vitro cytotoxic activity. In this work, the intestinal absorption mechanism of 1 was evaluated using Caco-2 cells with and without active carboxylesterases (CES). An LC-MS method was developed and validated for the quantification of 1. The estimation of permeability coefficients was possible only under CES-inhibited conditions in which 1 is able to cross the Caco-2 cell monolayer. The mechanism is probably by active transport, with no significant efflux, but with a high retention of the compound inside the cells. The enzymatic hydrolysis assay demonstrates the susceptibility of 1 to first-pass metabolism as substrate for specific CES expressed in human intestine.
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http://dx.doi.org/10.1021/acs.jnatprod.5b01139DOI Listing
April 2016

Novel binuclear μ-oxo diruthenium complexes combined with ibuprofen and ketoprofen: Interaction with relevant target biomolecules and anti-allergic potential.

J Inorg Biochem 2015 Dec 8;153:178-185. Epub 2015 Aug 8.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900, 14040-901 Ribeirão Preto -SP, Brazil. Electronic address:

This work presents the synthesis and characterization of two novel binuclear ruthenium compounds of general formula [Ru2O(carb)2(py)6](PF6)2, where py=pyridine and carb are the non-steroidal anti-inflammatory drugs ibuprofen (1) and ketoprofen (2). Both complexes were characterized by ESI-MS/MS spectrometry. The fragmentation patterns, which confirm the proposed structures, are presented. Besides that, compounds 1 and 2 present the charge transfer transitions within 325-330nm; and the intra-core transitions around 585nm, which is the typical spectra profile for [Ru2O] analogues. This suggests the carboxylate bridge has little influence in their electronic structure. The effects of the diruthenium complexes on Ig-E mediated mast cell activation were evaluated by measuring the enzyme β-hexosaminidase released by mast cells stimulated by antigen. The inhibitory potential of the ketoprofen complex against mast cell stimulation suggests its promising application as a therapeutic agent for treating or preventing IgE-mediated allergic diseases. In addition, in vitro metabolism assays had shown that the ibuprofen complex is metabolized by the cytochrome P450 enzymes.
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http://dx.doi.org/10.1016/j.jinorgbio.2015.08.004DOI Listing
December 2015

Quantitative determination of lercanidipine enantiomers in commercial formulations by capillary electrophoresis.

J Anal Methods Chem 2015 2;2015:294270. Epub 2015 Mar 2.

Department of Pharmaceutical Sciences, Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, 14040-903 Ribeirão Preto, SP, Brazil.

An enantioselective method based on capillary electrophoresis (CE) using cyclodextrin (CD) as chiral selector was developed and validated for determination of lercanidipine (LER) enantiomers, a drug calcium channel blocker which exerts antihypertensive effects of long duration, in a pharmaceutical formulation. Optimum separation of LER enantiomers was obtained on a 50 cm × 50 μm id capillary using a sodium acetate buffer solution 200 mmol/L pH 4.0 containing 10 mmol/L of 2,3,6-o-methyl-β-cyclodextrin (TM-β-CD) as background electrolyte. The capillary temperature and voltage were 15°C and 25 kV, respectively, hydrodynamic injection and detection at 237 nm. Linearity was obtained in the range 12.5-100 μg/mL for both enantiomers (r ≥ 0.995). The RSD (%) and relative errors (E, %) obtained in precision and accuracy studies (intraday and interday) were lower than 5%. After validation, the method was applied to quantify the enantiomers of LER in commercial tablets and the results were satisfactory in terms of accuracy and precision, both less than 5%. Therefore, this method was found to be appropriate for enantioselective quality control of LER enantiomers in pharmaceutical formulations.
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http://dx.doi.org/10.1155/2015/294270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4363879PMC
March 2015

A new and fast DLLME-CE method for the enantioselective analysis of zopiclone and its active metabolite after fungal biotransformation.

J Pharm Biomed Anal 2015 May 4;109:192-201. Epub 2015 Mar 4.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil. Electronic address:

Zopiclone (ZO) is a chiral drug that undergoes extensive metabolism to N-desmethylzopiclone (N-Des-ZO) and zopiclone-N-oxide (N-Ox-ZO). Pharmacological studies have shown (S)-N-Des-ZO metabolite presents anxiolytic activity and a patent for this metabolite was requested for anxiety treatment and related disorders. In this context, biotransformation employing fungi may be a promising strategy to obtain N-Des-ZO. To perform the biotransformation study in this work, an enantioselective method based on capillary electrophoresis (CE) and dispersive liquid-liquid microextraction (DLLME) was developed. CE analyses were carried out in sodium phosphate buffer (pH 2.5; 50mmolL(-1)) containing 0.5% (w/v) carboxymethyl-β-CD, at a constant voltage of +25kV. DLLME was conducted using 2mL of liquid culture medium pH 9.5. Chloroform (100μL) and methanol (300μL) were employed as extraction and disperser solvent, respectively. After CE and DLLME optimization, the analytical method was fully validated. The method was linear over a concentration range of 90-6000ngmL(-1) for each ZO enantiomer (r>0.999) and 50-1000ngmL(-1) for each N-Des-ZO enantiomer (r>0.998). Absolute recovery of 51 and 82% was achieved for N-Des-ZO and ZO, respectively. The accuracy and precision results agreed with the EMA (European Medicines Agency) guideline, and so did the stability study. Application of the developed method in a biotransformation study was conducted in order to investigate the ability of fungi, belonging to the genus Cunninghamella, in metabolizing ZO chiral drug. Fungi Cunninghamella elegans ATCC 10028B and Cunninghamella echinulata var elegans ATCC 8688A demonstrated to be able to enantioselectively biotransform ZO to its active metabolite, N-Des-ZO. Therefore, the proposed goals of this work, i.e. a fast DLLME-CE method and an outstanding strategy to obtain N-Des-ZO, were successfully attained.
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http://dx.doi.org/10.1016/j.jpba.2015.02.039DOI Listing
May 2015

In vitro metabolism of the lignan (-)-grandisin, an anticancer drug candidate, by human liver microsomes.

Drug Test Anal 2015 Sep 15;7(9):780-6. Epub 2015 Jan 15.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901, Ribeirão Preto-SP, Brazil.

(-)-grandisin is a tetrahydrofuran lignan that displays important biological properties, such as trypanocidal, anti-inflammatory, cytotoxic, and antitumor activities, suggesting its utility as a potential drug candidate. One important step in drug development is metabolic characterization and metabolite identification. To perform a biotransformation study of (-)-grandisin and to determine its kinetic properties in humans, a high performance liquid chromatography (HPLC) method was developed and validated. After HPLC method validation, the kinetic properties of (-)-grandisin were determined. (-)-grandisin metabolism obeyed Michaelis-Menten kinetics. The maximal reaction rate (Vmax ) was 3.96 ± 0.18 µmol/mg protein/h, and the Michaelis-Menten constant (Km ) was 8.23 ± 0.99 μM. In addition, the structures of the metabolites derived from (-)-grandisin were characterized via gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) analysis. Four metabolites, 4-O-demethylgrandisin, 3-O-demethylgrandisin, 4,4'-di-O-demethylgrandisin, and a metabolite that may correspond to either 3,4-di-O-demethylgrandisin or 3,5-di-O-demethylgrandisin, were detected. CYP2C9 isoform was the main responsible for the formation of the metabolites. These metabolites have not been previously described, demonstrating the necessity of assessing (-)-grandisin metabolism using human-derived materials.
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http://dx.doi.org/10.1002/dta.1743DOI Listing
September 2015

Jacobsen catalyst as a cytochrome P450 biomimetic model for the metabolism of monensin A.

Biomed Res Int 2014 28;2014:152102. Epub 2014 May 28.

Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, 14040-901 Ribeirão Preto, SP, Brazil.

Monensin A is a commercially important natural product isolated from Streptomyces cinnamonensins that is primarily employed to treat coccidiosis. Monensin A selectively complexes and transports sodium cations across lipid membranes and displays a variety of biological properties. In this study, we evaluated the Jacobsen catalyst as a cytochrome P450 biomimetic model to investigate the oxidation of monensin A. Mass spectrometry analysis of the products from these model systems revealed the formation of two products: 3-O-demethyl monensin A and 12-hydroxy monensin A, which are the same ones found in in vivo models. Monensin A and products obtained in biomimetic model were tested in a mitochondrial toxicity model assessment and an antimicrobial bioassay against Staphylococcus aureus, S. aureus methicillin-resistant, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Escherichia coli. Our results demonstrated the toxicological effects of monensin A in isolated rat liver mitochondria but not its products, showing that the metabolism of monensin A is a detoxification metabolism. In addition, the antimicrobial bioassay showed that monensin A and its products possessed activity against Gram-positive microorganisms but not for Gram-negative microorganisms. The results revealed the potential of application of this biomimetic chemical model in the synthesis of drug metabolites, providing metabolites for biological tests and other purposes.
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http://dx.doi.org/10.1155/2014/152102DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4058456PMC
February 2015

A new enantioselective CE method for determination of oxcarbazepine and licarbazepine after fungal biotransformation.

Electrophoresis 2014 Oct 18;35(19):2877-84. Epub 2014 Aug 18.

Departamento de Ciências Farmacêuticas, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brasil.

The present work describes, for the first time, the simultaneous separation of oxcarbazepine (OXC) and its active metabolite 10-hydroxy-10,11-dihydrocarbamazepine (licarbazepine, Lic) by chiral CE. The developed method was employed to monitor the enantioselective biotransformation of OXC into its active metabolite by fungi. The electrophoretic separations were performed using 10 mmol/L of a Tris-phosphate buffer solution (pH 2.5) containing 1% w/v of β-CD phosphate sodium salt (P-β-CD) as running electrolyte, -20 kV of applied voltage and a 15°C capillary temperature. The method was linear over the concentration range of 1000-30 000 ng/mL for OXC and 75-900 ng/mL for each Lic enantiomer (r ≥ 0.9952). Within-day precision and accuracy evaluated by RSD and relative errors, respectively, were lower than 15% for all analytes. The validated method was used to evaluate the enantioselective biotransformation of OXC, mediated by fungi, into its active metabolite Lic. This study showed that the fungi Glomerella cingulata (VA1) and Beuveria bassiana were able to enantioselectively metabolize the OXC into Lic after 360 h of incubation. Biotransformation by the fungus Beuveria bassiana showed 79% enantiomeric excess for (S)-(+)-Lic, while VA1 gave an enantiomeric excess of 100% for (S)-(+)-Lic. This study opens a new route to the drug (S)-(+)-licarbazepine.
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http://dx.doi.org/10.1002/elps.201400137DOI Listing
October 2014
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