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Mechanistic study of the biomimetic synthesis of flavonolignan diastereoisomers in milk thistle.

ABSTRACT: The mechanism for the biomimetic synthesis of flavonolignan diastereoisomers in milk thistle is proposed to proceed by single-electron oxidation of coniferyl alcohol, subsequent reaction with one of the oxygen atoms of taxifolin's catechol moiety, and finally, further oxidation to form four of the major components of silymarin: silybin A, silybin B, isosilybin A, and isosilybin B. This mechanism is significantly different from a previously proposed process that involves the coupling of two independently formed radicals.

SUBMITTER: Althagafy HS

PROVIDER: S-EPMC3855429 | biostudies-literature | 2013 Aug

REPOSITORIES: biostudies-literature

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Mechanistic study of the biomimetic synthesis of flavonolignan diastereoisomers in milk thistle.

Althagafy Hanan S HS Meza-Aviña Maria Elena ME Oberlies Nicholas H NH Croatt Mitchell P MP

The Journal of organic chemistry 20130722 15

The mechanism for the biomimetic synthesis of flavonolignan diastereoisomers in milk thistle is proposed to proceed by single-electron oxidation of coniferyl alcohol, subsequent reaction with one of the oxygen atoms of taxifolin's catechol moiety, and finally, further oxidation to form four of the major components of silymarin: silybin A, silybin B, isosilybin A, and isosilybin B. This mechanism is significantly different from a previously proposed process that involves the coupling of two indep ...[more]

PMID: 23876147

Similar Datasets

Chemoenzymatic Synthesis, Characterization, and Scale-Up of Milk Thistle Flavonolignan Glucuronides.

Project description:Plant-based therapeutics, including herbal products, continue to represent a growing facet of the contemporary health care market. Mechanistic descriptions of the pharmacokinetics and pharmacodynamics of constituents composing these products remain nascent, particularly for metabolites produced following herbal product ingestion. Generation and characterization of authentic metabolite standards are essential to improve the quantitative mechanistic understanding of herbal product disposition in both in vitro and in vivo systems. Using the model herbal product, milk thistle, the objective of this work was to biosynthesize multimilligram quantities of glucuronides of select constituents (flavonolignans) to fill multiple knowledge gaps in the understanding of herbal product disposition and action. A partnership between clinical pharmacology and natural products chemistry expertise was leveraged to optimize reaction conditions for efficient glucuronide formation and evaluate alternate enzyme and reagent sources to improve cost effectiveness. Optimized reaction conditions used at least one-fourth the amount of microsomal protein (from bovine liver) and cofactor (UDP glucuronic acid) compared with typical conditions using human-derived subcellular fractions, providing substantial cost savings. Glucuronidation was flavonolignan-dependent. Silybin A, silybin B, isosilybin A, and isosilybin B generated five, four, four, and three monoglucuronides, respectively. Large-scale synthesis (40 mg of starting material) generated three glucuronides of silybin A: silybin A-7-O-β-D-glucuronide (15.7 mg), silybin A-5-O-β-D-glucuronide (1.6 mg), and silybin A-4´´-O-β-D-glucuronide (11.1 mg). This optimized, cost-efficient method lays the foundation for a systematic approach to synthesize and characterize herbal product constituent glucuronides, enabling an improved understanding of mechanisms underlying herbal product disposition and action.

| S-EPMC4613946 | biostudies-literature

Milk thistle: early seeds of potential.

Project description: Not available

| S-EPMC4116427 | biostudies-literature

Complex Evaluation of Antioxidant Capacity of Milk Thistle Dietary Supplements.

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| S-EPMC6720444 | biostudies-literature

Chromosome-level genome assembly of milk thistle (Silybum marianum (L.) Gaertn.).

Project description:Silybum marianum (L.) Gaertn., commonly known as milk thistle, is a medicinal plant belonging to the Asteraceae family. This plant has been recognized for its medicinal properties for over 2,000 years. However, the genome of this plant remains largely undiscovered, having no reference genome at a chromosomal level. Here, we assembled the chromosome-level genome of S. marianum, allowing for the annotation of 53,552 genes and the identification of transposable elements comprising 58% of the genome. The genome assembly from this study showed 99.1% completeness as determined by BUSCO assessment, while the previous assembly (ASM154182v1) showed 36.7%. Functional annotation of the predicted genes showed 50,329 genes (94% of total genes) with known protein functions in public databases. Comparative genome analysis among Asteraceae plants revealed a striking conservation of collinearity between S. marianum and C. cardunculus. The genomic information generated from this study will be a valuable resource for milk thistle breeding and for use by the larger research community.

| S-EPMC10997770 | biostudies-literature

Milk Thistle Treatment for Children and Adults with Trichotillomania: A Double-Blind, Placebo-Controlled, Crossover Negative Study.

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| S-EPMC6420084 | biostudies-literature

Silibinin (Milk Thistle) potentiates ethanol-dependent hepatocellular carcinoma progression in male mice.

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| S-EPMC3449310 | biostudies-literature

In vivo efficacy study of milk thistle extract (ETHIS-094™) in STAM™ model of nonalcoholic steatohepatitis.

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Project description:A three step route to single diastereoisomers of the vicinal trifluoromethyl motif is described. The route starts from either syn- or anti-alpha,beta-epoxy alcohols and takes a direct approach in that each of the three steps introduces a fluorine atom in a regio- and stereo-specific manner. Starting from either the syn- or the anti-alpha,beta-epoxy alcohol, stereospecific reactions generate two separate diastereoisomeric series of this motif. The route is a significant improvement on an earlier six step strategy.

| S-EPMC2839549 | biostudies-literature

Effect of milk thistle on the pharmacokinetics of darunavir-ritonavir in HIV-infected patients.

Project description:The aim of this open-label, fixed-sequence study was to investigate the potential of the botanical supplement milk thistle (silymarin) to interact with the boosted protease inhibitor combination darunavir-ritonavir. Fifteen HIV-infected patients receiving antiretroviral therapy with darunavir-ritonavir (600/100 mg twice daily) for at least 4 weeks were included. Silymarin (150 mg every 8 h) was added to the antiretroviral treatment from days 1 to 14. Darunavir concentrations in plasma were determined by high-performance liquid chromatography immediately before and 1, 2, 4, 6, 8, 10, and 12 h after a morning dose of darunavir-ritonavir on day 0 and darunavir-ritonavir plus silymarin on day 14. Individual darunavir pharmacokinetic parameters were calculated by noncompartmental analysis and compared between days 0 and 14 by means of the geometric mean ratio (GMR) and its 90% confidence interval (CI). The median age was 48 years (interquartile range, 44 to 50 years), and the median body weight was 70 kg (interquartile range, 65 to 84 kg). Silymarin was well tolerated, and all participants completed the study. The GMRs for darunavir coadministered with silymarin relative to darunavir alone were 0.86 (90% CI, 0.70 to 1.05) for the area under the concentration-time curve from 0 to 12 h, 0.83 (90% CI, 0.80 to 0.98) for the maximum concentration, and 0.94 (90% CI, 0.73 to 1.19) for the concentration at the end of the dosing interval. In summary, coadministration of silymarin with darunavir-ritonavir seems to be safe in HIV-infected patients; no dose adjustment for darunavir-ritonavir seems to be necessary.

| S-EPMC3370734 | biostudies-literature

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