β-Asarone (1) belongs to the group of naturally occurring phenylpropenes like eugenol or anethole. Compound 1 is found in several plants, e.g., Acorus calamus or Asarum europaeum. Compound 1-containing plant materials and essential oils thereof are used to flavor foods and alcoholic beverages and as ingredients of many drugs in traditional phytomedicines. Although 1 has been claimed to have several positive pharmacological effects, it was found to be genotoxic and carcinogenic in rodents (liver and small intestine). The mechanism of action of carcinogenic allylic phenylpropenes consists of the metabolic activation via cytochrome P450 enzymes and sulfotransferases. In vivo experiments suggested that this pathway does not play a major role in the carcinogenicity of the propenylic compound 1 as is the case for other propenylic compounds, e.g., anethole. Since the metabolic pathways of 1 have not been investigated and its carcinogenic mode of action is unknown, we investigated the metabolism of 1 in liver microsomes of rats, bovines, porcines, and humans using (1)H NMR, HPLC-DAD, and LC-ESI-MS/MS techniques. We synthesized the majority of identified metabolites which were used as reference compounds for the quantification and final verification of metabolites. Microsomal epoxidation of the side chain of 1 presumably yielded (Z)-asarone-1',2'-epoxide (8a) which instantly was hydrolyzed to the corresponding erythro- and threo-configurated diols (9b, 9a) and the ketone 2,4,5-trimethoxyphenylacetone (13). This was the main metabolic pathway in the metabolism of 1 in all investigated liver microsomes. Hydroxylation of the side chain of 1 led to the formation of three alcohols at total yields of less than 30%: 1'-hydroxyasarone (2), (E)- and (Z)-3'-hydroxyasarone (4 and 6), with 6 being the mainly formed alcohol and 2 being detectable only in liver microsomes of Aroclor 1254-pretreated rats. Small amounts of 4 and 6 were further oxidized to the corresponding carbonyl compounds (E)- and (Z)-3'-oxoasarone (5, 7). 1'-Oxoasarone (3) was probably also formed in incubations with 1 but was not detectable, possibly due to its rapid reaction with nucleophiles. Eventually, three mono-O-demethylated metabolites of 1 were detected in minor concentrations. The time course of metabolite formation and determined kinetic parameters show little species-specific differences in the microsomal metabolism of 1. Furthermore, the kinetic parameters imply a very low dependence of the pattern of metabolite formation from substrate concentration. In human liver microsomes, 71-75% of 1 will be metabolized via epoxidation, 21-15% via hydroxylation (and further oxidation), and 8-10% via demethylation at lower as well as higher concentrations of 1, respectively (relative values). On the basis of our results, we hypothesize that the genotoxic epoxides of 1 are the ultimate carcinogens formed from 1.
Purpose We investigated the cytosolic and membrane-associated contents of polyphenols after 4 hours of incubation (50 μM of each polyphenol) in the colon carcinoma cell line T84 using a novel, rapid, and convenient method based on permeabilization of the cell membrane using digitonin. The colon carcinoma cell line was used to investigate the intestinal uptake of polyphenols present in apple products. Recent Findings The results showed that hydroxycinnamic acids (caffeic and 5-caffeoylquinic acid) were only detected in the cytosolic fractions. In contrast, 0.3 to 8.2% of the initial concentrations (50 μM) of the flavonoids phloretin, quercetin, phloretin 2′-O-glucoside, and quercetin 3-O-rhamnoside were found in the membrane-associated fractions. In the cytosolic fractions, 0.2–2.9% of these compounds were detected, corresponding to 25 to 40% of the total cell-associated (cytosolic plus membrane-associated fractions) polyphenol content. Summary Our results showed that after uptake, polyphenols were present in the cytosolic fraction of the cells as well as associated with the cell membrane. The presented method provides a useful in vitro tool for determining biologically active compounds in cellular fractions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.