- Microbial transformation of glycyrrhetinic acid derivatives by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741
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Glycyrrhetinic acid (GA), the major bioactive pentacyclic triterpene aglycone of licorice root, was known to play a vital role in anti-ulcer, anti-depressant, anti-inflammatory, and anti-allergic. In this study, we semi-synthesized five GA derivatives by a series of chemical reactions. They were selected as substrates for the biotransformation and yielded thirteen metabolites by Bacillus subtilis ATCC 6633 and Bacillus megaterium CGMCC 1.1741. Their structures were identified on the basis of extensive spectroscopic methods and nine of them were found for the first time. Two main types of reactions, regio- and stereo-selective hydroxylation and glycosylation, especially in the unactivated C-H bonds including C-11, C-19 and C-27, were observed in the biotransformation process, which greatly expand the chemical diversities of GA derivatives. All compounds were tested for their inhibitory effects on nitric oxide (NO) generation in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Among them, olean-12-ene-3β,7β,15α,19α,30-pentol (16) and olean-12-ene-3β,7β,15α,27,30-pentol (17) showed significant inhibitory effect with IC50 values of 0.64 and 0.07 μM, respectively.
- Shen, Pingping,Wang, Wei,Wang, Weiwei,Yu, Boyang,Zhang, Jian,Zhu, Yuyuan
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- Anti-tumor-promoter activity of modified glycyrrhetinic acid derivatives. Synthesis and structure-activity relationships
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A series of modified derivatives of 18α- and 18β-glycyrrhetinic acid was systematically synthesized and their structure-activity relationships investigated for inhibition of the promoter activity of 12-O-tetradecanoylphorbol-13-acetate in vitro. Increased hydrophobicity in the A-ring moiety and the presence of an 11-oxo function were shown to be important for the high inhibition. Replacement of the carboxy to the hydroxymethyl group at the 20-position also enhanced the inhibitory activity.
- Terasawa, T,Okada, T,Nishino, H
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