The enzymatic biosynthesis of acylated steroidal glycosides and their cytotoxic activity

Herein we describe the discovery and functional characterization of a steroidal glycosyltransferase (SGT) from and a steroidal glycoside acyltransferase (SGA) from and their application in the biosynthesis of acylated steroidal glycosides (ASGs). Initially, an gene, designated as OsSGT1, was isolated from . OsSGT1-containing cell free extract was then used as the biocatalyst to react with 49 structurally diverse drug-like compounds. The recombinant OsSGT1 was shown to be active against both 3- and 17-hydroxyl steroids. Unexpectedly, in an effort to identify OsSGT1, we found the bacteria gene in operon actually encoded an SGA, specifically catalyzing the acetylations of sugar moieties of steroid 17-glucosides. Finally, a novel enzymatic two-step synthesis of two ASGs, acetylated testosterone-17-glucosides (AT-17-Gs) and acetylated estradiol-17-glucosides (AE-17-Gs), from the abundantly available free steroids using OsSGT1 and EcSGA1 as the biocatalysts was developed. The two-step process is characterized by EcSGA1-catalyzed regioselective acylations of all hydroxyl groups on the sugar unit of unprotected steroidal glycosides (SGs) in the late stage, thereby significantly streamlining the synthetic route towards ASGs and thus forming four monoacylates. The improved cytotoxic activities of 3'-acetylated testosterone17-glucoside towards seven human tumor cell lines were thus observable.

Pharmacokinetic study on ginsenoside Rg3 and ginsenoside Rh2 in gut microbiota dysbiosis rats / 中草药

Objective: The aim of this study was to explore the pharmacokinetics of ginsenoside Rg3 and its deglycosylated metabolite, ginsenoside Rh2 in lincomycin-induced gut microbiota dysbiosis rats after ig administration of ginsenoside Rg3. Methods: An LC-MS/MS analytical method was developed and validated to detect ginsenoside Rg3 and Rh2 in plasma of rats. The method was validated by specificity, linearity, lower limits of quantification (LLOQ), precision, accuracy, matrix effect, recovery, and stability. Lincomycin (orally, 5 000 mg/kg, 7 d) was selected to induce gut microbiota dysbiosis. The fecal moisture contents and the β-D-glucosidase activity were also assessed in this study. And the plasma samples were collected and analyzed after ig administration of ginsenoside Rg3 (20 mg/kg). Results: The results indicated that this method could be used for the determination of the concentration of ginsenoside Rg3 and Rh2 in plasma of rats. The fecal moisture content in rats treated with lincomycin was significantly increased (P < 0.01) and the β-D-glucosidase activity was decreased (P < 0.01) compared with the control rats. The AUC0~∞ and Cmax in gut microbiota dysbiosis rats were increased, while the AUC0~t and Cmax of its active metabolite, ginsenoside Rh2 were significantly decreased (P < 0.01) compared with normal rats. Conclusion: The pharmacokinetic profile of ginsenoside Rg3 and Rh2 is changed in gut microbiota dysbiosis rats, which partly relates to the decreased β-D-glucosidase activity.

In vivo anticancer activity of maesopsin 4-O-β-glucoside isolated from leaves of Artocarpus tonkinensis A. Chev. Ex Gagnep

Objective: To investigate the antitumor effect of maesopsin 4-O-β-glucoside (TAT2) isolated from the leaves of Artocarpus tonkinensis (A. tonkinensis) A. Chev. ex Gagnep. Methods: The antitumor activity of TAT2 was evaluated in Lewis lung carcinoma (LLC) tumor-bearing mice. BALB/c mice had tumors induced by implantation with 2 × 10

In vivo anticancer activity of maesopsin 4-O-β-glucoside isolated from leaves of Artocarpus tonkinensis A. Chev. Ex Gagnep

OBJECTIVE@#To investigate the antitumor effect of maesopsin 4-O-β-glucoside (TAT2) isolated from the leaves of Artocarpus tonkinensis (A. tonkinensis) A. Chev. ex Gagnep.@*METHODS@#The antitumor activity of TAT2 was evaluated in Lewis lung carcinoma (LLC) tumor-bearing mice. BALB/c mice had tumors induced by implantation with 2 × 10(6) LLC cells into the subcutaneous right posterior flank. Tumor-bearing mice were treated orally with a range of doses of TAT2 and a standard drug, doxorubicin. Animals were observed for tumor growth and mortality rate. Blood was collected to determine hematological and biochemical parameters.@*RESULTS@#TAT2 was isolated from an ethanolic extract of A. tonkinensis leaves. Its structure was determined by MS and NMR spectroscopy, and identified as TAT2. The compound did not show acute toxicity at the highest dose tested (2000 mg/kg body weight). TAT2 exhibited antitumor activity by decreasing tumor growth, increasing the survival rate, and ameliorating some hematological and biochemical parameters at doses of 100 and 200 mg/kg body weight (P < 0.05).@*CONCLUSIONS@#These results indicate that TAT2 possesses clear antitumor activity. Due to its bioavailability and low toxicity, and the fact that it could be isolated in a large scale from A. tonkinensis leaves, the compound shows promise as a potential anticancer drug.

Studies on flavonoids from Bidens pilosa / 中草药

Objective: To study the bioactive flavonoids from Bidens pilosa. Methods: Various chromatographic methods including silica gel and Sephadex LH-20 columns, middle pressure liquid chromatography, and high speed counter current chromatography were applied to isolating and purifying the compounds. Their structures were confirmed based on the physicochemical properties and spectral data. Results: Six compounds were isolated from the ethyl acetate extract of B. pilosa, and their structures were identified as 2(R/S)-isookanin-3, 4'-dimethyl ether-7-O-β-D-glucopyranoside (1a-1b), quercetin-3, 4'-dimethyl ether-7-O-glucoside (2), quercetin 3, 4'-dimethyl ether-7-O-rutinoside (3), (Z)-6-O-(6'-O-acetyl-β-D-glucopyranosyl)-6, 7, 3', 4'-tetrahydroxyaurone (4), maritimein (5), and okanin 4-methyl ether-3'-O-β-glucoside (6). Conclusion: Compound 1a-1b is a novel compound named bidenoside H.