Black Tea Inhibits Small Intestinal α-Glucosidase Activity in <i>db/db</i> Mouse / 日本補完代替医療学会誌

The inhibitory effects of the freeze-dried powder of the aqueous extract of black tea leaf (JAT) on α-glucosidase activity were investigated. We initially examined the effects of JAT addition on yeast α-glucosidase activity. JAT significantly and dose-dependently inhibited α-glucosidase activity and more strongly inhibited the activity than acarbose, the positive control. Then, we examined the effects of oral administration of JAT on sucrose tolerance in type 2 diabetes mellitus model <i>db/db</i> mice. Both JAT and acarbose administered groups showed a dose-dependent decrease in plasma glucose levels after the sucrose loading compared with the control group. Notable was that the plasma glucose levels of the 500 mg/kg JAT administered group exhibited a significant decrease 30 min or longer after the sucrose loading. On the other hand, no significant difference in plasma insulin levels was seen between the JAT administered group and the control group. We also measured small intestinal sucrase activity in <i>db/db</i> mouse at 30 min after JAT oral administration. Compared to control mice, small intestinal sucrase activity was significantly decreased in the 500 mg/kg JAT administered mice. These findings indicate that JAT may be a useful natural material for the prevention and therapy of type 2 diabetes mellitus.<br>

Food and Drug Interactions: Effect of <i>Acanthopanax senticosus</i> Harms on CYP3A4 and CYP2C9 Activities (Part 3) / 日本補完代替医療学会誌

<b>Objective:</b> By using human liver microsomes (HLM), we analyzed the effects of 14 known components of <i>A.senticosus</i> Harms on the activities of CYP2C9 and CYP3A4.<br> <b>Methods and Results:</b> Sesamin and quercetin inhibited both enzyme activities, whereas quercitrin strongly inhibited CYP3A4 activity. The 50% inhibitory concentrations (IC₅₀s) of sesamin and quercetin on CYP2C9 activity were approximately 124- and 59-fold higher and the IC₅₀s of sesamin, quercetin, and quercitrin on CYP3A4 activity were approximately 427-, 135-, and 22-fold higher than that of <i>A. senticosus</i> Harms extract (ASE), respectively. All these components inhibited both CYP3A4 and CYP2C9 in a non-competitive manner. However, these components are present in small amounts in ASE.<br> <b>Conclusion:</b> Therefore, the food-drug interactions caused by <i>A. senticosus </i>Harms are presumed to be due to the additive or synergistic interaction of these components or the other existing components, including their metabolites.<br>