Isolation and Identification of α-Glucosidase Inhibitors from Tochu-cha (Eucommia ulmoides)

Abstract

α-Glucosidase inhibitory activity was found in aqueous methanol extracts of tochu-cha, dried leaves of Eucommia ulmoides (Eucommiaceae). Five active principles against yeast enzyme were isolated and characterized. Among them, quercetin (1, K_j: 8.5 × 10⁻⁶ m) was considered to contribute mostly to the activity of the tochu leaves. In regard to an animal α-glucosidase, rat intestinal sucrase activity was also inhibited by 1.

Key words:

• α-glucosidase inhibitor
• quercetin
• tochu-cha
• Eucommia ulmoides