New Iridoid Glucosides from Caryopteris incana (Thunb.) Miq. and Their α-Glucosidase Inhibitory Activities

Abstract

In our continued investigations of the plant Caryopteris incana, five new iridoid glucosides 1–5, including two cis-trans-isomers, 3 and 4, along with six known compounds 6–11, were isolated from the n-butyl alcohol (n-BuOH) soluble fraction of whole dried material of Caryopteris incana. Their structures were established by a combination of spectroscopic techniques, including 1D and 2D NMR and high resolution electrospray ionization mass spectroscopy (HR-ESI-MS). Furthermore, all isolates were evaluated for their yeast α-glucosidase inhibitory effects. Among these compounds, 4–8 and 10 exhibited potent inhibition of α-glucosidase.

Keywords

• Caryopteris incana
• iridoid glucosides
• type-II diabetes mellitus
• α-glucosidase inhibition