Rynchopeterine F, unique heterodimer of phenethanol-phenylacetyl linking with lactic acid from the medicinal insect...

A new heterodimer, rynchopeterine F (1), a new natural product, rynchopeterine G (2), and eleven known phenolics were isolated from Blap rynchopetera Fairmaire, a kind of medicinal insect utilized by the Yi and Bai Nationality in Yunnan Province of China. Their structures were established on the basis of extensive spectroscopic analyses (1D and 2D NMR, HR-MS) along with calculated electronic circular dichroism method. Rynchopeterine F was a unusual heterodimer of a 3,4-dihudroxy phenylethanol unit fused to a 3,4-dihudroxy phenylacetyl group through two ester bonds with lactic acid, and rynchopeterine G was a 3,4-dihudroxy phenylethanyl monoester succinate. Attributed to the adjacent dihydroxyl grops, compounds 1 and 2 exhibited significant anti-radical activity with an IC₅₀ value of 3.52 and 7.83 μg/mL for DPPH radical-scavenging, similar with that of the positive controls, vitamin C, 6.92 μg/mL and rutin, 8.28 μg/mL.