Aspongpyridiniums A−J, amino acid-derived pyridinium salts from insect species Aspongopus chinensis

Abstract

Aspongpyridiniums A−J (1−10), ten previously undescribed amino acid-derived pyridinium salts were isolated and identified from the n-BuOH fraction of the 50% MeOH extract of insect species Aspongopus chinensis, well-known for its use in traditional Chinese medicine for the treatment of pain, indigestion and kidney diseases. Their structures were determined by extensive spectroscopic data as well as electronic circular dichroism calculations and comparisons. Aspongpyridiniums A−J are structurally characterized by a unique 1,3,4-trisubstituted pyridinium skeleton with a variable functional group derived from an amino acid unit. In bioassays, Compounds 5 and 10 exhibited certain inhibitory activities against α-glucosidase, while 1−10 showed moderate to weak acetylcholinesterase inhibitory effects.