New dimeric and trimeric Erythrina alkaloids from Erythrina variegata

Abstract

HPLC-guided chromatography isolation led to five new polymeric Erythrina alkaloids, erythrivarines C–G (1–5), from the flowers of Erythrina variegata. Their structures were elucidated by intensive spectroscopic analyses. Dimeric alkaloids 1 and 2 consisted of two erythrinine units via an acetyl glucose, whereas trimers 3–5 were coupled through direct polymerization. Alkaloids 1 and 2 showed excellent insecticidal activities against aphid Rhodobium porosum.