Cucurbitane-type triterpenoids from the fruits of Citrullus colocynthis

A phytochemical investigation of the fruits of Citrullus colocynthis resulted in the isolation of 21 structurally diverse cucurbitane triterpenoids, including 9 previously undescribed ones, colocynins A-I (1-9). Their absolute configurations were elucidated by means of quantum chemical electronic circular dichroism (ECD) calculations, CD exciton chirality method, and single-crystal X-ray crystallography. Colocynins A-C (1-3) represent the first examples of nonanorcucurbitane-type triterpenoids. An anti-acetylcholinesterase activity assay showed that 6, 10, 13, 18, and 20 exhibited inhibitory activities, with IC50 values ranging from 5.0 to 21.7 mu M. In addition, 18 and 21 showed significant cytotoxicity against PACA, A431, and HepG2 cells, with IC50 values ranging from 0.042 to 0.60 and 3.6-14.4 mu M, respectively.

Automated summary

A phytochemical investigation of Citrullus colocynthis fruits led to the discovery of 21 structurally diverse cucurbitane triterpenoids, including 9 new compounds. The absolute configurations of these compounds were determined through quantum chemical electronic circular dichroism calculations, CD exciton chirality method, and single-crystal X-ray crystallography. Some of these compounds exhibited inhibitory activities against acetylcholinesterase and cytotoxicity against PACA, A431, and HepG2 cells.