Monoterpenoid indole alkaloids isolated from the stems and twigs of Strychnos cathayensis

Abstract

Seven undescribed monoterpenoid indole alkaloids, two N(4)-chloromethylation artifacts, and 10 known alkaloids were isolated from the stems and twigs of Strychnos cathayensis. The corresponding structures were elucidated via spectroscopic data interpretation and electronic circular dichroism. The absolute configuration of (17S)-12-hydroxy-11-methoxydiaboline, the major anomer of 12-hydroxy-11-methoxydiaboline, was characterized by X-ray diffraction analysis for the first time. At an intraperitoneal dose of 30 mg/kg, 12-hydroxy-11-methoxy-N(4)-chloromethyldiaboline and (-)-macusine A exhibited potential analgesic effects with prolongation rates of 99% and 47% for the latency time of hind-paw licking, respectively, compared to the blank control. 12-Hydroxy-11-methoxydiaboline, 12-hydroxy-11-methoxydiaboline N(4)-oxide, retuline N-oxide, and (-)-vincosamide exhibited antiviral activity against Coxsackie virus B3 (CVB3) with IC₅₀ values of 33.33 μM.

Keywords: Analgesic activity; Antiviral activity; Loganiaceae; Monoterpenoid indole alkaloids; Strychnos cathayensis Merr..