Quassinoids with Inhibitory Activities against Plant Fungal Pathogens from Picrasma javanica

A bioactivity-guided study on the leaves of Picrasma javanica led to the isolation of 19 quassinoids, including 13 new compounds. The structures of the new compounds were elucidated by a combination of spectroscopic data analysis, X-ray crystallography studies, and electronic circular dichroism (ECD) data interpretation. Compounds 1-7 are rare examples of quassinoids with a keto carbonyl group at C-12. The biological activities of 11 of the more abundant isolates were evaluated against five phytopathogenic fungi in vitro, and several of them including 6 and 15 showed moderate inhibitory effects that were comparative to those of the positive control, carbendazim. In addition, the preliminary structure-activity relationships (SARs) of these quassinoids were also investigated.

Automated summary

A bioactivity-guided study on the leaves of Picrasma javanica resulted in the isolation of 19 quassinoids, including 13 new compounds. The structures of the new compounds were determined through a combination of spectroscopic analysis, X-ray crystallography, and ECD data interpretation. Some of the new compounds showed moderate inhibitory effects against phytopathogenic fungi, with compounds 6 and 15 exhibiting comparable activity to the positive control carbendazim. Additionally, preliminary structure-activity relationships of these quassinoids were investigated.