Cassia grandis is an ornamental plant that has been reported to have ethnopharmacological uses to heal wounds, scabies and other skin medications in Indonesian traditional medicine. Phytochemical investigation of the heartwood C. grandis led to the isolation of two known stilbenes: piceatannol 1 and resveratrol 2 isolated from the methanol extract. The structures were established on the basis of chemical evidence and spectroscopic methods, especially NMR as well as by comparing with published data. The antibacterial activity was carried out by using broth microdilution method and evaluated against two pathogenic bacteria: Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922. One of the isolated compounds 1 was reported as secondary metabolite of Indonesian C. grandis. Compound 2 exhibited promising selective antibacterial potent against Escherichia coli ATCC 25922.

Keywords: Cassia grandis, stilbenes, piceatannol, resveratrol, antibacterial.