Isolation and Characterization of Sesquiterpenoids from Cassia Buds and Their Antimicrobial Activities

Cassia buds, the immature fruits of Cinnamomum cassia (Lauraceae), are widely consumed as a food spice, dietary supplements, flavoring agents, and preservatives. In this study, cassia buds were phytochemically investigated for the first time, leading to the isolation of 2 new sesquiterpenoids (1 and 2) and 10 known sesquiterpenoids (3-12). Their structures were determined by spectrometric and spectroscopic analyses, including nuclear magnetic resonance, high-resolution electrospray ionization mass spectrometry, and circular dichroism. Cinnamosim A (1) represents the ninth example of the rare cyperane-type sesquiterpenoids. All of the compounds (1-12) isolated from cassia buds were evaluated for antimicrobial activities, with compounds 1-3, 5-8, 11, and 12 exhibiting strong antimicrobial activities against Candida albicans and compounds 6, 7, and 11 showing moderate antibacterial activities against Escherichia coli and Staphylococcus aureus. The present investigation indicated that sesquiterpenoids from cassia buds might be used as potential antimicrobial agents to preserve food.