New Sesquiterpenoids from Eugenia jambolana Seeds and Their Anti-microbial Activities

Twenty four sesquiterpenoids, 1-24, including 11 new sesquiterpenoids, jambolanins A-K, and two new norsesquiterpenoids, jambolanes A and B, along with six known triterpenoids, were isolated from the seeds of Eugenia jambolana fruit. Their structures were elucidated on the basis of NMR and MS spectrometry data analysis. Among the isolates, compound 13 possessed a rare 6,7-seco-guaiene skeleton, and compounds 14 and 15 were norsesquiterpenoids containing a spiro[4.4]nonane skeleton. Antimicrobial assay evaluation revealed that sesquiterpenoids, 4, 5/6, 17, 19, 21, 23, and 24 inhibited the growth of the Gram-positive bacterium, Staphylococcus aureus. The current study advances scientific knowledge of E. jambolana phytochemicals and suggests that its sesquiterpenoids may contribute, in part, to the anti-infective effects attributed to the edible fruit of this plant.