Abstract: To study the chemical constituents from Bacillus HZ16.The compounds were isolated and purified by means of chromatographic techniques and their structures were identified on the basis of spectral features.8cyclic dipeptides,named Cordycedipeptide A (1),(2E/Z,5Z)-2-［(4-methoxyphenyl)methylene］-5-(2-methylpropylidene)-3,6-piperazinedione (2),Cyclo(Tyr-Pro) (3),Cyclo(Pro-Val) (4),Cyclo(Thr-Leu) (5),Cyclo(Pro-Thr) (6),Cyclo(Dehydroala-Leu) (7) and Cyclo(4-OH-Pro-Leu) (8),were isolated from the organic extract of fermentation broths of Bacillus HZ16.These 8 compounds wereisolated from Bacillus sp.for the first time and compouds 1,2,3 and 8 showed significant cytotoxic activity against the brine shrimp larvae,the mortality rate in 4 h were 96.3%,89.2%,96.8% and 99.5%,respectively.

Key words: Bacillus, cyclodipeptide, cytotoxicity