To study the bioactive metabolites produced by sponge-derived uncultured symbionts, a metagenomic DNA library of the symbionts of sponge Gelliodes gracilis was constructed. The average size of DNA inserts in the library was 20 kb. This library was screened for antibiotic activity using paper disc assaying. Two clones displayed the antibacterial activity against Micrococcus tetragenus. The metabolites of these two clones were analyzed through HPLC. The result showed that their metabolites were quite different from those of the host E. coli DNA and the host containing vector pHZ132. This study may present a new approach to exploring bioactive metabolites of sponge symbionts.
Aim To investigate the antitumor agents produced by marine-derived Penicillium flavidorsum SHK1-27.Methods The producing strain SHK1-27was fermented in a rotary shaker and bioactive metabolites in the fermentation broth were isolated through a bioassay-guided sepa-ration procedure.Structures of the bioactive compounds were investigated by spectroscopic meth-ods and their in vitro antitumor activities were assayed by the SRBmethod using K562 cells.Re-sults Eight anthraquinone derivatives were isolated from the fermentation broth of P.flavidor-sum SHK1-27 and were identified as nidurufin(1),averufin(2),8-O-methylaverufin(3),6,8-O-dimethylaverufin(4),versicolorin B(5),versicolorin A(6),versiconol(7)and averantin(8),re-spectively.Compounds 1-8 inhibited the proliferation of K562 cells and could be classified as strong(1 and 8 with the IC5o values of 12.6 and 27.7μmol·L"'respectively),moderate(2,5,6 and 7 with the ICso values of 72.4,91.0,98.7 and 93.4μmol·L-'respectively)and weak(3and 4 both with the same ICso value of>100μmol·L-')activity groups,respectively.The results showed some structure-activity relationships.Conclusion This is the first report of compounds 1-8 as the secondary metabolites of P.flavidorsum species,1,5 and 6 were isolated from fungal metabolites of the genus Penicillium for the first time,and 7 was found to occur in nature for the first time.The antitumor activities of compounds 1-8 on K562 cells were also reported for the first time in the present study.
