Cystocin, a novel antibiotic, produced by Streptomyces sp. GCA0001: biological activities.

Cystocin belongs to the class of nucleoside antibiotics from Streptomyces sp. GCA0001. Cystocin showed good activity against gram-positive bacteria, but showed less activity against the gram-negative bacteria. Cystocin exhibited about two to four folds higher activity than puromycin. Especially, cystocin shows relatively strong activity against Streptococcus strains. Cystocin shows quite potent antitumor activity against all of the cells tested showing IC50 values of 0.10 to 0.14 microg/mL. This in vitro result indicates that the cytotoxocity of cystocin is two ten folds more active than puromycin's.