Two novel antibiotics, furaquinocins A and B were isolated from the culture broth of Streptomyces sp. KO-3988. These antibiotics possess cytocidal activities against HeLa S3 cells in vitro at concentrations of 3.1μg/ml for A and 1.6μg/ml for B. Neither substance possessed antimicrobial activities against Gram-positive and Gram-negative bacteria, fungi or yeast at a concentration of 1, 000μg/ml.
