Abstract
In the course of our screening for new immunomodulators, a novel compound, melastin, was purified from the culture broth of Streptomyces. Melastin was purified through adsorption to Diaion HP-20, ethanol precipitation, and anion exchange column as a brown powder. The molecular weight was estimated as 5000±3000 by gel filtration HPLC. Melastin suppressed lipopolysaccharide (LPS)-induced blastogenesis of B cells more profoundly than concanavalin A (con A)- or phytohemagglutinin (PHA)-induced blastogenesis of T cells. Moreover, it selectively inhibited the growth of several leukemia cells as compared with interleukin-dependent nontransformed leukocytes. No selectivity was observed between nontransformed fibroblasts and their oncogene-transformed variants. Melastin did not selectively inhibit macromolecule synthesis of leukemia cells.
