In screening for anti-MRSA antibiotics, novel lydicamycin congeners, TPU-0037-A, B, C and D, were isolated from a culture broth of an actinomycete strain. The producing strain, TP-A0598, was isolated from a seawater sample collected in Toyama Bay, Japan, and identified as Streptomyces platensis based on taxonomic characteristics. TPU-0037-A, B, C and D were purified by HP-20 resin, ODS column chromatographies and preparative HPLC, consecutively, and their structures were determined to be 30-demethyllydicamycin, 14,15-dehydro-8-deoxylydicamycin, 30-demethyl-8-deoxylydicamycin and 8-deoxylydicamycin, respectively, by NMR and MS analyses. The new congeners showed antibiotic activity against gram-positive bacteria including MRSA with the MIC of 1.56 to approximately 12.5 microg/ml.