Streptimidone, a metabolite produced by Streptomyces, exhibits various biological activities, including inhibiting protein synthesis at 50 µg/ml in cell-free assays and reducing tumor growth in rat xenograft models of H.S. No. 1 human sarcoma and H.Ep. No. 3 human epidermoid carcinoma at daily doses of 12.5 and 25 mg/kg.