Heliquinomycin is a bacterial metabolite originally isolated fromStreptomycesthat has diverse biological activities.1It is active against a variety of Gram-positive bacteria, including strains ofB. anthracis, B. subtilis, and methicillin-sensitive or -resistantS. aureus(MICs = <0.05-0.39 μg/ml). Heliquinomycin inhibits the activity of DNA helicase with a Kivalue of 6.8 μM. It reduces the growth of L1210 leukemia, B16 melanoma, and FS-3 fibrosarcoma cells (IC50s = 0.97, 0.89, and 0.83 μg/ml, respectively).