Faculty Scholarship

During a survey of actinobacteria known to suppress the growth of Streptomyces scabies (the causative agent of potato scab disease) in vivo, six new rhamnosylated alkaloids, the solphenazines A–F (1–6), were isolated from a biological control strain of Streptomyces (DL-93). The known rhamnosyl analogue of paraben (9) was also isolated along with a new rhamnosylated derivative of N-methyl-p-aminobenzoic acid (10). None of the compounds exhibited any antibacterial or antifungal activity against a standard panel of microorganisms, but compounds 1, 2, and 6 displayed some cytotoxicity against HCT-116 cancer cells. Additional in vitro testing provided data suggesting that the cytotoxic activity is not due to DNA intercalation or topoisomerase inhibition.