Cytotoxic and Antifungal Staurosporine Derivatives from Marine‐Derived Actinomycete Streptomyces sp. ZS‐A121

A novel staurosporine derivate, streptomholyrine A (1), along with 6 known compounds were identified from the rice‐based solid fermentation of marine‐derived Streptomyces sp. ZS‐A121. The planar structure and absolute configuration of streptomholyrine A were elucidated using a combination of 1D, 2D NMR, HRESIMS data analysis, chemical transformation, ECD and NMR calculations. Screening of all these compounds revealed their cytotoxic activity against HCT‐116 cell lines, with IC50 values ranging from 0.012 to 11.67 μM, except for the known 1H‐indole‐3‐hydroxyacetyl, which showed no inhibition activity. Furthermore, streptomholyrine A, along with two known staurosporine derivatives, k252d and staurosporine, exhibited activities against Candida albicans, with MICs of 12.5, 25.0 and 50.0 μg/ml, respectively.