Allostreptopyrroles A-E, β-alkylpyrrole derivatives from an actinomycete Allostreptomyces sp. RD068384.

Five new β-alkylpyrrole derivatives, allostreptopyrroles A-E ( 1 - 5 ), were isolated from the culture broth of Allostreptomyces RD068384. Their structures were elucidated by 1D and 2D NMR spectroscopic analyses, HRESIMS, and chemical derivatization. The absolute configurations of compounds 2 and 3 were predicted by comparison of experimental and calculated specific rotation data. Compounds 1 - 5 are the first examples of natural pyrroles substituted by formyl and carboxyl functionalities. Compounds 1 , 4 , and 5 showed cytotoxicity against Kasumi-1 human acute myeloblastic leukemia cells with IC 50 values of 103, 105, and 105 μM, respectively, which are less active than the anticancer agent cisplatin, with an IC 50 value of 70 μM.