Isolation of an anthrabenzoxocinone 1.264-C from Streptomyces sp. FXJ1.264 and absolute configuration determination of the anthrabenzoxocinones

The anthrabenzoxocinones (ABXs) are hexacyclic aromatic compounds with various bioactivities. Some ABXs with two stereogenic carbon centers have been isolated from different actinomycetes. However, none of them have an absolute configuration assigned, which precludes further studies on the structure–activity relationship and biosynthetic mechanisms of the ABXs. An ABX compound 1.264-C was isolated from Streptomyces sp. FXJ1.264. The absolute configuration of 1.264-C was characterized by X-ray crystallographic, electronic, and experimental circular dichroism (CD) analyses. Based on the reported CD and specific rotation data, the absolute configurations of several other ABXs were also assigned.

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(6S,16S)-3,11,13,15-Tetrahydroxy-1,6,9,9-tetramethyl-9,16-dihydro-6H-6,16-epoxyanthra[2,3-e]benzo[b]oxocin-14(7H)-oneC27H24O7[α]D23=+375.4 (c 0.013, CH2Cl2)Source of chirality: natural product from Streptomyces sp. FXJ1.264Absolute configuration: (6S,16S)