Phaeochromycins I-K, Three Methylene-Bridged Dimeric Polyketides from Streptomyces sp. 166.

Three new dimeric polyketides, i.e., phaeochromycins I-K ( 1 - 3 , respectively) and a known polyketide phaeochromycin F ( 4 ), were isolated from the culture broth of a saline Qinghai-Tibet Plateau permafrost soil-derived Streptomyces sp. 166#. The structures were determined by analyzing one-dimensional and two-dimensional NMR as well as HRESIMS data. Compounds 2 and 3 exhibited a selective antiproliferative activity against H1299 and HUCCT1 cell lines, exhibiting IC 50 values ranging from 8.83 to 10.52 μM.