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

[Image: see text] 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.