In course of seeking novel bioactive compounds from extremophilic actinomycetes.two new erythromycin congeners erythronolides H (1) and 1 (2).three new linear polyketides actinopolysporins A-C (3-5),along with known compounds erythronolide B (6),erythromycin A (7) and C (8),desmethyl-erythromycin C (9) and tubercidin (10) as well as a cyclodipepride,were isolated from cultures of the new strain Actinopolyspora sp.YIM 90600,Their structures were determined by analysis of NMR and MS data.The presence of the C-14 hydroxyl moiety and the C-6 C-18-epoxide in erythronolidc H (1) and the spiroketal moiety of erythronolide 1 (2) shed new insights into structural diversity of erythromycin analog libraries potentially accessible by combinatorial biosynthesis.