Albocycline‐type Macrolides with Antibacterial Activities from Streptomyces sp. 4205

The actinomycete genus Streptomyces is characterized by producing bioactive secondary metabolites, including antibiotics. In this study, chemical and biological investigations were carried out on Streptomyces strain 4205 isolated from the paddy soil, leading to the identification and characterization of 10 albocycline‐type macrolides, among which 4 compounds were new, namely albocyclines A–D ( 1 – 4 ). The structures of 1 – 10 were identified according to the 1D‐ and 2D‐NMR spectroscopic data. Furthermore, compounds 1 – 10 were evaluated for antimicrobial activity. Compounds 5 – 7 displayed antimicrobial activities against Candidaalbicans ATCC 90028 with the same MIC value of 10.0 mg/mL and the IC₅₀ values of 1.5, 1.0, and 1.0 mg/mL, respectively. Thus, the research on Streptomyces sp. is of vital significance for developing new antibiotic agents.