Genome mining and metabolomics unveil new napyradiomycin antibiotics from Streptomyces sp. 0H2M

Napyradiomycins are a family of meroterpenoid natural products known for their promising antibiotic activities. In this study, four new napyradiomycins derivatives were identified, SF2415B4 (1), SF2415B5 (2), SF2415B6 (3), and SF2415B7 (4) from Streptomyces sp. 0H2M, alongside a known molecule, A80915A (5) through the synergy between genome mining and metabolomics analysis. Their structures were elucidated through a combination of spectroscopic and spectrometric analyses, including HRMS-ESI, NMR, and DP4+. Genome sequencing identified a putative biosynthetic gene cluster, and subsequent analyses revealed a distinct biosynthetic pathway with an unprecedented tailoring mechanism mediated by novel hydroxylases and halogenases. Biological assays demonstrated significant activity against Bacillus subtilis, Bacillus cereus and methicillin-resistant Staphylococcus aureus due to perturbation of cell membrane integrity, and minimum inhibitory concentration (MIC) values ranged from 0.24 to 30.7 μM. Additionally, in vitro cytotoxicity experiments indicated that compounds 2-5 very mildly inhibited the viability of human non-small cell lung cancer (NSCLC) cell line A549 in a concentration-dependent manner, with IC₅₀ values of 16.7, 39.1, 65.0, and 32.8 μM, respectively. Moreover, they were shown to induce apoptosis and autophagy in A549 cells, evidenced by increased levels of cleaved PARP, decreased expression of anti-apoptotic proteins (Bcl-2, Bcl-xL, and Survivin), and accumulation of LC3-II. These findings offer new insights into the natural product chemistry in Streptomyces and the pharmacology of napyradiomycin class antibiotics.