Nathmorinones A and B, two naphthyl cyclothiomorphone from Amycolatopsis sp. YINM00005

Abstract

Atypical actinomycetes have long been esteemed as a precious microbial resource, renowned for their capability to produce an extensive array of bioactive natural products. Two polycyclic naphthyl cyclothiomorphone, nathmorinones A (1) and B (2), were isolated from Amycolatopsis sp. YINM00005 associated with Peperomia dindygulensis Miq. Their structures, featuring a tricyclic framework with a naphthalene ring and a thiomorphine scaffold, were elucidated through extensive analysis of NMR spectra, HRESIMS data, and further confirmed by single-crystal X-ray diffraction experiments. Compound 2 exhibited moderate cytotoxic activities against SMMC-7721 and SW480 with IC₅₀ values of 13.65 ± 0.30 and 17.82 ± 0.30 μM, respectively. Hypothetical biosynthetic pathways for 1 and 2 were proposed.