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Abstract: One new angucyclinone derivative, amycomycin A (1), and one new angucycline, amycomycin B (2), along with 5 known compounds (3–7), were isolated from an actinobacterium Amycolatopsis sp. HCa1 associated with the grasshopper, Oxya chinensis. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR spectra. Compounds 1–7 were tested in vitro for their cytotoxic effects on five cell lines including human gastric adenocarcinoma cell line (BGC823), human hepatocarcinoma cell line (HepG2), human melanoma cell line (A375), human oral squamous carcinoma cell line (KB), and ghost cell line (Ghost-R5X4). Cell viability assays showed that compound 7 was active in four cell lines with IC50 values less than 18.0μM except in KB showing no activity up to 100μM. [Copyright &y& Elsevier]

Graphical abstract Highlights • New borrelidin-type macrolactones were isolated from an endophyte. • The structures of new compounds were elucidated by spectroscopic data. • Borrelidin A showed potent activity against M. luteus with MIC value of 1.0 μM. Abstract Three new borrelidin-type macrolactones, designated as borrelidins J−L (4 – 6), together with borrelidin A (1), borrelidin E (2), and 12-desnitrile-12-carboxyl-borrelidin (3) were isolated from a plant endophytic Streptomyces sp. NA06554. Their structures were determined by extensive spectroscopic analysis including HRESIMS, 1D and 2D NMR data. The antibacterial activities for compounds 1 – 6 were examined. Borrelidins A (1) and L (6) showed potent and moderate antibacterial activity against Micrococcus luteus , respectively, whereas other derivatives (2 – 5) are almost inactive, which allows us to propose a plausible structure-activity relationship. [ABSTRACT FROM AUTHOR]