Nine new brominated macrolactam glycosides, daklakamitocins A–I (1–9), were isolated from bromide-supplemented cultures of Amycolatopsis sp. CK6, a strain isolated from a red soil sample collected in Dak Lak Province, Vietnam. Their structures were elucidated using NMR spectroscopy, high-resolution mass spectrometry (HRMS), and electronic circular dichroism (ECD) spectroscopy. Daklakamitocin A (1) exhibited markedly stronger cytotoxicity against human cancer cell lines than its chlorinated analogue, ansacarbamitocin A, suggesting that bromination may contribute to enhanced antiproliferative activity. These findings expand the chemical diversity of maytansinoid metabolites and highlight halide supplementation as an effective strategy for generating brominated congeners for structure–activity comparison.
Bui et al. (Sat,) studied this question.