Seven lower toxicity celastrol derivatives by biotransformation of Pestalotiopsis sp. LGT-1.

Biotransformation of toxic components by plant endophytes has become an effective method to reduce the toxicity of target compounds and discover lead compounds. In this context, an endophytic fungus, Pestalotiopsis sp. LGT-1, from Tripterygium wilfordii Hook F. (TwHF), was used to reduce the toxicity of celastrol which is also produced by TwHF and is considered an attractive molecule with a variety of biological activities. Seven celastrol derivatives (1-7) were isolated from the coculture fermentation broth of LGT-1 and celastrol. Their structures were elucidated by spectroscopic data analysis including 1D and 2D NMR, as well as HRESIMS. Their absolute configurations were determined by analysis of NOESY, ECD data and NMR calculations. In cell proliferation experiments, the toxicity of seven compounds was 10.11- to 1.24-fold lower in normal cells than the prototype compound celastrol. These derivatives serve as potential candidates for future pharmaceutical applications.