In search of camptothecin (CPT)-producing microorganisms, 50 endophytic fungi were isolated from the inner bark of a fully mature Camptotheca acuminata. These endophytes were fermented and the fermentation broth and mycelia were analyzed by HPLC-DAD for CPT-producing capability that was confirmed by HPLC-DAD-HRMS analysis. The isolate designated LY013 was found to produce CPT in the culture broth. The endophyte LY013 was determined to be Aspergillus sp. on the basis of the morphological analysis of mycelia and spores. Subsequent subculturing of LY013 led to a substantial decrease of the production of CPT.

To understand the chemical background of the attenuated CPT-producing endophytic fungus Aspergillus sp. LY013, chemical investigations of the secondary metabolites of LY013 fermentation broth were performed. Nine complex alkaloids were isolated and identified as pseurotin A (1), FD-838 (2), fumitremorgin C (3), tryprostatin B (4), cyclotryprostatin B (5), 12,13-dihydroxyfumitremorgin C (6), spirotryprostatin A (7), fumiquinazoline J (8), and fumiquinazoline C (9) on the basis of the interpretation of spectral data and by comparison with the spectral data reported previously.

Researchers from Chengdu Institute of Biology of CAS conducted this research.