Bioactive polyketides from cultures of the entomopathogenic fungus Hypocrella luteola TBRC-BCC 76666

Entomopathogenic fungi of the genus Hypocrella are known to produce bioactive compounds, in particular polyketides. Here, a chemical investigation of the entomopathogenic fungus Hypocrella luteola strain TBRC-BCC 76666 was performed to identify possible novel compounds indicated from HPLC and ¹H NMR spectra profiles of culture extracts. Eight novel compounds were isolated, including six new polyketides (1-6) and two other naturally occurring compounds (7-8), along with seven known compounds. The compound structures were established by spectroscopic analysis, the application of modified Mosher's method, and electronic circular dichroism. Compounds 1 and 5 were cytotoxic against both NCI-H187 and Vero cells (IC₅₀ = 9.9 and 58.9 μM, respectively), whereas compound 4 was active only against MCF-7 cells (IC₅₀ = 42.5 μM). Ascherxanthone B (9) exhibited antiproliferative activity against all cell lines tested (Plasmodium falciparum, mammalian, and fungal), with IC₅₀ and MIC values in the range 0.9-30.5 μM.