Cytotoxic indole diterpenoids and rare pyridoxatin atropisomers from the endophytic fungus Tolypocladium sp. SHJJ1.

Phytochemical investigation on the extract of endophytic fungus Tolypocladium sp. SHJJ1 resulted in the identification of a pair of previously undescribed pyridoxatin atropisomers [ 1 ( M / P )] and three new indole diterpenoids (3 – 5), together with a pair of known pyridoxatin atropisomers [ 2 ( M / P )] and ten known indole diterpenoids (6 –1 5). Their structures, including their absolute configurations were elucidated by extensive spectroscopic analysis, quantum chemical calculations, and X - ray diffraction. Among the undescribed natural products, [ 1 ( M / P )] that two rapidly interconverting atropisomers are the third example to report in the pyridoxatin atropisomers. Except for compounds 1 ( M / P ) and 2 ( M / P ), all other compounds were tested for their cytotoxicity using HepG2, A549, and MCF-7 human cell lines. Compound 9 displayed moderate cytotoxicity against the HepG2, A549, and MCF-7 cell lines with IC 50 values of 32.39 ± 1.48 μM, 26.06 ± 1.14 μM, and 31.44 ± 1.94 μM, respectively, which was similar to the positive drug cisplatin (with IC 50 values of 32.55 ± 1.76 μM, 18.40 ± 1.43 μM, and 27.31 ± 1.22 μM, respectively). [Display omitted] [ABSTRACT FROM AUTHOR]