Undescribed polyketides and alkaloids from the endophytic fungus Penicillium steckii HJT-A-10.

Ten undescribed metabolites, including eight polyketides (1-7, 10) and two alkaloids (8, 9), along with three known compounds (11-13) were isolated from the endophytic fungus Penicillium steckii HJT-A-10. Their structures were established through comprehensive spectroscopic analyses of HR-ESI-MS, 1D and 2D NMR, as well as electronic circular dichroism calculations. A plausible biosynthetic pathway for all isolated compounds is proposed. In the bioassay, compounds 7 and 9 exhibited significant inhibition activity against lipopolysaccharides-induced nitric oxide production in RAW264.7 macrophages, with IC50 values from 9.4 to 4.2 μM, respectively.