Discovery of undescribed alkaloids with immunosuppressive activity from the endophytic fungus Penicillium sp. HZ-5.

Two undescribed alkaloids, mecichorine (1) and talaropyrazine D (2), along with four known compounds were isolated from an endophytic fungus Penicillium sp. HZ-5. Their structures were elucidated from the spectroscopic data. Furthermore, the isolated compounds were tested for their immunosuppressive activity, and compound 1 showed moderate immunosuppressive activity on Con A-induced T-lymphocyte proliferation in vitro, with an IC50 value of 15.2 ± 0.3 µM, and the others showed no obvious activities up to 40 µM.