A new C-23-methylated steroid from Penicillium herquei WY-25, an endophyte of Huperzia serrata.

A new steroid (1), together with seven known analogues (2-8), was isolated from Penicillium herquei WY-25, an endophytic fungus from Huperzia serrata. Compound 1 features a rare C-23-methylated steroid, a motif reported mainly from diatoms and geochemical records such as sediments and petroleum. The planar structure of 1 was elucidated by HRESIMS, IR, UV, and NMR analyses, and its absolute configuration was determined by single-crystal X-ray diffraction. Interestingly, the production of 1 was consistently observed in varied culture media via LC-MS profiling, highlighting its stable production. Furthermore, compound 4 exhibited inhibition of nitric oxide production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells with IC50 value of 6.88 ± 0.22 μM (indomethacin as the positive control, IC50 = 44.48 ± 3.58 μM).