Erinacenones M–Y, Part 2: Thirteen New Isoindolinone Alkaloids with α-Glucosidase Inhibitory Activity from Liquid Cultures of the Edible and Medicinal Mushroom Hericium erinaceus

As a continuation of our previous study on erinacenones A–L (Part 1), thirteen previously undescribed isoindolin-1-ones, erinacenones M–Y (1–13), were isolated from the fermentation broth of Hericium erinaceus. Their structures were elucidated by extensive spectroscopic analyses (1D and 2D NMR, HRESIMS), and the absolute configurations of 1–13 were determined by comparing their specific rotations with those of related phthalimidines (14–23). Compound 11 showed the highest α-glucosidase inhibitory activity among the tested compounds, with 31.5% inhibition at 50 μM. These findings significantly enrich the chemical diversity of isoindolinone metabolites from H. erinaceus and provide a foundation for future structure–activity relationship studies.