Asperalkals A-C, three undescribed alkaloids with immunosuppressive activity from Aspergillus sp. TJ507

Three undescribed alkaloids, asperalkals A-C (1-3), as well as two known analogues (4 and 5), were isolated from Aspergillus sp. TJ507. Their structures were elucidated through comprehensive spectroscopic analysis, chemical derivatization, and ECD calculations. Subsequently, the immunosuppressive effects of these compounds were assessed in mouse lymphocytes stimulated with either anti-CD3/anti-CD28 monoclonal antibodies (mAbs) or concanavalin A (ConA). The results revealed that moderate immunosuppressive activity was observed for compounds 2-4, exhibiting IC₅₀ values in the range of 13.77 ± 2.73 to 21.37 ± 3.33 μM, providing potential lead compounds for novel immunosuppressant development.