Two new indole alkaloids, colletotryptins G (1) and H (2), along with four known alkaloids (3-6), were isolated from an endophytic fungus Colletotrichum sp. HD-1 (Melanconiaceae) derived from the mangrove plant Acros-tichum aureum (Pteridaceae). The structures of new compounds were elucidated by comprehensive analysis of their UV, HRESIMS, and NMR data. All the isolates were evaluated for their alpha-glucosidase and acetylcholines-terase inhibitory, antibacterial, and antifungal activities. Only compound 2 showed stronger inhibitory activity against alpha-glucosidase with IC50 value of 133.4 mu M than that of the positive control acarbose (319.8 mu M).