Diaporisoindoles A-C: Three Isoprenylisoindole Alkaloid Derivatives from the Mangrove Endophytic Fungus Diaporthe sp. SYSU-HQ3.

Diaporisoindoles A (1) and B (2), two novel isoprenylisoindole alkaloids, and an unusual diisoprenylisoindole dimer diaporisoindole C (3), together with a precursor tenellone C (4) were all isolated from the endophytic fungus Diaporthe sp. SYSU-HQ3. The absolute configurations of 1-4 were elucidated by spectroscopic analysis, X-ray diffraction, and quantum chemical calculations. Diaporisoindole A (1) and tenellone C (4) exhibited inhibitory activity against Mycobacterium tuberculosis protein tyrosine phosphatase B with IC50 values of 4.2 and 5.2 μM.