Diaporisoindoles A–C: Three Isoprenylisoindole Alkaloid Derivatives from the Mangrove Endophytic Fungus <i>Diaporthe</i> sp. SYSU-HQ3

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