Phomopsischalins A–C, polycyclic-fused cytochalasins from the endophytic fungus Phomopsis sp. shj2 and their abilities to induce lysosomal function

Abstract

Phomopsischalins A (1) and B (2), two unprecedented cytochalasins featuring a 5/6/6/7-fused tetracyclic ring system, and phomopsischalin C (3), bearing a 5/6/5/8-fused tetracyclic ring system, were isolated from the endophytic fungus Phomopsis sp. shj2. Their structures were elucidated by extensive spectroscopic analysis, electronic circular dichroism (ECD), and single X-ray diffraction analysis. Compound 2 promoted lysosomal function independent of the transcriptional activity of transcription factor EB (TFEB), a master regulator of lysosomal biogenesis and function.