Cytochalasin H2, a New Cytochalasin, Isolated from the Endophytic Fungus Xylaria sp. A23

A new natural product, cytochalasin H2 (1), together with cytochalasin H (2) were obtained from the agar cultures of the strain Xylaria sp. A23, which was isolated from Annona squamosa. The chemical structures of them were elucidated by spectroscopic and mass spectrometric analyses, including 1D-, 2D-NMR and HR FTMS. Compound 1 showed week cytotoxicity against HeLa and 293T cell lines by MTT assay.