Chaetomadrasins A and B, Two New Cytotoxic Cytochalasans from Desert Soil-Derived Fungus 375.

Two new cytochalasans, Chaetomadrasins A () and B (), along with six known analogues (-), were isolated from the solid-state fermented culture of desert soil-derived 375. Their structures were clarified by comprehensive spectroscopic analyses, and the absolute configurations of Compounds and were confirmed by electronic circular dichroism (ECD) and calculated ECD. For the first time, Chaetomadrasins A (1), which belongs to the chaetoglobosin family, is characterized by the presence of all oxygen atoms in the form of Carbonyl. Chaetomadrasin B () represents the first example of chaetoglobosin type cytochalasan characterized by a hydroxy unit and carbonyl group fused to the indole ring. Compounds and displayed moderate cytotoxicity against HepG2 human hepatocellular carcinoma cells.