Cytochalasins from coastal saline soil-derived fungus Aspergillus flavipes RD-13 and their cytotoxicities

Chemical investigation of coastal saline soil-derived fungus Aspergillus flavipes RD-13 led to the isolation of two new seco-cytochalasins ( 1 ) and ( 2 ) along with nine known analogs. Their structures were elucidated by comprehensive spectral analysis, and the absolute configurations of these two new ones were determined through Rh 2 (OCOCF 3 ) 4 -induced CD experiment and chemical interconversions. Moreover, the absolute configuration of a known compound named cytochalasins Z 18 ( 3 ) was also determined for the first time. Structurally, compounds 1 , 2 and 3 were the open ring derivatives of compounds 5 , 8 , and 4 , respectively. All compounds were evaluated for their cytotoxic activities on A549, H1299 and H520 cells and 4 exhibited the strongest inhibitory activities towards the above cell lines with IC 50 values of 0.15, 0.23 and 0.43 μg/mL, respectively. Preliminary structure-activity relationship analysis suggested the importance of macrocyclic ring in cytochalasins to confer cytotoxicity.