Total Synthesis, Absolute Configuration, and Biological Activity of Xyloallenoide A

The novel natural product xyloallenoide A, isolated from the marine mangrove endophytic fungus from the South China Sea, and its diastereoisomer xyloallenoide A1, which contain N-methyl-substituted amino acids, were synthesized. The absolute configurations of the amino acid units of xyloallenoide A were finally confirmed to be L-Lys, Me-D-Val, and Me-L-Ala. This report represents a practical and attractive alternative for the synthesis of N-methyl-substituted cyclotripeptides. In the preliminary bioassay, synthetic xyloallenoide A showed marginal activities against KB (IC50=9.6 mu M) and KBv200 cells (IC50=10.3 mu M), and xyloallenoide A1 was inactive against KB and KBv200 cells.