5-methylcoumaranones from Mutisia friesiana and their bioactivity.

In addition to the known mutisicoumaranones A (1) and B (2), the methanolic extract of the aerial parts of the shrub Mutisia friesiana afforded two new 5-methylcoumaranones, mutisicoumaranones C (3) and D (4). Their structures were elucidated by spectroscopic methods. (13)C NMR data for mutisicoumaranones A and B are reported for the first time. All compounds showed antifungal activity against the phytopathogenic fungus Cladosporium cucumerinum and bactericidal activity against Staphylococcus aureus. The presence of 5-methylcoumaranones A-D is biosynthetically related to 5-methylcoumarins and phenolic derivatives previously isolated from M. friesiana.