Sphaeranthone A, a new carvotacetone from the leaves of .

A new carvotacetone sphaeranthone A and four known compounds 3-angeloyloxy-5-[2″,3″-epoxy-2″-methylbutanoyloxy]-7-hydroxycarvotacetone (), 3-angeloyloxy-5-[3″-chloro-2″-hydroxy-2″-methylbutanoyloxy]-7-hydroxycarvotacetone (), chrysosplenol D (), and 3--methylquercetin () were isolated from leaves of growing in Vietnam. Their chemical structures were elucidated by extensive 1D and 2D NMR analysis and high-resolution mass spectroscopy as well as comparisons in literature. Compounds were evaluated for the alpha-glucosidase inhibition. They showed moderate activity with IC values of 103 ± 1.7, 146.8 ± 2.5, 49 ± 0.8 µg/mL, respectively.