Indonesian medicinal plants. XXI. Inhibitors of Na+/H+ exchanger from the bark of Erythrina variegata and the roots of Maclura cochinchinensis.

Through bioassay-guided separation of the methanol extracts of Indonesian medicinal plants, three inhibitors of the Na+/H+ exchange system, erythrinin B (2), euchrenone b10 (3), and 1,3,5-trihydroxy-4-(3-methylbut-2-enyl)xanthen-9-one (4), were isolated from the bark of Erythrina variegata (Fabaceae) (for 2) and the roots of Maclura cochinchinensis (Moraceae) (for 2, 3, 4). Compounds 2, 3, and 4 significantly inhibited the Na+/H+ exchange system of arterial smooth muscle cells, with minimum inhibitory concentrations of 1.25, 1.25, and 10 micrograms/ml, respectively. Three new prenylated xanthones named isocudraniaxanthones B (5) and A (7) and isoalvaxanthone (9) were also isolated from M. cochinchinensis and the chemical structures were elucidated on the bases of their chemical and physicochemical properties.