Isolation of Translactone-containing Triterpenes with Thrombin Inhibitory Activities from the Leaves of Lantana camara

Methanolic extracts prepared from the leaves of Lantana camara have been found to inhibit human thrombin. An assay, in which thrombin activity is measured as a function of clot formation from fibrinogen, was used to guide the fractionation and purification of five principal active constituents (1−5), which were all characterized as 5,5-trans-fused cyclic lactone-containing euphane triterpenes.