New cassane diterpenes from Caesalpinia echinata.

An investigation of the ethanolic extract from stems of Caesalpinia echinata Lam (Leguminosae-Caesalpinioideae) led to the isolation of five new cassane diterpenes along with known lambertianic acid. Their structures were determined based on spectroscopic methods. A preliminary study on leishmanicidal activity demonstrated that compounds 1, 2 and 6 were found to inhibit the growth of amastigote-like forms of Leishmania amazonensis without affecting mononuclear cells obtained from human peripheral blood.