Two new friedelane lactones from the roots of Caloncoba glauca (Flacourtiaceae) and evaluation of their cardiotonic activity on isolated frog & rsquo;s heart

Two new friedelane triterpenoids, 20,20-dimethyl-3,27-dioxo-(D:A)-friedo-olean-27,22α-lactone (20,20-dimethylglaucalactone) (1) and 3α-ethanoyloxy-30-nor-(D:A)- friedo-olean-20(29)-en-27,22α-lactone (3-acetoxyglaucalactone) (2) and four known compounds (3–6) were isolated from the methanolic extract of the roots of Caloncoba glauca (P. Beauv.) Gild (Flacourtiaceae). Their structures were determined by comprehensive spectroscopic analyses (1D and 2D NMR in addition to HRESI-MS). The relative configuration of the 22-oxymethine was determined from the NOESY spectrum. The cardiotonic effects of the crude extract and isolated compounds were tested. The results suggest that the crude extract and 3-acetoxyglaucalactone (2) induced an interesting cardiotonic activity by exerting positive inotropic and chronotropic effects, which might be derived from the direct stimulation of the β-adrenergic pathway through β1-adrenergic receptors or opening of the calcium channel.