Apoptotic Anticancer Effect of Alvaradoin E Isolated from Alvaradoa haitiensis

Abstract

Two anthracenone C-glycosides, alvaradoins E and F, isolated from the leaves of Alvaradoa haitiensis Urb. (Simaroubaceae), were found to have potent inhibitory activities with cultured cancer cells. Using the in vivo hollow fiber model, these compounds demonstrated significant growth inhibition at the i.p. site when tested with KB, LNCaP, and Col2 cells. To determine if these anthracenone C-glycosides mediated anticancer activity through an apoptotic pathway, a series of assays were performed with the 10S isomeric compound, alvaradoin E. With a DAPI assay, treatment of LNCaP cells with alvaradoin E at concentrations of 0.4, 2, 10, or 50 μM for 24 or 48 h showed chromatin condensation, a morphological characteristic of apoptosis. Mitochondrial membrane potential, analyzed with a DiOC₆ uptake assay, showed that treatment of LNCaP cells with 0.07, 0.14, 0.28, 0.56, 0.86, and 1.12 μM alvaradoin E for 12 h caused dose-dependent membrane depolarization, another indication of early apoptosis. Also, with an annexin V-FITC assay system, treatment of HL-60 cells with 0.07 μM alvaradoin E for 24 h increased annexin V-FITC binding from 3 to 25.9% (8.6-fold). Finally, with the TUNEL assay system, treatment of HL-60 cells with 1.12 μM alvaradoin E for 32 h increased FITC-dUTP binding from 1.2 to 12.1% (10-fold). These data suggest alvaradoin E is an effective anticancer agent that induces apoptosis. Additional studies to establish clinical utility should be of interest.