The ripe purple berries of the native Indian plant Eugenia jambolana Lam., known as Jamun, are popularly consumed and available in the United States in Florida and Hawaii. Despite the growing body of data on the chemopreventive potential of edible berry extracts, there is paucity of such data for Jamun fruit. Therefore our laboratory initiated the current study with the following objectives: (1) to prepare a standardized Jamun fruit extract (JFE) for biological studies and (2) to investigate the antiproliferative and pro-apoptotic effects of JFE in estrogen dependent/aromatase positive (MCF-7aro), and estrogen independent (MDA-MB-231) breast cancer cells, and in a normal/nontumorigenic (MCF-10A) breast cell line. JFE was standardized to anthocyanin content using the pH differential method, and individual anthocyanins were identified by high performance liquid chromatography with ultraviolet (HPLC-UV) and tandem mass spectrometry (LC-MS/MS) methods. JFE contained 3.5% anthocyanins (as cyanidin-3-glucoside equivalents) which occur as diglucosides of five anthocyanidins/aglycons: delphinidin, cyanidin, petunidin, peonidin and malvidin. In the proliferation assay, JFE was most effective against MCF-7aro (IC(50) = 27 microg/mL), followed by MDA-MB-231 (IC(50) = 40 microg/mL) breast cancer cells. Importantly, JFE exhibited only mild antiproliferative effects against the normal MCF-10A (IC(50) > 100 microg/mL) breast cells. Similarly, JFE (at 200 microg/mL) exhibited pro-apoptotic effects against the MCF-7aro (p <or= 0.05) and the MDA-MB-231 (p <or= 0.01) breast cancer cells, but not toward the normal MCF-10A breast cells. These studies suggest that JFE may have potential beneficial effects against breast cancer.