Syzygium aromaticum extracts as good source of betulinic acid and potential anti-breast cancer

Syzygium aromaticum (L.) Merr. & L. M. Perry, Myrtaceae, is an evergreen tree with anticarcinogenic, antimutagenic, aphrodisiac, antimicrobial, antioxidant and antiinflammatory properties. This study aims to investigate the anti-breast cancer effect of extracts from leaves, stem and bark of S. aromaticum and to develop a method for preparation of betulinic acid fraction from the leaves. Betulinic acid, ursolic acid and oleanolic acid contents of the extracts were determined by HPLC. A betulinic acid fraction was prepared by simple crystallization of leaves extract and was characterized by HPLC and mass analysis. Anti-breast cancer effects were studied on MCF-7 and MDA-MB-231 cells. The extracts were found to contain high levels of betulinic acid particularly the leaves extract which contained 17% wt/wt. The betulinic acid fraction contains 75% betulinic acid. Cytotoxicity testing reveals high and selective cytotoxic effect of the stem extract on MCF-7 cells with IC50 33 +/- 1.6 mu g/mL. Cytotoxic effect of the stem extract was due to activation of apoptotic machinery of cell death. Combination studies of stem extract with tamoxifen reveals antagonistic effect at high concentration of tamoxifen and enhancement effect at low concentration. The selective cytotoxicity of the stem extract of S. aromaticum on MCF-7 is not due to betulinic acid but due to other constituents yet to be discovered.