Radical scavenging, antioxidant, and cytotoxic activities of the methanolic extracts from different organs of Ternstroemia pringlei

Ternstroemia pringlei (Rose) Standl. (Theaceae) is widely used in Mexican traditional medicine to treat a diverse array of illnesses including rheumatoid pains, and is listed as one of the most consumed medicinal plants in the country. We selected T. pringlei given the strong relationship between oxidative stress and arthritis pathology, and investigated antioxidant potential of leaf, petal, fruit and seed methanolic extracts. Our method included assessing the in vitro free radical scavenger activity using the 2,2´-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) test, as well as the in vivo antioxidant action in the H2O2 protection model with Saccharomyces cerevisiae. Leaves and fruits afforded the most active extract in the ABTS assay, with antiradical activity of IC50=33.91 and 38.09µg/mL, respectively; while fruit extracts at 250µg/mL proved the most protective action against H2O2 oxidative stress. All extracts were non-cytotoxic against HF-6 (colon), PC-3 (prostate), MCF-7 (breast), SiHa (cervical) cancer cell lines and also toward the HFS-30 fibroblast normal skin cell line (IC50>20µg/mL). Leaf methanolic extracts afforded ternstroside B, a known phenylethanoid glycoside with a strong free radical scavenging action. The presence of this kind of metabolites opens new research perspectives for the plant.