Two new triterpenoid estersaponins and biological activities of Pittosporum tobira ‘Variegata’ (Thunb.) W. T. Aiton leaves.

Two new triterpenoid estersaponins ( 1, 2 ) were isolated from the leaves of Pittosporum tobira ‘Variegata’ (Thunb.) W. T. Aiton, along with one known saponin ( 3 ) and one known flavonoid glycoside ( 4 ). Their structures were established by different spectroscopic methods including 1D and 2D NMR, UV, as well as ESI-MS analysis. The investigated 80% aqueous methanol extract showed significant dose dependent inhibition of acetic acid induced abdominal writhing in mice. The n -butanol fraction exerted moderate antimicrobial activity against Staphylococcus aureus and Escherichia coli . In addition, it showed in vitro antioxidant activity with IC 50 value (7.3 μg/ml) lower than that of the positive control ascorbic acid (11.2 μg/ml), using DPPH free radical scavenging activity method. Evaluation of its in vitro cytotoxicity showed strong activity against breast carcinoma (MCF-7), hepatocellular carcinoma (HepG2), and colon carcinoma (HCT) cell lines. [ABSTRACT FROM AUTHOR]