Antioxidant activity of Mayodendron igneum Kurz and the cytotoxicity of the isolated terpenoids


A petroleum ether extract of Mayodendron igneum Kurz, (Family Bignoniaceae) yielded five compounds identified as sitosterol, erythrodiol, oleanolic acid, ursolic acid and 5', 6' norigeumone. Antioxidant activity of total ethanol extracts of the plant was equal to 77.02% of the antioxidant activity of ascorbic acid (100%) as measured by electron spin resonance (ESR) and using DPPH as the stable free radical. The antioxidant activity of successive fractions of M. igneum leaves were tested with the strongest inhibition of DPPH stable free radicals exhibited by the successive ethanol fraction (equal to 100% of free radical scavenging activity relative to ascorbic acid). The ethyl acetate fraction had 64.96% of the antioxidant activity of ascorbic acid, and the petroleum ether and chloroform fractions had 12.46% and 0%, respectively, of the antioxidant activity of ascorbic acid. An examination of isolated oleanolic acid demonstrated moderate cytotoxic activity against four tested cancer cell lines (liver, cervix, breast, and colon). The highest activity level was against the cervix cancer cell line (HELA) (IC50= 32 µg/mL), followed by the liver cancer cell line (HEPG2) (IC50=33 µg/mL), the colon cancer cell line (HCT-116) (IC50= 35 µg/mL), and the breast cancer cell line (MCF7) (IC50= 37 µg/mL).