ABSTRACT
The antiproliferative of the brown algae Padina australis extracts against cell MCM-B2 (canine benign mammarygland mixed tumor) and cell K562 (human chronic myelogenous leukemia) in vitro was examined. The tested sampleswere water extract (n-hexane fraction, ethyl acetate fraction, and ethanol fraction) and ethanol extract (n-hexanefraction, ethyl acetate fraction, and ethanol fraction). Cytotoxicity was screened using brine shrimp lethality test.The antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl. The antiproliferative activity test wasconducted using trypan blue dye method and cells were counted using hemocytometer. The results showed thatethyl acetate fraction from water extract exhibited significant cytotoxicity with lethal concentration 50 value of200.53 ppm. The ethyl acetate fraction from water extract was then considered for further examination. Results ofantioxidant activity test showed that concentration for inhibitory activity of 50% of the ethyl acetate fraction reached113.37 ppm. This fraction at concentration of 400 ppm could inhibit the growth of MCM-B2 and K562 cancer celllines in vitro reaching 56.90% and 61.54%, respectively. Therefore, the present study suggested that ethyl acetatefraction of P. australis extract demonstrated a potential natural anticancer activity.