Use of supercritical CO2 to obtain Baccharis uncinella extracts with antioxidant and antitumor activity

•Sequential supercritical extraction at 150−200 bar and 60 °C with CO2+ethanol.•High antioxidant activity methanolic fraction from Baccharis uncinella extract.•Potential antitumor action of fractions of the B. uncinella extract.•Methanolic fraction have IC50 of 158.8 μg/mL to T24 and 213.9 μg/mL to U87 cells.•B. uncinella methanolic fraction has a low antiproliferative effect for Vero cells. The aim of the present study is to evaluate the antioxidant activity (AA) of different fractions of the supercritical extract of Baccharis uncinella, in addition to investigating and relating AA to the potential antitumor action in bladder cancer (T24) and glioblastoma cells (U87) and also its toxicity against normal cells (Vero) for the fraction with the highest percentage of free radical scavenging (% FRS). The extracts were obtained sequentially by extraction with supercritical CO2 (150 and 200 bar and 60 °C) using ethanol as a co-solvent. The fractionation was carried out by column chromatography with hexane, dichloromethane, ethyl acetate and methanol as eluents. AA was tested by the DPPH free radical scavenging method and cell toxicity tests were performed by the MTT assay. The methanolic fraction had the highest AA, with %FRS of 86.7 %, very close to the antioxidant standard used in the test, quercetin, with 87.9 %. The methanolic fraction was able to reduce cell viability to less than 50 % at a concentration of 158.8 μg/mL to T24, 213.9 μg/mL to U87 and 702.5 μg/mL to Vero cells. According to the results, the methanolic fraction of the supercritical extract of B. uncinella has an antiproliferative effect for the tumor cells tested, with less effects on the normal cells evaluated.