Polyphenols profile, antioxidant capacity, and in vitro cytotoxic effect on human cancer cell lines of a hydro-alcoholic extract from Calendula officinalis L. petals

Abstract

The hydro-alcoholic extract from Calendula officinalis petals, was evaluated showing beneficial effects against oxidative stress and therefore on diseases associated to inflammatory processes. The content of polyphenols of the extract was determined by TLC and HPLC-UV-DAD and the antioxidant efficiency estimated from Fe³⁺/Fe²⁺ reducing power, Cu²⁺ and Fe²⁺ chelation,  ^•OH radical scavenging, ABTS [2, 2´-azino bis (3 ethylbenzothiazoline-6-sulphonic acid)] and DPPH (2,2´diphenyl-1-picrylhydrazyl) assays. The in vitro growth inhibition (IC₅₀) in human cancer cell breast (MDA-MB-231), uterine cervix (HeLa), lung (A-549), colon (HT-29) and (Caco-2) was determined by MTT method. The extract showed that the polyphenols content in the hydro-alcoholic extract was 37.01±0.015 mg GAE g^–1, being rutin the most abundant one.  ABTS TEACand DPPHTEAC tests showed a high antioxidant capacity. The antioxidant activity profile displayed high reducing capacity and ability to chelate Cu²⁺ and Fe²⁺ as well as good ^•OH radical  scavenging capacity. The extract showed a cytotoxic effect on human cancer cell lines of colon (HT-29)and (Caco-2),breast (MDA-MB-231), uterine cervix (HeLa),and lung (A-549)(IC₅₀ = 10.84, 11.73, 11.26, 11.53, and 11.96 µg mL^–1, respectively). The correlation analysis suggests that the Calendula officinalis polyphenols are directly related to the antioxidant efficiency of the extract and inversely to the cell viability.