The SOS Chromotest applied for screening plant antigenotoxic agents against ultraviolet radiation

In this work, we investigated the usefulness of the SOS Chromotest for screening plant antigenotoxic agents against ultraviolet radiation (UV). Fifty Colombian plant extracts obtained by supercritical fluid (CO2) extraction, twelve plant extract constituents (apigenin, carvacrol, beta-caryophyllene, 1,8-cineole, citral, p-cymene, geraniol, naringenin, pinocembrin, quercetin, squalene, and thymol) and five standard antioxidant and/or photoprotective agents (curcumin, epigallocatechin gallate, resveratrol, a-tocopherol, and Trolox (R)) were evaluated for their genotoxicity and antigenotoxicity against UV using the SOS Chromotest. None of the plant extracts, constituents or agents were genotoxic in the SOS Chromotest at tested concentrations. Based on the minimal extract concentration that significantly inhibited UV-geno-toxicity (CIG), five plant extracts were antigenotoxic against UV as follows: Baccharis nitida (16 mu g mL(-1)) = Solanum crotonifolium (16 mu g mL(-1)) > Hyptis suaveolens (31 mu g mL(-1)) = Persea caerulea (31 mu g mL(-1)) > Lippia origanoides (62 mu g mL(-1)). Based on CIG values, the flavonoid compounds showed the highest antigenotoxic potential as follows: apigenin (7 mu M) > pinocembrin (15 mu M) > quercetin (26 mu M) > naringenin (38 mu M) > epigallocatechin gallate (108 mu M) > resveratrol (642 mu M). UV-genotoxicity inhibition with epi-gallocatechin gallate, naringenin and resveratrol was related to its capability for inhibiting protein synthesis. A correlation analysis between compound antigenotoxicity estimates and antioxidant activity evaluated by the oxygen radical absorbance capacity (ORAC) assay showed that these activities were not related. The usefulness of the SOS Chromotest for bioprospecting of plant antigenotoxic agents against UV was discussed.