In vitro and in vivo protective effects of a phytochemical mixture ( <i>Posoqueria latifolia</i> extract + Kaempferol) against <scp>UVB</scp> ‐induced radiation damage ^*

Plants may be a source of protective compounds that inhibit injuries caused by overexposure to solar radiation. Present work evaluated the protective effects of a phytochemical mixture based on Posoqueria latifolia extract + Kaempferol against ultraviolet-induced radiation DNA damage in human fibroblasts and mice skin. Cytotoxicity, genotoxicity, and antigenotoxicity of P. latifolia flower extract, Kaempferol, and the mixture of both were studied in MRC5 human fibroblasts using Trypan blue exclusion and Comet assays. Kinetics of DNA damage repair post irradiation, in the presence and absence of the phytochemicals, were also evaluated. The inhibition of UVB-induced erythema and cyclobutene pyrimidine dimers (CPD) by the phytochemicals and the mixture were also investigated in mice skin. We showed that the P. latifolia flower extract, Kaempferol, and the mixture inhibited UVB-induced DNA damage and increased DNA repair mechanisms in human fibroblasts. In addition, these phytochemicals inhibited the UVB-induced erythema and CPD in mice skin. The potential of the studied phytochemicals in human photoprotection was discussed.