Effect of extracts and isolated compounds derived from Retama monosperma (L.) Boiss. on anti-aging gene expression in human keratinocytes and antioxidant activity

Ethnopharmacological relevance: Moroccan folk medicine treats skin cicatrization with Retama monosperma (L.) Boiss. locally named "Rtem", but the mechanism involved is still not well known. Traditional healers use the plant in small doses as an anthelmintic, disinfectant and an effective abortive. In addition, the cladodes powder mixed with honey is employed as purgative and vermifuge. Equally, the SIRT1 and SIRT3 genes activation and sirtuin proteins expression, which delay cellular senescence, participate in wound healing and skin regeneration especially, SIRT1 the most studied gene, leads to fast skin restoration and cicatrization. Aim of the study: In this study, we evaluated the ability of the Retama monosperma (L.)Boiss. flowers and seeds extracts and the isolated compounds in augmenting the SIRT1 and SIRT3 gene expression in HaCaT cells and expressing the antioxidant activity. Materials and methods: We examined for quantitative expression levels of SIRT1 and SIRT3 in HaCaT cell by qRT-PCR and the antioxidant activity by four tests (conjugated diene, TBARS assay, DPPH scavenging activity and H₂O₂ radical scavenging assay) of diethyl ether extract of flowers (DEF extract) and ethyl acetate extract of seeds (EAS extract) of R. monosperma (L.) Boiss. and the isolated compounds (quercetin, 6-methoxykaempferol, kaempferol and genistein). Results: The screening system by EGFP fluorescence revealed that all samples and resveratrol significantly increase SIRT1 and SIRT3 promoters activities in HaCaT cells with p< 0.05. Furthermore, EAS, quercetin, 6-methoxykaempferol and kaempferol increase significantly (p< 0.05) SIRT1 (3.43, 1.18, 2.62, and 1.72 expression quantity, respectively) and SIRT3 (16.27, 5.01, 3.01, and 6.18 expression quantity, respectively) in HaCaT cells. On the other hand, genistein has a moderate activity on SIRT1 and SIRT3 with 1.43 and 2.04 expression levels. For the antioxidant activity, the EAS and the pure compounds exhibited stronger antioxidant activity than BHT. While DEF and genistein have a moderate antioxidant activity when compared with BHT. Conclusions: In this study, the expression levels of SIRT1 and SIRT3 in HaCaT cells increase in the presence of extracts of R. monosperma (L.) Boiss. and the pure compounds.