129 Tulsi extract induces a global defense and protection against endogenous and exogenous stresses contributing to skin aging

Abstract

Tulsi, or « sacred basil », has been traditionally used in ayurvedic medicine, in which this adaptogen plant is considered as an elixir of life. We developed a new active ingredient rich in polyphenols extracted from the leaves of Ocimum sanctum. Here, we have investigated the biological efficacy of the extract in vitro. We show that O. sanctum leaf extract significantly inhibited the production of reactive oxygen species by normal human keratinocytes stimulated by hydrogen peroxide. The production of nitric oxide induced by cortisol in keratinocytes was also significantly reduced by the extract. Cell bioenergetics as well as autophagy/mitophagy processes have been evaluated in primary human fibroblasts exposed to standardized urban pollutants. The extract was able to normalize energy efficiency by restoring oxygen consumption rate and ATP level that were decreased by the pollutants. It also reversed the pollution-induced increase in damaged mitochondria and normalized mitophagy and autophagy in pollution-exposed cells. Taken together, these results suggest a protection of the mitochondrial network. Finally, the extract was evaluated in a model reproducing inflammation processes observed during aging and known as inflamm’aging. Conditioned medium obtained from reconstructed epidermis subjected to inflammatory stimulation was applied on dermal fibroblasts. Typically, in these conditions, the expression of a number of genes linked to ageing processes is altered in fibroblasts, in particular markers of inflammatory processes, stress response and dermal matrix. The extract was able to normalize the modulation of gene expression in fibroblasts induced by inflamm’aging. Overall, these results suggest that the newly developed Ocimum sanctum leaf extract contributes to the skin global defense and helps it fight against exogenous and endogenous stress. The extract was able to neutralize the impact of these stresses which, in the long-term, can accelerate skin aging process.