Effect of gamma irradiation on phenolic content, biological activity, and cellular ultrastructure of Salvia officinalis L. cultured in vitro

Salvia officinalis L. (sage) is a valuable medicinal plant from the Lamiaceae family widely used in traditional medicine. Given the therapeutic potential of sage, there is currently great interest in increasing the production of biological material and in stimulating the synthesis of bioactive compounds in this plant. The combined effect of gamma irradiation and in vitro techniques is considered a good tool for improving the physiological and biochemical processes in plants. The aim of the present study was to evaluate the effect of low doses of gamma irradiation (10, 15, and 20 Gy) on the phenolic content, biological activity, and cellular ultrastructure of sage cultured in vitro. Although the increases were not important, gamma irradiation treatment had a stimulating effect on the phenolic content of sage extracts. Due to its constituents, S. officinalis proved to have potent antioxidant capacities and antiproliferative properties on tumoral (A431 cell line) and normal cells (BJ cell line). The irradiation up to 20 Gy did not change the biological activity of sage samples. The use of gamma irradiation on S. officinalis in vitro plantlets influenced the ultrastructure of organelles in two ways: first, it led to chloroplast redifferentiation, and second, had a destructive effect on chloroplast and mitochondria. Although, in general, gamma irradiation had no consistent stimulatory effect on the secondary metabolism of the analyzed plants, data obtained in the present study represent important results that can be used by further studies aimed at increasing the production of the compounds with important biological activities.