Effect of Salinity on Secondary Metabolites and Antioxidant Activity in Callus Extracts of Hyssopus officinalis L.

Callus cultures of medicinal plants have good prospects for biotechnology as sources of bioactive compounds. Hyssop callus cultures (Hyssopus officinalis L.) possess unique chemical composition and properties. To study the factors that enhance the synthesis of bioactive compounds, the author assessed the effect of salinity on the growth, phenolic content, and antioxidant potential in H. officinalis callus cultures. While the content of phenolic compounds and hydroxycinnamic acids was determined using standard methods, the radical absorption activity, reducing capacity, and chelating activity made it possible to measure the antioxidant activity of the callus cultures. High concentrations (200–500 mM) of NaCl suppressed the callus culture growth. The growth agents included three variants: MS-2 (2 mg/L kinetin, 3 mg/L 1-naphthaleneacetic acid), MS-5 (0.8 mg/L 6-benzylaminopurine, 1.5 mg/L 3-indoleacetic acid), and MS-6 (0.2 mg/L 6-benzylaminopurine and 1 mg/L 2,4-dichlorophenoxyacetic acid). The nutrient medium salinity affected the yield of phenolic compounds in the MS-2 callus culture. As the nutrient medium salinity increased, the amount of phenolic compounds went down. Adding 50 and 100 mM NaCl to MS-5 and MS-6 nutrient media boosted the content of phenolic compounds in the callus culture. The total content of hydroxycinnamic acids pointed at a significant decrease in their amount at different NaCl concentrations. Various salt concentrations in the nutrient medium inhibited the antioxidant activity of the callus culture extracts. In this research, salt stress failed to increase the accumulation of phenolic compounds and hydroxycinnamic acids in H. officinalis. callus culture extracts. It also proved ineffective as antioxidant activity catalyst.