SALINITY-INDUCED CHANGES IN THE SILYMARIN COMPLEX AND ANTIOXIDANT DEFENSE SYSTEM OF MILK THISTLE (SILYBUM MARIANUM L.) UNDER THE CONDITIONS OF SALINE SOILS OF THE BUKHARA OASIS

Abstract

This thesis examines salinity-induced changes in the silymarin complex and antioxidant defense system of milk thistle (Silybum marianum L.) under the conditions of saline soils of the Bukhara Oasis. Soil salinity causes osmotic imbalance, ion toxicity and oxidative stress, which may alter growth, photosynthetic activity and secondary metabolite biosynthesis. Milk thistle is a valuable medicinal plant because its fruits accumulate the silymarin complex, mainly composed of flavonolignans such as silybin, isosilybin, silychristin and silydianin. The thesis summarizes the adaptive role of antioxidant enzymes, osmoprotectants and phenolic metabolism in regulating silymarin accumulation. Modelled results indicate that moderate salinity may stimulate silymarin biosynthesis, whereas severe salinity can suppress plant growth and reduce metabolic efficiency. The findings are relevant for the cultivation of medicinal plants on saline soils and for improving the quality of pharmacognostic raw material.