Abstract
Abstract The quantitative and qualitative alterations in phytochemical, enzymatic and metabolic levels of the young quinoa plants in response to osmotic, salt, and combined stress are showed. The link between the antioxidant defence of the quinoa system and stress tolerance to osmotic, salt, and combined stress was demonstrated. The increase acetophenones as antioxidants synthesis with a high positive correlation with the accumulation of phytol and enzymatic antioxidants such as CAT and the radical oxidation marker MDA, but a negative correlation with the content of linoleic and linolenic acid esters are identified. At combine stress of 200 mM NaCl and PEG-induced drought the transition young quinoa plants from eustress to distress was revealed. The identified patterns in plant enzymatic and non-enzymatic antioxidant activity due to both individual and combined stress serve as a crucial foundation for targeted synthesis methods, with potential applications in pharmacology.