Antioxidant activity of safflower leaves and its modification by abiotic factors

Abstract

The purpose of this research was to study the changes in antioxidant activity of safflower leaves extracts under influences of various abiotic factors: a) meteorological conditions of vegetation season; b) time of sowing (fall or spring); c) pre-sowing treatment of seeds with different doses of γ-radiation. The antioxidant activity was determined by potentiometric methods against peroxyl free radicals and expressed as gallic acid equivalent (µMGAE) per g of dry residue of extract. Obtained data showed that the antioxidant activity of extracts from leaves of safflower growing in the same vegetation season had no differences and did not depend on time of sowing (fall or spring). If to compare the different vegetation seasons the differences in antioxidant activity indices was approximately by 2.0 times (in season of 2015-2016 years the antioxidant activity of leaves extracts was in medium 32-34µMGAE/g, but in season of 2016-2017 this index was equal 61-62µMGAE/g. The extracts of leaves collected from safflower, seeds of which were pre-sowing treated with different doses of γ-radiation (50, 100, 150Gy), possessed higher antioxidant activity than the extracts of safflower leaves derived from untreated seeds.