Evaluation of phenolic compounds and antioxidant activity in Tilia cordata Mill. leaves and flowers.

The aim: To estimate total content of phenolic compounds, total content of flavonoids and antioxidant activity in extracts of leaves and flowers of little-leaf linden. Object and methods: Research object – leaves and flowers of naturally growing little-leaf linden. Spectrophotometric Folin-Ciocalteu method was used for the determination of total content of phenolic compounds in plant material. Specific reaction with AlCl3 was used to determine total content of flavonoids. Two spectrophotometric methods ABTS and CuPRAC were used to determine total antioxidant activity. Phenolic compounds were identified and quantified by HPLC method. Results: Significant (p<0.05) variation of total content of phenolic compounds was determined in leaves and flowers of little-leaf linden during the vegetation period. In leaves the highest (p<0.05) amount of phenolic compounds was determined in early August, in the end of massive flowering, 2013 y. – 77.87 ± 2.94 mg/g, 2014 y. – 89.18 ± 4.04 mg/g. In flowers the highest amounts of phenolic compounds were determined in period of massive flowering (2013 y. 81.58 ± 3.07 mg/g) and in the end of massive flowering (2014 y. 87.72 ± 4.25 mg/g). The highest amount of flavonoids in leaves was determined in early May, in phase of unfolding leaves – 3.68 ± 0.12 mg/g (2013 y.) and 3.37 ± 0.15 mg/g (2014 y.). In flowers the highest (p<0.05) amounts of flavonoids were determined in period of buds and period of massive flowering, respectively, 6.93 ± 0.34 mg/g and 5.93 ± 0.26 mg/g. It was determined, that plant material, which was collected in 2014 y, showed a higher (p