The analysis of variability of flavonoids, phenolic compounds quantities and antioxidant activity in herb of Polygonum persicaria L.

The aim of the research: to examine the variety of antioxidant activity, flavonoids and phenolic compounds quantity during vegetation in herb, leaves and stems samples of naturally growing lady’s thumb (Polygonum persicaria L.) and variety of these parameters in samples selected from different regions of Lithuania. The objectives of the research: to select optimal conditions for extraction of flavonoids and total phenolic compounds quantity evaluation in samples of lady’s thumb; to evaluate the variety of total flavonoids quantity during vegetation in samples of lady’s thumb herb, leaves and stems and variety of these parameters in samples collected from different Lithuania regions; to evaluate variety of total phenolic compounds quantity in samples of lady’s thumb herb, leaves and stems; to analyse the antioxidant activity of lady’s thumb samples using DPPH and ABTS methods. The methods of the research: the method of spectrophotometry was used to evaluate the total amount of flavonoids and phenolic compounds. The antioxidant activity was established using DPPH, ABTS and spectrophotometry methods. The results of the research: the total amount of flavonoids in herb samples varied from 0.36 to 1.00 %, in leaves samples: 0.46 - 1.13 %, in stems samples: 0.08 - 0.20 %. During vegetation the amount of flavonoids in herb samples varied from 0.36 to 1.03 %. Total amount of phenolic compounds in herb samples varied from 32.12 mg/g to 85.63 mg/g, in leaves samples: 37.84 mg/g - 99.98 mg/g, in stems samples: 18.30 mg/g - 59.71 mg/g. During vegetation the amount of phenolic compounds in herb samples varied: 48.80 mg/g - 70.34 mg/g. Antioxidant activity established using DPPH method in herb samples varied from 36.85 to 81.93 %, in leaves samples: 58.29 - 87.74 %, in stems samples: 22.61 - 77.26 %. During vegetation antioxidant activity in herb samples varied: 55.16 - 84.59 %. Antioxidant activity established using ABTS method in herb samples varied from 23.07 mg/g to 81.92 mg/g, in leaves samples: 32.53 mg/g - 88.48 mg/g, in stems samples: 11.60 mg/g - 59.45 mg/g. During vegetation antioxidant activity in herb differed: 62.27 mg/g - 82.24 mg/g. The conclusions: optimal conditions for extraction of flavonoids: solvent - 80 % (V/V) ethanol, extraction time – 20 min. The greatest quantity of flavonoids, phenolic compounds and antioxidant activity was measured in leaves samples. Meaningful strong correlation was established among antioxidant activity and flavonoids and phenolic compounds quantity (p