The study of the total antioxidant capacity of St. John’s Wort (Hypericum perforatum L.) herb

Aim. To determine the total antioxidant capacity of St. John’s Wort herb. Materials and methods. The content of phenolic compounds, anthraquinone derivatives, flavonoids, and derivatives of hydroxycinnamic acids was determined by the spectrophotometric analysis, while organic acids were identified by the alkalimetric method; the antioxidant activity of extracts obtained was evaluated by the potentiometric method. Results and discussion. The total antioxidant capacity of St. John’s Wort herb was 91.35 mmol-equiv/m dry weight, the total content of phenolic compounds was 22.70 mg of gallic acid/mL, anthraquinone derivatives – 0.46 mg of hyperecin/mL, flavonoids – 8.10 mg of rutin/mL, derivatives of hydroxycinnamic acids – 7.90 mg of chlorogenic acid/mL and organic acids – 10.80 mg of citric acid/mL in St. John’s Wort herb extracts obtained during the sequential exhaustive extraction. The correlation analysis showed a very high positive correlation between the antioxidant activity and the total content of phenolic compounds, flavonoids, hydroxycinnamic acid derivatives in St. John’s Wort herb extracts. Conclusions. The total antioxidant capacity of H. perforatum herb was 91.35 mmol-equiv./m dry weight. The results of the analysis of the BAS content and the antioxidant activity of H. perforatum herb extracts revealed that the aqueous extract had a significant content of phenolic compounds, flavonoids, hydroxycinnamic acids, organic acids and the antioxidant activity, while anthraquinone derivatives dominated in 96 and 60 % EtOH extracts. The quantitative analysis showed that flavonoids and hydroxycinnamic acids dominated among phenolic compounds. The results can be applied in developing optimal technologies for obtaining drugs based on the extract of H. perforatum herb.