PRELIMINARY PHYTOCHEMICAL SCREENING AND EVALUATION OF IN VITRO ANTIOXIDANT ACTIVITY OF IRAQI SPECIES OF HYPERICUM PERFORATUM AERIAL PART

Abstract

The aim of the presented study is to evaluate the antioxidant activity of Hypericum perforatum fractions (chloroform, ethyl acetate, n-butanol, water and methanol) and compare it with their total phenolic content. The powdered plant was macerated in (80 %) ethanol then fractionated with organic solvents: petroleum ether, chloroform, ethyl acetate, n-butanol and water. In addition, crude methanolic extract was obtained by soxhlet method. Phytochemical screening along with TLC analysis confirmed the presence of many important constituents as: hypericin, flavonoids, phenols and others. The antioxidant activity determined as a percentage of radical scavenging activity by the 2, 2-diphenylpicrylhydrazyl (DPPH) method and total antioxidant capacity by phosphomolybdenum method. Methanol and n-butanol fractions had higher percentage of inhibition (90.4 %, 75 %) respectively while ethyl acetate and chloroform fractions had lower values (34 %, 37 %) respectively, the comparison was made with ascorbic acid (96.3 %). Total antioxidant capacity was higher in methanol and water fractions (1.119, 1.105) respectively while chloroform and ethyl acetate fractions had lower values (0.857, 0.572) respectively. These values compared with the total antioxidant capacity of ascorbic acid (reference standard) which has a value of 0.791. The total phenolic content was higher in chloroform and ethyl acetate fractions (40 and 45 mg/g of dry extract) while n-butanol and water fractions had lower content (16.5 and 18 mg/g of dry extract). So the antioxidant activity is related to the quality not the quantity of phenolics and relation between the antioxidant activity and total phenolic is weak.