2016, Vol. 4, Issue 6, Part A

author(s)
AP Attanayake, KAPW Jayatilaka and BMAS Malkanthi

abstract
The present study was conducted to evaluate the total flavonoid content, total antioxidant activities and to determine the phytochemical constituents of selected aqueous medicinal plant extracts. The total flavonoid content was determined by aluminium chloride method. The antioxidant activities were determined by three methods namely phosphomolybdenum assay, ferric thiocyanate assay and thiobarbituric acid. L-ascorbic acid was used as the reference compounds in expressing the antioxidant activities by the three assays. The total flavonoid content of plant extracts varied from 1.0 ± 0.1 -7.1±0.1 µgQE/g of dry weight. The antioxidant activities ranged from ascorbic acid equivalents of 102.6 ± 9.2- 542.3 ± 7.2 mg AAE/g of the extract for phosphomolybdenum assay, percentage of inhibition of 56.3-±2.4- 81.1±0.2% for ferric thiocyanate assay and IC₅₀ of 112.4±2.4- 390.8±5.2 μg/mL for thiobarbituric acid assay method. The study demonstrates that the selected medicinal plant extracts possess antioxidant activities with relatively high content of flavonoids.