Evaluation of antioxidant potential, total phenolic content and phytochemical screening of aerial parts of a folkloric medicine, Haplophyllum tuberculatum (Forssk) A. Juss

Objective: To quantify total phenols, flavonoids and to investigate the in vitro antioxidant power of Haplophyllum tuberculatum (H. tuberculatum) leaves extracts of varying polarities. Methods: The authenticated sample of H. tuberculatum (50 g) leaves was dried under shade, powdered and extracted exhaustively with ethanol by cold percolation method. The alcoholic extract was further partitioned into petroleum ether, acetone, chloroform and methanol to obtain the fractions of varying polarities which were subjected to qualitative phytochemical testing. Total phenolics and flavonoids content in the acetone, chloroform and methanol extracts were quantified by using standard colorimetric methods. Petroleum ether extract was omitted because it did not show the presence of either tannins or flavonoids. In vitro antioxidant activity and total antioxidant capacity were determined by using 1,1 diphenyl-2-picrylhydrazyl radical and phosphomolybdenum reagent. Ascorbic acid was used as a reference antioxidant for comparison purpose. Results: Qualitative phytochemical results of leaves extracts confirmed the presence of major secondary plant metabolites. The extraction of phenolic compounds varied considerably according to the polarity of solvent. The most polar fractions i.e. methanol were observed to have the highest phenolic content (561.22 mg/g of gallic acid equivalent) and flavonoids (165.54 mg/g of quercetin equivalent). Although the free radical scavenging activity of leaves fractions was noted to be slightly lower than the reference compound, a direct relationship was observed between phenolic content and in vitro antioxidant activity. On the other hand, leaves fractions exhibited significant total antioxidant capacity as ascorbic acid equivalent. Conclusions: The aerial part of H. tuberculatum is rich in phenolic compounds which might play a vital role in the discovery of natural antioxidants