Antioxidant activities and flavonoid contents of selected plants belonging to Family Loranthaceae

Abstract

The methanolic extract of three parasitic plants belonging to family Loranthaceae (Plicosepalus acacia, Plicosepalus curviflorus and Phragmanthera austro arabica) were investigated for their antioxidant activity. The free radical and nitrogen oxide scavenging abilities were evaluated using diphenyl-1-picrylhydrazyl (DPPH), and Griess reagent was used to determine the total antioxidant activity. The three extracts showed comparable activities. The three activities ranged from 18 to 56% of the activity of standard ascorbic. The total flavonoid contents were determined and calculated in terms of quercetin which was detected in all the examined extracts. The quercetin concentration was determined using high performance thin layer chromatography using CHCl₃ : MeOH : glacial acetic acid (8.5: 1.5: 0.1) for development. The maximum sensitivity was obtained when the plates were scanned at 360 nm. The concentration of quercetin varied from 0.157 (P. austro arabica) to 0.062 g% (P. acacia) and P. curviflorus contained 0.115 g% w/w quercetin. All validation parameters were found to be satisfactory regarding accuracy, precision, limits of detection and quantitation.

Key words: Loranthaceae, antioxidant, spectrophotometry, high performance thin layer chromatography (HPTLC), flavonoids, quercetin, ascorbic acid.