Phytochemical analysis, antioxidant and xanthine oxidase inhibitory activity of <i style="">Tephrosia purpurea </i>Linn. root extract

52-58An attempt has been made to search for xanthine oxidase (XO) inhibitors from the root extracts of Tephrosia purpurea Linn. which is traditionally used in folk medicine in India. Root extracts were screened for in vitro antioxidant and xanthine oxidase inhibitory activity. Antioxidant activity was measured using ABTS, DPPH, FRAP and ORAC methods. The enzyme inhibitory activity was tested on purified milk xanthine oxidase. The root extracts and phytochemicals, obtained in distilled water, inhibited bovine milk XO in a concentration-dependent manner, with an additional superoxide scavenging capacity, the average antioxidant activity of T. purpurea root extract in the concentration range of 100-200 g/mL. The reacting system revealed significant antioxidant activity, viz. 42.2 (ABTS), 28.7 (DPPH), 36.5 (FRAP) and 25.6 per cent by ORAC assay. Screening of xanthine oxidase inhibitory activity by extract in terms of kinetic parameters revealed noncompetitive mode of inhibition, where the Km and Vmax values in presence of (25 to 100 g/mL) T. purpurea root extract is 0.18 g and 0.040,0.037,0.034 and 0.030 (g/min) while for control Km and Vmax is 0.21 g and 0.043 (g/min), respectively. The phytochemical analysis revealed presence of significant amount of polyphenols and flavonoids (90% and 80%, respectively). These findings suggest that T. purpurea root extract possess prominent medicinal properties and can be exploited as natural drug to treat the diseases associated with free radical formation, oxidative stress and xanthine oxidase activity

Antioxidant activity and flavonoid derivatives of Plumbago zeylanica

ABSTRACT Plumbago zeylanica (Chitrak) is a useful Indian medicinal plant. The root of the plant and its constituents are credited with potential therapeutic properties. The isolation and spectral data for new flavonoid 2-(2, 4-Dihydroxy-phenyl)-3, 6, 8-trihydroxy-chromen-4-one from the roots of Plumbago zeylanica were determined and the antioxidant activity were studied by free radical scavenging and superoxide radical scavenging assays. The plant roots extract reveled significant antioxidant activity as compared to standard flavonoid (quercetin). The antioxidant activity by DPPH is 96µg/ml and by NBT is 4.6µg/ml which grater than that of standard (Quercetin) 45 µg/ml by DPPH and 10µg/ml by NBT assay. The phytochemical investigation showed presence of flavonoids, tannins and saponins. The total phenolic and total flavonoid content was found to be 260±48.0 and 45.5±5.2 mg of GAE/g and CE/g respectively

Polyphenolic Contents and Antioxidant Properties of Different Grape (V. vinifera, V. labrusca, and V. hybrid) Cultivars

The polyphenolic contents and the antioxidant activity of the skins and pulps of different grape cultivars were estimated using HPLC and DPPH antioxidant assay, respectively. The phenolics and flavonoids identified were quercetin, kaempferol, caffeic acid, p-coumaric acid, cinnamic acid, and (−)-epicatechin. The total phenolic contents were found to be the highest in the grape skin of Flouxa (>400 mg/100 g), followed by Campbell Early and Tamnara (>300 mg/100 g), and then by Red Globe and Ruby Seedless (>250 mg/100 g), and the total phenolic content was the lowest in Italia and Delaware (<60 mg/100 g). The antioxidant activities of the grape extracts varied from 12.5% (Ruby Seedless) to 60.2% (Hongiseul) for skins, whereas the antioxidant activities of the grape extracts varied from 35.4% (Campbell Early) to 84.5% (Hongiseul) for pulps. The grape pulps have stronger antioxidant activities than those of the grape skins. Our results suggest that the phenolic and flavonoid contents in extracts of grape skins and pulps showed statistically significant correlations with the free radical scavenging activity

Temperature-dependent studies on the total phenolics, flavonoids, antioxidant activities, and sugar content in six onion varieties

Heating effect on total phenol, flavonoids, antioxidant activity, and sugar content of six onion varieties has been quantitatively investigated to explore the effect of different temperatures. The onion varieties comprised one red-skinned variety, two white-skinned varieties, and three yellow-skinned varieties. The heating temperature was scanned at 80°C, 100°C, 120°C, and 150°C for 30 minutes each, and quantitative analysis was performed relative to the powdered onion at ambient temperature. Quercetin, glucosides and sugar content were analyzed using high-performance liquid chromatography. The total phenolic and antioxidant content increased in all six varieties. The total flavonoid levels showed a considerable change. On heating the onion samples at 120°C for 30 minutes, the red-skinned variety showed the highest level of total phenolic content [13712.67 ± 1034.85 μg of gallic acid equivalent/g dry weight (μg GAE/g DW)] and total flavonoids [3456.00 ± 185.82 μg of quercetin equivalents/g dry weight (μg Q/g DW)], whereas the content of total phenolics and total flavonoids were 13611.83 ± 341.61 μg GAE/g DW and 3482.87 ± 117.17 μg Q/g DW, respectively, for the yellow-skinned (Sunpower) variety. Quercetin and its glucoside contents increased up to 120°C and then decreased at 150°C, whereas the sugar content continuously decreased with heating. All cultivars showed the same pattern in the heating effect, and the predominant flavonoids were destroyed at higher temperatures. Therefore, it is improper to expose onion powder to a temperature higher than 120°C