In continuation of our study the in vitro antioxidant activity of some novel quinoxaline derivatives was investigated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) method with respect to ascorbic acid. To determine the antioxidant activity, a number of substituted indoxyls (3A-G), cyclic ketones (2A-G), and quinoxalines (1A-G) were synthesized by both microwave and conventional heating methods. The p...

A xanthone, 1,3,6,7-tetrahydroxy-xanthone (compound (1)) had been isolated from Garcinia benthami Pierre. The isolation was conducted through the chromatography technique and spectroscopy methods by spectroscophyc: mass spectrometry (LC-MS), infra red (IR), UV, 1H-NMR, 13C-NMR (1D and 2D-NMR). Antioxidant activity test by using DPPH (1,1diphenyl-2-picrylhydrazyl) method from the isolated compou...

The DPPH radical scavenging activity of 2',4',6'-trihydroxy- and 2'-hydroxy-4',6'-dimethoxychalcones carrying a 2,3- and 3,4-dihydroxylated, and 3,4,5-trihydroxylated B-ring was evaluated in alcoholic and non-alcoholic solvents. All test compounds scavenged more than two equivalent of radicals by a possible conversion to the corresponding B-ring quinones and in most cases subsequently underwent...

1,1-Dipehnyl-2-picrylhydrazyl (DPPH) radical scavenging activities were found in the extract of dried leaves of oregano (Origanum vulgare). The water-soluble active ingredients were isolated, and their structures were determined to be 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl protocatechuate and 4'-O-beta-D-glucopyranosyl-3',4'-dihydroxybenzyl 4-O-methylprotocatechuate by (1)H-, (13)C-NM...

Pleurotus ostreatus better known as oyster mushroom is widely cultivated and consumed as food in Malaysia. The present study aims to assess the antioxidative potential and total phenolic content of P. ostreatus aqueous extract. The antioxidant activities were evaluated against DPPH and ABTS radical-scavenging activity, ferric-reducing antioxidant power (FRAP) and β-carotene-linoleate bleaching ...

This paper describes the development of an HPLC-UV-MS method for quantitative determination of andrographolide and dehydroandrographolide in Andrographis Herba and establishment of its chromatographic fingerprint. The method was validated for linearity, limit of detection and quantification, inter- and intra-day precisions, repeatability, stability and recovery. All the validation results of qu...

The aim of this study was to compare the contents of the main biochemical compounds and the antioxidant capacity of five Spanish olive oils by four different antioxidant tests and to find out the most valuable oil for disease preventing diets. Fatty acids, sterols and individual antioxidant compounds in Arbequina, Hojiblanca, Extra Virgin, Picual and Lampante Spanish olive oils were determined....

This study aimed to determine total antioxidant and antioxidant activity of selected local varieties of lettuce (Lactuca sativa L.). Five varieties (iceberg, butterhead, romaine, green coral and red coral) were subjected to DPPH radical scavenging activity and ferric reducing antioxidant power assay (FRAP) assays for determination of antioxidant activity. Total phenolic content and total flavon...

The stone fish (Actinopyga lecanora) ethanolic and methanolic tissue extracts were investigated for total phenolic contents (TPCs) as well as antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH(•)) radical scavenging activity and ferric reducing antioxidant power (FRAP) assays. Both extracts showed low amount of phenolics (20.33 to 17.03 mg of gallic acid equivalents/100 g dried samp...

Objective: The present investigation was an attempt to evaluate the phytochemical constituents, free radical scavenging activities and antioxidant properties of the methanol extract of leaves of Hypericum hookerianum. Methods: The total antioxidant activity was assayed by DPPH free radical scavenging assay method. The phytochemicals in the methanol extract of leaves of Hypericum hookerianum wer...