ABSTRACT
Grape juice and grape skin extracts are important commercial source of polyphenolic compounds which exert different functional properties such as color potential, antimicrobial, antioxidant activity, and health benefits. In this paper we describe a sensitive and specific assay for determination of bioactive polyphenolic compounds in Campbell Early (Vitis labrusca cv. baile). Five polyphenolic components were separated on an Agilent Zorbax Extend C18 Column (250 mm × 4.6 mm × 5 μm) and detected by a diode array detector. The mobile phase was composed of (a) aqueous phosphoric acid (0.2%, v/v); and (b) acetonitrile using a gradient elution. Analytes were performed at 25°C with a flow rate of 0.8 ml/min and UV detection at 280, 360, and 520 nm. All calibration curves showed good linear regression (r2 ≥ 0.9999) within tested ranges. Overall intra- and inter-day variations were less than 1.90%, and the average recoveries were 95.5-105% for analytes. The antioxidant activity determined by DPPH radical assay, ranged from 86-105 for extracts, and 165-252 for studied standards (µM trolox/100 g dry wt.). The proposed method would be sensitive enough and reliable for quality control in functional food and modernization of Campbell Early (Vitis labrusca cv. baile) as potent antioxidant agent.
ABSTRACT
Objective To investigate the optimal extraction technique and antioxidant activity of curcuminoids from Curcuma longa L. Methods The optimized extraction process of curcuminoids from Curcuma longa L. with ethanol as extracting solvent were studied based on orthogonal test.The effect of each factor such as the ethanol concentration, the amount of solvent, extraction temperature and extraction time were investigated based on a single-factor experiment.The effects of extraction yield of curcuminoids under different processing conditions were compared by HPLC method. Content of curcuminoids and antioxidant activity of the extract were used as comprehensive survey index. Free radical scavenging DPPH method was used to assess the antioxidant effect. And the extraction technique parameters were optimized. Results The condition of optimal extraction technique was: ethanol concentration 60%, amount of solvent 20 folds, extraction time 2 h, extraction temperature 90 ℃. Under these conditions, the extraction yield of curcuminoids was 3. 65%. DPPH free radical scavenging yield of the curcumin extract was 79.79%. Conclusion This optimized technology is simple and have a good reappearing rate, and the extracts of Curcuma longa L.show good antioxidant activity.