For determination of antioxidant activity DPPH is one of the most frequent used method.
In the present study, Methanol Green Grape’s extract, Methanol Black Grape’s extract, Ethanol Green Grape’s extract, Ethanol Black Grape’s extract, Aqueous Green Grape’s and Aqueous Black Grape’s extracts were subjected to DPPH Radical Scavenging Assay. All the extracts were taken in five different concentrations in triplets. The antioxidant activities are expressed as IC50 Value. The result of DPPH Assay is summarized in table…….
In the present study, IC50 value of Methanol Green Grape’s extract is 28.49µg/ml and Methanol Black Grape’s extract is 48µg/ml. Similarly IC50 value of Ethanol Green Grape’s extract is 63.45µg/ml and Ethanol Black Grape’s extract is 81.41µg/ml. Likewise Aqueous Green Grape extract’s IC50 value is 88.8µg/ml and Aqueous Black Grape extract’s IC50 value is 102.54µg/ml. The results showed that the highest antioxidant properties were present in Methanol Green Grape’s extract as compared to rest of all test extracts.
DPPH is based on the principle that a hydrogen donor is an antioxidant. In this method radical scavenger compounds are measured. The antioxidant effect is directly proportional to the disappearance of DPPH in test samples.
Present findings can be correlated with the work done on grape seed and grape pomace extracts by Murthy K.N. et al. (2002), Li H. et al. (2008) and Gengaihi S.E. et al. (2014).
Two varieties “Red Seedless” and “White Seedless” grapes did not have a significant difference in total antioxidant activity Hosseini E. et al. (2014).
In previously generated protocol green grapes did not show good antioxidant activity. Thompson seedless (green) grapes had less antioxidant potential as compared to Pusa navrang variety (black) Sravanthi J. and Gangadhar R.S. (2015).
When different varieties of fruits are compared, it is always the presence and absence of certain phytochemicals in them which enables them to be a good or worst antioxidant. In present finding green and black grapes were compared and results are in coherent with the findings of Handayani V. et al. (2016).
DPPH is a rapid, simple, accurate and inexpensive assay for determining the capability of different compounds to act as free radical scavengers, and to estimate the antioxidant activity of foods and beverages Prakash A. (2001).
The reason why methanolic extract of both black and green grapes exhibited best antioxidant activities respectively might be the polar nature of solvent i.e. methanol. Most of the bioactive components like tannins, alkaloids, glycosides etc. are easily soluble in this solvent. Also methanol’s boiling point is less as compared to ethanol and water i.e. 64.7ºC due to which during extraction process when it comes to evaporation stage, it needs less heat to evaporate and thus extract is damaged less as compared to ethanolic and aqueous extract.
As far as green and black grapes are concerned, green grapes showed best antioxidant activities in all three solvents which could be attributed to its phytochemical properties. It consists of large number of polyphenols such as flavonoids which increases its antioxidant potential and thus adds to its properties.