The DPPH radical is stable and is widely used to evaluate the radical scavenging activity of antioxidant compounds. The ability to act as donor of hydrogen atoms in the transformation of the DPPH radical to its reduced form was investigated for different parts of the gac fruit extract. The amount of gac fruit required to scavenging 50% of DPPH, IC50 are summarised in Table 4. The results show that the antioxidant capacity of all the extracts decreased during maturation of the gac fruit (Table 4). The IC50 by
fractions followed the order: green < yellow < red for peel and pulp. The IC50 value varied from 2.56 to 6.96 mg/g of peel and 2.35 to 5.43 mg/g of pulp fractions. The corresponding value for the aril fraction was 3.66 mg/g, whilst seed had the highest IC50 value (range: 4.20–6.66 mg/g). It was observed that pulp (green) having low IC50 was a very potent radical scavenger. In the DPPH assay, the lower the IC50 the better it is able to scavenge the radicals and thereby break the free radical chain reaction (Lim, Lim, & Tee,2007). The varied radical scavenging activity of the extracts depended on the amount of total phenolic in each fraction (Butsat & Siriamornpun, 2010). These findings support the data previously reported in a study where the antioxidant activity was dependent on the actual composition of the peel and pulp fractions. For example, in the case of pulp (green), the antioxidant activity of the extract IC50 value decreased from green to the full ripe stage, likewise antioxidant activity in peel and seed. The decreases in
the antioxidant activity might be caused by the decreases in the levels of phenolics during the development stage of fruit.