EFFECT OF IN VITRO DIGESTION ON THE ANTIOXIDANT CAPACITY OF FIVE INDIGENOUS FRUITS OF BANGLADESH

Abstract

Methanolic extracts of five indigenous fruits (Amla, Elephant apple, Hog plum, Olive and Bilimbi) of Bangladesh were evaluated for biochemical properties, bioactive compound and their antioxidant capacity. Furthermore, the present study also investigated the effect of physiological digestion (in vitro) on antioxidant capacity of the studied samples. To improve the knowledge of the antioxidant compound absorption process antioxidant capacity was investigated through ABTS (2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid)), FRAP(Ferric reducing antioxidant power) and DPPH(2,2-diphenyl-1-picrylhydrazyl) assay for undigested and digested extracts. Amla showed the highest value of Vitamin C (523.31mg/100 g FW) and Flavonoid (51.12 mg QE/100 g) in both the case of before and after digestion. On the other hand, maximum value of total phenolics (379.36 mg of GAE/100 g FW) and Flavonol (400.82 µg QE/100g) were found in Elephant apple in both (undigested and digested) condition. All five fruits were significant sources of antioxidants both in terms of total antioxidant capacity and total polyphenols, although results varied significantly (p<0.05) among fruits [1.74–12.66 mg FeSO4.7H2O/ml, 85.67-92.00% inhibition of DPPH• , 88.42- 91.67% inhibition of ABTS• ]. Elephant apple revealed maximum level of DPPH• and ABTS• inhibition and Amla displayed highest value for FRAP (mg FeSO4.7H2O/ml) whereas the other fruits (Hog plum, Bilimbi and Olive) scored lower in the ABTS• , DPPH• and FRAP assay at both (digested and undigested) stage. Fruit types and in vitro digestion exerted significant (p<0.05) effect to all of the indices evaluated.