To seek out a cheap source of dietary polyphenols and antioxidants along with anti-amylase and anti-glucosidase activities, ethanol extracts of eleven cheap Bangladeshi fruits were investigated. The extracts were also examined for anti-allergic activity using rat peritoneal exudate cells exposed to the calcium ionophore A23187. Phyllanthus emblica (emblic myrobalan) had the highest total polyphenol content (339 mg gallic acid equivalent (GAE)/g), followed by Syzygium cumini (Indian blackberry; 192.3 mg GAE/g), and Aegle marmelos (wood apple; 53.7 mg GAE/g). P. emblica, and S. cumini also exhibited the most potent DPPH radical scavenging activity, with an IC50 of 2.1 and 8.6 μg/mL respectively. These extracts also showed promising reducing powers with P. emblica having the greatest such activity (optical density (O.D.) 1.66), followed by S. cumini (O.D. 1.34), at a concentration of 0.2 mg/mL. The extracts of Artocarpus heterophyllus (jackfruit) and S. cumini showed promising chelating activities. At a concentration of 1 mg/mL, Dillenia indica (chalta) showed the highest inhibition of α-amylase activity (60%), and A. marmelos, D. indica, P. emblica, Spondias dulcis (hog-plum) & S. cumini completely inhibited α-glucosidase activity (100%). Apart from A. heterophyllus, D. indica and Phyllanthus acidus (star-gooseberry), all other extracts inhibited the release of histamine from the peritoneal exudate cells, with S. cumini having the strongest effect. These fruits therefore have activities beneficial to physiological health.
