Glucosidase inhibition and compound identification of stingless bee honey and preserved fruits of Citrus japonica

Abstract

Food preservation has many benefits, such as increasing shelf life, retaining nutritional values and biological activities. In the current study, total phenolic content (TCP), antioxidant and anti-glucosidase activities, and kinetic of glucose inhibition of stingless bee honey, honey mixed with fruits, and extracts of Citrus japonica were evaluated by measuring color of a reaction using a spectrophotometer. The result showed that high TPC was found in ethanol extract of C. japonica leaves and fruits (26.79 ± 6.94 and 12.79 ± 0.87 mg of gallic acid per g extract), while stingless bee honey revealed the highest antioxidant activity (1/EC50 = 0.2921) and honey mixed with fruits revealed the strongest anti-glucosidase activity (1/EC50 = 1.8181), significantly (P-value <0.05). Kinetic of glucosidase inhibition of honey were found as uncompetitive and mixed competitive inhibition, while the honey mixed with fruits showed mixed competitive inhibition. The FTIR and GC-MS analysis demonstrated the presence of several bioactive compounds. Very strong positive relationship between total phenolic content with GC-MS data was found (r = 0.926, P-value < 0.05). This knowledge confirmed that stingless bee honey and honey mixed with fruits had greater anti-diabatic potential in comparison with the extracts of C. japonica leaves and fruits.