Abstract
Background. Oxidative stress induced by reactive oxygen and nitrogen species is critically involved in the impairment of β -cell function during the development of diabetes. Methods. HIT-T15 cells were cultured in 5% CO2 and then preincubated with Gelam honey extracts (20, 40, 60, and 80 µg/mL) as well as quercetin (20, 40, 60, and 80 µM), prior to stimulation by 20 and 50 mM of glucose. Cell lysate was collected to determine the effect of honey extracts and quercetin on the stress activated NF- κ B, MAPK pathways, and the Akt (ser473) activated insulin signaling pathway. Results. HIT-T15 cells cultured under hyperglycemic conditions demonstrated insulin resistance with a significant increase in the levels of MAPK, NF- κ B, and IRS-1 serine phosphorylation (ser307); however, Akt expression and insulin contents are significantly decreased. Pretreatment with quercetin and Gelam honey extract improved insulin resistance and insulin content by reducing the expression of MAPK, NF- κ B, and IRS-1 serine phosphorylation (ser307) and increasing the expression of Akt significantly. Conclusion. Gelam honey-induced differential expression of MAPK, NF- κ B, IRS-1 (ser307), and Akt in HIT-T15 cells shows that Gelam honey exerts protective effects against diabetes- and hyperglycemia-induced oxidative stress by improving insulin content and insulin resistance.