Biological activity of olive leaf extract and regulation of tissue transglutaminase expression in diabetic wound healing

Abstract

Background and Objective: Impaired wound healing was seriously associated with diabetes. More complications such as microbial infections, delay in fibrogenesis is process and collagen deposition were shown to be linked with hyperglycemia. In this study, an aqueous extract of olive leaf was analyzed for antioxidant activity, wound healing property and then its effect on the activity and expression of tTG was tested in vivo by applying on the wounds of rats with streptozotocin (STZ)-induced diabetes. Methodology: Fifty healthy male wistar rats were treated intravenously with STZ (55 mg kgG1 body weight) to induce diabetes. To evaluate wound healing activity of olive leaf extracts, animals with diabetic wounds were treated topically twice daily with ointments of olive extracts at doses of 2 and 5% (w/w). Wound closer, epithelialization, hydroxyproline (HPX), tissue transglutaminase (tTG) and total antioxidant capacity (TAC) were estimated as parameters of wound healing capacity of olive extracts in diabetic treated and non-treated rats. Also, in vitro phytochemical screening analyses were performed to estimate active constituents present in OLE. Results: In diabetic group, wound healing time was found to be (18.8±0.61) and (16.8±1.3) in OLE wound treated rats at a doses of 2 and 5% compared to non-treated (27.9±0.96) and standard drug (21.5±0.6) respectively. Wound contraction, scar formation and epithelialization processes positively correlated with the increase in the levels of HPX, tTG as markers of collagen deposition and TAC activity and negatively with diabetes (HbA1c)in treated wound tissues. Due to antioxidant and anti-diabetic activity of OLE constituents, particularly oleuropein, collagen deposition and accelerated epithelialization processes were estimated in diabetic wound healing. Conclusion: Finally, the data showed that OLE as ointment in doses of 2 and 5% efficiently accelerates wound healing process via promoting antioxidant capacity, expression of both HPX and tTG, which are essential for collagen deposition and re-epithelialization process. These findings suggested that methanolic extract olive leaf enriched with of oleuropein could be a suitable therapeutic agent for diabetic wound healing.