Hippophae rhamnoides L. leaf extract augments dermal wound healing in streptozocin-induced diabetic rats

The present investigation was undertaken to determine the healing efficacy of Hippophae rhamnoides L. (sea buckthorn (SBT)) leaf aqueous lyophilised extract (SBTL-ALE) on a diabetic wound model in rats. The effect of SBTL-ALE was also evaluated on human epithelial cell lines (A431) by using in vitro wound closure and transwell migration assays.

A total of four full-thickness excision-type wounds were created on the dorsal surface of streptozocin-induced diabetic rats. The animals were divided into two groups: control rats treated with soft white petroleum jelly and experimental rats treated with SBTL-ALE (5.0%, weight/weight) ointment applied topically, twice daily for seven days.

SBTL-ALE significantly (p<0.05) accelerated the migration of epithelial cells in in vitro wound closure and transwell migration assays. Further, SBTL-ALE augmented the healing process by significantly (p<0.05) enhanced wound area contraction, faster complete epithelial closure, increased hydroxyproline (collagen) and hexosamine levels in diabetic rats. Histopathological findings confirmed the healing potential of SBTL-ALE. Immunohistochemical analyses showed increased expression of transforming growth factor (TGF)-β and α-smooth muscle actin in SBTL-ALE-treated wounds of diabetic rats. Superoxide dismutase, catalase and reduced glutathione levels increased, whereas reactive oxygen levels were decreased significantly (p<0.05) in SBTL-ALE-treated wounds compared to diabetic controls, which conferred redox homeostasis.

Our results suggest that SBTL-ALE accelerated transdermal wound healing in diabetic rats by increasing the rate of wound contraction, enhancing levels of collagen, hexosamine and endogenous antioxidants, and reducing oxidative stress.