Treatment for diabetic ulcer wounds using a fern tannin optimized hydrogel formulation with antibacterial and antioxidative properties

Ethnopharmacological relevance: Blechnum orientate Linn. (B. orientate) is a fern traditionally used by the natives as a poultice to treat wounds, boils, ulcers, blisters, abscesses, and sores on the skin. Aim of the study: To investigate the wound healing ability of a concentrated extract of B. orientate in a hydrogel formulation in healing diabetic ulcer wounds. Materials and methods: The water extract from the leaves of B. orientate was separated from the crude methanolic extract and subjected to flash column chromatography techniques to produce concentrated fractions. These fractions were tested for phytochemical composition, tannin content, antioxidative and antibacterial activity. The bioactive fraction was formulated into a sodium carboxymethylcellulose hydrogel. The extract-loaded hydrogels were then characterized and tested on excision ulcer wounds of streptozotocin-induced diabetic rats. Wound size was measured for 14 days. Histopathological studies were conducted on the healed wound tissues to observe for epithelisation, fibroblast proliferation and angiogenesis. All possible mean values were subjected to statistical analysis using One-way ANOVA and post-hoc with Tukey's T-test (P < 0.05). Results: One fraction exhibited strong antioxidative and antibacterial activity. The fraction was also highly saturated with tannins, particularly condensed tannins. Fraction W5-1 exhibited stronger antioxidant activity compared to three standards (a-Tocopherol, BHT and Trolox-C). Antibacterial activity was also present, and notably bactericidal towards Methicillin-resistant Staphylococcus aureus (MRSA) at 0.25 mg/ml. The extract-loaded hydrogels exhibited shear-thinning properties, with high moisture retention ability. The bioactive fraction at 4% w/w was shown to be able to close diabetic wounds by Day 12 on average. Other groups, including controls, only exhibited wound closure by Day 14 (or not at all). Histopathological studies had also shown that extract-treated wounds exhibited re-epithelisation, higher fibroblast proliferation, collagen synthesis, and angiogenesis. Conclusion: The ethnopharmacological effects of using B. orientate as a topical treatment for external wounds was validated and was also significantly effective in treating diabetic ulcer wounds. Thus, B. orientate extract hydrogel may be presented as a potential treatment for diabetic ulcer wounds. (C) 2016 Elsevier Ireland Ltd. All rights reserved.