Topical Application of Melatonin in a Grapeseed Oil-based Microemulsion Accelerated Wound Healing in Rat Models

Abstract

Objective: Melatonin has been associated with accelerated tissue regeneration and grapeseed oil has abundant unsaturated fatty acids, particularly linoleic acid that makes it a strong antioxidant, having the potential to promote wound healing by enhancing the presence of free radicals at the wound site. The study is aimed to evaluate the potential of a microemulsion gel using grapeseed oil as the organic phase and melatonin encapsulated in the vesicles to exhibit synergistic wound healing in Swiss albino rats. Materials and Method: Microemulsion containing grapeseed oil encapsulating melatonin was developed using the water-titration method. The surfactant and co-surfactant ratio (Smix) were fixed at 1:1. A pseudo-ternary diagram was used to determine the microemulsion zone and the developed microemulsion was further incorporated in carbopol 934P gel. The formulations were evaluated for their physicochemical properties and cytotoxicity assay. The optimized formulation was topically applied to cutaneous wounds of Swiss albino rat models. 30 Swiss albino rats were divided into five groups of 6 animals each: (i) Negative control group, (ii) Standard marketed formulation treated group, (iii) Optimized microemulsion containing Grapeseed oil and melatonin treated group, (iv) Grapeseed oil treated group and (v) Melatonin treated group. All the rats in each group were topically applied with the desired formulations daily for up to 14 days. Results: The treatment with a formulation comprising 10.18% Grapeseed oil, 24.88% water, and 64.94% Smix exhibited the highest entrapment efficiency of 86.65 ± 1.88% with an enhanced in vitro drug release of up to 83.02 ± 1.09%, also demonstrating first-order release kinetics. Furthermore, it did not inhibit L929 mouse fibroblast cell proliferation up to 500 μg/mL and promoted wound closure prior to other groups. Additionally, increased tissue maturation with higher collagen deposition was mostly seen by day 7. Thus demonstrating it is suitable for dermal application and sustained release of melatonin. The in vivo wound healing study and histological investigations on rat models demonstrated comparable results as observed in the marketed formulation of melatonin. Conclusion: The results showed that GSO oil based microemulsion encapsulating MEL could be a promising wound treatment option to exhibit accelerated wound healing effects.