Anti-inflammatory and epidermal barrier protecting activities of virgin coconut oil

Abstract

Coconut oil (CO) has been used for centuries as skin moisturizers and disinfectants in Southeast Asia. However, the underlying procedure on the skin protecting activities is still elusive. Thus in the present study, the potential anti-inflammatory and skin barrier protecting activities of CO were investigated using in vitro and in vivo models. The virgin coconut oil (VCO) was extracted using the integrated wet process and its physical, chemical and antioxidant properties were analysed. Furthermore, a comparative study between VCO, refined CO, and main fatty acid derivatives from CO such as myristic and palmitic acid on anti-inflammatory and scratch-wound healing, was tested using in vitro assays. In addition, a double-blinded study on the skin barrier recovery activities using a non-invasive tape stripping method was performed on 10 healthy female subjects. The subjects were topically treated with VCO or palm oil (PO). The results revealed that VCO holds the highest amount of lauric acid (50.23 ± 1.22 %) and possesses excellent antioxidant properties (IC50, 2.842 ± 1.14 mg/L) compared to other samples. VCO exhibited a high percentage of cell viability and tolerance to keratinocytes and fibroblasts at concentrations up to 1.0 mg/mL. Treatment with VCO significantly inhibited the reactive oxygen species, tumour necrosis factor-a, and interleukin-6 production. Furthermore, in the scratch-wound healing study, VCO has significantly (p <0.05) enhanced proliferation and migration of fibroblast cells as compared to the untreated control and other fatty acid derivatives. VCO also exhibited the highest percentage of scratch-wound closure (11.65 ± 8.21 %) compared to other samples. VCO also shows a reduction in hyaluronidase enzymes (31.52 ± 4.60 %) that plays a critical role in wound pathogenesis. In the epidermal damage study by tape stripping method, topical application of VCO indicated a significant reduction of transepidermal water loss compared to PO and untreated control (p <0.05). Improvement in skin hydration was also observed in VCO (30 %) and PO (29 %) treated areas. Interestingly, a statistically significant difference was discovered in ceramides and free fatty acids contents on samples treated with VCO and PO as compared to the untreated samples. The ceramide/cholesterol ratio in VCO treated sample was found to be marginally higher compared to PO and untreated samples. From these findings, VCO was found to significantly improve the skin barrier properties through reduction of inflammation, acceleration of wound closure, and balancing of the stratum corneum lipid composition, compared to PO. Taken together, the results of this study demonstrated that VCO might offer great potential as a topical therapeutic agent, as well as in epidermal barrier repair and protection.