Enhanced permeability and photoprotective potential of optimized p-coumaric acid-phospholipid complex loaded gel against UVA mediated oxidative stress

Photo-oxidative skin damage is mainly caused by the UV-A radiation of the sun. Synthetic sunscreens used to counter this acts mostly on the superficial skin layer and possess serious side effects. P-coumaric acid (PCA) is a UV-A protective plant phenolic having quick diffusion and distribution in superficial skin layers limiting its application as herbal sunscreen. The present study was designed to formulate an optimized phospholipid complex of PCA (PCAPC) through response surface methodology to enhance its skin permeation to deeper skin layers providing protection against photo-oxidative stress. PCAPC was characterized by FT-IR, DTA, PXRD, TEM, zeta potential etc. PCAPC was then incorporated into a gel formulation (PCAPC-GE) to facilitate its transdermal delivery. Physicochemical properties of the gel were assessed by pH, homogeneity, rheology, spreadability etc. In-vitro SPF and UVA-PF of the gel was evaluated and compared with conventional gel (PCA-GE). Ex-vivo skin permeation flux, permeability coefficient, skin deposition and dermatokinetic analysis were carried out to measure the rate and level of skin permeation. This was accompanied by in-vivo evaluation of PCAPC-GE and PCA-GE in the experimental rat model by measuring the various oxidative stress markers such as superoxide dismutase, catalase etc. PCAPC-GE provided high SPF and UVA-PF value compared to PCA-GE. The physicochemical parameters were suitable for transdermal application. PCAPC-GE enhanced the permeation rate of PCA by almost 6 fold compared to PCA-GE. Besides, a significant reduction of UV-A induced oxidative stress biomarkers were observed for PCAPC-GE. Thus, the PCAPC-GE may be an effective alternative of synthetic sunscreens due to its enhanced permeation and protection against UVA-induced oxidative stress.