Topical oleic acid reduces nociception and inflammation in a UVB radiation-induced sunburn model in mice

Injuries resulting from sun exposure constitute a public health problem and are characterised by pain, oedema, and erythema. Although generally effective, the available drugs for treating burns cause adverse effects that limit their use, demonstrating the need for new pharmacological options. Natural products, such as oleic acid (OA), which are naturally present in cellular structures and the diet, appear promising therapeutic alternatives due to their antinociceptive, anti-inflammatory, and antioxidant actions. Thus, we evaluated the effects of topical OA (0.3%, 1%, and 3%) in a sunburn model induced by UVB radiation (0.75 J/cm²) in mice and compared these effects with dexamethasone (Dex) 0.1%. We evaluated nociceptive parameters (mechanical allodynia, pain affective-motivational behaviour, and thermal hypersensitivity), inflammatory parameters (paw oedema formation and infiltration of polymorphonuclear cells), and reactive oxygen species levels in the mice's serum. OA (3%) attenuated mechanical allodynia (100% of inhibition), pain affective-motivational behaviour (72 ± 14.05% of inhibition), and thermal sensitivity (100% of inhibition). Furthermore, OA (3%) reduced paw oedema (58.18 ± 11% of inhibition) and polymorphonuclear infiltration (54.35 ± 10% of inhibition) in the mice's plantar tissue and reduced reactive oxygen species serum levels (100% of inhibition). Topical 0.1% Dex showed similar effects to OA on the analysed parameters. Our results suggest that OA is a promising therapeutic alternative for treating inflammatory conditions, such as sunburn.