Unripe Carica papaya protects skin keratinocytes against UVB-induced cell death via antioxidative and anti-inflammatory mechanisms

Abstract

Objective: To investigate the mechanisms by which unripe papaya extract (UCP) protects skin keratinocytes from UVB-induced inflammation and apoptosis. Methods: High-performance liquid chromatography was used to identify the phytochemical composition of UCP. The free radical scavenging capacity of UCP was assessed against O 2.-, and H 2 O 2. HaCaT cells were pre-treated with varying concentrations of UCP and exposed to 40 mJ/cm 2 UVB radiation. Cell viability, reactive oxygen species (ROS) levels, apoptotic markers, and inflammatory mediators were evaluated using standard biochemical assays and molecular techniques. Results: UCP treatment significantly improved cell viability and reduced intracellular ROS and the release of O 2.- and H 2 O 2. UCP also inhibited apoptosis, as evidenced by reduced cytochrome c release and suppression of Akt phosphorylation. Additionally, UCP exhibited anti-inflammatory effects by downregulating COX-2 expression, suppressing PGE 2 release, and inhibiting c-Jun and NF-κB signaling pathways. Conclusions: UCP effectively protects skin keratinocytes from UVB-induced oxidative stress, inflammation, and apoptosis. These findings support its potential as a natural therapeutic agent for preventing UV-related skin damage. However, in vivo studies are warranted to confirm its efficacy.