Ferulic acid photoconversion maintains Nrf2-mediated antioxidant defense against UVA damage

Chronic UVA exposure induces oxidative stress, DNA damage, and ultimately photoaging. Although natural antioxidants are considered safer than synthetic UV filters, many suffer from poor photostability and can even shift toward pro-oxidant activity upon UV irradiation.

To evaluate the photostability and photoprotective efficacy of ferulic acid (FA) and determine whether its photoconversion retains protective activity.

FA photoconversion was analysed by UV-Vis and LC-QTOF-MS. Photoprotective effects were assessed in UVA-exposed HaCaT cells using ROS assays, mitochondrial function, DNA damage markers, RT-PCR, and in-silico docking of FA with Keap1.

Upon UVA exposure, FA converted into caffeic acid (CA), yet both preserved antioxidant potential. FA reduces ROS, stabilizes mitochondria, minimizes DNA lesions, and maintaines normal cell cycle progression. Molecular analysis confirmed docking predicted activation of the Nrf2-Keap1 antioxidant pathway and suppression of oxidative, inflammatory, and apoptotic markers. Notably, FA photoproduct showed no pro-oxidant behaviour and retained its antioxidant activity.

This study demonstrates a unique photoconversion-driven stability, where FA transforms into CA without loss of efficacy. By combining ROS scavenging and Nrf2-mediated gene regulation, FA represents a promising, safe bioactive agent for broad-spectrum sun-care formulations.