Ultraviolet B-induced oxidative damage in human skin keratinocytes is alleviated by Pinus morrisonicola leaf essential oil through activation of the Nrf2-dependent antioxidant defense system

This is the authors' abstract. We don't add key points for this paper.

Background Ultraviolet B (UVB) radiation contributes to skin disorders such as photodamage, photoaging, and cancer. Natural antioxidants can mitigate UVB-induced damage. Pinus morrisonicola (Taiwan white pine), known for its anti-cancer, anti-inflammatory, and antioxidant properties, is used in health-promoting beverages, but its skin-protective effects remain underexplored.Purpose This study investigates the protective effects of P. morrisonicola leaf essential oil (PMLEO) against UVB-induced damage in HaCaT keratinocytes.Methods HaCaT cells were exposed to UVB and treated with PMLEO. Cell viability, reactive oxygen species (ROS) levels, and antioxidant enzyme expression were assessed. The role of Nrf2, a key antioxidant regulator, was evaluated through knockdown experiments. The effects on UVB-induced melanogenesis were examined via α-MSH secretion followed by p53-mediated POMC expression.Results PMLEO and P. morrisonicola bark essential oil (PMBEO) were non-cytotoxic up to 200 µg/mL. UVB reduced cell viability to 43%, but PMLEO co-treatment significantly restored viability and reduced ROS levels via Nrf2 activation, increasing NQO-1 and HO-1. Nrf2 knockdown impaired PMLEO's protection. PMLEO also inhibited UVB-induced α-MSH secretion by downregulating p53-mediated POMC expression, suggesting an anti-melanogenic effect.Conclusion PMLEO protects dermal keratinocytes against UVB-induced oxidative stress, cell death, and melanogenesis via Nrf2 activation, highlighting its potential as a natural skin protectant.