Melaleuca leucadendron (L.) L. flower extract exhibits antioxidant and photoprotective activities in human keratinocytes exposed to ultraviolet B radiation.

Recently, there has been a demand for the replacement of chemical sunscreens with natural compounds that could prevent or restore UV-induced skin damage. Here, we investigated the photoprotective influence of the Melaleuca leucadendron ethanolic flower extract (EEMec) on factors involved in cellular and molecular UVB-induced oxidative stress in human skin keratinocytes (HaCaT). The phytochemical constituents, antioxidant potential by DPPH assay, content of total phenolic and flavonoid compounds in EEMec were evaluated. HaCaT cells were treated with EEMec followed by irradiation with UVB. CAT activity; GSH and ROS levels; and SOD1, GPx, CAT and COX-2 expression assays were employed to verify the oxidative stress, as well as EEMec effect on transmembrane transport, and pro-inflammatory and pro-apoptotic protein expression. EEMec reverted the viability loss of HaCaT cells after irradiation with UVB, exhibited significant antioxidant capacity and free radical scavenging activity in vitro, inhibited COX-2 expression and ensure protection of DNA-damage. EEMec shown a great photoprotective property to prevent keratinocytes damage induced by UV radiation and, thus a candidate potential to application as an adjuvant in sunscreen formulations as a strategy to reduce risk of sunburn and prevent skin diseases associated with UV-induced inflammation and cancer.