Protective effects of Lagerstroemia speciosa extract against UV-A damage on skin cells

Abstract

Ultraviolet (UV)-A radiation stimulates the oxidative stress, expression of inflammatory cytokines, and matrix metalloproteinases (MMPs). These pathways result in death of cells, inflammatory responses, and extracellular matrix degradation that lead to premature skin aging or photoaging. The present study aimed to investigate the protective effect of ethanol extract from Lagerstroemia speciosa flowers (LSE) on UV-A-irradiated human keratinocytes (HaCaTs) and normal human dermal fibroblasts (NHDFs). The HaCaT and NHDF cells were pretreated with LSE for 4 h and then exposed to UV-A. Ultraviolet-A significantly decreased the cell viability, however, LSE significantly increased the viability of the HaCaT and NHDF cells in a dose-dependent manner. To further investigate the protective effects of LSE on UV-A-induced oxidative stress in HaCaT cells, the cellular levels of reactive oxygen species (ROS) and endogenous antioxidant enzymes, including superoxide dismutase, catalase, and glutathione peroxidase, were analyzed. Pretreatment with LSE significantly decreased the intracellular ROS level and increased the activity of antioxidant enzymes. In addition, it also diminished the UV-A-induced elevation of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 expressions in UV-A-irradiated HaCaT cells. Furthermore, LSE decreased MMP-1, MMP-2, and MMP-9 expression and production and increased procollagen type I expression and production in UV-A-irradiated NHDF cells. Taken together, LSE possesses a protective potential against UV-A-induced photoaging in human skin cells via reduction of oxidative stress, inhibition on the expression of inflammatory cytokines and MMPs, and promotion of procollagen type I synthesis. These results suggest that LSE can be a potential therapeutic agent for the prevention of skin photoaging.