Abstract
BackgroundSinapic acid is a phenolic compound in various plants, including spices, berries, citrus fruits, vegetables, grains, and oil seeds. It has been studied mainly for the various pathological symptoms it induces related to its anticancer, antioxidant, and neuroprotective effects. However, little has been studied about sinapic acid in human keratinocytes (HaCaT). Therefore, this study examined its reactive oxygen species (ROS) scavenging capacity, protective effect against DNA damage, and DNA repair mechanism.MethodsTo confirm the protective effects of sinapic acid on HaCaT irradiated by ultraviolet (UV) B, this study used the water-soluble tetrazolium salts (WST)-1 assay to determine the cytotoxicity of sinapic acid for verifying the cell survival rate and dichlorofluorescein diacetate (DCF-DA) to measure the changes in the concentration of ROS generated by UVB. This study also used the comet assay, cyclobutane pyrimidine dimer (CPD) formation, and malondialdehyde (MDA) assay to measure the degree of protection against cell damage. In addition, this study used quantitative real-time polymerase chain reaction (qRT-PCR) to measure the expression of repaired genes from cell damage.ResultsSinapic acid protects cells from UVB-induced cytotoxicity and reduces ROS generation by UVB. This study showed that sinapic acid reduced the generation of tailed DNA, CPD, and lipid peroxidation, which are the indicators of DNA damage. Depending on the increase in the concentration of sinapic acid, the gene expressions of XPC and ERCC1 (repair factors for damaged DNA) increased.ConclusionsThe findings of this study confirmed that sinapic acid is effective in removing ROS generated by UVB, reducing intracellular damage, and repairing damaged DNA in HaCaT. These results also showed that sinapic acid is effective in DNA damage repair, indicating its protective effect on HaCaT against UVB damage.
Highlights
Sinapic acid is a phenolic compound in various plants, including spices, berries, citrus fruits, vegetables, grains, and oil seeds
This study verified the protective effects of sinapic acid from DNA damage by observing the changes in tailed DNA, cyclobutane pyrimidine dimer (CPD), and lipid peroxidation as the indicators of DNA damage
This study examined the expression of ERCC excision repair 1 (ERCC1), which directly removes the damaged DNA regions, and XPC complex subunit (XPC) that is the first to recognize DNA damage among the genes in which sinapic acid repairs intracellular DNA
Summary
Sinapic acid is a phenolic compound in various plants, including spices, berries, citrus fruits, vegetables, grains, and oil seeds. It has been studied mainly for the various pathological symptoms it induces related to its anticancer, antioxidant, and neuroprotective effects. This study examined its reactive oxygen species (ROS) scavenging capacity, protective effect against DNA damage, and DNA repair mechanism. Ultraviolet (UV) rays are classified into UVC (200–290 nm), UVB (290–320 nm), and UVA (320–400 nm). With a shorter wavelength but higher energy level than UVA, UVB is a strong UV ray that causes sunburns and skin cancer (Kligman et al 1985; Debacq-Chainiaux et al 2005).
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