Abstract
Overexposure to solar ultraviolet (UV) radiation is the major cause of a variety of cutaneous disorders, including sunburn, photoaging, and skin cancers. UVB radiation (290–320 nm) causes multiple forms of DNA damage, p53 induction, protein and lipid oxidation, and the generation of harmful reactive oxygen species (ROS). In recent years, botanicals containing polyphenols with antioxidant and anti-inflammatory properties as skin photoprotective agents have emerged. This study evaluated the protective effects of two formulations against UVB-induced damage in a skin cell model. One of the formulations (F2) contained a combination of citrus and olive extracts and the other one (F1) also contained a rosemary extract. The antioxidant capacity of both formulations was estimated by different in vitro methods, and the cell viability, intracellular ROS generation, mitochondrial depolarization, and DNA damage were studied in UVB-irradiated human keratinocytes. Both formulations exerted photoprotective effects on skin cells and decreased mitochondrial depolarization and DNA damage. F1 which contained iridoids, rosemary diterpenes, glycosides and aglycones of citrus flavanones, and monohydroxylated flavones exhibited higher cellular photoprotective effects and mitochondrial membrane potential restoration, as well as an enhanced capacity to decrease DNA double strand breaks and the DNA damage response. In contrast, F2, which contained mostly iridoids, citrus flavanone aglycones, and mono- and dihydroxylated flavones, exhibited a higher capacity to decrease intracellular ROS generation and radical scavenging capacity related to metal ion chelation. Both formulations showed a similar capability to decrease the number of apoptotic cells upon UVB radiation. Based on our results and those of others, we postulate that the stronger capacity of F1 to protect against UVB-induced DNA damage in human keratinocytes is related to the presence of rosemary diterpenes and citrus flavanone aglycones. Nevertheless, the presence of the dihydroxylated flavones in F2 may contribute to inhibiting the generation of metal-related free radicals. To confirm the efficacy of these formulations as potential candidates for oral/topical photoprotection, human trials are required to circumvent the limitations of the cellular model.
Highlights
The skin is the largest organ of the human body, accounting for approximately 15% of total body weight, and it performs vital functions such as thermoregulation and protection against external agents [1]
Alterations in the NF-κB, mitogen-activated protein kinase (MAPK), phosphoinositide-3 kinase (PI3K), and extracellular signal-regulated kinase (ERK1/2) pathways have been found in UV-irradiated cells, and these changes may contribute to the development of skin cancer [10,11]
Photoprotective Effects of the Formulations on the Viability of HaCaT Cells Exposed to UVB Irradiation
Summary
The skin is the largest organ of the human body, accounting for approximately 15% of total body weight, and it performs vital functions such as thermoregulation and protection against external agents [1]. UVA (320–400 nm) accounts for 95% of all solar UV radiation that arrives at the Earth’s surface and plays a crucial role in photoaging, while UVB (280–320 nm) is mainly responsible for sunburn and skin cancers Both UVA and UVB contribute to reactive oxygen species (ROS) generation and oxidative stress [3]. Alterations in the NF-κB, mitogen-activated protein kinase (MAPK), phosphoinositide-3 kinase (PI3K), and extracellular signal-regulated kinase (ERK1/2) pathways have been found in UV-irradiated cells, and these changes may contribute to the development of skin cancer [10,11] Photoaging is another harmful effect of UVB exposure that has been extensively studied. Two specific botanical combinationsofcontaining olive, and rosemary shows were the general structure of the effects phytochemicals declared by the manufacturer in the extracts used to inhibit the harmful of UVB in a skin cell model. Formulations grouped into terpenes (A), flavanones (B), and flavones (C)
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