Free Radicals and Extrinsic Skin Aging

Abstract

Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS) of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR). It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2 − ∙), hydrogen peroxide (H2O2), hydroxyl radical (OH∙), and singlet oxygen (1O2). The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants) and antioxidants we consume from the food (vitamin A, C, E, etc.). The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

Skin Aging Remedies in Traditional Persian Medicine

“…Although environmental factors like sunlight, air pollution, seasonal changes (especially extreme cold or hot weather), chemical and mechanical stimulation are the main causes of skin aging, internal factors such as genetic, malnutrition, obesity, alcohol consumption, smoking, etc. via the production of free species of oxygen can speed up the process of aging (1)(2)(3).…”

Paulownia tomentosa (Princess Tree) Extract Reduces DNA Damage and Induces DNA Repair Processes in Skin Cells

“…UVR penetrates the skin, reaches the cells, and is absorbed by DNA, leading to the formation of photoproducts that inactivate the DNA functions. Oxidation of DNA can product different types of DNA damages: strand breaks, sister chromatid exchange, DNA-protein crosslinks, sugar damage, abasic sites and base modifications [83,84]; [4]. One of the major DNA oxidation products formed as a result of such damage is 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG).…”

Physical Stability and Antioxidant Activity Assay of a Nanoemulsion Gel Formulation Containing Tocotrienol

“…The skin forms a protective barrier over the body's surface, which is continuously exposed to air, solar radiation, and pollutants that can stimulate the formation of free radicals [1]. The skin's sebum and cell membrane lipids contain an unsaturated fatty acids double chain, which is the main target of free radicals [2].…”

“…However, free radicals can be produced in excess through cigarette smoke, air pollution, ultraviolet (UV) rays, and other means [7], with UV radiation being responsible for up to 80% of the oxidative stress on the skin [1]. Antioxidants prevent the tissue damage caused by free radicals by preventing the excess formation of free radicals.…”