Solar UV radiation (UVA and UVB) produces reactive oxygen species (ROS), within both dermal and epidermal cells. The reactive oxygen resulted from a dissociation of molecular oxygen in atomic oxygen has high affinity for different organic molecules, increasing their potential for oxidation, which can affect proteins structure, causes local inflammation and initiates several unfavorable skin cell reactions.
Both layers of the skin, epidermis (the upper layer) and dermis (the lower layer) are affected by UV rays. UVB radiation easily penetrates the epidermis and stimulates melanocytes, one of the cells types on the epidermis to produce a brownish pigment called melanin. Melanin protects the skin by absorbing and scattering ultraviolet rays. UVB rays are shorter and are responsible for the sunburns we feel when our skin is unprotected. UVA goes deeper into the skin and cause major changes in the dermis. The collagenous constituents of dermis, responsible for the skin?s strength, show marked alterations in their composition. This radiation is responsible for the acceleration of the skin aging process by breaking down the collagen and elastin tissues. UVA rays cause skin tanning, age spots, and wrinkling of the skin, as well as contribute to the development of skin cancer.
Sunscreen agents with SPF of 15 or greater are considered sun blocks because they may absorb more than 92% of UVB radiation. Currently, there is no standard method to assess sunscreen agents for UVA protection.
Usually, it is recommended to use creams, lotions and mineral make-up with sunscreen capabilities to protect your skin against UVB radiation. However, sun UVB blockers constituents, such as the derivatives of cinnamon (cinnamic aldehyde, cinnamic oil, octyl methoxycinnamate), PABA ( para- aminobezoic acids) and esters or salicylates (octyl salicylates , triethanolamine salicylate) can cause allergic reactions, irritation and might photosensitizes your skin. Titanium dioxide and Zinc oxide reflect radiation and reduce the chance of an allergic skin reaction. However, the researches have been shown that microscopic particles of titanium dioxide, also called nano-particles, may increase the formation of free-radicals (reactive oxygen species) onto the skin.
Topical antioxidants can be effective in protecting against and reversing photodamage of the skin. Researches have been shown that topical vitamin C and E, as well as the mineral selenium can protect against sunburn, suntan and skin cancer. Only certain forms of these antioxidants are stable and active after absorption onto the skin. For example, vitamin C must be non-esterified and has to be acidic, vitamin E must be non-esterified and has to be the isomer, D-alpha tocopherol. Selenium is active only when applied topically as L-selenomethionine. It was also shown that topical application is several times more effective than oral administration of these antioxidants.
Antioxidants found naturally in their milieu, such as herbal extracts or oils are most likely more active than the same isolated antioxidants. For example by looking for vitamin C you may find it in active form and substantial quantities in Rosehip seed extract or oil. Further Sea Buckthorn oil is extremely rich in carotenoids, vitamin E and selenium. It has been already shown the important role of carotenoids in prevention and treatment of different cancer types due to their antioxidant capabilities. There is no wonder that the Russian cosmonauts have been using Sea Buckthorn base creams to protect themselves against cosmic radiation. Grape seed extract is rich in flavonoids and phytochemicals that have antioxidant properties, which some consider are even greater than vitamin C and vitamin E. The most valuable flavonoids in grape seed extract are proanthocyanidins, commonly called PCOs. The experts compare the therapeutic qualities of grape seed extract with those of Pycnogenol, a very powerful and expensive antioxidant used as an alternative treatment for heart and cancer disease.
In conclusion, be careful when select your sun blocker creams, lotions and make-up. They might not be appropriate for your skin type and they can trigger skin damage. For highly UV protection, I recommend the usage of skin care products based on complex combination of antioxidants. Not all antioxidants act in the same way to protect your skin. The richer environment in antioxidants, the greater protection against free radicals (ROS) is expected.