Although relatively little reaches the earth’s surface, UVB radiation possesses much more energy than UVA (remember that energy is inversely proportional to wavelength). By some estimates, UVB is 1,000 times more erythematogenic than UVA. In other words, although more UVA reaches the earth, it is mainly UVB that burns the skin. In contrast, the ability to penetrate the skin is proportional to the wavelength of the radiation. Thus, UVA, with its longer wavelength, can penetrate deep into the dermis of the skin, while UVB is absorbed superficially in the epidermis. (Figure 1)

The epidermis is a physiological barrier that protects the organism against pathogens and chemical or physical damage. Acute UV irradiation can elicit various responses including sunburn, inflammation, DNA damage and apoptosis. Chronic and repetitive UV irradiation can lead to photoaging, sustained immune suppression and carcinogenesis of the skin. (Figure 2) Therefore, adequate protection of skin against the harmful effects of UV irradiation is essential.

Polyphenols are exclusively produced in plants through the phenylpropanoid biosynthetic pathway to help plants combat stress such as UV irradiation and oxidative stress. Several lines of evidence from cell culture, animal experiments, and epidemiological studies suggest that herbal compounds protect human skin from UV radiation. These natural compounds show strong antioxidant effects and also show other biochemical effects in human cells such as enzyme inhibition and anti-inflammatory and anti-carcinogenic capacities. (Table 1) These characteristics make flavonoids potential candidates for photoprotective applications

·Antagonist Effects of Veratric Acid against UVB-Induced Cell Damages. Molecules. 2013,18(5), 5405-5419.

·Korean application No.: 10-2012-0139564 / Filing Date 04 Dec, 2012.

·VageStop