Natural daylight comprises various wavelengths of radiation, including UV (ultraviolet). In general, UV-C is absorbed by the atmospheric ozone layer, whereas UV-B and UV-A can penetrate that ozone layer and reach the earth. Excessive exposure to UV-B and UV-A radiation can have deleterious effects on human beings, including sunburn, sun-damaged skin, cataracts, snow blindness, skin cancer, and immune system deficiencies (van der Leun, 1996; Duthie et al., 1999; Hawk, 1999; Hockwin et al., 1999).
To provide protection from UV-B damage, numerous products have been developed by isolating active compounds from natural sources as well as through chemical synthesis. These are now used commercially as protectants or filters in many industries. However, only a limited number of compounds have been developed to guard against UV-A radiation.
Thanaka has been traditionally used in UV-filtering cosmetics in Myanmar. It absorbs a wide range of UV-A radiation. Because the powder from Thanaka bark has long been used as a cosmetic in Myanmar without causing toxicity, marmesin could be commercially useful as a UV A-blocking product. In addition, the contained active ingredient marmesin might serve in synthesizing even stronger UV A-filtering compounds through structural modifications.
- Se-Hwan, J., Sang-Cheol, L. & Seong-Ki Kim (2004). UV Absorbent, Marmesin, from the Bark
of Thanakha, Hesperethusa crenulata L. Journal of Plant Biology, 47(2), 163-165.
- van der Leun JS (1996) UV radiation from sunlight: Summary, conclusions and recommendations. J Photochem Photobiol B 35:237-244
- Duthie MS, Kimber I, Norval M (1999) The effects of ultra- violet radiation on the human immune system. Br J Dermato1140:995-1009
- Hawk JL (1999) Sunlight and health. BMJ 319:1066-1067
- Hockwin O, Kojima M, Sakamoto Y, Wegener A, Shui YB, Sasaki KJ (1999) UV damage to the eye lens: Further results from animal model studies. Epidemiol 9:39-47