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=//Para// aminobenzoic Acid = By Jim Vuong (Note: Please use Safari browser.) 
 * 4-Aminobenzoic acid** (also known as **para-aminobenzoic acid** or **PABA**) is an organic compound with the formula H2NC6H4CO2H. PABA is a white crystalline substance that is only slightly soluble in water. It consists of a benzene ring substituted with an amino group and a carboxyl group. Industrially, PABA is mainly prepared by two routes: reduction of 4-nitrobenzoic acid and the Hoffman degradation of the monoamide derived from terephthalic acid. Food sources of PABA include liver, brewer's yeast (and unfiltered beer), kidney, molasses, and whole grains. (Left: Structure of PABA, Right: Mill Creel Aloe Vera & PABA Lotion (16 fl oz), Down: Synthesis Path)



The most well known property of PABA is as an effective sunscreen, when used topically. Para-aminobenzoic acid is a chemical sunscreen, which absorbs ultraviolet (UV) and visible sun light. It is a UVB absorber, meaning that it can absorb wavelengths between 290-320 nm. Patented in 1943, PABA was one of the first active ingredients to be used in sunscreen. Initially, in vivo studies on mice showed that PABA reduced UV damage. Additionally, PABA was shown to protect against skin tumors in rodents. Animal and in vitro studies in the early 1980's suggested PABA might increase the risk of cellular UV damage. On the basis of these studies as well as problems with allergies and clothing discoloration, PABA fell out of favor as a sunscreen. However, water-insoluble PABA derivatives such as octyl dimethyl PABA (padimate O) are currently used in some products. As an antioxidant, PABA also provides protection against ozone, smoking, and other air pollutants, which damage other cell structures and membranes through oxidative stress. Limiting exposure to the sun and using sunscreen agents can help prevent early wrinkling and skin cancer. PABA is important for healthy hair and skin, and taking it in supplement form may prevent hair loss by protecting hair follicles. Pharmaceutical doses of PABA are indicated for Peyronie's disease, scleroderma, morphea and linear scleroderma. It is also effective in the treatment of vitiligo, a condition that causes discoloration of the skin. PABA has been reported to enhance the effects of cortisone. It may also prevent or even reverse accumulation of abnormal fibrous tissue.

Natural sources of PABA include bran, eggs, kidney, liver, molasses, wheat germ, brewer's yeast, and yogurt. Dietary sources of PABA include bran, kidney, liver, brewer's yeast, molasses, whole grains, wheat germ, yogurt, mushrooms, blackstrap molasses, leafy green vegetables such as spinach, and spinach. In humans, PABA is biosynthesized by intestinal bacteria and appears to be vital to their metabolism.


 * __Chemical and Physical Properties:__**

1 g/90 mL (90 °C) ||
 * [|Molecular formula] || C7H7NO2 ||
 * [|Molar mass] || 137.14 g mol−1 ||
 * Appearance || White crystals ||
 * [|Density] || 1.374 g/mL ||
 * [|Melting point] || 187–189 °C ||
 * [|Solubility] in [|water] || 1 g/170 mL (25 °C)

 Sources: http://en.wikipedia.org/wiki/4-Aminobenzoic_acid http://www.vitamins-supplements.org/aminobenzoic-acid-paba.php http://upload.wikimedia.org/wikipedia/en/e/e9/THFsynthesispathway.png http://upload.wikimedia.org/wikipedia/commons/2/2b/4-Aminobenzoic_acid.svg http://www.healthsuperstore.com/p-mill-creek-aloe-vera-paba-lotio.htm

Comments:  Great Job Jim!!! You even put a comment section for me. Your post is very informative and I learned many things while reading this. I feel like I remember seeing the name of this acid on food labels since things like bran, eggs, and wheat are found in many food products. I thought it was interesting how this acid provides protection against smoking and air pollutants and thats something I would do research on to find out how it works. Overall this is an excellent wiki post! - Anand