Propylparaben

Food Under FDA regulations, propylparaben is safe to use with a maximum of 0.1% of the weight of the finished food or 200–450 ppm for a variety of foods like coffee extracts, juices, jams, baked goods, and dairy products. It is found naturally in a plant called Stocksia brahuica. It is often used as a food and cosmetic preservative as it has no odor or taste, and does not change the texture. A study of combining plasma-activated water (PAW) with propylparaben shows increased antimicrobial efficacy of PAW for fresh produce sanitation. PAW is used for fresh produce sanitation. However, when used in food applications, its effectiveness decreased because of interfering substances like polysaccharides, proteins, and lipids. With propylparaben and PAW, bacteria undergo more oxidative stress and cell damage, increasing preservation of produce. For now, the potential health risk and residue level of propylparaben with this new method is still unknown. Propylparaben is also used as a food additive, and is designated with the E number E216. Propylparaben is commonly used as a preservative in packaged baked goods, particularly pastries and tortillas. Propylparaben is also a Standardized Chemical Allergen and is used in allergenic testing. Cosmetic Propylparaben is one of the most commonly used paraben in cosmetic formulation. In cosmetic products, propylparaben is typically combined with other parabens (such as methylparaben) or other preservatives to protect against a broader range of microorganisms. Pharmaceutical Used since the mid-1920s as a preservative, parabens are present in eyewashes, pills, cough syrups, injectable solutions, contraceptives, and even weight-gain drinks. much stricter and defined than cosmetics. Propylparaben also cannot be used alone in ophthalmic products such as eyewash, because it may cause irritation at the effective concentration level to have antimicrobial activities. A MES (Maximal Electroshock) test also shows anticonvulsant activity in propylparaben. Since propylparaben has minimum to no toxicity and well absorbed in the GI tract, it can potentially be develop to new anticonvulsant medicine to control seizures. == Chemical properties ==

Propylparaben is a stable and non-volatile compound with antimicrobial properties and has been used as preservatives in food for over 50 years. it is a white crystalline solid with a molecular weight of 202.18 amu. Humans most often absorb the chemical through their skin or ingestion as it is in many cosmetic and food products as an antifungal preservative. It is metabolized in two major pathways leading to the production of either conjugated metabolites or hydrolysates (PHBA, PHHA). These products are excreted from the body in urine. Propylparaben is an effective antimicrobial, especially against green and blue molds on citrus fruits. Its high solubility in water allows it to be applied to the fruits easily. == Synthesis ==

One of the simplest ways to produce propylparaben is through the esterification of 4-hydroxy benzoic acid with propanol using an acidic catalyst. The first major step includes the protonation of the carbonyl due to the acidic conditions. This protonation results in a positive charge on the carbonyl which will offset the electron density from the ester carbon atom, this allows the propanol to preform a nucleophilic attack on the carbonyl. The proton of the nucleophilic propanol is then transferred by the solvent to the esters hydroxyl group. The hydroxyl can then act as a good leaving group and be expelled from the tetrahedral intermediate as water, allowing the ester carbonyl group to reform. Finally, deprotonation of the reformed carbonyl group will produce the final ester product, propylparaben. == Safety ==

Studies on propylparaben, among other parabens, have been raising concerns on possible interaction with and disruption of estrogen in the endocrine system. Exposure to high levels of propylparaben has been correlated to lower sperm and testosterone production in males in animal studies, with one study showing that it can act as an spermicide. Animal studies of propylparaben in the body show that propylparaben is metabolized from the GI tract and excreted rapidly through urine with no accumulation in the body. On cracked or damaged skin, the use of propylparaben in cosmetics or skincare can result in skin sensitization, but for normal skin it is considered safe. The new law bans the manufacture, sale, and distribution of propylparaben and three other additives (brominated vegetable oil, potassium bromate, and Red 3), although it is not related to the endocrine disrupting effects. This is the first law in the U.S. to ban it. == References ==