| benzoic acid | C6H5COOH;occurs naturally in gum benzoin; it is used as a food preservative, locally as a fungistatic, and orally as an antiseptic, diuretic, and expectorant. It is excreted rapidly as hippuric acid. Synonym: benzoyl hydrate, flowers of benzoin. (05 Mar 2000) |
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| benzoic | <chemistry> Pertaining to, or obtained from, benzoin. Benzoic acid, or flowers of benzoin, a peculiar vegetable acid, obtained from benzoin, and some other balsams, by sublimation or decoction. It is also found in the urine of infants and herbivorous animals. It crystallizes in the form of white, satiny flakes; its odour is aromatic; its taste is pungent, and somewhat acidulous. Benzoic aldehyde, oil of bitter almonds; the aldehyde, C6H5.CHO, is an intermediate in composition between benzoic or benzyl alcohol, and benzoic acid. It is a thin colourless liquid. Structure: C6H5.CO2H Origin: Cf. F. Benzoique. (06 Aug 1998) |
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| benzoic aldehyde | C6H5CHO;an aldehyde produced artificially or obtained from oil of bitter almond, containing not less than 80% of benzaldehyde; a flavoring agent used in orally administered medicines. Synonym: benzoic aldehyde. (05 Mar 2000) |
| Rambourg's chromic acid-phosphotungstic acid stain | <technique> A stain for glycoproteins, used with an electron microscope, with which ultrathin tissue sections reveal complex carbohydrates in the same locations as shown by Rambourg's periodic acid-chromic methenamine-silver stain. (05 Mar 2000) |
| a1-acid glycoprotein | <biology> Plasma protein of mammals and birds, 38% carbohydrate. In humans a single chain glycoprotein of 39 kD. Increased levels are associated with inflammation, pregnancy and various diseases. (18 Nov 1997) |
| abscisic acid | <biochemistry> A lipid hormone that inhibits cell growth in plants, it is associated with fruit drop, leaf death and seed dormancy. It is synthesised in the plastids from carotenoids. This hormone helps plants deal with water loss, and its effects can be reversed with gibberellins. (06 May 1997) |
| abscisic acid 8'-hydroxylase | <enzyme> Catalyses conversion of abscisic acid to 8'-hydroxyabscisic acid, which rearranges to phaseic acid Registry number: EC 1.14.99.- Synonym: aba 8'-hydroxylase (26 Jun 1999) |
| acetic acid | <chemical> The acid most commonly associated with vinegar, it is the most commercially important organic acid and is used to manufacture a wide range of chemical products, such as plastics and Acetobacter but, except for making vinegar, is usually made through synthetic processes. Derivatives of acetic acid which may be formed by substitution reactions. Mono- and di-substituted, as well as, halogenated compounds have been synthesised. Experimentally, alpha- and n2- substituted acetic acids have been examined for their anti-inflammatory activity and effect on the central nervous system respectively. Additionally, limited exposure data has been collected on dibromo and dichloroacetic acids to determine whether they pose health effects. Synonym: ethanoic acid. (26 Jun 1999) |
| acetoacetic acid | CH3COCH2COOH;one of the ketone bodies, formed in excess and appearing in the urine in starvation or diabetes. Synonym: diacetic acid. (05 Mar 2000) |
| acetohydroxamic acid | C2H5NO2; N-Hydroxyacetamide;an inhibitor of urease, used as adjunctive therapy in chronic urea-splitting urinary infections. (05 Mar 2000) |
| acetrizoic acid | <chemical> A water-soluble, iodinated radiographic contrast medium, used as sodium acetrizoate in hysterosalpingography. Pharmacological action: contrast media. Chemical name: Benzoic acid, 3-(acetylamino)-2,4,6-triiodo- (12 Dec 1998) |
| acetylsalicylic acid | <drug> An odourless, white, slightly bitter drug used to reduce pain, fever, inflammation and sometimes to prevent blood clotting. Also called aspirin. Some people cannot tolerate it because it can cause stomach bleeding, however. It is soluble in both water and alcoholand melts at 132 to 136 degrees C. (06 May 1997) |
| acetyltannic acid | An astringent used for treatment of diarrhoea. Synonym: diacetyltannic acid, tannylacetate. (05 Mar 2000) |
| acid | <chemical, chemistry> A fundamental category of many compounds whose water-based solutions have a sour taste, turn blue litmus paper red and can combine with metals to form salts. They are chemical compounds which yield hydrogen ions or protons when dissolved in water, whose hydrogen can be replaced by metals or basic radicals, or which react with bases to form salts and water (neutralization). An extension of the term includes substances dissolved in media other than water. Specific types of acids include: Arrhenius acid: any chemical that increases the number of free hydrogen ions (H+) when added to a water-based solution. The more free hydrogens produced, the stronger the acid. Bronsted or Bronsted-Lowry acid: any chemical that acts as a proton donor in a chemical reaction. Lewis acid: any chemical that accepts two electrons to form a covalent bond during a chemical reaction. (13 Nov 1997) |
| acid agglutination | The clumping together of certain microorganisms at high hydrogen ion concentration. (05 Mar 2000) |
| acid anhydride hydrolases | <enzyme> A group of enzymes that catalyze the hydrolysis of diphosphate bonds in compounds such as nucleoside di- and tri-phosphates, and sulfonyl-containing anhydrides such as adenylylsulfate. (enzyme nomenclature, 1992). Registry number: EC 3.6 (12 Dec 1998) |