In organic chemistry, an aldehyde is an organic compound containing a functional group with the structure R−CH=O. The functional group itself can be referred to as an aldehyde but can also be classified as a formyl group. Aldehydes are a common motif in many chemicals important in technology and biology.
Pectin is a heteropolysaccharide, a structural acid contained in the primary lamella, in the middle lamella, and in the cell walls of terrestrial plants. The principal, chemical component of pectin is galacturonic acid which was isolated and described by Henri Braconnot in 1825. Commercially produced pectin is a white-to-light-brown powder, produced from citrus fruits for use as an edible gelling agent, especially in jams and jellies, dessert fillings, medications, and sweets; and as a food stabiliser in fruit juices and milk drinks, and as a source of dietary fiber.
A reducing sugar is any sugar that is capable of acting as a reducing agent. In an alkaline solution, a reducing sugar forms some aldehyde or ketone, which allows it to act as a reducing agent, for example in Benedict's reagent. In such a reaction, the sugar becomes a carboxylic acid.
Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharides consisting of repeating disaccharide units. The repeating two-sugar unit consists of a uronic sugar and an amino sugar, except in the case of the sulfated glycosaminoglycan keratan, where, in place of the uronic sugar there is a galactose unit. GAGs are found in vertebrates, invertebrates and bacteria. Because GAGs are highly polar molecules and attract water; the body uses them as lubricants or shock absorbers.
Aldaric acids are a group of sugar acids, where the terminal hydroxyl and carbonyl groups of the sugars have been replaced by terminal carboxylic acids, and are characterised by the formula HOOC-(CHOH)n-COOH.
A peroxy acid is an acid which contains an acidic –OOH group. The two main classes are those derived from conventional mineral acids, especially sulfuric acid, and the peroxy derivatives of organic carboxylic acids. They are generally strong oxidizers.
Glucuronic acid is a uronic acid that was first isolated from urine. It is found in many gums such as gum arabic, xanthan, and kombucha tea and is important for the metabolism of microorganisms, plants and animals.
The Dakin oxidation (or Dakin reaction) is an organic redox reaction in which an ortho- or para-hydroxylated phenyl aldehyde (2-hydroxybenzaldehyde or 4-hydroxybenzaldehyde) or ketone reacts with hydrogen peroxide (H2O2) in base to form a benzenediol and a carboxylate. Overall, the carbonyl group is oxidised, whereas the H2O2 is reduced.
A sugar acid or acidic sugar is a monosaccharide with a carboxyl group at one end or both ends of its chain.
Uronic acids or alduronic acids are a class of sugar acids with both carbonyl and carboxylic acid functional groups. They are sugars in which the hydroxyl group furthest from the carbonyl group has been oxidized to a carboxylic acid. Usually the sugar is an aldose, but fructuronic acid also occurs. Oxidation of the terminal aldehyde instead yields an aldonic acid, while oxidation of both the terminal hydroxyl group and the aldehyde yields an aldaric acid. The names of uronic acids are generally based on their parent sugars, for example, the uronic acid analog of glucose is glucuronic acid. Uronic acids derived from hexoses are known as hexuronic acids and uronic acids derived from pentoses are known as penturonic acids.
An aldonic acid is any of a family of sugar acids obtained by oxidation of the aldehyde functional group of an aldose to form a carboxylic acid functional group. Thus, their general chemical formula is HOOC-(CHOH)n-CH2OH. Oxidation of the terminal hydroxyl group instead of the terminal aldehyde yields a uronic acid, while oxidation of both terminal ends yields an aldaric acid.
In enzymology, a fructuronate reductase (EC 1.1.1.57) is an enzyme that catalyzes the chemical reaction
In enzymology, a glucuronate isomerase is an enzyme that catalyzes the chemical reaction
Rhamnogalacturonan-II (RG-II) is a complex polysaccharide component of pectin that is found in the primary cell walls of dicotyledonous and monocotyledonous plants and gymnosperms. It is supposed to be crucial for the plant cell wall integrity. RG-II is also likely to be present in the walls of some lower plants. Its global structure is conserved across vascular plants, albeit a number of variations within the RGII side chains have been observed between different plants. RG-II is composed of 12 different glycosyl residues including D-rhamnose, D-apiose, D-galactose, L-galactose, Kdo, D-galacturonic acid, L-arabinose, D-xylose, and L-aceric acid, linked together by at least 21 distinct glycosidic linkages. Some resides are further modified via methylation and acetylation. It moreover supports borate mediated cross-linking between different RGII side-chain apiosyl residues. The backbone consists of a linear polymer of alpha-1,4-linked D-galactopyranosiduronic acid. RG-II can be isolated from different sources, such as apple juice and red wine.
Endo-polygalacturonase (EC 3.2.1.15, pectin depolymerase, pectolase, pectin hydrolase, and poly-α-1,4-galacturonide glycanohydrolase; systematic name (1→4)-α-D-galacturonan glycanohydrolase (endo-cleaving)) is an enzyme that hydrolyzes the α-1,4 glycosidic bonds between galacturonic acid residues:
The Pinnick oxidation is an organic reaction by which aldehydes can be oxidized into their corresponding carboxylic acids using sodium chlorite (NaClO2) under mild acidic conditions. It was originally developed by Lindgren and Nilsson. The typical reaction conditions used today were developed by G. A. Kraus. H.W. Pinnick later demonstrated that these conditions could be applied to oxidize α,β-unsaturated aldehydes. There exist many different reactions to oxidize aldehydes, but only a few are amenable to a broad range of functional groups. The Pinnick oxidation has proven to be both tolerant of sensitive functionalities and capable of reacting with sterically hindered groups. This reaction is especially useful for oxidizing α,β-unsaturated aldehydes, and another one of its advantages is its relatively low cost.
Aromatic acids are a type of aromatic compound. Included in that class are substances containing an aromatic ring and an organic acid functional group. There are several categories of aromatic acids including:
Galactose oxidase is an enzyme that catalyzes the oxidation of D-galactose in some species of fungi.
In organic chemistry, a benzylidene acetal is the functional group with the structural formula C6H5CH(OR)2 (R = alkyl, aryl). Benzylidene acetals are used as protecting groups in glycochemistry. These compounds can also be oxidized to carboxylic acids in order to open important biological molecules, such as glycosaminoglycans, to other routes of synthesis. They arise from the reaction of a 1,2- or 1,3-diols with benzaldehyde. Other aromatic aldehydes are also used.
Guluronic acid is a uronic acid monosaccharide that may be derived from gulose. l-Guluronic acid is a C-3 epimer of l-galacturonic acid and a C-5 epimer of d-mannuronic acid. Along with d-mannuronic acid, l-guluronic acid is a component of alginic acid, a polysaccharide found in brown algae. α-L-Guluronic acid has been found to bind divalent metal ions through the carboxylate moiety and through the axial-equatorial-axial arrangement of hydroxyl groups found around the ring.
