Polyhydroxy acids

Composition. Shellac is primarily a mixture of aUphatic polyhydroxy acids in the form of lactones and esters. It has an acid number of ca 70, a saponification number of ca 230, a hydroxyl number of ca 260, and an iodine number of ca 15. Its average molecular weight is ca 1000. Shellac is a complex mixture, but some of its constituents have been identified. Aleuritic acid, an optically inactive 9,10,16-trihydroxypalmitic acid, has been isolated by saponification. Related carboxyflc acids such as 16-hydroxy- and 9,10-dihydroxypalmitic acids, also have been identified after saponification. These acids may not be primary products of hydrolysis, but may have been produced by the treatment. Studies show that shellac contains carboxyflc acids with long methylene chains, unsaturated esters, probably an aliphatic aldehyde, a saturated aliphatic ester, a primary alcohol, and isolated or unconjugated double bonds. 

Vitamin C formulations Alpha hydroxy acids Polyhydroxy acids Beta hydroxy acids... 

Polyhydroxy Acids (PHAs) provide similar effects as AHASjbut do not cause the sensory irritation responses that limit the use of AHAs. PHAs have also been found to have some addi-... 

Grimes PE, Green BA, Wildnauer RH, Edison BL (2004) The use of polyhydroxy acids (PHAs) in photoaged skin. Cutis 73[Suppl 2] 3-13... 

Weerman, R.A. (1918) L action de I hypochlorite de sodium surles amides d a-hydroxy-acides et de polyhydroxy-acides, ayant un group hydroxyle a la place a. Recueil des Travaux Chimiques des Pays-Bas et de la Belgique, yi, 16-51. 

The mucin of the submaxillary gland appears to contain two muco-proteins.170 One js a D-glucosamine-di-n-mannose complex similar to that in the serum proteins, while the other is claimed to be a crystalline substance ChH260iiN, containing D-glucosamine, two acetyl residues and a polyhydroxy acid which is not a uronic acid. It appears to be a type of sulfate-free chondroitin. 

The carbon-chain structure of the sugar obtained from hamameli-tannin was established by the classical method of Kiliani,26 which is based on the reduction, with hydrogen iodide, of polyhydroxy acids to fatty acids. Treatment of the calcium salt of hamamelonic acid under these conditions led to inconclusive results. The reduction of the corresponding, crystalline ammonium salt, however, furnished 3.5 to 5% of 2-methylvaleric acid, which was identified by the properties of its crystalline p-iodophenacyl ester. Thus, it was proved that the sugar must have structure XIV. 

Shellac A natural product from insect secretions. It is a hard tough coating like a varnish, which contains mostly aliphatic polyhydroxy acids about C6o. 

Polyhydroxy acids are split in the characteristic way by periodic acid. Gluconic and saccharic acids, like tartaric acid, yield glyoxylic acid.28-37... 

The reported number of lanolin acids (C7 to C41) varies dramatically from 32 to 138.17 18 21,23-26 The possible explanation for this discrepancy is that different methods were used to produce the alcohols.8 The lanolin acids comprise four major classes normal, iso (co-l-methyl substituted), anteiso (co-2-methyl substituted), and a- and co-hydroxy acids. The relative proportions are 12.1% normal acids, 22.1% iso acids, 26.3% anteiso, 27.1% a-hydroxy acids, and 5.1% co-hydroxy acids.27 28 Minor constituents include polyhydroxy acids (4.7%) and unsaturated acids (2.1%).23-25... 

Kiliani accomplished the purpose of his plan of research he established the aldopentose structure for arabinose and proved that glucose and galactose are aldohexoses and fructose a 2-keto-hexose. His discovery that these polyhydroxy acids lose water readily and pass to stable lactones of crystalline habit soon became of great significance. 

The most suitable use of borate buffers will be in the separations of mixtures of isomeric polyhydroxy acids. The behavior of phosphate, triose phosphate, and hexose phosphate under a variety of conditions in nonborate buffers was examined by Neil and Walker, who found that the... 

This polyhydroxy acid is formed from the chlorogenic acids (Section 2.1.4). 

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