Catechin

Catechins are polyphenolic plant metabolites from the group of flavanols and therefore are universal to the secondary plant substances. They are particularly important because of a high antioxidant potential.

Representative

Catechins are regarded as hydrogenated flavones or anthocyanidins and as derivatives of chroman. The four most common substances of the group can be divided into two pairs of isomers: ( ) -catechin (CAS 154-23-4 ) and ( -)- epicatechin (CAS 490-46-0 ) with the empirical formula C15H14O6 and molar mass 290 g / mol and ( )- gallocatechin (CAS 970-73-0 ) and ( -)- epigallocatechin (CAS 970-74-1 ) with the empirical formula C15H14O7 and molar mass 306 g / mol are found relatively frequently in various plant species. And also, for (-)- Robinetinidol, ( )- Fisetinidol, (-)- Fisetinidol, ( )- Afzelechin, ( )- Epiafzelechin and (-) - Epiafzelechin, usually limited to a few plant species before.

Occurrence, properties, and significance

Catechins are present in many plant tissues, along with other polyphenols ( epigallocatechin usually ) as intermediates in the biosynthesis of other flavonoids. They form the monomeric building blocks of condensed proanthocyanidins, a number of natural tannins, such as in black tea or cocoa, where they also contribute to flavor formation. This degree of condensation up to the Catechingerbstoffe have a solubility in pure ethanol, which is particularly important for the production of drugs. The Catechingerbstoffe belong to the non-hydrolyzable tannins. Other names for Catechingerbstoffe are " condensed tannins " or " condensed anthocyanidins ." The catechol (1,2- dihydroxybenzene ) does not belong in this group of substances, however, is a structural component of catechins.

One finds catechins beyond in many other teas, including white tea, green tea ( epigallocatechin gallate, an ester of gallic acid with epigallocatechin ) and oolong. Here the levels are relatively even higher because the polyphenol of black tea is fermented, a certain amount of catechins to theaflavins. Catechins are also found in vegetables and wine, and in the wood of the eponymous Gerber Acacia Acacia catechu. Also very many varieties of fruit - such as apples, apricots, pears, blackberries, strawberries, raspberries, black currants, peaches, plums, quinces, cherries, gooseberries, cherries and grapes - contain catechins.

Detection reactions

• Reaction of catechins with vanillin and HCl. This reaction produced a characteristic red color from the condensation of catechol with vanillin.
• Proof of phenols with ferric chloride: It comes in a green color.
• Detection with tungstophosphoric acid on phenols: These reduce tungsten phosphoric acid to blue tungsten oxide, which can be detected in the UV.

• The assay can be performed with the phosphotungstic acid - hide powder method or gravimetrically.