B type proanthocyanidin

Last updated

B type proanthocyanidins are a specific type of proanthocyanidin, which are a class of flavanoids. They are oligomers of flavan-3-ols.

Contents

Dimeric B type proanthocyanidins

These molecules have the molecular formula C30H26O12 (molar mass : 578.52 g/mol, exact mass : 578.142426).

Molecules with 4→8 bonds

Dimeric 4-8 B type proanthocyanidin chemical structure Dimeric 4-8 Procyanidin B numbered.PNG
Dimeric 4→8 B type proanthocyanidin chemical structure

The 4-8 bond can be in the alpha or in the beta position.

Molecules with 4→6 bonds

chemical structure of a 4-6 dimeric B type proanthocyanidin Dimeric 4-6 Procyanidin B numbered.PNG
chemical structure of a 4-6 dimeric B type proanthocyanidin

Chemistry

B-type procyanidin (catechin dimer) can be converted to A-type procyanidin by radical oxidation. [1]

Dimeric proanthocyanidins can also be synthesized with procyanidin-rich grape seed extracts reacted with flavan-3-ols under acid catalysis. [2]

Trimeric B type proanthocyanidins

Chemical synthesis

A stereoselective synthesis of benzylated catechin trimer under intermolecular condensation is achieved using equimolar amount of dimeric catechin nucleophile and monomeric catechin electrophile catalyzed by AgOTf or AgBF4. The coupled product can be transformed into procyanidin C2 by a known procedure. [3]

Iterative oligomer chemical synthesis

A coupling utilising a C8-boronic acid as a directing group was developed in the synthesis of natural procyanidin B3 (i.e., 3,4-trans-(+)-catechin-4α→8-(+)-catechin dimer). The key interflavan bond is forged using a novel Lewis acid-promoted coupling of C4-ether 6 with C8-boronic acid 16 to provide the α-linked dimer with high diastereoselectivity. Through the use of a boron protecting group, the new coupling procedure can be extended to the synthesis of a protected procyanidin trimer analogous to natural procyanidin C2. [4]

See also

Related Research Articles

Flavan-3-ol Any chemical compound having a flavan skeleton as a core structure with a hydroxy group attached in 3 position

Flavan-3-ols are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2H-chromen-3-ol skeleton. These compounds include catechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, proanthocyanidins, theaflavins, thearubigins.

Catechin A type of natural phenol and antioxidant. A plant secondary metabolite

Catechin is a flavan-3-ol, a type of natural phenol and antioxidant. It is a plant secondary metabolite. It belongs to the group of flavan-3-ols, part of the chemical family of flavonoids.

Proanthocyanidins are a class of polyphenols found in a variety of plants such as blueberry. Chemically, they are oligomeric flavonoids. Many are oligomers of catechin and epicatechin and their gallic acid esters. More complex polyphenols, having the same polymeric building block, form the group of tannins.

Procyanidin

Procyanidins are members of the proanthocyanidin class of flavonoids. They are oligomeric compounds, formed from catechin and epicatechin molecules. They yield cyanidin when depolymerized under oxidative conditions.

Phenolic content in wine

The phenolic content in wine refers to the phenolic compounds—natural phenol and polyphenols—in wine, which include a large group of several hundred chemical compounds that affect the taste, color and mouthfeel of wine. These compounds include phenolic acids, stilbenoids, flavonols, dihydroflavonols, anthocyanins, flavanol monomers (catechins) and flavanol polymers (proanthocyanidins). This large group of natural phenols can be broadly separated into two categories, flavonoids and non-flavonoids. Flavonoids include the anthocyanins and tannins which contribute to the color and mouthfeel of the wine. The non-flavonoids include the stilbenoids such as resveratrol and phenolic acids such as benzoic, caffeic and cinnamic acids.

Trimethylsilyl trifluoromethanesulfonate

Trimethylsilyl trifluoromethanesulfonate is a trifluoromethanesulfonate derivate with a trimethylsilyl R-group. It has similar reactivity to trimethylsilyl chloride, and is also used often in organic synthesis.

Prodelphinidin is a name for the polymeric tannins composed of gallocatechin. It yields delphinidin during depolymerisation under oxidative conditions.

Procyanidin C2

Procyanidin C2 is a B type proanthocyanidin trimer, a type of condensed tannin.

Procyanidin B2

Procyanidin B2 is a B type proanthocyanidin. Its structure is (−)-Epicatechin-(4β→8)-(−)-epicatechin.

A type proanthocyanidins are a specific type of proanthocyanidins, which are a class of flavonoid. Proanthocyanidins fall under a wide range of names in the nutritional and scientific vernacular, including oligomeric proanthocyanidins, flavonoids, polyphenols, condensed tannins, and OPCs. Proanthocyanidins were first popularized by French scientist Jacques Masquelier.

The molecular formula C30H26O12 may refer to:

Procyanidin B1

Procyanidin B1 is a procyanidin dimer.

Procyanidin B4

Procyanidin B4 is a B type proanthocyanidin.

Procyanidin B5

Procyanidin B5 is a B type proanthocyanidin.

Procyanidin B6

Procyanidin B6 is a B type proanthocyanidin.

Procyanidin B8 Chemical compound

Procyanidin B8 is a B type proanthocyanidin.

Procyanidin A1

Procyanidin A1 is an A type proanthocyanidin dimer.

Procyanidin C1

Procyanidin C1 is a B type proanthocyanidin. It is an epicatechin trimer found in grape.

Condensed tannin

Condensed tannins are polymers formed by the condensation of flavans. They do not contain sugar residues.

Gambier (extract)

Gambier or gambir is an extract derived from the leaves of Uncaria gambir, a climbing shrub native to tropical Southeast Asia. Gambier is produced in Indonesia and Malaysia where it was an important trade item into the late nineteenth century. It can be used as a tanning agent, a brown dye, a food additive and as herbal medicine. Also known as pale catechu, white catechu or Japan Earth, it is often confused with other forms of catechu.

References

  1. Conversion of procyanidin B-type (catechin dimer) to A-type: evidence for abstraction of C-2 hydrogen in catechin during radical oxidation. Kazunari Kondo, Masaaki Kurihara, Kiyoshi Fukuhara, Takashi Tanaka, Takashi Suzuki, Naoki Miyata and Masatake Toyoda, Tetrahedron Letters, Volume 41, Issue 4, 22 January 2000, Pages 485-488, doi : 10.1016/S0040-4039(99)02097-3
  2. New Approach for the Synthesis and Isolation of Dimeric Procyanidins. Nils Köhler, Victor Wray and Peter Winterhalter, J. Agric. Food Chem., 2008, 56 (13), pages 5374–5385, doi : 10.1021/jf7036505
  3. Efficient Stereoselective Synthesis of Catechin Trimer Derivative Using Silver Lewis Acid-Mediated Equimolar Condensation. Yukiko Oizumi, Yoshihiro Mohri, Yasunao Hattori and Hidefumi Makabe, Heterocycles, 2011, Volume 83, No. 4, pages 739-742, doi : 10.3987/COM-11-12159
  4. Procyanidin oligomers. A new method for 4→8 interflavan bond formation using C8-boronic acids and iterative oligomer synthesis through a boron-protection strategy. Dennis Eri G., Jeffery David W., Johnston Martin R., Perkins Michael V. and Smith Paul A., Tetrahedron, 2012, volume 68, no 1, pages 340-348, INIST : 25254810