Phenolics are broadly distributed in the plant kingdom and are the most abundant secondary metabolites of plants. Plant polyphenols have drawn increasing attention due to their potent antioxidant properties and their marked effects in the prevention of various oxidative stress associated diseases such as cancer. In the last few years, the identification and development of phenolic compounds or extracts from different plants has become a major area of health- and medical-related research. This review provides an updated and comprehensive overview on phenolic extraction, purification, analysis and quantification as well as their antioxidant properties. Furthermore, the anticancer effects of phenolics in-vitro and in-vivo animal models are viewed, including recent human intervention studies. Finally, possible mechanisms of action involving antioxidant and pro-oxidant activity as well as interference with cellular functions are discussed.

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Plant phenolics: extraction, analysis and their antioxidant and anticancer properties.

Antimicrobial properties of tannins

https://zenodo.org/record/1259683/files/article.pdf

The conversion of procyanidins and prodelphinidins to cyanidin and delphinidin

Extraction and analysis of phenolics in food

Phenolics in Food and Nutraceuticals is the first single-source compendium of essential information concerning food phenolics. This unique book reports the classification and nomenclature of phenolics, their occurrence in food and nutraceuticals, chemistry and applications, and nutritional and health effects. In addition, it describes antioxidant activity of phenolics in food and nutraceuticals as well as methods for analysis and quantification. Each chapter concludes with an extensive bibliography for further reading. Food scientists, nutritionists, chemists, biochemists, and health professionals will find this book valuable.

Phenolics in food and nutraceuticals

Homogeneous polymeric proanthocyanidins have been isolated from 22 plant sources and all are based on a C(4)–C(8)[or C(6)] linked polyflavan-3-ol structure. 13C N.m.r, spectroscopy in 2[H6]acetone–water is used to calculate the ratio of procyanidin to prodelphinidin monomer units, the average heterocyclic ring stereochemistry of the monomers, and the ratio of monomers to chain-terminating units. The majority of polymers isolated in this study possess monomers with predominantly a 2,3-cis stereochemistry [the same configuration as (–)-epicatechin]. The number-average molecular weight, calculated from monomer to terminal unit ratios, of the polymers is 1 500–5 000. The structure of the chain-terminating group is established by thiolysis degradation and g.l.c. analysis of the products.

Polymeric proanthocyanidins. Stereochemistry, structural units, and molecular weight

The phytochemistry of proanthocyanidin polymers.

Means to generate the C-4 carbocations (3) and (4) corresponding to (+)-catechin (1) and (–)-epicatechin (2), respectively, are outlined, and the use of these intermediates for the synthesis of model procyanidins and for the biogenetically patterned synthesis of natural procyanidins is discussed. 13C N.m.r. data for model flavan systems and natural procyanidins are reported and analysed and the information is used to assign the 4R-configuration to four natural procyanidin dimers. The phenomenon of conformational isomerism is demonstrated for the natural procyanidin dimers, and two different forms of restricted rotation about the interflavan bond are proposed. The information is used to clarify many earlier structural anomalies, to predict preferred conformations, and to specify a C(4)–C(8) link for the four principal dimers (B-1–4). The properties of some procyanidin polymers are noted, and structures of opposite helicity are proposed for two of the major types found in nature.

Plant proanthocyanidins. Part 3. Conformational and configurational studies of natural procyanidins

https://www.srs.fs.usda.gov/pubs/ja/ja_williams008.pdf

Lawrence J. Porter

Papers

The conversion of procyanidins and prodelphinidins to cyanidin and delphinidin

Polymeric proanthocyanidins. Stereochemistry, structural units, and molecular weight

The phytochemistry of proanthocyanidin polymers.

Plant proanthocyanidins. Part 3. Conformational and configurational studies of natural procyanidins

Molecular weight profiles of proanthocyanidin polymers