Naturally occurring polyphenols as antioxidants


Naturally occurring polyphenols comprise a wide range of compounds found in plants and algae. Such compounds have shown potential as antioxidant, antimicrobial and neuroprotective agents. The current review delineates the health applications of naturally occurring polyphenols by highlighting their structural activity relationship and mechanisms explaining their action. Structural components that determine the antioxidant activity of polyphenols include hydroxylation especially in the B ring, o-methylation and carbohydrate substitution. Antimicrobial activity of isoflavones, is also influenced by phenolic hydroxylation, prenyl substituents at C6 position and cyclization between hydroxyl and prenyl substituents. Mechanisms of action of polyphenols include scavenging reactive species, inhibition of DNA replication enzymes in bacteria, and inhibition of fatty acid synthase. Potential adverse effects of polyphenols arise with the prooxidant activity noted in in vivo assays.


Polyphenols comprise a wide range of compounds that have multiple phenolic functionalities (Handique and Baruah 163). The compounds occur naturally mainly in higher plants, but also in algae. Naturally occurring polyphenols exhibit a wide range of biological activities and have application in medicine and industries involved in manufacture of products such as dyes (tannins) and plastics (Handique and Baruah 163). In medicine, naturally occurring polyphenols are potential candidates for drugs to combat illnesses such as neural disorders and cancers (Braidy, et al. 368 – 382; Jacquemin, Shirley and Micheu 3115-3130). Naturally occurring polyphenols also possess strong antioxidant activity and are associated with positive outcomes in ailments such as cardiovascular disease, high blood pressure and other diseases associated with oxidative stress (Weichselbaum and Buttriss 158- 163). Polyphenols occurring naturally in plants include flavonoids, catechins and isoflavones. The review presented here discusses the drug development processes from naturally occurring polyphenols highlighting the historical background of the drugs development, rationale for drug design and the mechanisms of drug action and side effects. Searches in online databases such as Sciencedirect, WileyInterscience, SpringerLink, Pubmed and Sage provided the articles for review. Go to part two here.

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