There has been increasing interest in the research on flavonoids from plant sources because of their versatile health benefits reported in various epidemiological studies. Since flavonoids are directly associated with human dietary ingredients and health, there is need to evaluate structure and function relationship. The bioavailability, metabolism, and biological activity of flavonoids depend upon the configuration, total number of hydroxyl groups, and substitution of functional groups about their nuclear structure. Fruits and vegetables are the main dietary sources of flavonoids for humans, along with tea and wine. Most recent researches have focused on the health aspects of flavonoids for humans. Many flavonoids are shown to have antioxidative activity, free radical scavenging capacity, coronary heart disease prevention, hepatoprotective, anti-inflammatory, and anticancer activities, while some flavonoids exhibit potential antiviral activities. In plant systems, flavonoids help in combating oxidative stress and act as growth regulators. For pharmaceutical purposes cost-effective bulk production of different types of flavonoids has been made possible with the help of microbial biotechnology. This review highlights the structural features of flavonoids, their beneficial roles in human health, and significance in plants as well as their microbial production.

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Chemistry and Biological Activities of Flavonoids: An Overview

Advances in copper complexes as anticancer agents.

Lignin, a major component of lignocellulose, is the largest source of aromatic building blocks on the planet and harbors great potential to serve as starting material for the production of biobased products. Despite the initial challenges associated with the robust and irregular structure of lignin, the valorization of this intriguing aromatic biopolymer has come a long way: recently, many creative strategies emerged that deliver defined products via catalytic or biocatalytic depolymerization in good yields. The purpose of this review is to provide insight into these novel approaches and the potential application of such emerging new structures for the synthesis of biobased polymers or pharmacologically active molecules. Existing strategies for functionalization or defunctionalization of lignin-based compounds are also summarized. Following the whole value chain from raw lignocellulose through depolymerization to application whenever possible, specific lignin-based compounds emerge that could be in the fu...

Bright Side of Lignin Depolymerization: Toward New Platform Chemicals

Citrus Flavonoids: molecular structure, biological activity and nutritional properties: a review

It would be desirable to establish and standardize methods that can measure the total antioxidant capacity level directly from vegetable extracts containing phenolics. Antioxidant capacity assays may be broadly classified as electron transfer (ET)- and hydrogen atom transfer (HAT)-based assays. The majority of HAT assays are kinetics-based, and involve a competitive reaction scheme in which antioxidant and substrate compete for peroxyl radicals thermally generated through the decomposition of azo compounds. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes colour when reduced. ET assays include the ABTS/TEAC, CUPRAC, DPPH, Folin-Ciocalteu and FRAP methods, each using different chromogenic redox reagents with different standard potentials. This review intends to offer a critical evaluation of existing antioxidant assays applied to phenolics, and reports the development by our research group of a simple and low-cost antioxidant capacity assay for dietary polyphenols, vitamins C and E, and human serum antioxidants, utilizing the copper(II)-neocuproine reagent as the chromogenic oxidizing agent, which we haved named the CUPRAC (cupric ion reducing antioxidant capacity) method. This method offers distinct advantages over other ET-based assays, namely the selection of working pH at physiological pH (as opposed to the Folin and FRAP methods, which work at alkaline and acidic pHs, respectively), applicability to both hydrophilic and lipophilic antioxidants (unlike Folin and DPPH), completion of the redox reactions for most common flavonoids (unlike FRAP), selective oxidation of antioxidant compounds without affecting sugars and citric acid commonly contained in foodstuffs and the capability to assay -SH bearing antioxidants (unlike FRAP). Other similar ET-based antioxidant assays that we have developed or modified for phenolics are the Fe(III)- and Ce(IV)-reducing capacity methods.

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Comparative Evaluation of Various Total Antioxidant Capacity Assays Applied to Phenolic Compounds with the CUPRAC Assay

The Mediterranean diet is rich in vegetables, cereals, fruit, fish, milk, wine and olive oil and has salutary biological functions. Epidemiological studies have shown a lower incidence of atherosclerosis, cardiovascular diseases and certain kinds of cancer in the Mediterranean area. Olive oil is the main source of fat, and the Mediterranean diet's healthy effects can in particular be attributed not only to the high relationship between unsaturated and saturated fatty acids in olive oil but also to the antioxidant property of its phenolic compounds. The main phenolic compounds, hydroxytyrosol and oleuropein, which give extra-virgin olive oil its bitter, pungent taste, have powerful antioxidant activity both in vivo and in vitro. The present review focuses on recent works analysing the relationship between the structure of olive oil polyphenolic compounds and their antioxidant activity. These compounds' possible beneficial effects are due to their antioxidant activity, which is related to the development of atherosclerosis and cancer, and to anti-inflammatory and antimicrobial activity.

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The phenolic compounds of olive oil: structure, biological activity and beneficial effects on human health.

Flavanones in Citrus fruit: Structure¿antioxidant activity relationships

Polyunsaturated fatty acids (PUFAs) have an important role in human diet, both for the prevention and the therapy of different pathologies. In this review, a critical evaluation of PUFAs dietary sources and biological functions in human organism has been done. In particular, the efficacy of omega-3 fatty acids in the improvement of the lipidic pattern and in the excitability of myocardium has been analyzed, and, therefore, their usefulness in the prevention of cardiovascular diseases and postinfarction arrhythmias. As PUFAs are precursors of prostaglandins and leucotriens, which are involved in phlogosis and immune response, a diet rich in fish oil reduces the production of PGE2 involved in many phlogosis events. Moreover, an increase in the eicosapentaenoic acid (EPA) intake leads to a reduction in the production of inflammatory cytokines (interleukin 1, 2, 6 and tumor necrosis factor); so, it is important to use omega-3 in chronic inflammatory diseases, as the rheumatoid arthritis. It seems that omega-3 could prevent the onset of hormone-dependent tumours (i.e. breast and prostatic cancer); in vitro observations, in fact, have shown that the PG of the series 2, derived from omega-6, have a carcinogenic action; instead, the anticancer effect of omega-3 could derive from their effect in antagonizing the formation of such PG; it can be useful, therefore, to increase the dietary omega-3/omega-6 ratio. Moreover, the effects of omega-3 on the anatomic and functional central nervous system development and of their possible therapeutical use in some psychiatric pathologies were evaluated.

Elisa Tripoli

Papers

Citrus Flavonoids: molecular structure, biological activity and nutritional properties: a review

The phenolic compounds of olive oil: structure, biological activity and beneficial effects on human health.

Flavanones in Citrus fruit: Structure¿antioxidant activity relationships

Omega 3 fatty acids: biological activity and effects on human health.

The phenolic compounds of olive oil and human health