Antioxidant and prooxidant properties of flavonoids.

Anthocyanins and betalains play important roles both in plant physiology, visual attraction for pollinators and seed dispersers, but also in food mainly defining its aesthetic value. Since anthocyanin and betalain structures allow to predict only part of their appearance, additional chemical and anatomical functions are required to modulate the appearance of plants and coloured food. Physiological effects that the same pigments exert in plants are supposedly similar to those which they show in humans following ingestion of coloured food. Therefore, anthocyanins and betalains both in fresh and also processed fruit and vegetables serve two functions: They improve the overall appearance, but also contribute to consumers' health and well-being.

Functional properties of anthocyanins and betalains in plants, food, and in human nutrition

Flavonoids are small molecular secondary metabolites synthesized by plants with various biological activities. Due to their physical and biochemical properties, they are capable of participating in plants' interactions with other organisms (microorganisms, animals and other plants) and their reactions to environmental stresses. The majority of their functions result from their strong antioxidative properties. Although an increasing number of studies focus on the application of flavonoids in medicine or the food industry, their relevance for the plants themselves also deserves extensive investigations. This review summarizes the current knowledge on the functions of flavonoids in the physiology of plants and their relations with the environment.

Flavonoids as Important Molecules of Plant Interactions with the Environment

Structure-radical scavenging activity relationships of phenolic compounds from traditional Chinese medicinal plants.

Phenolic compounds form one of the main classes of secondary metabolites. They display a large range of structures and are responsible for the major organoleptic characteristics of plant-derived foods and beverages, particularly color and taste properties. They also contribute to the nutritional qualities of fruits and vegetables. Among these compounds, flavonoids constitute one of the most ubiquitous groups of plant phenolics. Owing to their importance in food organoleptic properties and human health, a better understanding of their structures and biological activities indicates their potentials as therapeutic agents and also for predicting and controlling food quality. Due to the variety of pharmacological activities in the mammalian body, flavonoids are more correctly referred as “nutraceuticals”. Keywords : Bioflavonoids, Structure-Classification, Nutraceuticals, Antimicrobial activities, Anti-oxidant activity, Metabolic effects Tropical Journal of Pharmaceutical Research Vol. 7 (3) 2008: pp. 1089-1099

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Flavonoids as Nutraceuticals: A Review

The relationship between the structural characteristics of 29 flavonoids and their antiradical activity was studied. The obtained results suggest that the free radical scavenger potential of these polyphenolic compounds closely depends on the particular substitution pattern of free hydroxyl groups on the flavonoid skeleton. The possible mechanism of action of flavonoids lacking B ring OHs as free radical scavengers has been proposed.

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Structure-radical scavenging activity relationships of flavonoids

Flavonoids are a group of naturally occurring phytochemicals abundantly present in fruits, vegetables, and beverages such as wine and tea. In the past two decades, flavonoids have gained enormous interest because of their beneficial health effects such as anti-inflammatory, cardio-protective and anticancer activities. These findings have contributed to the dramatic increase in the consumption and use of dietary supplements containing high concentrations of plant flavonoids. The pharmacological effect of flavonoids is mainly due to their antioxidant activity and their inhibition of certain enzymes. In spite of abundant data, structural requirements and mechanisms underlying these effects have not been fully understood. This review presents the current knowledge about structure-activity relationships (SARs) and quantitative structure-activity relationships (QSARs) of the antioxidant activity of flavonoids. SAR and QSAR can provide useful tools for revealing the nature of flavonoid antioxidant action. They may also help in the design of new and efficient flavonoids, which could be used as potential therapeutic agents.

SAR and QSAR of the Antioxidant Activity of Flavonoids

Calculation of Retention Times of Anthocyanins with Orthogonalized Topological Indices

published in Advance ACS Abstracts, November 1, 1995. 0095-233819511635-1034$09.00/0 0 ing various combinations of molecular descriptors. The structures of the flavone derivatives used in this study are shown in Figure 1. A total of 34 descriptors were generated for each flavone derivative. The descriptor pool contained topological and electronic descriptors. The topological descriptors that were calculated include valence connectivity indexes6 0f”’5xv, Wiener number Wand path numbers7 pO-plo, Balaban indexs J, Harary indexes9 HI -&, and molecular topological indexi0 MTI. The electronic descriptors include hardness indexes’ ’ (absolute hardness r, relative hardness qr), energy of the highest occupied molecular orbital E(HOMO), and energy of the lowest unoccupied molecular orbital E(LUMO), topological resonance energy indices’ (topological resonance energy TRE and topological resonance energy per electron TRE(PE)), and the sum of the charges of the atoms located in the chromone moiety

Structure-activity correlation of flavone derivatives for inhibition of camp phosphodiesterase

The relationship between molecular descriptors and the inhibitory activity of aldose reductase (AR) for a series of coumarin and flavonoid derivatives has been investigated using a novel multivariate linear regression based on the ordered orthogonalized descriptor set First, starting from the set of 31 descriptors we produced absolutely the best nonorthogonalized QSAR models with I descriptors (I = 1−7) These models are always better than the models that the most authors achieve by the use of the stepwise inclusion-exclusion procedure In the next step we realized all possible orthogonalization orderings of a given set of N descriptors (there are N! of these) The key result is that some orthogonalization orderings lead to QSAR models with I ordered orthogonalized descriptors that have higher values of both the correlation coefficient R and cross-validated correlation coefficient Rcv than the corresponding models with the same number of nonorthogonalized descriptors In order to achieve the highest poss

The use of the ordered orthogonalized multivariate linear regression in a structure-activity study of coumarin and flavonoid derivatives as inhibitors of aldose reductase

Dušanka Davidović-Amić

Papers

Structure-radical scavenging activity relationships of flavonoids

SAR and QSAR of the Antioxidant Activity of Flavonoids

Calculation of Retention Times of Anthocyanins with Orthogonalized Topological Indices

Structure-activity correlation of flavone derivatives for inhibition of camp phosphodiesterase

The use of the ordered orthogonalized multivariate linear regression in a structure-activity study of coumarin and flavonoid derivatives as inhibitors of aldose reductase