Review article chemistry and biological activities of. Flavonoids are able to chelate free radicals immediately by donating a hydrogen atom or by singleelectron transfer. Structure and classification of flavonoids flavonoids occur as aglycones, glycosides and methylated derivatives 4. Basic skeleton structure of flavonoids and their classes. Study of the molecular structure of flavonoid compounds using 1hnmr and cnmr has become the method of choice for structure elucidation of flavonoid compounds. The antioxidant activity of selected representatives of flavonoids, coumarins, and cinnamic acids was examined by measuring their protective action toward linoleic acid peroxidation in micelles of sodium dodecyl sulfate in buffer solution, ph 7. The term flavonoid generally is used to describe a broad collection of. Flavonoids are benzopirone derivatives which are ubiquitous in.
Extraction, detection and identification of flavonoids from. Flavonoids are a group of natural compounds with variable phenolic structures. Chemical properties and analytical methodologies of identification and quantitation in foods and plants. Classification and chemistry flavonoids are phenolic substances isolated from a wide range of vascular plants, and more than 8150 different flavonoids have been. Relationship between chemical structure and antioxidant. The chemical nature of flavonoids depends on their structural class, degree of hydroxylation, other substitutions and conjugations, and degree of polymerization. In addition, the bioavailability of flavonoids to the lens is considered. They are believed to have various bioactive effects including antiviral, antiinflammatory, cardioprotective, antidiabetic, anticancer, antiaging, etc. However, most of their contributions to plant color appear in the petals of flowers.
Flavonoids can be divided into various classes on the basis of their molecular structure. Flavonoids are natural products widely distributed in the plant kingdom and form one of the main classes of secondary metabolites. Cantrell 391 molecular aspects of chemical carcinogens and. Some of the factors influencing the metabolic fate and bioavailability of dietary flavonoids are mentioned below. The name derives from the ancient greek word polus, meaning many, much and the word phenol which refers to a chemical structure formed by attaching to an aromatic benzenoid ring a hydroxyl oh group as is found in alcohols hence the ol suffix.
The 4 main groups of flavonoids are listed in table 1, together with the bestknown members of each group and the food source in which they are present. Structure degradation relationships of flavonoids and. They display a large range of structures and ecological significance e. Isolation and structure characterization of flavonoids. Flavonoids, coumarins, and cinnamic acids as antioxidants in. Thus, a series of 40 flavonoids were investigated with the purpose of correlating these properties via structure and activity.
Their structure is based on a flavan nucleus which consists of three phenolic rings referred to as the a, b and c rings figure 1. They can be used as an initial compound for synthesis of a lot of compounds. Because of their diverse chemical structure and variety resulting from the attached substituents, they have a number of important functions in plants. All contain fifteen carbon atoms in their basic nucleus. Anthocyanidins are a group of phyto chemicals, as natural pigments are responsible for blue. The three phenolic rings are referred to as the a, b, and c or pyrane rings. Interestingly, flavonoids have similar precursors to those utilized for lignin biosynthesis but exhibit a number of basal structures that result in generation of diverse structures including flavones, flavonols, flavan3ols, flavanones, isoflavanones, isoflavans, and pterocarpans fig. Hausen, and karlheinz schulz 387 crystal structures, bonding, and hydrogen bonding in flavonoid compounds joseph s. Flavonoid structural unll flavone structure luteolin flavonol structure myricetin oh anthocyanin structure cyanidin3glucoside figure 4. Flavonoids linus pauling institute oregon state university. The chemical structure corresponds to dihydrokaempferol.
Quercetin, the most abundant dietary flavonol, is a potent antioxidant. The study of flavonoid chemistry has emerged, like that of most natural products, from the search for. Depending on their structure, flavonoids can impact the breakdown of auxin by iaa oxidases and l. Luteolin is a tetrahydroxyflavone in which the four hydroxy groups are located at positions 3, 4 5 and 7. Miller, nd abstract flavonoids occur in most plant species, and account for a significant percentage of the chemical constituents of some. Flavonoids are polyphenolic compounds possessing 15 carbon atoms, two benzene rings joined by a linear three carbon atom chain structure a. Flavonoid is the general name of the compounds based upon a fifteencarbon skeleton. Abstract flavonoids are biologically active low molecular weight secondary metabolites that are produced by plants, with over 10,000 structural. In general, almost all flavonoids occur as glycosides, bonded through the hydroxyl group on ring a or c, if available. The relation between the chemical structure of flavonoids.
Flavonoids as important molecules of plant interactions. These are organized into five subclasses based on their chemical structure. The correlation between chemical structures and antioxidant. This chapter was designed to document useful techniques for isolation and structure characterization of flavonoids. Dec 29, 20 flavonoids are hydroxylated phenolic substances and are known to be synthesized by plants in response to microbial infection. Flavonoids are some of the most common phenolics, widely distributed in plant tissues, and often responsible alongside the carotenoids and chlorophylls for their blue, purple, yellow, orange and red colors. The isolation and structural determination of flavonoids.
Flavonoids also possess other critical functions in defense against microorganisms and germination of pollen 20,21. Quercetin, ubiquitous in plant food sources and a major bioflavonoid in the human diet, may produce antiproliferative effects resulting from the modulation of either egfr or estrogen. Therefore, the chemical structure of flavonoids is a strong determinant of the human bioavailability of flavonoids. The usda database for the flavonoid content of selected foods, released in march 2003, contains information on the most prevalent dietary flavonoids. Pdf isolation and structure characterization of flavonoids. Besides the wellknown methods that have been used so far, we would also put together updated information about novel challenge techniques published in recent articles on isolation and characterization of flavonoids. The relation between the chemical structure of flavonoids and. Flavonoids with 5,7,4trihydroxylflavonoid structures were rapidly degraded by the human intestinal microflora, which in turn, resulted in lesser apparent absorption and excretion in urine over 24 h. Flavonoid structures with specific examples the yellowcolored flavones and flavonols occur in the leaves of some plants. Glycosides of apigenin and luteolin are the most diffuse. The position of hydroxyl groups and other features in the chemical structure of flavonoids are important for their antioxidant and free radical scavenging activities. Recent interest in these substances has been stimulated by the potential health benefits arising from the antioxidant activities of these. Chemically, flavonoids have the general structure of a 15carbon skeleton, which consists of two phenyl rings a and b and a heterocyclic ring c.
Food sources of flavonoids are vegetables, fruits, nuts, seeds, roots, and beverages like tea and wine. Using the glutathione trapping method followed by hplc, 1h nmr, malditof, and lcms analysis to identify the glutathionyl adducts, the chemical behavior of the quinonesquinone methides of the different flavonoids could be deduced. Types of phytochemicals phytochemicals phenolic acids flavonoids anthocyanins, flavones, flavanones, isoflavones flavonols flavanols catechins and epicatechins proanthocyanidins procyanidins prodelphinidins. Flavonoids are low molecular weight polyphenolic substances based on the flavan nucleus. Chemical structuredependent differential effects of. Flavonoids have specific chemical structure, which can undergo metal ion chelation process. Flavonoids are hydroxylated phenolic substances and are known to be synthesized by plants in response to microbial infection. Flavonoids are naturally occurring compounds present in plants. Flavonoids or bioflavonoids from the latin word flavus, meaning yellow, their color in nature are a class of polyphenolic plant and fungus secondary metabolites chemically, flavonoids have the general structure of a 15carbon skeleton, which consists of two phenyl rings a and b and a heterocyclic ring c. Introduction bioflavonoids bfs are a large, exceptional group of natural plant components, all very similar in chemical structure. The unique structure and combination of different flavonoids in each species produce yellow pollen with a range of visible and uv reflection spectra that can be detected by the targeted insects and larger animals, facilitating successful pollination. Extraction, detection and identification of flavonoids from microalgae. Flavonoids and their properties to form chelate complexes.
Flavonoids belong to a group of natural compounds with variable low molecular weight polyphenolic structures found in material of plant origin. The structure and distribution of the flavonoids in plants. Their structures and chemical bonds were analyzed using ultravioletvisible spectrophotometer uvvis spectrophotometer, fourier transforminfra red spectroscopy ftir, nuclear magnetic resonance nmr c and 1h,lcms, dsc, sem and edx techniques. General chemical structure of flavonoids and their different classes. The structures of coumarin and its derivatives are as shown below. Pdf flavonoids continue to capture the interest of scientists from many different disciplines because of their structural diversity, biological and. Structure solubility relationships and thermodynamic aspects of solubility of some flavonoids in the solvents modeling biological media. Such structural differences determine their biological behaviours and the interactions among flavonoids or between flavonoids and other non flavonoid antioxidants from the same whole fresh foods like fruits.
Introduction in recent years there is an increase in the areas related to newer developments in prevention of disease especially the role of flavonoids and phenolic acids as antioxidants moreover flavonoids and phenolic acids components play important roles in the control of different human. Flavonoids have a diversity of chemical structures constituted of 15 carbon atoms in their basic skeletons with a c 6 c 3 c 6 framework made by two aromatic rings a and b linked. Flavonoids are one of the most studied phytochemicals due to their diverse health benefits. A wide range of flavonoids with various chemical structures was associated with different antiinflammatory mechanistic effects 44. Structure activity relationship sar a myriad of epidemiological studies have suggested a negative correlation between medicinal flavonoids consumption and development of various diseases,, thereinto, flavonoids with typical structures can interact with enzyme systems involved in crucial pathways, showing effective polypharmacological behaviors. Flavonoid structure, function, and biosynthesis in plants flavone ring structures are found in fruits, vegetables, grains, nuts, stems, leaves, flowers and roots and are ubiquitous throughout nature, playing an integral role in plant growth and development harborne, 1973. Flavonoids contain a backbone of two benzene rings linked by a chain containing three carbon atoms, which joins to form a heterocycle in which oxygen is the noncarbon atom. Pdf molecular mechanisms of antiinflammatory activity. This compound comprises a variety of structurally diverse chemicals, with flavonoids as their largest group.
Cumulative representation of roles of flavonoids in various bioactivities, human health. Extraction, detection and identification of flavonoids. Their basic structure is a skeleton of diphenylpropane, namely, two benzene rings ring a and b, see figure linked by a three carbon chain that forms a closed pyran ring heterocyclic ring containing oxygen, the c ring with benzenic a ring. Investigation of flavonoids bearing different substituents. Chemical and structural properties of chalcones i begum evranos aksoz, rahmiye ertan chemical and structural properties of chalcones i chalcones belong to the flavonoid family and display several pharmacological activities which are very important. Flavonoids classification, isolation and identification 1. Science college, nashik05, maharashtra, india corresponding author abstract introduction micro algae are naturally present in ponds. Flavonoids have demonstrated in vivo and in vitro leishmanicidal, trypanocidal, antioxidant, and prooxidant properties.
Flavonoids with 5,7,4trihydroxyl flavonoid structures were rapidly degraded by the human intestinal microflora, which in turn, resulted in lesser apparent absorption and excretion in urine over 24 h. Each group of flavonoids possesses unique chemical properties and has a particular distribution in plants. The chemotherapy of trypanosomiasis and leishmaniasis lacks efficacy, presents high toxicity, and is related to the development of drug resistance. The chemical nature of flavonoids varies according to the hydroxylation pattern, conjugation between the aromatic rings, glycosidic moieties, methoxy groups and other substituents 3739. The term polyphenol has been in use at least since 1894. Chemical structure of polyphenols the term polyphenols refers to a wide variety of molecules that can be divided into many subclasses, subdivisions that can be made on the basis of their origin, biological function, or chemical structure. Because of their diverse chemical structure and variety. Structureradical scavenging activity relationships of. Reprinted, with permission, from kumar, et al5 figure 2. Flavonoids are characterized by the presence of 15 carbon atoms in their basic skeleton, arranged in the form c6c3c6, which corresponds to two aromatic rings a and b linked by a unit of three carbon atoms, which may or may not give rise to a third ring. Structure radical scavenging activity relationships of flavonoids dragan ami,a, duanka davidoviami,a drago belo,a and nenad trinajstib afaculty of agriculture, the josip juraj strossmayer university, p. Quercetin is a polyphenolic flavonoid with potential chemopreventive activity. Flavonoids are the wide group of compounds, which demonstrate the properties to form chelate complexes.
The chemical structures of the flavonoids have been characterized by constitutional descriptors, twodimensional topological and connectivity indices. C3c6 skeleton, have been found in plants, and are divided into several classes, i. The molecular structure of each group of flavonoids is given in figure 1. Recent interest in these substances has been stimulated by the potential health benefits arising from the antioxidant activities of these polyphenolic compounds. Flavonoids have been recognised as one of the largest and most widespread groups of plant secondary metabolites, with marked antioxidant properties. Flavonoids or bioflavonoids from the latin word flavus, meaning yellow, their color in nature are a class of polyphenolic plant and fungus secondary metabolites. Laurifolin flavonoid c20h20o6 cid 44257868 structure, chemical names, physical and chemical properties, classification, patents, literature, biological. Weston eh graham centre, charles sturt university, wagga wagga, nsw 2678, australia email. The capacity of flavonoids to act as antioxidants depends upon their molecular structure.
Chemical shifts and signal multiplicity of specific atoms and clutch with other atoms in the molecule allows for the identification of aglycone structure, glycosylation pattern. Aspects of the relationships between chemical structure and sensitizing potency of flavonoids and related compounds helmut w. Flavonoids as important molecules of plant interactions with. Flavonoids classification, isolation and identification. Nov 18, 2015 flavonoids classification, isolation and identification 1. Flavonoids are not produced in animals, but only in plants, and are classified based on the chemical structures of the c ring as illustrated in scheme 1. Solubility of flavonoids in organic solvents journal of. Our pls model gave a proper description and a suitable. Review article chemistry and biological activities of flavonoids. Isolation and structure identification of flavonoids intechopen. Flavonoids, a class of polyphenol secondary metabolites, are presented broadly in plants and diets. Chemical structure dependent differential effects of flavonoids on the catalase activity as evaluated by a chemiluminescent method nataliya doronicheva, hiroyuki yasui, and hiromu sakurai department of analytical and bioinorganic chemistry, kyoto pharmaceutical university.
Results are expressed as relative antioxidant efficiency rae, defined as the ratio of the antioxidant efficiency ae of the tested compound to. Flavonoids are small molecular secondary metabolites synthesized by. The plant phenolic compounds 8,000 phenolic structures known account for 40% of organic carbon circulating in the biosphere evolution of vascular plants. The chemical structure of flavonoids are based on a c15 skeleton with a chromane ring bearing a second aromatic ring b in position 2, 3 or 4 structure b. They belong to a class of lowmolecularweight phenolic compounds that are widely.