7 Flavonoids in some Iranian Angiosperms

All flavonoids contain fifteen carbon atoms in their basic nucleus and these are arranged in a C6-C3-C6 configuration, that is, two aromatic rings linked by a three carbon unit which may or may not form a third ring. They are divided into different groups depending on the configuration of the rings and substitutions on these rings of a variety of side-groups which characterize the individual compounds [Stace 1980] (Scheme 1).


Occurance
Flavonoids are found in fruit, vegetables, grains, bark, roots, stems, leaves, flowers, tea and wine [Middleton 1998, Robles et al 2003].The flavonoid nucleus is normally linked to a sugar moiety to form a water-soluble glycoside.Most flavonoids are stored in the plant cell vacuoles, although they also occur on the surfaces of leaves and stems (Farman 1990).In contrast to earlier studies, all these compounds are no longer judged as waste products, nor as evolutionary remnants without current function, nor as mere metabolic end products that are toxic to the plant and are therefore to be stored away in vacuoles [Parr and Bolwell 2000].

Biological activities and their usages
Flavonoids possess a wide range of biological activities, medicinal and pharmacological effects [Parr and Bolwell 2000, Noori 2002, Noori et al 2009].

Biological activities
A large variety of colours such as orange, scarlet, crimson, mauve, violet, blue and purple that we encounter in different part of plants, especially flowers and fruits, are caused by anthocyanins (=anthocyanidin glycosides).Chalcones and some flavones and flavonols also absorb light in the visible region and are associated with bright yellow or cream coloured flowers.Other flavones account for the whiteness in most white flowers, without which they would perhaps appear translucent.Even some of the brown and black pigments found in plants are either due to oxidative products of flavonoids or related phenolic compounds.[Farman 1990].They are beneficial for the plant itself as physiological active compounds, as stress protecting agents, as attractants or as feeding deterrents, and, in general, by their significant role in plant resistance [Treutter 2006].Also these compounds serve essential functions in plant reproduction by recruiting pollinators and seed disperses.They are also responsible for the beautiful display of fall color in many plant species, which has recently been suggested to protect leaf cells from photo-oxidative damage, thereby enhancing the efficiency of nutrient retrieval during senescence [Field et al 2001].

Medicinal and pharmacological effects
Flavonoids medicinal and pharmacological effects are their contributions to human health which has made them prominent in the past 10 years (Parr and Bolwell 2000).Many flavonoids are active principles of medicinal plants and exhibit pharmacological effects [Yilmaz and Toledo 2004].

Chemotaxonomy
Flavonoid compounds are taxonomically important.They are popular characters for chemosystematic studies because: the almost universal presence of flavonoids in vascular plants; 2. Their structural diversity; 3. The fact that each species usually contains several flavonoids; 4. The chemical stability of many flavonoids in dried plant material enabling herbarium material to be used; 5. Flavonoid profiles using different chromatographic techniques are easily obtained.6. Flavonoids are reasonably easy to identify using published www.intechopen.com

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UV spectra data and available standards; 7. Flavonoids often show correlations with existing classifications at the family, genus and species level, and support revisions of existing classifications at the family, genus and species level.However, flavonoids rarely provide key characters (the flavonoid may be absent in one or more members of the taxon, and the same flavonoid may occur in an unrelated taxon, e.g.isoflavonoids occur in the Leguminosae and Iridaceae and biflavonyls in the Gymnospermae and some Angiospermae) [Harborne and Turner 1984].

Flavonoids in Leguminosae
The Leguminosae is economically the single most important family in the dicotyledonae, and also of major significance in nature The family is especially rich in flavonoids, producing about 28% of all known flavonoids and 95% of all isoflavonoid aglycones (Hegnauer and Grayer-Barkmeijer 1993).The importance of the phenolic constituents in the family has been stressed by Bate-Smith (Bath-Smith 1962).As Gomes et al (1981a) showed in "Advances in Legume Systematics" the Leguminosae are especially well endowed with flavonoid constituents, many of which are only known in these plants.Whithin the Leguminosae, some 850 compounds, including 362 isoflavones, are known [Dewick 1993].There is a basic structures, Such as genistein (4´, 5, 7-trihydroxyisoflavone), 5-dexy derivatives (some 66% of structures), prenylated derivatives (some 51% of structures) and compounds with extra hydroxylation (e. g. at the 6-, 8-or 2´-positions).Isoflavonoids usually occur in the free state, and are obtained from root, wood, bark or seed rather than leaf or flower [Ingham 1981[Ingham , 1983]].Flavonoids, as distinct from isoflavonoids and neoflavonoids, are widespread in the Papilionoidaea and there is little doubt that they occur not only in the species of the some tribes, but will eventually be found in all tribes [Gomes et al 1981b].Harborn (1965) obtained quercetagetin from hydrolyzed petal of Coronilla glauca L..He also found halogenin, 3-O rutinoside and limocitrin, 3-O rutinoside from C. glauca flower (Harborn 1981).Catechin, epigallocatechin, leucodelphinidin and 3, 3´, 4´, 5, 5´, 7hexahydroxyflavan have been identified from Alhaji maurorum Medikus ground parts [Islambeko et al 1982].Malvidin from hydrolyzed flower, myricitrin from flower and laef of Cercis siliquastrum L. have been isolated [Torck et al 1969, Sagareishvili andAnaniya 1990].

Polygonaceae flavonoids
Based on Isobe and Noda (1987) flavonoids and flavonol glycosides are of wide-spread occurrence in the genus Polygonum.Among them, glycosylation at C-3 of the quercetin nucleus has been found to be the most common trend, and present in all species of this genus [Park, 1987].While rhamnose, gloucose, arabinose and rhamnosyl-rhamnose are the most common sugars found as aglycones of the flavonol glycosides [Mun and Park 1995], galactosylation is rather uncommon in the genus Polygonum or in the family polygonaceae [Collins et al 1975].Kawasaki et al (1986) isolated thirty-three kinds of flavonoids from Polygonaceae species leaves.Quercetin glycosides were commonly found in the family.In the quercetin glycosides, 3-O-rhamnoside was most frequently found, 3-O-glucuronide is also distributed widely.Myricetin glycosides were rare.Methylated flavonols were found in some species of the section Echinocaulon and Persicaria [Kawasaki et al 1986].The aerial exudate of Polygonum senegalense has been reported to contain 12 flavonoids of the chalcone and flavanone types, and they are distinctly different from internal tissue aglycones [Midiwo et al 2007].Also Hsu (2006) studies revealed that Polygonum aviculare L. extract has high phenolics and flavonoid contents.Trichopoulou et al (2000) showed that some wild edible species of Rumex such as R. acetosa L. and R. japonicas Houttuyn have a very high flavonol content.Hasan et al (1995) studies showed besides rutin, quercetin 3-rhamnoside and kaempferol 3-rhamnosyl (1 -> 6) galactoside, a new flavonol glycoside, quercetin 3-glucosyl (1 -> 4) galactoside, and 1, 6, 8trihydroxy-3-methyl anthraquinone (emodin) have been characterized from leaves of R. chalepensis.

Aim
The aim of this study was to compare the leaf flavonoids profiles of some Iranian Angiosperm species from Leguminosae, Polygonaceae, Euphorbiaceae, Resedaceae and Cyperaceae.

Collection of plant material and praperation
Mature fresh leaves of eight Legumes, seven Polygonum, seven Rumex, seventeen Euphorbia, two Chrozophora, four Reseda and five Scirpus species from different parts of Iran were collected during 2006-2010 as described in Table 1.Plants identified using available references [Rechinger 1964, Mobayen 1979, 1980, Ghahreman 1979-2006].Specimens of each sample were prepared for reference as herbarium vouchers that were deposited at the Arak University herbarium.Samples were air dried for detection and identification of flavonoids.

Extraction of the plant material
For a comparative analysis of the flavonoids, small extracts of all the accessions were prepared by boiling 200 mg of powdered air dried leaf material for 2 min in 5 ml of 70% EtOH.The mixture was cooled and left to extract for 24 h.The extract was then filtered, evaporated to dryness by rotary evaporation at 40, and taken up in 2 ml of 80% MeOH for analysis by 2-Dimensional Paper Chromatography (2-D PC).

Flavonoid analysis by 2-Dimensional Paper Chromatography (2-D PC)
For the detection of flavonoids, ca 20 l of each of the small extracts was applied to the corner of a quarter sheet of Whatman No 1 chromatography paper as a concentrated spot (10 applications of 2l).The chromatogram for each sample was developed in BAW (n-BuOH-HOAc-H 2 O=4:1:5; V/V; upper layer), 1 st direction, and HOAc (=15% aqueous acetic acid), 2 nd direction, with rutin (= quercetin 3-O-rutinoside) as a standard.After development, the chromatograms were viewed in longwave UV light (366 nm) and any dark absorbing and fluorescent spots were marked.R f -values in BAW and 15% HOAc were calculated.

Methods of identification of the flavonoids
When sufficient amounts of purified flavonoids had been obtained, as in the cases of the flavonoids from studied samples, they were identified by means of UV spectroscopy using shift reagents to investigate the substitution patterns of the flavonoids [Mabry et al. 1970, Markham 1982] and by acid hydrolysis to identify the aglycone and sugar moieties.Cochromatography with standards was also performed where possible.Flavonoid standards available for comparison during the study obtained commercially from Merck, Sigma and Fluka.

Acid hydrolysis and identification of flavonoid aglycones
A small amount of each purified flavonoid (ca 0.5 mg) was dissolved in 0.5 ml of 80% MeOH in a test tube.To this sample 2 ml of 2M HCl were added and the mixture was heated in a water bath at 100C for 0.5 h.The solution was cooled, 2 ml of EtOAc were added and thoroughly mixed with the aqueous layer using a whirley mixer.The upper EtOAc layer was removed with a pipette, evaporated to dryness, dissolved in 0.5 ml of MeOH and applied as spots on thin layer chromatograms (cellulose).The TLC plates were run in three solvents alongside standards to identify the aglycone moiety [Harborne 1998].

Results
All studied plant species exceptional two subspecies Sophora alopecuroides and Medicago sativa contained flavonoid compounds in their leaves.Their flavonoid profiles show a wide variety between the species.Data in Table 1 shows the sampling and also two-dimensional paper and thin layer chromatographical data of 48 studied plant samples from Markazi Province, Iran.

Discussion
Studies of leaf flavonoids showed some phytochemical characters such as total number of flavonoids, flavonoid group such as aglycone, flavones C-and C-/O glycoside and flavonoid sulphate and kind of flavonoids such as kaempherol, quercetin, myricetin are valuable for chemotaxonomy and their usage.
Chemical study of two Chrozophora species using two dimentional paper chromatography (2-DPC) and thin layer chromatography (TLC) showed both Chrozophora species contain flavonoid sulphates, flavone C and C-/O-glycosides and aglycon.Also all of studied species have apigenin and quercetin while rutin was just found in C. tinctoria species that is recorded first time for Markazi Province.All of studied species have flavonoid compounds that have variation in their flavonoid type and number (Table 1).
Phytochemical studies of the Euphorbiaceae have been extremely useful in clarifying systematic relationships within the family (Simpson and Levin 1994).Flavonoids occur widely in plants and are a biologically major and chemically diverse group of secondary metabolites that are popular compounds for chemotaxonomic surveys of plant genera and families [Harborne 1994].There are some studies in this connection.Mues and Zinsmeister (1988) have discussed about variation of occurrence phenolic compounds in mosses and liverworts.Also they showed there is a clear flavonoid distinction between the subclasses Marchantiidae and Jungermanniidae.Another important chemotaxonomic programme has concerned the ferns and fern allies [Harborne 1986].The phenolic patterns appear to be more useful for studying relationships within relatively narrow taxonomic limits, e. g. at the species and genus level.Turning to the angiosperms, a chemotaxonomic survey of 255 species of the family Iridaceae has been carried out by Williams et al (1986), who found that flavone C-glycosides were present in 66% of the samples [Harborne 1986].Another family survey has been carried out in the Polygonaceae, in which 28 species were analysed for their flavonoid pattern [Harborne 1986].Studying flavonoid pattern can be used for chemosystematic and lower taxonomic levels.25 Avena species (Poaceae) were investigated for the flavonoid content of leaf tissue [Saleh et al 1988].Diploid triticum species could be divided into two groups depending on the presence or absence of two major di-Cglycosylflavones (Harborne et al 1986).Flavonoid data of the genus Vitis indicate three chemical groups [Moore and Giannasi 1994].Several studies indicated that flavonoids occurred in various species of Euphorbia.They may be useful taxonomic markers within the genus.Also Euphorbia flavonoids are very important for their toxicity and some different potential clinical applications such as their antiatherosclerotic, antiinflammatory, antitumor, antithrombogenic, antiosteoporotic and antiviral effects [Nijveldt et al 2001].Papp et al (2005) showed populations of Euphorbia cyparissias can be separated clearly from each other according to their morphology and flavonoid pattern.Our results showed all studied Euphorbia species contained flavonoid compounds in their leaves that their flavonoid profiles show a wide variety between the taxa.There are flavonoid sulphate and flavone C and C-/O-glycosides in all species, but E. bungei, E. heteradena and E. microsciadea in addition these two flavonoid types have dihydroflavonol 3-O-monoglycosides.E. cordifoila, E. heteradena, E. microsciadeae and E. petiolata have the highest number of total flavonoid compounds ( 9) and E. bungei and E. helioscopia have the lowest number of flavonoid compounds (2) in their leaves (Table 1).Identification of flavonoids by standards showed all of studied Euphorbia species contain rutin with the exception of E. macroclada and E. petiolata.Also all taxa studied, except 2 species (E.cordifolia and E. tehranica) have quercetin.Harborne and Baxter (1999) reported that quercetin is widely distributed in various plant families.Kaempferol found in 8 species and myricetin was found just in E. macroclada and E. petiolata (Table 1).As Volobueva (1970) showed two-dimentional paper chromatography and acid hydrolysis of E. helioscopia alcoholic extract yielded quercetin and kaempferol.Also Gautam and Mukhraya (1981) 1).
Phytochemical examination of the studied polygonum species showed all of Polygonum species contain flavon C-and C-/O-glycosides.P. hyrcanicum had the most flavonoid variation and concentration and P. convolvolus species with having just one flavonoid had the least.Flavonoid sulphates was found just in P. persicaria species (Table 1).
Chemical study of four Reseda species using two dimentional paper chromatography (2-DPC) and thin layer chromatography (TLC) showed all studied Reseda species contained flavonoid compounds in their leaves and kempferol is the most representative compound for the genus (Table 1).They may be useful taxonomic markers within the genus.Also Reseda flavonoids are very important for their toxicity and some different potential clinical applications such as their antiatherosclerotic, antiinflammatory, antitumor, antithrombogenic, antiosteoporotic and antiviral effects [Nijveldt et al 2001].The presence of quercetin and absence of myrestin in R. lutea are taxonomic characters for separation of the species from two other species (R. buhseana and R. bungei).Among the many functions of flavonoids at the interface between plant and

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Phytochemicals -A Global Perspective of Their Role in Nutrition and Health 162 environment, their activity as signals was intensively studied.Flavonoids are also beneficial for the plant itself as physiological active compounds, as stress protecting agents, as attractants or as feeding deterrents, and, in general, by their significant role in plant resistance [Treutter 2006].
Chemical studies of seven Rumex species using two dimentional paper chromatography (2-DPC) and thin layer chromatography (TLC) showed all of studied Rumex species contain flavonoid compounds with wide variation.R. chalpensis, R. obtosifolius and R. tuberusos species had the most flavonoid number and R. crispus species had the least.Identified flavonoid compounds in all of studied species with the exception R. crispus (lack flavonoid sulphate) are flavones C and C-/O glucoside.R. acetosella and R. conglomerates had aglycon.Rutin and luteolin found in all of studied species exceptional R. chalpensis, R. obtosifolius and R. pulcher.All of studied species showed wide variation in existing and concentration of myricetin, apigenin, narengenin, rhamnetin, quercetin and kaempferol.All of studied species with the exception R. chalpensis and R. tuberusos had quercetin and also kaempferol found in 3 species (R. chalpensis, R. pulcher and R. acetosella) (Table 1).
Phytochemical studies on five species of Scirpus (S. holoschenus L., S. lacustris L., S. littoralis Kuntze, S. maritimus L. and S. multicaule) from different parts of Markazi Province, Iran area using two-dimentional paper chromatography (2-DPC) and thin layer chromatography (TLC) showed all of studied taxa contain vitexin, luteolin, rutin and rhamnetin.There were chrysin and naringenin in all of populations with the exception of S. lucustris and apigenin was found in 3 species weheras others lack.Quercetin was not found in S. maritimus and S. littoralis where as three other species had (Table 1).
Our studies showed the most of collected plant species are weed and grow in poor soils and destroyed pasture.Progress continues to be made in understanding the roles of flavonoids in stress protection, as well as in defining the mechanisms that control the amount and varieties of flavonoids that are produced in plants in responses to diverse environmental cuse [Chalker-Scott 1999].Finally, further work is needed using high performance liquid chromatography with diode array detection, atmospheric pressure chemical ionization liquid chromatography-mass spectroscopy to evaluate all flavonoid profiles in studied and other species.

Table 1 .
The sampling and also two-dimensional paper and thin layer chromatographically data of 48 studied plant samples from Markazi Province, Iran.

Table 1 .
Continued www.intechopen.comPhytochemicals -A Global Perspective of Their Role in Nutrition and Health 160 isolated quercetin 3-O glucoside and kaempferol 3-O glucoside from E. larica, E. virgata, E. chamaesyce and E. magalanta and rutin obtained with the exception E. chamaesyce.Both quercetin and kaempferol are flavonols.The flavonols may be among the most important flavonoids, they are the most ancient and widespread of the flavonoids, synthesized even in mosses and ferns, and have a wide range of potent physiological activities[Stafford 1991].Chemical study of 17 Euphorbia species using two dimentional paper chromatography (2-DPC) and thin layer chromatography (TLC) showed rutin, quercetin and kaempferol are the most representative compounds for the genus and the presence of myricetin is a taxonomic character for separation of some Euphorbia species.It is believed that Euphorbia species can be separated from each other according to their flavonoid pattern.
D PC), on leaves of Alhagi camelorum Fisch, Cersis silliquastrum L., Coronilla varia L., Glycirhiza glarba L. and Robnia peseudoacia from Markazi Province showed all of five named species contain aglycones.A. camelorum and G. glarba had the most flavonoid variation and concentration having flavon glycoside and two subspecies of Sophora alopecuroides and Medicago sativa had not or had the least.The most flavonoid compounds similarity was between C. silliquastrum and R. peseudoacia (Table