**Isolation and Structure Identification of Flavonoids**

Weisheng Feng, Zhiyou Hao and Meng Li

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/67810

#### Abstract

[56] Weston LA, Mathesius U. Flavonoids: their structure, biosynthesis and role in the rhizosphere, including allelopathy. Journal of Chemical Ecology. 2013;**39**:283-297.

[57] Demuner AJ, Barbosa LCA, Chinelatto Junior LS, Reis C, Silva AA. Sorção e persistência da sorgoleona em um latossolo vermelho-amarelo. Química Nova. 2005;**28**:451-455. [58] Vyvyan JR. Allelochemicals as leads for new herbicides and agrochemicals. Tetrahedron.

[59] Wang Q, Li Z, Ruan X, Pan C, Jiang D. Phenolics and plant allelopathy. Molecules.

[60] Almeida LFR. Composição química e atividade alelopática de extratos foliares de *Leonurussibiricus* L. (Lamiaceae). 2006, 105 p. Tese (Doutorado em Ciências Biológicas) –

[61] Kong C, Xu X, Zhou B, Hu F, Zhang C, Zhang M. Two compounds from allelopathic rice accession and their inhibitory activity on weeds and fungal pathogens. Phytochemistry.

[62] Chang CF, Akinori S, Sumio K, Saburo T. Chemical studies on clover sickness. II. Biological functions of isoflavonoids and related compounds. From Agricultural and

[63] Macías FA, Molinillo JMG, Torres A, Varela RM, Castellano D. Bioactive flavonoids from

[64] Levizou E, Karageorgou P, Petropoulou Y, Grammatikopoulos G, Maneta SY. Induction of a geotropic response in lettuce radicle growth by epicuticular flavonoid aglycons of

[65] Yan Z, Zeng L, Jin H, Qin B. Potential ecological roles of flavonoids from *Stellera chamae-*

Instituto de Biociências, Universidade Estadual Paulista, Botucatu, 2006.

*Helianthus annuus* cultivars. Phytochemistry. 1997;**45**:683-687.

*jasme*. Plant Signaling & Behavior, 2015;**10**:e1001225-1–e1001225-3.

*Dittrichia viscosa*. Biologia Plantarum. 2004;**48**:305-307.

2002;**58**:1631-1646.

16 Flavonoids - From Biosynthesis to Human Health

2010;**15**:8933-8952.

2004;**65**:1123-1128.

Biological Chemistry. 1969;**33**:398-408.

Flavonoids, which possess a basic C15 phenyl-benzopyrone skeleton, refer to a series of compounds in which two benzene rings (ring A and B) are connected to each other through three carbon atoms. Based on their core structure, flavonoids can be grouped into different flavonoid classes, such as flavonols, flavones, flavanones, flavanonols, anthocyanidins, isoflavones and chalcones. Flavonoids are often hydroxylated in positions 3, 5, 7, 3<sup>0</sup> , 4<sup>0</sup> and/or 5<sup>0</sup> . Frequently, one or more of these hydroxyl groups are methylated, acetylated, prenylated or sulfated. In plants, flavonoids are often present as O- or C-glycosides. The O-glycosides have sugar substituents bound to a hydroxyl group of the aglycone, usually located at position 3 or 7, whereas the C-glycosides have sugar groups bound to a carbon of the aglycone, usually 6-C or 8-C. The most common carbohydrates are rhamnose, glucose, galactose and arabinose. This chapter mainly introduces the methods of isolation and structure identification of flavonoids.

Keywords: flavonoids, structures and classification, extraction, isolation, structure identification

### 1. Introduction

Flavonoids are important natural organic compounds of secondary metabolites that are produced during the long process of natural selection. They widely exist in the roots, stems, leaves, flowers and fruits of higher plants and ferns [1], which are of numerous categories and chemical structures. Because of the special chemical structures, flavonoids possess wide range of physiological and biochemical effects to the cells of mammal and other kinds of animals. Firstly, flavonoids possess strong chemical reactivity. For example, some flavonoids have antioxidant activity via scavenging free radicals in organism [2]. Furthermore, flavonoids possess various pharmacological activities of inhibiting the activity of enzymes, antitumor,

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antibiosis, antivirus, anti-inflammatory and so on [3–9]. The potential treatment and prevention effects have been shown in degenerative diseases such as tumors, aging and cardiovascular diseases [10–15]. Additionally, some compounds of flavonoids possess potential application prospects as weak hormones at treating menopausal syndrome of women [14–17].
