Flavanones chemical structure

As previously mentioned, certain flavonoids can penetrate into the hydrophobic core of membranes, a feature that mainly relies on their hydrophobic character, which is dictated by flavanoid chemical structure and spatial conformation. When flavonoid hydrophobicity was assessed from the partition coefficient between ra-octanol and an aqueous solution, the following order of hydrophobicity was observed flavone, genistein > eriodictyol, myricetin, quercetin, kaempferol, hesperetin, daidzein > > galangin, morin, flavanone, naringenin, taxifolin (Table 4.1). 

FIGURE 16 The chemical structures of some drugs resolved on different CSPs based on a- and /1-cyclodextrin derivatives (Fig. 15) Troger s base (I), tra .s-2,.1-diphenyloxirane (II), l-(9-anthryl)-2,2,2-trifluoroethanol (III), 1,2,2,2-tetraphenylethanol (IV), 2,2 -dihy-droxy-6,6-dimethylbiphenyl (V), 2-phenylcyclohexanone (VI), flavanone (VII), benzoin (VIII), and tnms -cyclopropanedicarboxylic acid anilide (IX). (From Ref. 49.)... 

Flavonoids are divided into many classes and subclasses, each with a slightly different chemical structure and function. Classes of flavonoids include flavanols, flavanones, catechins, anthocyanins, and isoflavones. 

Figure 4.2 Chemical structures of various flavonoidsThe flavone heterocyclic ring can be reduced or oxidized in various ways. Reduction of the double bond leads to a flavanone. Additional loss of the carbonyl oxygen yields a flavan.Jhe flavone can be hydroxylated to form a flavonol. This can be reduced to a flavanol. The flavan, flavanol, and flavanone each have a chiral center. The biological isomers are not known.

Figure 6.1 Chemical structures of flavanoids including catechins and theaflavins. These tiavanoids consisted of two major groups flavanones, including naringenin, taxifolin, and fustin, and flavanols including green tea polyphenols (EC, ECG, EGC, EGCG), black tea polyphenols (TF-1, TF-2a, TF-2b, TF-3), and oolong tea polyphenol (TSA).

Fukai, T, and T. Nomura NMR Spectra of Isoprenoid Substituted Phenols. 3. Structure of 6- or 8-Isoprenoid Substituted Flavanone Chemical Shift of the Hydrogen-Bonded Hydroxyl Group. Heterocycles, 31, 1861 (1990). 

The most important members of the flavonoid family include anthocyanidins (e.g., cyanidin, delphinidin, malvidin), flavonols (e.g., quercetin, kaempferol), flavones (e.g., luteolin, apigenin), flavanones (e.g., myricetin, naringin, hesperetin, naringenin), flavan-3-ols (e.g., catechin, epicatechin, gallocatechin) and, although sometimes classified separately, the isoflavones (e.g., genistein, daidzein). For chemical structures see Figure 1. All these phytochemical are frequently referred to as bioflavonoids due to well established effects in human health maintenance. 

Within the plant secondary metabolites of flavonoids, flavanones define one of the minor subclasses. They may be called dihydroflavones. The basic chemical structure of flavanones involves two benzene rings (A and B), which are linked by a heterocyclic ring (C). The most characteristic point of flavanone structures is that the C-ring is saturated. Flavanones have an asymmetric carbon at C2-position. 

Improvements in the instrumentation, ionization sources, high-resolution mass analyzers, and detectors [67-69], in recent years have taken mass spectrometry to a different level of HPLC-MS for natural product analysis. Mass spectrometry detection offers excellent sensitivity and selectivity, combined with the ability to elucidate or confirm chemical structures of flavonoids [70-72]. Both atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) are most commonly used as ionization sources for flavonoid detection [73-76]. Both negative and positive ionization sources are applied. These sources do not produce many fragments, and the subsequent collision-induced dissociation energy can be applied to detect more fragments. Tandem mass spectrometry (MS , n> 2) provides information about the relationship of parent and daughter ions, which enables the confirmation of proposed reaction pathways for firagment ions and is key to identify types of flavonoids (e.g., flavones, flavonols, flavanones, or chalcones) [77-80]. 

TABLE 19.1. Name and Chemical Structures ofAglycone Flavanones andFlavones, Neohesperidosides, and Rudnosides. 

The studies performed both in vitro and in vivo have shown that hesperetin play an important role in the prevention of degenerative and infective diseases, which is related to particular chemical structures. Hesperetin belongs to flavanones, which is a widely distributed group of polyphenohc compoimds, called nutraceutical substances , with anticancer, antiatherogenic, antimicrobial and anti-inflammatory properties. 

Fig. 18.4. Chemical structures of flavonoids Flavanols (Faol), Anthocyanidines (Acn), Flavanones (Faon), Flavones (Fon), Flavonols (Fool), Isoflavones (Ifon, cf. 16.2.9). R H, OH or OCH3...

Fig. 1.2 The chemical structures of flavonoids (a) flavonol, (b) flavone, (c) flavanone, (d) antho-cyanidins and (e) isoflavone...

Among the most intensively investigated of all the chalcone Diels Alder adducts are a group obtained solely from Morus species in which the diene component of the reaction is a dehydroprenylflavanone. The structures of several such compounds published prior to 1992 have now been revised on the basis of new spectroscopic and chemical data. Among the most important of the techniques used were two-dimensional NMR and circular dichroism spectroscopy. The revised structures listed in Table 16.5 are those of sanggenons C (210), D (211), E (212), and O (213). In these compounds, the flavanones show the common feature... 

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