Flavanoids 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 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).

Before a species is analyzed with respect to its flavonoid content, knowledge about earlier reports on the chemistry and flavonoid distribution within the genus and related species may be of value. The most exhaustive source for such information is Chemical Abstracts, and excellent reviews on structures and distribution of flavanoids have been compiled regularly.Several reviews have recently addressed the general field of flavonoid analysis.Among the earlier reviews in the field, we will particularly recommend consulting Techniques of Flavonoid Identification by Markham and Plant Phenolics by Harborne. References to review articles on specific spectroscopic techniques applied on flavonoids will be cited under the various spectroscopic methods covered in this chapter. Spectroscopic information of importance is also presented in several other chapters in this book. 

Asakawa Y 1971 Chemical constituents of Ainus sieboldiana (Betulaceae). II. The isolation and structure of flavanoids and stilbenes. Bull Chem Soc Jpn 44 2761... 

---