Flavonoids isoflavanones

The isolation of flavonoids from the methanol extract of G. uralensis was carried out under non-basic conditions, because some flavonoids isomerize under basic conditions, e.g. racemization of flavanones and isoflavanones, ring-open reaction of flavanones etc. Bioactive fractions were separated by some chromatographic methods and each step was monitored with anti-H. pylori activity with the paper disk method. Eighteen compounds were isolated from these bioactive fractions and... 

Isoflavones, isoflavanones and neoflavonoids are also members of the flavonoid group. They all have the C6-C3-C6 stmcture but the B-ring is in a different position on the oxygen heterocycle. Examples are isoflavone (1.33) and the neoflavonoid dalbergin (1.34). 

Flavonoids are a specific class of polyphenols. It is generally believed that flavonoids include a wide variety of phenolic compounds, such as flavones, flavonols, flavanones, flavanonols, anthocyanidins, flavan-3,4-diols, xanthones, flavan-3-ols, isoflavones, isoflavanones, chal-cones, dihydrochalcones, aurones, and homoisoflavones. Their separation poses special problems because there is often irreversible adsorption and even hydrolysis on solid supports. 

The majority of the plant pigments hitherto isolated from woods in pure form are the flavonoids, such as flavone, flavanone, isoflavone, isoflavanone, pterocar-pane, and chalcone derivatives, along with the phenols stilbene and xanthone, which are almost white or yellow in color. Other flavonoids such as aurone and neoflavone derivatives (orange pigments) have a limited distribution and sometimes occur as wood extractives in species of the Anacardiaceae and Leguminosae (4, 7). The presence of the typical anthocyanin derivatives of flowers and fruits is extremely rare in wood, but their leuco-compounds such as flavan-3-ol and flavan-3,4-diol have been found to occur in the wood of a considerable number of tree species (14). Besides anthocyanidin, the few other deep-colored (red, purple, or blue) pigments from woods usually possess a quinone structure. 

IsofLavones-. These flavonoids are among the less-widely distributed flavonoids in nature, but they are the compounds most frequently tested for in humans [13]. The only important amount of these compounds were found in leguminous species, especially in soybeans, black beans, and green peas, the most common isoflavones being genistein, daidzein, and glycitein. In addition, these compounds undergo various reactions such as methylation, hydroxylation, or polymerization that lead from simple (isoflavanones, isoflavans, and isoflavanols) to more complex structures (rotenoids, pterocarpans, and coumestans) [12]. 

---