Bioactive flavanones

Labbe, C. et al.. Bioactive flavanones from Luma checken. Coll. Czech. Chem. Commun., 67, 115,2002. 

Flavonoids are a complex group of polyphenolic compounds with a basic C6-C3-C6 structure that can be divided in different groups flavonols, flavones, flavanols (or flavan-3-ols), flavanones, anthocyanidins, and isoflavones. More than 6,000 flavonoids are known the most widespread are flavonols, such as quercetin flavones, such as lu-teolin and flavanols (flavan-3-ols), such as catechin. Anthocyanidins are also bioactive flavonoids they are water-soluble vegetable pigments found especially in berries and other red-blue fruits and vegetables. 

The major types of bioactive constituents reported from Broussonetia papyrifera are the prenylated flavonoids, which include compounds of the diphenylpropane, chalcone, flavan, flavanone, flavone, flavonol, and aurone classes (Table 2), Fig. (7). An early study on B. papyrifera resulted in the isolation of two diphenylpropanes, broussonins A (29) and B (30), and a coumarin, marmesin (52), with antifungal activity [39]. Also, a diprenylated diphenylpropane derivative, kazinol F (31) [40], was reported as an antioxidant and tyrosinase inhibitory constituent [34]. 

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... 

Using the technique of activity-guided chromatographic isolation, it is possible to generate many structurally novel bioactive plant secondary metabolites, and examples have been provided in this chapter of plant secondary metabolites with potential anticancer or potential cancer chemopreventive activity, comprised by compounds representative of the chal-cone, flavanone, flavone, furocoumarin, isoflavone, lignan, oligostilbenoid (resveratrol... 

The comparison in terms of preservation of the total antioxidant activity and of the bioactive antioxidant components of the juice (ascorbic acid, anthocyanins, hydroxycinnamic acids, flavanones) demonstrates that this integrated membrane... 

The apparent bioactivity of the chalcones in the mixture, coupled with reports that chalcones are known to have anti-plasmodial activity,and that they are available in large quantities, led us to submit them to assays for anti-plasmodial activity the chalcones, flavanones and the homoisoflavanone (Table 5) were found to have redueed but still significant anti-plasmodial activities with IC50 values in the range of 2-20 ig/ml. This is an illustration of the principle that plant extracts and component compounds that are bioactive should be surveyed for anti-malarial activity and for activities against other diseases for which they are not already known. 

Fig. 11.25 (a b). Some bioactive dihydrochalcones and flavanones (modified in part from Harbome, 1982). 

Hesperetin (4 -methoxy-3, 5,7-trihydroxyflavanone), which is a bioactive plant flavonoid belonging to the ehemieal elass flavanone (abundantly present in citrus fruits), is rapidly emerging as an espeeially attractive therapeutie agent with an enormous speetrum of activities. This flavonoid eorresponds to the aglycone form of hesperidin. Although hesperetin can be eonsidered much more biologieally active, firstly hesperidin is obtained, which is the natural form of these compounds. 

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