Structural Modification of Flavonoids from Surface Exudate of Polygonum senegalense

 

 

 

 

 

 

 

 

 

 

Surface exudate of Polygonum senegalense contains flavonoids of the chalcone and flavanone types. Our interest is in the anti-plasmodial activities of synthetically modified flavonoids and chalcones in comparison with the starting natural compounds.

 

New compounds were produced by structural modification via environmentally benign reactions. The reactions undertaken involved the transformation of 2’, 6’-Dihydroxy-4’-methoxychalcone into 5-hydroxy-7-methoxyflavanone using base catalysis, sodium hydroxide solution, in purely aqueous medium.

 

The product was then reacted with ethyl amine and methyl amine at room temperature yielding 5-hydoxy-4-ethylimino-7-methoxyflavanone and 5-hydroxy-7-methoxy-4-methyliminoflavanone respectively.

 

The reduction of the above imines to the respective amines was achieved by reaction with NaBH4 after dissolution of the imines in ethanol. Nitration of 2’-hydroxy-4’,6’-dimethoxydihydrochalcone at temperatures below room temperature led to the production of three nitro derivatives as indicated by TLC analysis. Determination of the structures was via spectroscopic evidence (1H, 13 C NMR) and the products formed were tested to assess their in vitro anti-plasmodial activities.

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