Synthesis, characterization and antioxidant activity of prenylated and fluorine based flavonoids.
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Date
2013
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Abstract
Twenty flavonoids II-XXI were successfully synthesized using the Claisen-Schmidt
condensation reaction between 2-hydroxy and 3-hydroxyacetophenone with various substituted
fluorobenzaldehydes. The twenty flavonoids consisted of sixteen chalcones, eight of which were
new novel prenyl chalcones (XIV-XXI), and four flavanones (X-XIII). The compounds were
produced in yields of between 54-90%. It was shown in II-XIII that the rate of reaction is
influenced electronically by the substitution patterns of the fluorine atom on the B-ring, in the
order; 2',4'-difluoro > 2'-fluoro> 4'-fluoro > 3'-fluoro. All compounds were characterized by
NMR, IR, UV and mass spectral analyses. Compounds II-IX bearing hydroxyl groups were
subjected to antioxidant screening using the DPPH free radical scavenging assay. Antioxidant
activities of these compounds were established as moderate to low in comparison to the standard,
ascorbic acid. The difluoro compounds V and IX with fluorine on the ortho and para positions in
the B-ring showed the highest activities, possibly due to both the position and number of fluorine
atoms in the molecule.
Description
M. Sc. University of KwaZulu-Natal, Durban, 2013.
Keywords
Flavonoids., Theses--Chemistry.