Flavonoids
are a group of natural compounds having a benzo-pyrone ring, and over 4,000
flavonoid compounds have been characterized and classified according to
chemical structure. Available reports tend to show that secondary metabolitesof phenolic nature, including flavonoids are responsible for the variety ofpharmacological activities . Their activities are structure dependent. The
chemical nature of flavonoids depends on their structural class, degree of
hydroxylation, reduction, other substitutions, conjugations, and degree of
polymerization. Flavonoids are widely present in the plant kingdom exhibiting a
broad range of biological activities, including antibacterial, antifungal,
antiviral, anti-allergic, anti-inflammatory, and anti-proliferative and
antioxidant activities.
It has been reported that the intensity of the
antimicrobial activity of a flavonoid strongly depends on its chemical
structure, which is particularly influenced by the number and position of
various functional groups such as, hydroxyl, methoxy, halogens, nitro, methyl,
cyano groups attached to the two aromatic rings (A and B). The third ring C islinked through a three carbon chain, mostly organized as an oxygenatedheterocyclic ring. A very few reports are available to the substitution pattern
in ring C at 3-position. However 3-hydroxy flavones and 3-methyl flavones have
been synthesized by many researchers, but their further reductions at
2,3-position in ring C are rare and yet to be explored. Substitution pattern at
3-position of ring C mainly regulates bioavailability and metabolism. Whereas
substitution at ring A and B influence biological activity. Flavonoids are well
known as antibacterial agents against a wide range of pathogenic microorganism.
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