Mmushi T MSc (Microbiology).pdf

Fig.1.2. The chemical structure of the isopentenyl pyrophosphate, a
terpenoid (Wikipedia, 2010).
1.2.3.3. Phenolic compounds
1.2.3.3.1. Flavonoids
Flavonoids are water soluble phenolic molecules containing 15 carbon atoms and are a
group of low molecular weight chemical compounds, e.g. the phenylbenzopyrones,
found in all vascular plants. They are common constituents of fruit, vegetables, nuts,
seeds, stems, flowers, tea, wine and honey (Grange and Davey, 1990). The
physiologically active constituents have been used to treat human diseases (Cushnie
and Lamb, 2005). These have been reported to possess many useful medicinal
properties, including anti-inflammatory activity, oestrogenic activity, enzyme inhibition,
antimicrobial activity (Havsteen, 1983), antiallergic activity (Harborne and Baxter, 1999),
antioxidant activity (Middleton and Chithan, 1993), vascular activity and cytotoxic
antitumour activity (Harborne and Williams, 2000). Some of the recognized activities of
flavonoids include anti-allergic, anti-cancer, antioxidant, anti-inflammatory, anti-viral and
many health promoting effects (Harborne, 1996). Figure 1.3 shows the chemical
structure of a typical flavonoid with the basic unit of a ketone.
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