ABSTRACT
The flavonoids are present in all vascular plants, although some types such as flavones and flavonols are ubiquitous, while others such as isoflavones and biflavonyls are much more restricted in their distribution. Flavonoids generally occur in the plants as glycosides, a variety of sugars being utilized, and in fact some compounds may be found conjugated to different sugars. Flavonoids contain conjugated aromatic systems and consequently show intense absorption bands in the UV and visible regions of the spectrum. Animal models of virus infection have been used for some years to evaluate the potential of flavonoids as antiviral agents. Some of the flavonoids, as well as others, appear to have additional antiviral effects that may involve other viruses, particularly those with membranes, and other mechanisms, including virucidal activity. Since flavonoids bind specifically to certain proteins, the possibility of using flavonoids as inhibitors of viral enzymes is an attractive concept.
