**1.9. Tannins**

The tannin compounds are found mainly in many plant species which help to confer on them protection from predators and probably pesticides; they also help in regulating plant growth [25]. The dry and puckery feeling in the mouth after eating unripe fruits or red wine is attributed to the astringency from the tannins [26]. The destruction or modification of tannins with time in like manner plays an important role in the ripening of fruit and the aging of wine. They are acidic in reaction, and this is attributed to the presence of phenolics or carboxylic group [27]. They form complexes with proteins, carbohydrates, gelatin, and alkaloids.

Tannins are divided into hydrolysable tannins and condensed tannins. Hydrolysable tannins, when hydrolyzed, produce gallic acid and ellagic acid, and depending on the type of acid produced, the hydrolysable tannins are called gallotannins or ellagitannins; when tannins are heated, they form pyrogallic acid [25]. The presence of phenolic group in tannins confers on them their usefulness as an antiseptic [27]. Common examples of hydrolysable tannins include the aflavins (from tea), daidzein, genistein, and glycitein.

Plants that contain tannins have been reported to be astringent in nature and are useful in treating intestinal disorders like diarrhea and dysentery. This means that tannins possess antimicrobial activity [28, 29]. The antimicrobial activities possessed by these plants could support their use in West Africa for treating gastrointestinal disorders [30]. Tannins are also potent antioxidants [31, 32].
