ANTI-NUTRITIONAL CONSTITUENT OF COLOCASIA ESCULENTA ...

(the in vitro haemolytic activity) (Oda et aI., 2000). Although the concept that they are
harmful to human health has been questioned (Reddy and Pierson, 1994), saponins have
been reported to retard growth in animals (Cheek:e 1971; 1976).
The ability of saponins to lower cholesterol, demonstrated in animal (Matsuura, 2001)
and human trials (Iones et aI., 1997) has been extensively researched. This trait of
saponins has been attributed to their inhibiting cholestrol absorption from the small
intestine or their inhibiting reabsorption of bile acids (Oakenfull and Sidhu, 1990).
Clinical studies have suggested that the health-promoting components of saponins affect
the immune system, impacting this system through adjuvant activity (Cheeke, 1999). The
ability of saponins to operate as immunological adjuvants by improving the immune
response to antigens has been recognized since the 1940s (Bomford et al., 1992; Francis
et al., 2002). It is through the immunde response that the immune system helps to protect
the human body against cancers. A number oftriterpene and steroid saponins have shown
anti-eancer activity (Berhow et al., 2000; Kerwin, 2004). A saponin-rich diet offers
several benefits, including a reduction in the occurrence ofrenal stones, the inhibition of
dental carries, improved platelet aggregation and a positive response to treating
hypercalciuria in humans (Shi et al., 2004).
2.1.3 Aim and outline ofSection B-2
Saponins can be found in a wide variety of plants including alfalfa (Cheeke et aI.,
1977), soybeans (Berhow et al., 2002; Kitagawa et al., 1998) and legume seeds
(Price et al., 2006). Little is known about levels of saponins in Colocasia
esculenJa (Amadurnbe).
The aim of Section B-2 was to extract, isolate and identify saponins from Amadurnbe.
The objectives were:
• to extract and isolate saponin using chromatographic methods (TLC and column
chromatography);
• to elucidate saponin structure, using spectroscopy (IR and GC-MS).
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