ANTI-NUTRITIONAL CONSTITUENT OF COLOCASIA ESCULENTA ...

of free cholesterol depends on mixed micelles: mixtures of free cholesterol, mono- and
diacylglycerols, fatty acids, phospholipids and bile salts (De Jong et al., 2003). Evidence
has been presented to support the view that cholesterol absorption would take place only
in the presence offat. It has been demonstrated that the absorption ofcholesterol is made
possible by fat. The fatty acid component of fat is the active factor for this absorption
(Kim and Ivy, 1952; Swell et al., 1956). The most efficient fatty acid promoting
cholesterol absorption has been reported to be oleic acid (Swell et al., 1956). Cholesterol
is structurally similar to beta-sitosterol. Consequently, the solubility of beta-sitosterol
was enhanced by esterifying it with oleic acid. The results in this study showed that beta­
sitosterol became active in the rats when 0.01 mg kg-I day-I ofoleic acid was added to the
beta-sitosterol.
Changes in the physiological state ofmammals can alter the concentration ofa number of
organic constituents in the blood serum: for example, glucose, protein, cholesterol and
liver enzymes (Malini and Vanithakumari, 1990). Triacylglycerol levels, which are
independent risk factors for cardiovascular problems (Wierzbicki and Mikhailidis, 2002),
showed a significant decrease in levels for rats fed beta-sitosterol compared with rats fed
oleic acid. Similar effects have been observed in cells incubated with oleic acid; oleic
acid increased both the intracellular pool and biosynthesis oftriacylglycerols (Pullinger et
aI., 1989; Ellsworth et al., 1986). The potential target for the influence ofoleic acid is in
the assembly of the apoB-containing (apolipoprotein B) lipoproteins. This occur in
regions of the ER with hig1I diacylglycerol:acyltransferase activity that has a hig1I
capacity for the formation of triacylglycerol (Boren et aI., 1990). Oleic acid could be
nsed to manipulate important steps in the assembly process (Boren et aI., 1993). The
decreased level observed in beta-sitosterol fed rats is in line with the known
hypercholesterolemic activity ofbeta-sitosterol (Duivenvoorden et al., 2006).
A slig1It decrease in serum protein level was observed in the group receiving beta­
sitosterol in its diet. The slig1It change in the serum protein levels may have resulted
from altered rates of anabolism and catabolism (Malinia and Vanithakumari, 1990).
When compared to the two control groups, serum cholesterol was slig1Itly, but not
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