Hypocholesterolaemic effects

Carew, T.E., Schwenke, D.C. and Steinberg, D. (1987). Antiatherogenic effect of probucol unrelated to its hypocholesterolaemic effect evidence that antioxidants in vivo can selectively inhibit low density lipoprotein degradation in macrophage-rich fatty streaks and slow the progression of atherosclerosis in the Watanabe heritable hyperlipidaemic rabbit. Proc. Natl Acad. Sci. USA 84, 7725-7729. 

Howard, A. N. and Marks, J. 1977. Hypocholesterolaemic effect of milk (letter). Lancet 2, 255-256. 

Aro, A., Uusitupa, M., Voutilainen, E., Hersio, K., Korhonen, T. and Siitonen, O. 1981. Improved diabetic control and hypocholesterolaemic effect induced by long-term dietary supplementation with guar gum in type 2 (insulin independent) diabetes,... 

Agerbaek M, Gerdes LU, Richelsen B (1995) Hypocholesterolaemic effect of a new fermented milk product in healthy middle-aged men. Eur J Clin Nutr 49 346-352 Agerholm-Larsen L, Raben A, Haulrik N, Haulrik N, Hansen AS, Manders M, Astrup A (2000) Effect of 8 week intake of probiotic milk products on risk factors for cardiovascular diseases. Eur J cun Nutr 54 288-297... 

In addition to anticancer effects, tocotrienol-rich fractions of palm oil have hypocholesterolaemic effects in humans and offer protection against heart diseases (Qureshi el al. 1991 Serbinova el al. 1993). Tocotrienols differ from tocopherols in the degree of saturation of the side chains the prenyl side chain is considered to be responsible for the differential membrane distribution and metabolism of tocotrienols in comparison to tocopherols. Full investigations into the role and mechanisms of each tocotrienol and their interactions with other minor components, such as carotenoids, in inhibiting cancer development, as well as conferring protection against other age-related diseases, are now important areas of research. 

The saponin fraction of S. officinalis has shown antiinflammatory activity in vitro against carrageenan-induced rat-paw oedema and inhibited prostaglandin synthetase [49]. Purified saponins have been recently shown to possess hypocholesterolaemic effects in vivo, which is believed to be due to the ability of the saponin to form an insoluble complex with cholesterol, preventing its absorption from the small intestine [50]. The saponins also demonstrated spermicidal activity, which may come from their hemolytic property [51]. 

A report suggests that the hypocholesterolaemic effect of colestipol is unaffected in insulin-treated diabetics but it may be ineffective in those taking phenformin and sulphonylureas. Diabetic control was not affected. Colestyramine may enhance the effect of acarbose, and insulin levels may rebound if both drugs are stopped at the same time. There is evidence that the absorption of glipizide may be reduced by about 30% if it is taken at the same time as colestyramine, but tolbutamide does not appear to be affected. 

The concurrent use of phenformin and a sulphonylurea (chlorpropamide, tolbutamide or tolazamide) inhibited the normal hypocholesterolaemic effects of the colestipol in 12 diabetics with elevated serum cholesterol levels. No such antagonism was seen in two patients with type 2 diabetes receiving insulin. The control of diabetes was not affected by the colestipol. ... 

Recently, there have been two extensive reviews of the role of polyunsaturated fatty acids in the diet. Hoffman and Forster (1981) discussed the influence of dietary linoleic acid on blood pressure regulation-particularly in relation to salt-loaded individuals. In addition, the mechanism of the hypochol-esterolaemic effects of polyunsaturated fatty acids was discussed by Paul et aL (1980). These authors classified the hypocholesterolaemic effect as being due to reduced absorption of cholesterol, redistribution of cholesterol from blood to tissues, reduced cholesterol synthesis and increased excretion of cholesterol or its catabolites. These various factors have all been involved in the hypocholesterolaemic effect but the evidence is equivocal in each case. Other sources of information on dietary polyunsaturated fatty acids are Vergroesen (1975) and Kunau and Holman (1977). 

Plant sterols (such as P-sitosterol, which differs from cholesterol in the structure of the side-chain) and stands (which differ from sterols in having a saturated B-ring see Figure 4.13) inhibit the absorption of cholesterol from the small intestine. As discussed in section 4.3.2.1, in addition to about 500 mg of dietary cholesterol, about 2 g of cholesterol is secreted each day in the bile. Almost all of this is normally reabsorbed any inhibition of cholesterol absorption is therefore likely to have a more marked hypocholesterolaemic effect than might be expected simply by considering the dietary intake. A number of products, such as margarine, yoghurts and cream, that contain plant sterols and/or stand esters have been marketed. 

Neomycin precipitates bile acids and fatty acids from micellar solutions in vitro [279] and promotes faecal excretion of bile acids in man [280], facts supporting the hypothesis that this is due to the ability of the drug to interact with bile and fatty acids during the micellar phase of lipid absorption [281]. Precipitation is more complete with taurochenodeoxycholate micelles than with taurocholate micelles and of the derivatives of neomycin studied dimethylamino-propyl neomycin was the most active, followed in order by neomycin, dodeca-iV-methyl neomycin hexamethochloride and N-methylated neomycin [281]. Hexa-N-acetyl neomycin failed to precipitate any of the micellar components. The same order of activity was found when the compounds were tested for their hypocholesterolaemic effect in newborn chicks [281]. 

The properties of a soluble enzyme system from plants which catalyses cyclization of squalene 2(3),22(23)-diepoxide into oc-onocerin (28) have been reported. The enzyme requires both substrate epioxide groups for recognition and cyclization of the substrate. Additional inhibitors of squalene 2,3-oxide cyclase have been described, and a comparison of the effects of numerous hypocholesterolaemic agents on squalene metabolism in rat liver and the protozoan Tetrahymena pyriformis has been reported. ... 

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