Cholesterol and bile acid balance in Macaca fascicularis. Effects of alfalfa saponins.

We determine the effects of alfalfa top saponins on cholesterol and bile acid balance in eight cynomolgus macaques (Macaca fascicularis). The monkeys ate semipurified food containing cholesterol with or without added saponins. The saponins decreased cholesterolemia without changing the levels of high density lipoprotein-cholesterol; hence, they reduced the total cholesterol/high density lipoprotein-cholesterol ratio. Furthermore, they decreased intestinal absorption of cholesterol, increased fecal excretion of endogenous and exogenous neutral steroids and bile acids, and decreased the percent distribution of fecal deoxycholic and lithocholic acids. The fecal excretion of fat was also slightly increased, but steatorrhea did not occur. We saw no signs of toxicity in the monkeys after 6 or 8 wk of saponin ingestion. The data suggest that alfalfa top saponins may be of use in the treatment of patients with hypercholesterolemia, but long-term studies on possible toxicity are needed before this therapy can be recommended for humans.

Alfalfa saponins and alfalfa seeds. Dietary effects in cholesterol-fed rabbits.

Since alfalfa meal prevents hypercholesterolemia and atherosclerosis in rabbits and alfalfa saponins prevent the expected rise in cholesterolemia induced by dietary cholesterol in monkeys, the experiments being reported here were performed to determine whether alfalfa saponins affect atherogenesis in rabbits. In addition, the effects of alfalfa seeds were studied. Cholesterol-feb rabbits were randomly assigned to 3 groups: (a) control animals (N = 18); (b) animals maintained on a diet containing 1.0 to 1.2% alfalfa saponins (N = 18); and (c) animals maintained on a diet containing 40% alfalfa seeds (N = 17). Results after a 4-month observation period demonstrated that alfalfa saponins and alfalfa seeds reduce hypercholesterolemia, aortic sudanophilia, and the concentration of cholesterol in aortic intima-plus-media and in the liver, but do not induce changes in the hematocrit.

Effects of dietary proteins from a variety of sources on plasma lipids and lipoproteins of rats.

Five experiments were conducted to study the effect of various protein sources on fasting blood lipids and lipoproteins in the rat. Plasma levels of total cholesterol, high density lipoprotein (HDL)-cholesterol and total triglyceride, as well as weight gain, food intake protein efficiency ratio and net protein utilization were measured over 28-day test periods with male Sprague-Dawley rats. The purified proteins studied included casein, egg albumin, lactalbumin, soy and alfalfa. Crude proteins studied included yeast, fish meal and blood meal. Diets low in methionine were supplemented with this amino acid to insure that all diets were nutritionally adequate. Although the plasma total cholesterol levels varied by 40-50% and HDL-cholesterol by 90% among the various diets, the changes were not associated with any particular dietary protein source or level. Plasma total triglyceride levels varied independently of the dietary source and level of protein. Plasma HDL-cholesterol accounted for approximately 70% of the plasma total cholesterol. Plasma HDL-cholesterol concentrations correlated positively (R = 0.72) with plasma total cholesterol and negatively (R = -0.34) with plasma triglyceride levels. These results clearly show that the pure and crude plant proteins did not have a hypocholesterolemic effect compared with pure and crude animal proteins in rats. Plasma HDL-cholesterol levels were the same in rats fed plant and animal proteins.

Comparative effects of alfalfa saponins and alfalfa fiber on cholesterol absorption in rats.

Intestinal absorption of cholesterol was measured in control rats fed semipurified diets and in rats fed alfalfa meal, in which saponins had been previously extracted, or this extracted material plus alfalfa saponins. A dose of 2 mg radioactive cholesterol was administered intragastrically, and fecal excretion of labeled neutral steroids measured. Absorption of cholesterol was about 76% in control animals, and about 47% in alfalfa-red rats. Extraction of saponins from alfalfa eliminated the cholesterol absorption-lowering effect, while addition of 0.26% alfalfa saponins to the extracted alfalfa restored its activity. The results demonstrate that alfalfa saponins are responsible for the effect of alfalfa meal in reducing cholesterol absorption, and that alfalfa fiber is not involved in this activity.

Processing and use of crop residues including alfalfa press cake.

Better utilization of roughage can improve the production of red meat and dairy products. Feed value of low grade roughages can be greatly increased by chemical and/or physical treatments. Both alkali and ammonia treatments are already being used commercially in Europe, although there is still opportunity for process improvement. In the United States, the low cost of grain and oilseeds makes the economics of processing cellulosic byproducts less desirable, but their eventual use seems inevitable. New processes for forage fractionation are yielding surprising increases in the fiber digestibility of high grade roughages, resulting in substantial increases in the overall feed value obtainable per ton of raw material. The improved economic returns achieved by the new processes will speed adoption of the new technology.

Effect of alfalfa saponins on intestinal cholesterol absorption in rats.

Five to 20 mg of saponins obtained from alfalfa tops or roots were introduced intragastrically in rats also receiving oral and intravenous ring-labeled cholesterol. The saponins were tested before and after partial acid hydrolysis. Absorption of cholesterol was determined by estimation of fecal sterols and by a dual isotope technique involving assay of plasma radioactivity. Alfalfa top saponins (nonhydrolyzed) reduced absorption of cholesterol. Acid hydrolysis of alfalfa top or root saponins enhanced their ability to inhibit cholesterol absorption.

Availability of oxidized sulfur amino acids for the growing chick.

In four trials, experimental diets were fed to one week old broiler cockerels for a period of 14 days to compare the availability of oxidized sulfur amino acids to DL-methionine on an equimolar basis. The data were analyzed by the slope-ratio technique. Chick weight gain per unit feed consumed was the dependent variable and dietary level of supplemental amino acid was the independent variable. There was no significant (P=.05) differences in availability of DL-, L-, and D-methionine. D-, DL-, and L-methionine sulfoxide were 52, 59 and 77%, respectively, as available as DL-methionine. The differences in availability between the three sulfoxides and DL-methionine were significant. Both DL- and D-methionine sulfoxide were significantly less available than L-methionine sulfoxide. No response was obtained from L-cysteic acid or DL-methionine sulfone.

Microbiological assay for saponin in alfalfa products.

A bioassay is described for determining medicagenin-type saponin in dried alfalfa, leaf protein concentrates, and alfalfa sprouts. Samples are extracted by refluxing 2 1/2 hr with 50% ethanol, ethanol is evaporated, and aliquots of an aqueous solution are added to potato dextrose agar (PDA) and assayed for saponin by using the fungus Trichoderma viride. The growth of the fungus on PDA is compared with a standard saponin, and saponin levels are calculated by means of a slope ratio analysis.