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Biomedical subjects

A L Livingston

Publications and source records attributed to A L Livingston.

6 recordsLinked to original sources
PubMed1979

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.

Animals↗
PubMed1977

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.

Animals↗
PubMed1977

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.

Biological Assay↗
PubMedDate not supplied

Forage plant estrogens.

Forage plant estrogens occur at high levels in certain forage species. Such levels are responsible for reproductive and other effects in animals. Current progress regarding the chemical, metabolic, and biological effects, as well as occurrence of the several naturally occurring forage estrogens, is described. Forage estrogens occur as natural plant responses to foliar and other plant diseases. Their potency in animals is approximately 1/1000 to 1/10,000 that of the principal animal hormones such as estradiol. Coumestans and isoflavones comprise the two principal classes of forage estrogens, with coumestrol and genistein being the most potent and predominant of each class. Only very low levels of the coumestans occurred in alfalfa leaf protein concentrates prepared at alkaline pH.

Animal Feed↗