Alfalfa Saponins Research Articles

Saponins in alfalfa (Medicago sativa L.) root and their structural elucidation.

Twenty-four saponins have been identified in alfalfa roots, including 13 medicagenic acids, 2 zanhic acids, 4 hederagenins, 1 soyasapogenol A, 2 soyasapogenol B's, 1 soyasapogenol E, and 1 bayogenin glycoside. Ten of the identified compounds, including 3-O-[beta-D-glucopyranosyl(1-->3)-beta-D-glucopyranosyl]-28-O-beta-D- glucopyranoside medicagenate, 3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta -D-glucopyranoside] medicagenic acid, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D -glucopyranosyl]-28-beta- D-glucopyranoside medicagenate, 3-O-[beta-D-glucuronopyranosyl methyl ester]-28-O-[beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl(1--> 2)-alpha-L-arabinopyranoside] medicagenate, 3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-be ta-D-glucuronopyranosyl]-21-O-alpha-L-rhamnopyranoside soyasapogenol A, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)glucopy ranosyl]-28-O-[beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyranosyl (1- ->2)-alpha-L-arabinopyranoside] medicagenate, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)glucopy ranosyl]-28-O-¿beta-D-xylopyranosyl(1-->4)-)-[beta-D-apiofurano syl-(1 -->3)]- alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside¿ medicagenate, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D -glucopyranosyl]-28-O-[beta-D-xylopyranosyl(1-->4)-alpha-L-rhamnopyra nosyl(1-->2)-alpha-L-arabinopyranoside] zanhic acid, 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl(1-->2)-beta-D -glucopyranosyl]-28-O-¿beta-D-xylopyranosyl(1-->4)-[beta-D-apiofurano side-(1-->3)]- alpha-L-rhamnopyranosyl(1-->2)-alpha-L-arabinopyranoside¿zanhic acid, and 3-O-[beta-D-galactopyranosyl(1-->2)-beta-D-glucuronopyranosyl]-28- O-b eta-D-glucopyranoside bayogenin, were not reported before, and their structures were established by spectral (FAB-MS and NMR) techniques. In addition, 3-O-[alpha-L-rhamnopyranosyl(1-->2)-beta-D-galactopyranosyl(1-->2)-be ta-D-glucuronopyranoside] soyasapogenol E was identified in the roots for the first time.

Alfalfa Saponins and Their Implication in Animal Nutrition.

Alfalfa (Medicago sativa L.) is of immense importance as livestock fodder for both developed and lesser developed countries as it contains a high amount of protein, and yield of dry matter is also very high. The main antinutritional components present in this plant are saponins, and their unfavorable effects on animal performance have restricted the optimum use of this high-protein plant as an animal feed. The occurrence, chemistry, analysis, and consequences of intake of alfalfa saponins are reviewed. The information synthesized may lead to planning of more detailed studies on isolation and characterization of saponins and sapogenins to gain a better understanding of the biological activities of the aglycon and carbohydrate moieties of saponins.

Antifungal and hemolytic activity of aerial parts of alfalfa (Medicago) species in relation to saponin composition.

Saponins occurring in alfalfa (Medicago sativa L.) are composed of a complicated mixture of triterpenoid glycosides1–3. According to the structure of aglycones, they can be divided into several groups: derivatives of medicagenic acid, oleanolic acid, zanhic acid, hederagenin and soyasapogenols. It is generally accepted that the structure of the aglycone determines the biological activity of glycosides although the sugar moiety can essentially modify this activity4–8. A broad spectrum of the biological properties of alfalfa saponins is attributed to the occurrence of medicagenic acid and hederagenin glycosides. They have been found to be fungistatic against many fungal strains such as:

Effects of alfalfa root saponins on digestive function in sheep.

The effects of alfalfa saponins on ruminal pH and VFA concentrations, protozoal numbers, forestomach motility, and digesta flow from the rumen were examined in this experiment. In a preliminary study, either 800 or 1600 mg/kg of saponins per kg BW were administered intraruminally in a single dose to one of two 60-kg wethers. Ruminal contractions were suppressed within 15 min. The study was terminated when one wether didn't recover. Saponins were then administered intraruminally in two equal doses daily into four ruminally and duodenally cannulated wethers (60 +/- 1 kg) in amounts equivalent to 0, 200, 400, and 800 mg/kg BW daily in a 4 x 4 Latin Square arrangement. Saponins increased VFA concentrations (P = .001) and lowered ruminal pH (P = .001) after 2 d of administration. On d 2 and d 14, saponins decreased (P < .01) protozoal populations. On d 11, pressure changes during ruminal contractions increased by 79% during resting (P = .06), 202% during feeding (P = .05), and 53% during an 8-h period (P = .08) as the level of saponins increased from 0 to 800 mg/kg BW. Administered saponins increased duodenal flows of OM and total N by 19 and 26%, respectively (P = .04 and .01). Apparent total tract N digestibility was reduced (P = .02) by 5% at the highest saponin dosage. We conclude that alfalfa may contain enough saponins to adversely impact ruminoreticular motility. Saponins also caused decreased ruminal protozoal populations, increased flow of total duodenal N, and reduced ruminal and total tract apparent digestibilities.

Pasture management strategies for reducing the risk of legume bloat in cattle

Results from two decades (1973-1993) of bloat research at Kamloops are reviewed. The trials were conducted with groups of ruminally fistulated cattle either grazing or fed daily fresh-cut alfalfa (Medicago sativa) herbage. Studies were conducted during the growing season (May to September) and in the fall (October and November). The alfalfa was usually in the vegetative to early bloom stages of growth. Visual assessments of bloat severity on a scale of 1 to 5 were made .5 to 2 h after feeding started, at which time ruminal cannulas were opened to relieve ruminal pressure. Every cultivar of alfalfa tested caused bloat, but sainfoin (Onobrychis viciifolia), birdsfoot trefoil (Lotus corniculatus), and cicer milkvetch (Astragalus cicer) did not. This confirms the bloat-safe features of these alternate legume forages. Bloat was positively associated with the level of Fraction 1 protein and total soluble protein in alfalfa, supporting the concept of a decreased probability of bloat with advancing stages of plant maturity. There was no association between alfalfa saponins and bloat. Prefeeding ruminal chlorophyll levels were higher and ruminal clearance rates were lower in cattle that were susceptible to bloat. Cattle that bloated on a given day consumed 18 to 25% less alfalfa immediately before bloat than non-bloaters did in the same time period. Ruminal cations were associated with bloat incidence but cation manipulation through supplementation did not prevent bloat. Of all the feed additives tested, only poloxalene (Bloat Guard) completely prevented bloat.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of some purified alfalfa (Medic ago sativa) saponins on transmural potential difference in mammalian small intestine

AbstractThe effect of a range of structurally divergent alfalfa saponins on the potential difference (PD) across the rat small intestine has been examined in vitro Typically, there was an immediate reduction in PD, although there was considerable variation in response to particular compounds. Among the glycosides of medicagenic acid, bisdesmosides containing four sugar moieties had activities equal to the monodesmoside and to medicagenic acid itself. The exception was 3Glc, 28Glc‐medicagenic acid, which did not affect the membrane potential. Zanhic acid glycosides reduced the PD to a much greater extent than medicagenic acid derived compounds. The tridesmoside of zanhic acid was the most active compound tested. This compound is however not precipitated by cholesterol and hence would not have been present in the ‘biologically active’ fractions used in previous studies. The present data show that both the lipophilic aglyconc portion of saponins, and the sugar composition can influence the ability of these compounds to depolarized the intestinal mucosa. The observations are discussed in the light of anti nutritional properties of alfalfa saponins when fed to monogastric animals.

Determination of Alfalfa (Medicago sativa) Saponins by High-Performance Liquid Chromatography

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of Alfalfa (Medicago sativa) Saponins by High-Performance Liquid ChromatographyJoanna Nowacka and Wieslaw OleszekCite this: J. Agric. Food Chem. 1994, 42, 3, 727–730Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://doi.org/10.1021/jf00039a025RIGHTS & PERMISSIONSArticle Views583Altmetric-Citations33LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (557 KB) Get e-Alerts Get e-Alerts

Alfalfa saponins and sapogenins: Isolation and quantification in two different cultivars

AbstractThe chemical characterization of the saponins and sapogenins isolated from roots and aerial parts of two alfalfa cultivars with differing saponin content is reported. A procedure for the extraction and quantification of saponins is described, and the identification of the major components of the saponin mixture has been performed using thin layer chromatography and high performance liquid chromatography. Characterization, using gas chromatography (GC) and GC/mass spectral analysis, of sapogenins released following acid hydrolysis allowed the identification of medicagenic acid, hederagenin, soyasapogenols B, C, D, E and F as the major compounds, together with oleanolic acid. Quantitative analysis of the sapogenins in aerial parts and roots of the two cultivars is reported and discussed.

Allelopathic potentials of alfalfa (Medicago sativa) saponins: Their relation to antifungal and hemolytic activities

A wheat seedling bioassay was used to indicate the relationship between the chemical structure of alfalfa saponins and their allelopathic activity. None of the tested saponins significantly influenced wheat germination. Seedling growth bioassays indicated significant differences among the activities of individual glycosides. The most active were medicagenic acid, its glycosides substituted at the C-3 position with glucose, and hederagenin monoglycoside. Medicagenic acid glycosides, substituted at the C-3 position with glucuronic acid, and zahnic acid tridesmoside were less active. No significant correlation was found among the allelopathic, hemolytic, and antifungal activities of the individual glycosides.

Structural specificity of alfalfa (Medicago sativa) Saponin Haemolysis and Its Impact on Two Haemolysis based Quantification Methods

AbstractSeveral individual alfalfa (Medicago sativa L) root saponins were tested for their haemolytic activities using two methods, namely the haemolytic index test and a haemolytic micromethod. It was shown that individual saponins gave different haemolytic activities depending on their structure and also on the haemolytic test used. Generally it was found that saponin monodesmosides were more active than their bisdesmosidic analogues. These differences in haemolytic activities may strongly influence the results of saponin determination with haemolysis‐based methods.

Solid‐phase extraction‐fractionation of alfalfa saponins

AbstractA simple method was developed to isolate alfalfa saponins and fractionate them into medicagenic acid, hederagenine and soyasapogenol glycosides. This method is based on the selective extraction of saponins from a C18 solidphase column with methanol‐water solutions. Selectivity of the C18 sorbent to retain saponins strongly depended on the pH of the loaded sample. This characteristic was the basis of a new method of column chromatography for isolation of individual saponins.

Effect of Selecting for Downy Mildew Resistance in Alfalfa on Saponin Content1

Alfalfa (Medicago sativa L.) saponin is toxic to several plant disease organisms, including some Oomycetes closely related to Personospora trifoliorum d By., the alfalfa downy mildew fungus. Resistance in alfalfa to downy mildew has been changed significantly during selection to alter the forage saponin content. The primary objective of this research was to determine the effects of selecting for downy mildew resistance in alfalfa on forage saponin levels. Alfalfa ‘CUF 101’ and germplasms UC 123 and UC 143 derived from it by one and two cycles, respectively, of recurrent phenotypic selection for resistance to P. trifoliorum were evaluated for forage saponin content. The percent of plants resistant (symptomless) to P. trifoliorum isolates I–7 and I–8, respectively, were 28 and 3 for CUF 101; 62 and 3 for UC 123; and 62 and 72 for UC 143. Saponin indices (higher index = lower saponin content) were CUF 101, 101; UC 123, 92; UC 143, 100; ‘Lahotan’ (low‐saponin check), 98; and ‘Uinta’ (high‐saponin check), 35. Alfalfa germplasms KS80, KS145, KS167, and K78‐10, all higly resistant to P. trifoliorum and several other fungi and insects, had saponin indices about midway between those of Lahonton and Uinta. Saponin apparently played no role in the resistance of UC 143 to P. trifoliorum since UC 143 was derived from the very low‐saponin CUF 101 cultivar without affecting the saponin index.

Alfalfa Saponins Affect Site and Extent of Nutrient Digestion in Ruminants

Alfalfa saponins isolated by ethanol extraction and partial acid hydrolysis were intraruminally administered to sheep to investigate the biological activities and nutritional implications in ruminants. Mature wethers fitted with ruminal, duodenal and ileal cannulas were fed a concentrate or roughage diet formulated to be isonitrogenous and isoenergetic. Microbial fermentation and nutrient degradation in the rumen were reduced by saponins. Total protozoal count in the rumen was reduced 34 and 66% by saponins at levels of 2 and 4% dietary dry matter, respectively. Bacterial nitrogen flow to the duodenum was reduced 20 and 30% in the same sequence. Apparent digestion coefficients of organic matter, hemicellulose and cellulose in the total digestive tract were increased by saponins in sheep fed concentrate diets. Fractional digestion coefficients of organic matter, hemicellulose, cellulose and nitrogen were reduced in the stomach while they were increased in the small intestine by saponins in both diets. Saponins inhibited microbial fermentation and synthesis in the rumen and altered the sites of nutrient digestion in sheep.

Alteration of Fermentation in Continuous Culture of Mixed Rumen Bacteria by Isolated Alfalfa Saponins

Saponins isolated from alfalfa by ethanol extraction and acid hydrolysis were incorporated into protein-free purified diets at 0, .5, 1, 2, and 4% of dietary dry matter to investigate the effect of saponins on fermentation by mixed rumen bacteria maintained in continuous culture. Inoculum was obtained from a lactating dairy cow fed alfalfa hay and a 13% crude protein grain mixture with forage to grain ratios of 33:67, 67:33, or 100:0. Outflow of microbial protein was lower in fermenters fed purified diet containing 1% saponins. Accumulation of ammonia was observed in fermenters fed purified diets containing alfalfa saponins. Total volatile fatty acid production was reduced by addition of isolated alfalfa saponin fraction at .5, 1, 2, and 4% concentrations. Acetate to propionate ratios were reduced from 1.93 in control to 1.37 in fermenters with 1% saponins. Extent of change in fermentation was not proportional to the concentration of added saponins.

ヒナの発育と血漿コレステロール濃度に及ぼすアルファルファサポニンの影響

Alfalfa saponin extract was prepared from Du Puits leaf protein concentrate (LPC) and its effects on chick performance and plasma cholesterol level were investigated in two experiments. When the alfalfa saponin containing 41.8 mg/g of medicagenic acid was added at a level of 0.3% to the casein-amino acid diet, chick performance was not affected. The addition of 1.0% cholesterol significantly increased plasma total- and LDL-cholesterol levels, and in this case, the alfalfa saponin addition was effective in lowering these levels. While, chick performance was depressed when 0.3% alfalfa saponin was added to the alfalfa LPC diet containing 0.97 mg medicagenic acid per gram diet, and the adverse effect of saponin was alleviated by 1.0% dietary cholesterol addition. The alfalfa saponin lowered both total- and LDL-cholesterol levels in the plasma, irrespective of the cholesterol addition. HDL-cholesterol level was not affected by the alfalfa saponin in both experiments.

FEED PREFERENCE RESPONSES OF SEVERAL AVIAN SPECIES FED ALFALFA MEAL, HIGH- AND LOW-SAPONIN ALFALFA, AND QUININE SULFATE

The response of male geese, turkeys, Japanese quail and chickens to dietary levels of 0.5, 1, 2.5, 5, 10, 20 and 30% alfalfa meal was measured, using a two-choice feed preference test. At each alfalfa level, the birds were given a choice between the alfalfa-containing diet and an alfalfa-free diet. At levels of 10% or more alfalfa meal, all species showed a significant (P &lt; 0.05) preference for the alfalfa-free diet. At a dietary level of 5% alfalfa meal, all species except chickens discriminated against the alfalfa-containing diet and preferred the alfalfa-free diet. Geese discriminated against the alfalfa-containing diet at 2.5% alfalfa, while no species showed discrimination at alfalfa levels of 0.5 and 1%. The birds did not discriminate between low- saponin and high- saponin alfalfa-containing diets, each compared at alfalfa levels of 1, 5, 10 and 20%. Quinine sulfate was included at levels of 0.01, 0.05 and 0.1% of the diet; discrimination against the quinine-containing diets was noted, indicating that poultry can detect substances in the diet perceived as bitter by humans. Key words: Poultry, quinine, alfalfa saponins, feed preferences

Experimental models of atherosclerosis regression

Regression of atherosclerosis has been demonstrated in several species of animals, including rabbits, chickens, rats, dogs, pigeons, pigs, and nonhuman primates. Regression has been associated with withdrawal of cholesterol from the diet or with the ingestion of cholestyramine, alfalfa meal, or alfalfa saponins in monkeys fed high-cholesterol diets. Although regression of atherosclerosis has been documented by sequential contrast arteriography in humans, the correspondence of regression in animals and in humans needs to be established.

Alfalfa saponins and microbial transformations of nitrogen in peat

Alfalfa saponins, their sugar fraction or glucose, but not their sapogenin fraction, favored nitrogen immobilization and denitrification and inhibited proteolysis and ammonification in both peatinoculated and Pseudomonas sp.-inoculated media. Alfalfa root saponins and sapogenins significantly reduced the fungal peat population, but did not affect the bacterial population. The inhibition of N mineralization in peat by saponins and by their sapogenin fraction during dry and wet cycles was mostly due to their fungistatic activity. The inhibitory effect of the sugar fraction of alfalfa roots on mineral-N accumulation in peat is mainly under moist conditions.

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-fed 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.

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, 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-fed 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.