Interactions of alfalfa plant and sprout saponins with cholesterol in vitro and in cholesterol-fed rats

Saponaria officinalis saponins as a factor increasing permeability of Candida yeasts' biomembrane

Saponins are a large group of compounds, produced mostly by plants as a side product of their metabolic activity. These compounds have attracted much attention over the years mostly because of their surface activity and antibacterial, anti-inflammatory and antifungal properties. On the other hand, most of the hitherto research has concerned the action of saponins against microbial cells as a whole. Therefore, knowing the possible interaction of saponins with biomembrane, we decided to check in-vitro the influence of saponin-rich extract of Saponaria officinalis on spheroplasts of two Candida sp. The obtained results show that 10 mg L- 1 of extract increased the permeability of spheroplasts up to 21.76% relative to that of the control sample. Moreover, the evaluation of surface potential has revealed a decrease by almost 10 mV relative to that of the untreated samples. Such results suggest its direct correlation to integration of saponins into the biomembrane structure. The obtained results have proved the antifungal potential of saponins and their ability of permeabilization of cells. This proves the high potential of saponins use as additives to antifungal pharmaceutics, which is expected to lead to improvement of their action or reduction of required dosage.

Effect of Germination on Alfalfa and Buckwheat: Phytochemical Profiling by UHPLC-ESI-QTOF-MS/MS, Bioactive Compounds, and In-Vitro Studies of Their Diabetes and Obesity-Related Functions

Germination can be used to enhance nutritional value and health functions of edible seeds. Sprouts are considered healthier than raw seeds because they are richer in the basic nutritional components (carbohydrates, protein, vitamins, and minerals) and also contain more bioactive components responsible for various biological activities. The effect of sprouting on the antioxidant, antidiabetic, antiobesity activities, and metabolite profiles of alfalfa and buckwheat seeds was investigated in this study. DPPH radical scavenging activity was highest in buckwheat sprouts followed by alfalfa sprout, buckwheat seed, and alfalfa seed, respectively. ABTS radical scavenging potential showed a similar trend as DPPH with buckwheat sprouts exerting the best scavenging capacity. Alfalfa sprout and buckwheat seed exhibited the highest percentage inhibitory activity of α-glucosidase (96.6 and 96.5%, respectively). Alfalfa sprouts demonstrated the strongest inhibitory activity against pancreatic lipase (57.12%) while alfalfa seed showed the highest advanced glycation end products (AGEs) formation inhibitory potential (28.7%). Moreover, thirty-three (33) metabolites were characterized in the seed and sprout samples. Sprouts demonstrated a higher level of metabolites compared to raw seeds. Hence, depending on the type of seed and the target activity, sprouting is a good technique to alter the secondary metabolites and functional properties of edible seeds.

Edible Plant Sprouts: Health Benefits, Trends, and Opportunities for Novel Exploration

The consumption of plant sprouts as part of human day-to-day diets is gradually increasing, and their health benefit is attracting interest across multiple disciplines. The purpose of this review was to (a) critically evaluate the phytochemicals in selected sprouts (alfalfa, buckwheat, broccoli, and red cabbage), (b) describe the health benefits of sprouts, (c) assess the recent advances in sprout production, (d) rigorously evaluate their safety, and (e) suggest directions that merit special consideration for further novel research on sprouts. Young shoots are characterized by high levels of health-benefitting phytochemicals. Their utility as functional ingredients have been extensively described. Tremendous advances in the production and safety of sprouts have been made over the recent past and numerous reports have appeared in mainstream scientific journals describing their nutritional and medicinal properties. However, subjects such as application of sprouted seed flours in processed products, utilizing sprouts as leads in the synthesis of nanoparticles, and assessing the dynamics of a relationship between sprouts and gut health require special attention for future clinical exploration. Sprouting is an effective strategy allowing manipulation of phytochemicals in seeds to improve their health benefits.

Saponin as regulator of biofuel: implication for ethnobotanical management of diabetes

There has been a sharp rise in the global prevalence of diabetes, obesity, and their comorbid conditions within the last decade prompting significant research into possible causes and cure via therapeutic intervention and lifestyle adjustments. Here, the molecular bases of antidiabetic plants used in the prehistorical treatment of diabetes and obesity are reviewed with particular focus on saponin as the phytotherapeutic principle. Until recently, the phytotherapeutic potentials of saponins have been masked in the heterogeneity of phytochemicals co-extractable during traditional preparations. With improved technique of purification and cutting edge biological assay methods, saponins have emerged as a regulator of primary biofuel availability through direct interaction with energy metabolism, cell signaling, and gene expression. Specific cases of lipoprotein lipase/peroxisome proliferator-activated receptor (PPAR)-gamma/phosphatidylinositide 3-kinase (PI-3-K)/protein kinase B (Akt) activation, adiponectin gene upregulation, fatty acid binding protein 4 repression (FABP4), and glucose transporter type 4 (Glut4) membrane exocytosis have been documented which provide molecular basis for hypocholesterolemic, hypoglycemic, and anti-obesity manifestations observed in experimental animals following saponin treatment. Although intensified research is required to characterize the pharmacophoric features in saponins exhibiting these interactions, however, this preliminary lead is valuable if the world will be free of diabetes, obesity, hypertension, hyperlipidemia, and atherosclerosis in no distant future.

The regulation of alfalfa saponin extract on key genes involved in hepatic cholesterol metabolism in hyperlipidemic rats

To investigate the cholesterol-lowering effects of alfalfa saponin extract (ASE) and its regulation mechanism on some key genes involved in cholesterol metabolism, 40 healthy 7 weeks old male Sprague Dawley (SD) rats were randomly divided into four groups with 10 rats in each group: control group, hyperlipidemic group, ASE treatment group, ASE prevention group. The body weight gain, relative liver weight and serum lipid 1evels of rats were determined. Total cholesterol (TC) and total bile acids (TBA) levels in liver and feces were also measured. Furthermore, the activity and mRNA expressions of Hmgcr, Acat2, Cyp7a1 and Ldlr were investigated. The results showed the following: (1) The abnormal serum lipid levels in hyperlipidemic rats were ameliorated by ASE administration (both ASE prevention group and treatment group) (P<0.05). (2) Both ASE administration to hyperlipidemic rats significantly reduced liver TC and increased liver TBA level (P<0.05). TC and TBA levels in feces of hyperlipidemic rats were remarkably elevated by both ASE administration (P<0.05). (3) mRNA expressions of Hmgcr and Acat2 in the liver of hyperlipidemic rats were remarkably down-regulated (P<0.05), as well as mRNA expressions of Cyp7a1 and Ldlr were dramatically up-regulated by both ASE administration (P<0.05). The activities of these enzymes also paralleled the observed changes in mRNA levels. (4) There was no significant difference between ASE treatment and ASE prevention group for most parameters evaluated. Our present study indicated that ASE had cholesterol-lowering effects. The possible mechanism could be attributed to (1) the down-regulation of Hmgcr and Acat2, as well as up-regulation of Cyp7a1 and Ldlr in the liver of hyperlipidemic rats, which was involved in cholesterol biosynthesis, uptake, and efflux pathway; (2) the increase in excretion of cholesterol. The findings in our study suggested ASE had great potential usefulness as a natural agent for treating hyperlipidemia.

Effects of dietary plant meal and soya-saponin supplementation on intestinal and hepatic lipid droplet accumulation and lipoprotein and sterol metabolism in Atlantic salmon (Salmo salar L.)

Altered lipid metabolism has been shown in fish fed plant protein sources. The present study aimed to gain further insights into how intestinal and hepatic lipid absorption and metabolism are modulated by plant meal (PM) and soya-saponin (SA) inclusion in salmon feed. Post-smolt Atlantic salmon were fed for 10 weeks one of four diets based on fishmeal or PM, with or without 10 g/kg SA. PM inclusion resulted in decreased growth performance, excessive lipid droplet accumulation in the pyloric caeca and liver, and reduced plasma cholesterol levels. Intestinal and hepatic gene expression profiling revealed an up-regulation of the expression of genes involved in lipid absorption and lipoprotein (LP) synthesis (apo, fatty acid transporters, microsomal TAG transfer protein, acyl-CoA cholesterol acyltransferase, choline kinase and choline-phosphate cytidylyltransferase A), cholesterol synthesis (3-hydroxy-3-methylglutaryl-CoA reductase) and associated transcription factors (sterol regulatory element-binding protein 2 and PPARγ). SA inclusion resulted in reduced body pools of cholesterol and bile salts. The hepatic gene expression of the rate-limiting enzyme in bile acid biosynthesis (cytochrome P450 7A1 (cyp7a1)) as well as the transcription factor liver X receptor and the bile acid transporter abcb11 (ATP-binding cassette B11) was down-regulated by SA inclusion. A significant interaction was observed between PM inclusion and SA inclusion for plasma cholesterol levels. In conclusion, gene expression profiling suggested that the capacity for LP assembly and cholesterol synthesis was up-regulated by PM exposure, probably as a compensatory mechanism for excessive lipid droplet accumulation and reduced plasma cholesterol levels. SA inclusion had hypocholesterolaemic effects on Atlantic salmon, accompanied by decreased bile salt metabolism.

Evaluation of the spermicidal and contraceptive activity of Platycodin D, a Saponin from Platycodon grandiflorum

BACKGROUND

The extract of Platycodon grandiflorum has been reported to have effective spermicidal activity. This study was designed to evaluate the spermicidal and contraceptive activity, as well as the safety, of Platycodin D (PD), a major saponin in Platycodon grandiflorum.

METHODS

Using the computer-aided sperm analysis (CASA) test criteria, the sperm-immobilizing activity of PD was studied using highly motile human sperm. The sperm viability was assessed by fluorescent staining using SYBR-14 (living sperm) and propidium iodide (dead sperm). The sperm membrane integrity was assessed by evaluating the hypo-osmotic swelling (HOS) and examinations by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The in vivo contraceptive efficacy was evaluated in rats using post-intrauterine PD application. The comet assay was employed to determine whether PD caused DNA damage in the sperm. Vaginal biopsies were also performed to determine whether the PD gel induced vaginal inflammation.

RESULTS

A dose-dependent effect of PD on the sperm motility and viability was observed. The maximum spermicidal effect was observed with a 0.25 mM concentration of PD. More than 70% of the PD-treated sperm lost their HOS responsiveness at a concentration of 0.20 mM PD, indicating that PD caused injury to the sperm plasma membrane. TEM and SEM revealed significant damage to both the head and tail membranes of the sperm. PD decreased the fertility to zero in rats, was non-DNA damaging and was not harmful to the vaginal tissue in the rats.

CONCLUSION

PD has significant spermicidal activity that should be explored in further studies.

Phytochemical and pharmacological potential of Medicago sativa: a review

CONTEXT

Many herbal remedies have so far been employed for the treatment and management of various ailments since the beginning of human civilization. Medicago is an extensive genus of the family Leguminosae, comprising about 83 different species. Medicago sativa (Linn.) has long been used as traditional herbal medicine in China, Iraq, Turkey, India and America for the treatment of a variety of ailments.

OBJECTIVES

The aim of this review was to collect all available scientific literature published and combine it into this review. The present review comprises the ethnopharmacological, phytochemical and therapeutic potential of M. sativa.

METHODS

The present review includes 117 references compiled from major databases as Chemical Abstracts, Science Direct, SciFinder, PubMed, Dr. Dukes Phytochemical and Ethnobotany, CIMER, and InteliHealth.

RESULTS

An exhaustive survey of literature revealed that saponins, flavonoids, phytoestrogens, coumarins, alkaloids, amino acids, phytosterols, vitamins, digestive enzymes and terpenes constitute major classes of phytoconstituents of this plant. Pharmacological reports revealed that it is used as neuroprotective, hypocholesterolemic, antioxidant, antiulcer, antimicrobial, hypolipidemic, estrogenic, and in the treatment of atherosclerosis, heart disease, stroke, cancer, diabetes and menopausal symptoms in women.

CONCLUSION

M. sativa seems to hold great potential for in-depth investigation for various biological activities, especially their effects on central nervous and cardiovascular system. Through this review, the authors hope to attract the attention of natural product researchers throughout the world to focus on the unexplored potential of M. sativa, and it may be useful in developing new formulations with more therapeutic value.

Ethyl acetate extracts of alfalfa (Medicago sativa L.) sprouts inhibit lipopolysaccharide-induced inflammation in vitro and in vivo

This study aimed to investigate if food components that exert anti-inflammatory effects may be used for inflammatory disorders by examining alfalfa sprout ethyl acetate extract (ASEA). The cytokine profile and life span of BALB/c mice with acute inflammation after intra-peritoneal (ip) injection of 15 mg/kg BW lipopolysaccharide (LPS) were determined. The results showed that the life span of LPS-induced inflammatory mice were negatively correlated with serum levels of TNF-α, IL-6, and IL-1β at 9 hr after LPS-injection, which indicated that suppressing these cytokines in the late phase of inflammation may be beneficial for survival. The in vitro experiment then showed that ASEA significantly reduced IL-6 and IL-1β production and the NF-κB trans-activation activity of mitogen-stimulated RAW264.7 cells. To further evaluate the anti-inflammatory effects of ASEA in vivo, BALB/c mice were tube-fed with 25 mg ASEA/kg BW/day in 50 μl sunflower oil, while the control and PDTC (pyrrolidine dithiocarbamate, an anti-inflammatory agent) groups were tube-fed with 50 μl sunflower oil/day only. After one week of tube-feeding, the PDTC group was injected with 50 mg/kg BW PDTC and one hour later, all of the mice were injected with 15 mg/kg BW LPS. The results showed that the ASEA and PDTC groups had significantly lower serum TNF-α, IL-6, and IL-1β levels at 9 hr after LPS challenge, and significantly higher survival rates than the control group. This study suggests that ASEA supplementation can suppress the production of pro-inflammatory cytokines and alleviate acute inflammatory hazards.

The ethyl acetate extract of alfalfa sprout ameliorates disease severity of autoimmune-prone MRL-lpr/lpr mice

Previous study showed that soy isoflavone supplement alleviates disease severity in autoimmune-prone mice. As the ethyl acetate extract of alfalfa sprout (AS) has selective oestrogenic and anti-inflammatory activity, this study evaluated the effects of alfalfa sprout ethyl acetate extract (ASEA) on disease severity of systemic lupus erythematosus, using autoimmune-prone female MRL- lpr/lpr mice. In Experiment 1, five groups of 12-week-old female mice were per oral treated with vehicle (control), lyophilized AS (550 mg wt/kg BW), ASEA (ASEA, 25 mg/kg BW), coumestrol (CUM, 0.075 mg/kg BW) and tamoxifen (TAM, 0.375 mg/kg BW) as the positive control. The onset of proteinuria was delayed, and the life span was significantly longer in the ASEA and TAM groups but neither in the AS nor in the CUM groups, compared to the control. To examine the changes in the immunological parameters related to disease process, three more groups of MRL- lpr/lpr female mice (control, ASEA and TAM) were fed in a similar manner for 6 weeks in the Experiment 2. Flow cytometric analysis of splenocytes showed a significantly lower percentage of activated T cells in the ASEA and TAM groups. The ex-vivo interferon-γ and interleukin (IL)-4 production from splenocytes and tumour necrosis factor-α and IL-1β production from peritoneal exudate cells were also significantly lower in the ASEA group compared with the control. The ASEA group also had less severe glomerulonephritis. Thus, ASEA attenuated cytokine and inflammatory responses of self-reactive lymphocytes, decreased the disease severity, increased survival and life span of the autoimmune-prone MRL- lpr/lpr mice, suggesting a potential of ASEA in the treatment of autoimmune diseases.

Spermicidal activity of extract from Cestrum parqui

OBJECTIVE

The leaf extract of Cestrum parqui was examined for its effects on sperm motility in vitro.

METHODS

Washed sperm were prepared by discontinuous buoyant density gradient centrifugation and incubated with varying concentrations of extract from C. parqui (40-250 microg/mL) at 37 degrees C and 5% CO(2). Sperm motility and viability were assessed at different intervals ranging from 5 to 240 min. Morphological changes in human ejaculated spermatozoa after exposure to the extract were evaluated under transmission electron microscope.

RESULTS

A dose- and time-dependent effect of this extract on sperm motility and viability was observed. The maximal spermicidal effect was observed with a 250-microg/mL dose of the extract. Transmission electron microscope revealed a significant damage to sperm membrane in both head and acrosomal membranes, notable swelling and disruption.

CONCLUSION

The present study indicates that this natural extract has potential spermicidal effect in vitro.

Effect of Alfalfa Meal in diets of laying quails on performance, egg quality and some serum parameters

This study was conducted to investigate the effects of increasing levels of alfalfa meal in the diet of laying quails on egg production, feed consumption, feed efficiency, egg quality, egg yolk cholesterol and selected serum parameters. In this study, 192, 10-week old quails (Coturnix coturnix japonica) were evenly distributed to four groups with four replicates of 12 quails each. The control group was fed a basal diet containing 0% alfalfa meal and the remaining groups received 3, 6 or 9% alfalfa meal for 12 weeks. Live weight, feed consumption, and egg production were recorded and feed efficiency were calculated. Eggs were examined for interior and exterior quality and egg yolk cholesterol content. At the end of the experiment, blood samples were collected and sera were analysed for serum Ca, inorganic P (P(i)), Mg, triglycerides and total cholesterol. Any level of alfalfa meal had no effect on live weight, egg production, feed consumption, feed efficiency, egg weight, and egg yolk index. Six percent and 9% alfalfa meal increased specific gravity of whole egg and eggshell thickness as well as serum P(i) levels. Nine percent alfalfa meal reduced serum triglycerides, total cholesterol levels and egg yolk cholesterol content. The results of this experiment indicated that addition of 9% alfalfa meal into the laying quail diet may improve eggshell quality and reduced serum triglycerides and serum and egg yolk cholesterol without any adverse effect on performance.

Cholesterol levels and sensory characteristics of meat from broilers consuming moderate to high levels of alfalfa

There is an urgent need in industrialized societies to develop novel products that can lower human dietary cholesterol intake. Dehydrated alfalfa is a good source of hypocholesterolemic compounds such as saponins. Whether consumption of alfalfa by chickens would decrease the cholesterol content of broiler meat remains, however, to be established. We determined meat quality characteristics, lipid and cholesterol contents, and consumer preference of broiler meat derived from production systems based on restricted feeding of a commercial diet combined with provision of free-choice dehydrated alfalfa. Results demonstrated that it was possible to produce chicken breast meat with reduced cholesterol content. In addition, total lipids in chicken meat were significantly decreased when a higher level of restriction was applied. Members of a 50-person consumer panel preferred meat from animals not consuming or consuming moderate levels of alfalfa. Those members that preferred meat from animals consuming the higher percentage of alfalfa identified taste as the primary attribute influencing that decision. Together the results suggest that it is possible to develop novel broiler production systems that will produce leaner meat that is acceptable to consumers and has a reduced cholesterol content.

The biological action of saponins in animal systems: a review

Saponins are steroid or triterpenoid glycosides, common in a large number of plants and plant products that are important in human and animal nutrition. Several biological effects have been ascribed to saponins. Extensive research has been carried out into the membrane-permeabilising, immunostimulant, hypocholesterolaemic and anticarcinogenic properties of saponins and they have also been found to significantly affect growth, feed intake and reproduction in animals. These structurally diverse compounds have also been observed to kill protozoans and molluscs, to be antioxidants, to impair the digestion of protein and the uptake of vitamins and minerals in the gut, to cause hypoglycaemia, and to act as antifungal and antiviral agents. These compounds can thus affect animals in a host of different ways both positive and negative.

Natural products with hypoglycemic, hypotensive, hypocholesterolemic, antiatherosclerotic and antithrombotic activities

This article reviews compounds of botanical origin which are capable of lowering plasma levels of glucose and cholesterol and blood pressure, as well as compounds inhibiting atherosclerosis and thrombosis. Hypoglycemic natural products comprise flavonoids, xanthones, triterpenoids, alkaloids, glycosides, alkyldisulfides, aminobutyric acid derivatives, guanidine, polysaccharides and peptides. Hypotensive compounds include flavonoids, diterpenes, alkaloids, glycosides, polysaccharides and proteins. Among natural products with hypocholesterolemic activity are beta-carotene, lycopene, cycloartenol, beta-sitosterol, sitostanol, saponin, soybean protein, indoles, dietary fiber, propionate, mevinolin (beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitor) and polysaccharides. Heparins, flavonoids, tocotrienols, beta-hydroxy-beta-methylglutaryl coenzyme A reductase inhibitors (statins), garlic compounds and fungal proteases exert antithrombotic action. Statins and garlic compounds also possess antiatherosclerotic activity.

Fecal steroid excretion is increased in rats by oral administration of gymnemic acids contained in Gymnema sylvestre leaves

Gymnemic acids are the saponins with a triterpenoid structure contained in Gymnema sylvestre leaves and have the hypoglycemic effects. In spite of the cholesterol-binding properties of saponins, the effect of gymnemic acids on cholesterol metabolism has not been elucidated to date. We investigated the effects of gymnemic acids on fecal steroid excretion in rats. Three kinds of extracts from Gymnema sylvestre leaves, extract (GSE), acid precipitate (GSA) and column fractionate (GSF), of which the gymnemagenin (an aglycone of gymnemic acids) concentrations are 58.87, 161.6, and 363.3 mg/g respectively, were used for the experiments. These were administered to rats orally at the dose of 0.05-1.0 g/kg for 22 d. Rats were given free access to water and nonpurified diet without cholesterol, and the differences in fecal excretion of steroids and gymnemic acids were investigated. Although there were no significant effects of GSE, GSA and GSF decreased body weight gain and food intakes in a dose-dependent manner (P < 0.01). GSF (1.0 g/kg) significantly increased fecal excretion of neutral steroids and bile acids in a dose-dependent manner (P < 0.05), especially those of cholesterol and cholic acid (CA)-derived bile acids. The increases in fecal steroid excretion of cholesterol, total neutral steroids, total bile acids and CA-related bile acids were acute and significantly correlated with fecal gymnemagenin levels (r2 = 0.2316-0.9861, P < 0. 05). These results demonstrated for the first time that a high dose of gymnemic acids increases fecal cholesterol and CA-derived bile acid excretion. Further studies are needed to clarify the effect of gymnemic acids on cholesterol metabolism.

Effect of oat saponins and different types of dietary fibre on the digestion of carbohydrates

The effects of oat saponins (a mixture of avenacosides A and B) and dietary fibre (cellulose and guar gum) on the disaccharidase activities in the proximal small intestine of the rat were investigated. The influence of avenacosides A and B on the activity of disaccharidases and alpha-amylase (EC 3.2.1.1) was also studied in vitro. In vivo, oat diets with three avenacoside contents (negligible, normal and twice normal) were used. No significant differences in sucrase (EC 3.2.1.48), maltase (EC 3.2.1.20), trehalase (EC 3.2.1.28) and lactase (EC 3.2.1.21) activities were found between the oat groups after 19 d feeding. The rats that were given cellulose tended to have higher disaccharidase activities compared with the other groups. The avenacosides inhibited the lactase activity significantly in vitro while no or small effects on the other disaccharidases were found. In contrast, the in vitro hydrolysis of starch by alpha-amylase was increased in the presence of saponins, probably due to their detergent effect. Thus, the in vitro studies showed that the avenacosides could influence the enzyme activities. In vivo, these effects are probably minor due to the low avenacoside concentrations found in oats.

Effect of oat saponins on plasma and liver lipids in gerbils (Meriones unguiculatus) and rats

The effects of oat saponins (a mixture of avenacosides A and B) on plasma and liver lipids in gerbils (Meriones unguiculatus) and rats were investigated. Cholesterol-containing diets high in total and saturated fat and with different avenacoside contents (zero (ethanol-extracted oats), normal (oats) and twice normal (ethanol-extracted oats plus added avenacosides)) were used. Compared with a cellulose control group the oat diets in both species gave a significantly higher cholesterol content in the HDL fraction and a significantly lower liver cholesterol content. No significant differences in total plasma cholesterol, HDL-cholesterol and plasma triacylglycerols were found, however, between the groups fed on oats with different avenacoside content. The liver weight, total liver cholesterol and free liver cholesterol were also similar, whereas the liver lipid content was significantly lower in rats given the highest amount of avenacosides compared with zero or normal amounts. The tendency was the same in gerbils. Thus, the oat saponins had only minor effects on lipid metabolism in gerbils and rats.

The effect of an ethanol extract derived from fenugreek (Trigonella foenum-graecum) on bile acid absorption and cholesterol levels in rats

The hypocholesterolaemic properties of an ethanol extract from defatted fenugreek (Trigonella foenum-graecum) seeds were investigated. Purification of the crude extract by dialysis produced an isolated component with haemolytic properties. The dialysate was also found to contain saponins demonstrated by thin-layer chromatography. Experiments in vitro employing the everted-sac technique showed that the ethanol extract had the ability to inhibit taurocholate and deoxycholate absorption in a dose-dependent manner. In two separate feeding experiments, hypercholesterolaemic rats were fed on 30 or 50 g ethanol extract/kg for a 4-week period. Reductions in plasma cholesterol levels ranged from 18 to 26% and a tendency for lower concentrations of liver cholesterol was observed. These results indicate that the ethanol extract from fenugreek seeds contained hypocholesterolaemic components which appear to be saponins that interact with bile salts in the digestive tract.

Changes in endogenous lipid excretion in rats fed diets containing non-heated and thermally oxidized olive oils

The objective of this study was to determine the effects of diets containing non-heated and thermally oxidized olive oils on fecal endogenous lipids. Male Wistar rats were fed fat-free diets and diets supplemented with 12% non-heated, heated, and a 1:1 mixture of non-heated/heated olive oils. After a 15-day experimental period two groups of fecal lipids from major endogenous sources were quantitated: neutral sterols and fatty acids associated with intestinal microflora action. Fecal endogenous sterols, particularly cholesterol, were significantly higher when diets contained oil, and excretion increased as the dietary oil alteration increased. Similar results were obtained for endogenous fatty acids. Increments of fecal sterols, dependent on oil alteration, could be explained by impairments in triglyceride hydrolysis and subsequent effect on cholesterol micellar solubilization. Moreover, high concentrations of poorly digestible lipids may have led to intestinal microbial modifications.

Kleingrass (Panicum coloratum L.) poisoning in sheep

Twenty-four lambs grazing pastures of Panicum coloratum developed photosensitization secondary to hepatic dysfunction. Lesions were necrosis of scattered hepatocytes, obstruction of small bile ducts and bile canaliculi by small aggregates of birefringent crystals, and accumulation of birefringent crystals in phagocytes within sinusoids. The number of crystals in livers of affected sheep varied, depending on the amount of time of exposure to toxic plants and severity of hepatic abnormalities. Crystals in the liver were soluble in acidified ethyl alcohol, acetic acid, pyridine, chloral hydrate, and methanol, but not in xylene, petroleum ether, diethyl ether, acetone, water, or cold ethyl alcohol. Crystals were not stained by oil red O. There was necrosis of epithelial cells in renal distal convoluted tubules, papillary muscles of the heart, and the adrenal cortex. Lesions of Panicum coloratum-associated disease are similar to those associated with photosensitization induced by Tribulus terrestris, Agave lecheguilla, and Nolina texana.

Adjuvant effects of orally administered saponins on humoral and cellular immune responses in mice

We have described adjuvant effects of orally administered Quillaja saponins on the immune responses of mice fed inactivated rabies antigen (AG). The in vivo lymphocyte proliferation in mice fed antigen + saponin (AG + SAP) was significantly greater than that in mice fed antigen (AG) alone. Further, the mitogen-induced cell proliferative responses in animals primed with AG + SAP was markedly increased compared with those in the AG group. These changes in clonal expansion were associated with an enhanced helper T cell (Th) and B cell co-operation. The in vivo cell proliferation and in vitro mitogen-induced responses of mice fed AG + SAP correlated with enhanced antibody synthesis. In mice fed saponin alone, there were significant increases in clonal expansion and lymphocyte function. Our present data indicate that the immunocompetence in animals fed AG + SAP was indeed evoked by saponins. Cytotoxic T lymphocyte activity in mice fed SAP or AG + SAP was detected 7 days after booster, in contrast to 21 days in mice fed AG alone. The natural killer cell activity in mice fed SAP alone was greatly enhanced and persisted for an extended period of time.

An in vitro study of immunomodulatory effects of some saponins

The in vitro immunomodulatory activities of a number of saponins (crude Quillaja saponin, Quillayanin, Quil-A and glycyrrhizic acid) are described. Addition of these saponin preparations to mouse spleen cell cultures resulted in significant cell proliferation. B-cells were induced to proliferate in the presence of the crude saponin, and T-cells in the presence of Quil-A. On the other hand, Quillayanin and glycyrrhizic acid stimulated both T- and B-lymphocytes equally. The selective proliferation of subtypes of lymphocytes correlated with restimulation responses by polyclonal mitogens. Pretreatment by lymphocytes with crude saponins induced significant T-cell responses to PHA and Con A, and to T-independent B-cell stimulation by LPS. Pulse exposure of spleen cells to Quil-A resulted in enhanced cell proliferation when restimulated with PHA, Con A and PWM. In comparison, similar exposure of lymphocytes to Quillayanin or glycyrrhizic acid produced markedly increased responses to PHA, Con A, PWM and LPS. Incubation of lymphocytes in the presence of Quillaja saponins and Quillayanin caused effector cell generation as determined in a one-way mixed lymphocyte reaction. In the case of lymphocytes cultured in the presence of crude saponins or glycyrrhizic acid, the supernatants contained active soluble factors. This was demonstrated by the observation that the addition of supernatants to spleen cell cultures induced spontaneous cell proliferation, and also amplified their responses to a suboptimal dose of PHA. The experimental data suggest that different components in the Quillaja saponin preparations may have selective effects on various subtypes of cell populations. Glycyrrhizic acid has the most profound immunomodulatory activity in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

The chemistry and biological significance of saponins in foods and feedingstuffs

Saponins occur widely in plant species and exhibit a range of biological properties, both beneficial and deleterious. This review, which covers the literature to mid 1986, is concerned with their occurrence in plants and their effects when consumed by animals and man. After a short discussion on the nature, occurrence, and biosynthesis of saponins, during which the distinction between steroidal and triterpenoid saponins is made, the structures of saponins which have been identified in a variety of plants used as human foods, animal feedingstuffs, herbs, and flavorings are described. Many of these compounds have been characterized only during the last 2 decades, and modern techniques of isolation, purification, and structural elucidation are discussed. Particular consideration is given to mild chemical and enzymatic methods of hydrolysis and to recent developments in the application of NMR and soft ionization MS techniques to structural elucidation. Methods currently used for the quantitative analysis of saponins, sapogenols, and glycoalkaloids are critically considered; advances in the use of newer methods being emphasized. The levels of saponins in a variety of foods and food plants are discussed in the context of the methods used and factors affecting these levels, including genetic origin, agronomic, and processing variables, are indicated. Critical consideration is given to the biological effects of saponins in food which are very varied and dependent upon both the amount and chemical structure of the individual compounds. The properties considered include membranolytic effects, toxic and fungitoxic effects, adverse effects on animal growth and performance, and the important hypocholesterolemic effect. A final section deals briefly with the pharmacological effects of saponins from ginseng, since use of this plant is increasing in certain sections of western society as well as being traditional in the Orient.

Influence of saponins on gut permeability and active nutrient transport in vitro

The influence of four saponins, three triterpenoid glycosides and one steroidal amine glycoside, upon intestinal transport was investigated in vitro. In the presence of Gypsophylla saponin, carrier-mediated galactose transport was inhibited, although the uptake of the passively transported L-isomer of glucose increased. The uptake of the extracellular space marker, polyethylene glycol 4000, was also higher, indicating that the saponin inhibited active transport by increasing the general permeability of the enterocytes. Gypsophylla saponin, in contact only with the mucosal surface of everted jejunal sacs, induced a rapid decline in glucose-stimulated transmural potential difference. The rate of decline increased as the saponin concentration was raised over the approximate range of 0.3 to 8 mM. Saponaria saponin and alpha-tomatine also reduced transmural potential difference, but soya saponins were much less effective. The results indicate that some saponins readily increase the permeability of the small intestinal mucosal cells, thereby inhibiting active nutrient transport, and facilitating the uptake of materials to which the gut would normally be impermeable.