Soy protein with or without isoflavones, soy germ and soy germ extract, and daidzein lessen plasma cholesterol levels in golden Syrian hamsters

Beneficiary and Adverse Effects of Phytoestrogens: A Potential Constituent of Plant-based Diet

BACKGROUND

Phytoestrogens are non-endocrine, non-steroidal secondary derivatives of plants and consumed through a plant-based diet also named as "dietary estrogens". The major sources of phytoestrogens are soy and soy-based foods, flaxseed, chickpeas, green beans, dairy products, etc. The dietary inclusion of phytoestrogen based foods plays a crucial role in the maintenance of metabolic syndrome cluster, including obesity, diabetes, blood pressure, cancer, inflammation, cardiovascular diseases, postmenopausal ailments and their complications. In recent days, phytoestrogens are the preferred molecules for hormone replacement therapy. On the other hand, they act as endocrine disruptors via estrogen receptor-mediated pathways. These effects are not restricted to adult males or females and identified even in development.

OBJECTIVE

Since phytoestrogenic occurrence is high at daily meals for most people worldwide, they focused to study for its beneficiary effects towards developing pharmaceutical drugs for treating various metabolic disorders by observing endocrine disruption.

CONCLUSION

The present review emphasizes the pros and cons of phytoestrogens on human health, which may help to direct the pharmaceutical industry to produce various phytoestrongen based drugs against various metabolic disorders.

Targeting Abdominal Obesity and Its Complications with Dietary Phytoestrogens

In the assessment of the health risk of an obese individual, both the amount of adipose tissue and its distribution and metabolic activity are essential. In adults, the distribution of adipose tissue differs in a gender-dependent manner and is regulated by sex steroids, especially estrogens. Estrogens affect adipocyte differentiation but are also involved in the regulation of the lipid metabolism, insulin resistance, and inflammatory activity of the adipose tissue. Their deficiency results in unfavorable changes in body composition and increases the risk of metabolic complications, which can be partially reversed by hormone replacement therapy. Therefore, the idea of the supplementation of estrogen-like compounds to counteract obesity and related complications is compelling. Phytoestrogens are natural plant-derived dietary compounds that resemble human estrogens in their chemical structure and biological activity. Supplementation with phytoestrogens may confer a range of beneficial effects. However, results of studies on the influence of phytoestrogens on body composition and prevalence of obesity are inconsistent. In this review, we present data from in vitro, animal, and human studies regarding the role of phytoestrogens in adipose tissue development and function in the context of their potential application in the prevention of visceral obesity and related complications.

Flavonoids and type 2 diabetes: Evidence of efficacy in clinical and animal studies and delivery strategies to enhance their therapeutic efficacy

Diabetes mellitus type 2 (T2DM) is a metabolic disorder develops due to the overproduction of free radicals where oxidative stress could contribute it. Possible factors are defective insulin signals, glucose oxidation, and degradation of glycated proteins as well as alteration in glutathione metabolism which induced hyperglycemia. Previous studies revealed a link between T2DM with oxidative stress, inflammation and insulin resistance which are assumed to be regulated by numerous cellular networks such as NF-κB, PI3K/Akt, MAPK, GSK3 and PPARγ. Flavonoids are ubiquitously present in the nature and classified according to their chemical structures for example, flavonols, flavones, flavan-3-ols, anthocyanidins, flavanones, and isoflavones. Flavonoids indicate poor bioavailability which could be improved by employing various nano-delivery systems against the occurrences of T2DM. These bioactive compounds exert versatile anti-diabetic activities via modulating targeted cellular signaling networks, thereby, improving glucose metabolism, α -glycosidase, and glucose transport or aldose reductase by carbohydrate metabolic pathway in pancreatic β-cells, hepatocytes, adipocytes and skeletal myofibres. Moreover, anti-diabetic properties of flavonoids also encounter diabetic related complications. This review article has designed to shed light on the anti-diabetic potential of flavonoids, contribution of oxidative stress, evidence of efficacy in clinical, cellular and animal studies and nano-delivery approaches to enhance their therapeutic efficacy. This article might give some new insights for therapeutic intervention against T2DM in near future.

Flavonoids and Their Anti-Diabetic Effects: Cellular Mechanisms and Effects to Improve Blood Sugar Levels

Diabetes mellitus (DM) is a prevailing global health metabolic disorder, with an alarming incidence rate and a huge burden on health care providers. DM is characterized by the elevation of blood glucose due either to a defect in insulin synthesis, secretion, binding to receptor, or an increase of insulin resistance. The internal and external factors such as obesity, urbanizations, and genetic mutations could increase the risk of developing DM. Flavonoids are phenolic compounds existing as secondary metabolites in fruits and vegetables as well as fungi. Their structure consists of 15 carbon skeletons and two aromatic rings (A and B) connected by three carbon chains. Flavonoids are furtherly classified into 6 subclasses: flavonols, flavones, flavanones, isoflavones, flavanols, and anthocyanidins. Naturally occurring flavonoids possess anti-diabetic effects. As in vitro and animal model's studies demonstrate, they have the ability to prevent diabetes and its complications. The aim of this review is to summarize the current knowledge addressing the antidiabetic effects of dietary flavonoids and their underlying molecular mechanisms on selected pathways: Glucose transporter, hepatic enzymes, tyrosine kinase inhibitor, AMPK, PPAR, and NF-κB. Flavonoids improve the pathogenesis of diabetes and its complications through the regulation of glucose metabolism, hepatic enzymes activities, and a lipid profile. Most studies illustrate a positive role of specific dietary flavonoids on diabetes, but the mechanisms of action and the side effects need more clarification. Overall, more research is needed to provide a better understanding of the mechanisms of diabetes treatment using flavonoids.

Polyamine Metabolism and Gene Methylation in Conjunction with One-Carbon Metabolism

Recent investigations have revealed that changes in DNA methylation status play an important role in aging-associated pathologies and lifespan. The methylation of DNA is regulated by DNA methyltransferases (DNMT1, DNMT3a, and DNMT3b) in the presence of S-adenosylmethionine (SAM), which serves as a methyl group donor. Increased availability of SAM enhances DNMT activity, while its metabolites, S-adenosyl-l-homocysteine (SAH) and decarboxylated S-adenosylmethionine (dcSAM), act to inhibit DNMT activity. SAH, which is converted from SAM by adding a methyl group to cytosine residues in DNA, is an intermediate precursor of homocysteine. dcSAM, converted from SAM by the enzymatic activity of adenosylmethionine decarboxylase, provides an aminopropyl group to synthesize the polyamines spermine and spermidine. Increased homocysteine levels are a significant risk factor for the development of a wide range of conditions, including cardiovascular diseases. However, successful homocysteine-lowering treatment by vitamins (B6, B12, and folate) failed to improve these conditions. Long-term increased polyamine intake elevated blood spermine levels and inhibited aging-associated pathologies in mice and humans. Spermine reversed changes (increased dcSAM, decreased DNMT activity, aberrant DNA methylation, and proinflammatory status) induced by the inhibition of ornithine decarboxylase. The relation between polyamine metabolism, one-carbon metabolism, DNA methylation, and the biological mechanism of spermine-induced lifespan extension is discussed.

A BRIEF COMMUNICATION

Nutritional supplements containing soybean phytoestrogens, the isoflavones genistein (G) and daidzein (D), are increasingly used as alternative therapy for osteoporosis, cancer, and cardiovascular and other diseases with a frequency that increases with advancing age. In this study we examined the effects of subcutaneous administration of either G or D on serum lipid levels in orchidectomized (Orx) and intact (IA) middle-aged male rats, which are experimental models of andropause. Sixteen-month-old Wistar rats were treated with 10 mg/kg and 30mg/kg of either G or D. The control groups received testosterone, estradiol, or vehicle for 3 weeks, after which the total serum cholesterol (TC), low-density lipoprotein (LDL-C), high-density lipoprotein (HDL-C), and total triglycerides (TT) were measured. Compared with the matching vehicle-treated controls, the higher doses of G and D and testosterone treatment significantly ( P < 0.05) lowered the TC and lipoprotein cholesterol levels. The greatest effect was observed regarding LDL-C in both Orx and IA males after G and D treatments, in which LDL-C decreased by more than 30%. The lower isoflavone doses induced a significant cholesterol-lowering effect ( P < 0.05) only in the Orx group. Like the estradiol treatment, the higher doses of G and D increased the TT levels in both rat models by more than 50% ( P < 0.05). The lower doses of isoflavones increased TT only in the Orx group. In male middle-aged rats, injections of higher doses of G and D decreased the serum cholesterol levels, as did testosterone injection, and brought about an increase in serum triglycerides similar to that observed after estradiol treatment.

Molecular Mechanisms of the Anti-Obesity and Anti-Diabetic Properties of Flavonoids

Obesity and diabetes are the most prevailing health concerns worldwide and their incidence is increasing at a high rate, resulting in enormous social costs. Obesity is a complex disease commonly accompanied by insulin resistance and increases in oxidative stress and inflammatory marker expression, leading to augmented fat mass in the body. Diabetes mellitus (DM) is a metabolic disorder characterized by the destruction of pancreatic β cells or diminished insulin secretion and action insulin. Obesity causes the development of metabolic disorders such as DM, hypertension, cardiovascular diseases, and inflammation-based pathologies. Flavonoids are the secondary metabolites of plants and have 15-carbon skeleton structures containing two phenyl rings and a heterocyclic ring. More than 5000 naturally occurring flavonoids have been reported from various plants and have been found to possess many beneficial effects with advantages over chemical treatments. A number of studies have demonstrated the potential health benefits of natural flavonoids in treating obesity and DM, and show increased bioavailability and action on multiple molecular targets. This review summarizes the current progress in our understanding of the anti-obesity and anti-diabetic potential of natural flavonoids and their molecular mechanisms for preventing and/or treating obesity and diabetes.

Probiotic Soy Product Supplemented with Isoflavones Improves the Lipid Profile of Moderately Hypercholesterolemic Men: A Randomized Controlled Trial

Background: Cardiovascular disease is the leading cause of worldwide morbidity and mortality. Several studies have demonstrated that specific probiotics affect the host’s metabolism and may influence the cardiovascular disease risk. Objectives: The aim of this study was to investigate the influence of an isoflavone-supplemented soy product fermented with Enterococcus faecium CRL 183 and Lactobacillus helveticus 416 on cardiovascular risk markers in moderately hypercholesterolemic subjects. Design: Randomized placebo-controlled double-blind trial Setting: São Paulo State University in Araraquara, SP, Brazil. Participants: 49 male healthy men with total cholesterol (TC) >5.17 mmol/L and <6.21 mmol/L Intervention: The volunteers have consumed 200 mL of the probiotic soy product (group SP-10¹⁰ CFU/day), isoflavone-supplemented probiotic soy product (group ISP–probiotic plus 50 mg of total isoflavones/100 g) or unfermented soy product (group USP-placebo) for 42 days in a randomized, double-blind study. Main outcome measures: Lipid profile and additional cardiovascular biomarkers were analyzed on days 0, 30 and 42. Urine samples (24 h) were collected at baseline and at the end of the experiment so as to determine the isoflavones profile. Results: After 42 days, the ISP consumption led to improved total cholesterol, non-HDL-C (LDL + IDL + VLDL cholesterol fractions) and electronegative LDL concentrations (reduction of 13.8%, 14.7% and 24.2%, respectively, p < 0.05). The ISP and SP have prevented the reduction of HDL-C level after 42 days. The C-reactive protein and fibrinogen levels were not improved. The equol production by the ISP group subjects was inversely correlated with electronegative LDL concentration. Conclusions: The results suggest that a regular consumption of this probiotic soy product, supplemented with isoflavones, could contribute to reducing the risk of cardiovascular diseases in moderately hypercholesterolemic men, through the an improvement in lipid profile and antioxidant properties.

Rohitukine inhibits in vitro adipogenesis arresting mitotic clonal expansion and improves dyslipidemia in vivo

We developed a common feature pharmacophore model using known antiadipogenic compounds (CFPMA). We identified rohitukine, a reported chromone anticancer alkaloid as a potential hit through in silico mapping of the in-house natural product library on CFPMA. Studies were designed to assess the antiadipogenic potential of rohitukine. Rohitukine was isolated from Dysoxylum binacteriferum Hook. to ⬧95% purity. As predicted by CFPMA, rohitukine was indeed found to be an antiadipogenic molecule. Rohitukine inhibited lipid accumulation and adipogenic differentiation in a concentration- and exposure-time-dependent manner in 3T3-L1 and C3H10T1/2 cells. Rohitukine downregulated expression of PPARγ, CCAAT/enhancer binding protein α, adipocyte protein 2 (aP2), FAS, and glucose transporter 4. It also suppressed mRNA expression of LPL, sterol-regulatory element binding protein (SREBP) 1c, FAS, and aP2, the downstream targets of PPARγ. Rohitukine arrests cells in S phase during mitotic clonal expansion. Rohitukine was bioavailable, and 25.7% of orally administered compound reached systemic circulation. We evaluated the effect of rohitukine on dyslipidemia induced by high-fat diet in the hamster model. Rohitukine increased hepatic expression of liver X receptor α and decreased expression of SREBP-2 and associated targets. Rohitukine decreased hepatic and gonadal lipid accumulation and ameliorated dyslipidemia significantly. In summary, our strategy to identify a novel antiadipogenic molecule using CFPMA successfully resulted in identification of rohitukine, which confirmed antiadipogenic activity and also exhibited in vivo antidyslipidemic activity.

Evaluation of some selected blood parameters and histopathology of liver and kidney of rats fed protein-substituted mucuna flour and derived protein rich product

This comparative study reports the nutritional and toxicological characteristics of Mucuna pruriens flour and a protein-rich product developed from it. The protein-rich mucuna product (PRMP) was obtained by the three steps procedure: protein solubilization, heat-coagulation and sieving. Three weeks rats (n=6 per group) were fed for 28 days on standard protein-substituted rat feed with mucuna flour or PRMP. The experimental design was a factorial design with three mucuna accessions (Velvet, Black and White) and two treatments (flour and PRMP). The protein content ranged 27.2-31.5 g/100 g for flour and 58.8-61.1% for PRMP. Processing flour into PRMP led to a significant (p<0.05) reduction of tannins (50%), total polyphenols (50%) and trypsin inhibitors (94%). The rats fed PMRP diets witnessed weight gain similar to casein, while those fed mucuna flour lost weight. The levels of total cholesterol, HDL-cholesterol and LDL-cholesterol observed in animals groups fed mucuna flour and PRMP were significantly lower (p<0.05) than the control group. In addition lymphocytes, granulocytes, red blood cells, hemoglobin and hematocrit of rats fed mucuna flour were significantly (p<0.05) lower than values in other rats groups. Kidneys glomerular sclerosis and high creatinine levels were observed in group fed mucuna flour. PRMP then represents a good alternative of using mucuna proteins for human nutrition.

Cassava starch as a stabilizer of soy-based beverages

Soy-based beverages are presented as healthy food alternatives for human nutrition. Cassava (Manihot esculenta, Crantz) starch is relatively inexpensive, widely available in Brazil and is broadly used by the food industry due to its desired properties that result from pasting. The objective of this study was to develop soy-based beverages with good sensory quality using native cassava starch as a stabilizer and maintaining the nutritional value that makes this product a functional food. The developed formulations featured a range of cassava starch and soybean extract concentrations, which were tested in a 2² experimental design with three central points. The results of sensory analysis showed that the studied variables (cassava starch and soybean extract concentrations) did not have a significant effect with respect to a 5% probability level. When considering the apparent viscosity, on the other hand, the variables had a significant effect: the increase in soybean extract and cassava starch concentrations caused an increase in the viscosity of the final product. The profile of isoflavones in the tested formulations was similar to the profiles reported in other papers, with a predominance of the conjugated glycosides over the aglycone forms.

Soy germ protein concentrate diet decreased body fat weight and increased hindlimb muscle weight in rats

The purpose of this study was to investigate the effects of soy germ protein intake on body composition. Wistar rats were fed experimental diets for 16 weeks. These consisted of soy germ protein, soy protein, or casein. Abdominal adipose tissue weights significantly lower and hindlimb muscle weights were significantly higher in the soy germ protein group than in the casein group.

Anti-hyperlipidemic effect of soybean extract fermented by Bacillus subtilis MORI in db/db mice

The purpose of this study was to investigate the anti-hyperlipidemic effect of soy bean extract solution fermented by Bacillus subtilis MORI (BTD-1E) in obese db/db mice. Eight-week-old male db/db mice were administered 33.3 mg/kg BTD-1E solution orally once a day for four weeks. The BTD-1E group showed significantly lower body weight compared with the db control group (P<0.05). The BTD-1E group showed significantly lower serum total cholesterol and LDL cholesterol levels compared with the db control group, respectively (P<0.05, P<0.01). The BTD-1E group showed significantly decreased liver weight relative to final body weight compared with the db control group (P<0.01). After four weeks of BTD-1E administration, lipid droplets in the liver were apparently decreased in the BTD-1E group compared to the db control group. In summary, our results suggest that BTD-1E has an anti-hyperlipidemic effect in the obese mouse model.

Date fruits (Phoenix dactylifera Linn): an emerging medicinal food

Date palm is one of the oldest trees cultivated by man. In the folk-lore, date fruits have been ascribed to have many medicinal properties when consumed either alone or in combination with other herbs. Although, fruit of the date palm served as the staple food for millions of people around the world for several centuries, studies on the health benefits are inadequate and hardly recognized as a healthy food by the health professionals and the public. In recent years, an explosion of interest in the numerous health benefits of dates had led to many in vitro and animal studies as well as the identification and quantification of various classes of phytochemicals. On the basis of available documentation in the literature on the nutritional and phytochemical composition, it is apparent that the date fruits are highly nutritious and may have several potential health benefits. Although dates are sugar-packed, many date varieties are low GI diet and refutes the dogma that dates are similar to candies and regular consumption would develop chronic diseases. More investigations in these areas would validate its beneficial effects, mechanisms of actions, and fully appreciate as a potential medicinal food for humans all around the world. Therefore, in this review we summarize the phytochemical composition, nutritional significance, and potential health benefits of date fruit consumption and discuss its great potential as a medicinal food for a number of diseases inflicting human beings.

Soy protein supports cardiovascular health by downregulating hydroxymethylglutaryl-coenzyme A reductase and sterol regulatory element-binding protein-2 and increasing antioxidant enzyme activity in rats with dextran sodium sulfate-induced mild systemic inflammation

Animal and human studies have indicated that the presence of soy in the diet improves cardiovascular health. Inflammation plays a pivotal role in the progression of cardiovascular disease (CVD). However, little is known about how dextran sodium sulfate (DSS)-induced systemic inflammation impacts overall heart health and, correspondingly, how soy protein modulates risk of CVD development in DSS-induced systemic inflammation. We hypothesized that soy protein-fed rats would have a lower risk of CVD by beneficial alteration of gene expression involving lipid metabolism and antioxidant capacity in DSS-induced systemic inflammation. Forty Sprague-Dawley rats were divided into 4 groups: casein, casein + DSS, soy protein, and soy protein + DSS. After 26 days, inflammation was induced in one group from each diet by incorporating 3% DSS in drinking water for 48 hours. Soy protein-fed rats had lower final body weights (P = .010), epididymal fat weights (P = .049), total cholesterol (P < .001), and low-density lipoprotein cholesterol (P < .001). In regard to gene expression, soy protein-fed rats had lower sterol regulatory element-binding protein-2 (P = .032) and hydroxymethylglutaryl-coenzyme A reductase (P = .028) levels and higher low-density lipoprotein receptor levels (P = .036). Antioxidant enzyme activity of superoxide dismutase and catalase was higher among the soy protein groups (P = .037 and P = .002, respectively). These results suggest that soy protein positively influences cardiovascular health by regulating serum lipids through modified expression of sterol regulatory element-binding protein-2 and its downstream genes (ie, hydroxymethylglutaryl-coenzyme A reductase and low-density lipoprotein receptor) and by promoting the antioxidant enzyme activity of superoxide dismutase and catalase.

Influence of a probiotic soy product on fecal microbiota and its association with cardiovascular risk factors in an animal model

BACKGROUND

Previous work showed that daily ingestion of an aqueous soy extract fermented with Enterococcus faecium CRL 183 and Lactobacillus helveticus 416, supplemented or not with isoflavones, reduced the total cholesterol and non-HDL-cholesterol levels, increased the high-density lipoprotein (HDL) concentration and inhibited the raising of autoantibody against oxidized low-density lipoprotein (ox-LDL Ab) and the development of atherosclerotic lesions.

OBJECTIVE

The aim of this study was to characterize the fecal microbiota in order to investigate the possible correlation between fecal microbiota, serum lipid parameters and atherosclerotic lesion development in rabbits with induced hypercholesterolemia, that ingested the aqueous soy extract fermented with Enterococcus faecium CRL 183 and Lactobacillus helveticus 416.

METHODS

The rabbits were randomly allocated to five experimental groups (n = 6): control (C), hypercholesterolemic (H), hypercholesterolemic plus unfermented soy product (HUF), hypercholesterolemic plus fermented soy product (HF) and hypercholesterolemic plus isoflavone-supplemented fermented soy product (HIF). Lipid parameters and microbiota composition were analyzed on days 0 and 60 of the treatment and the atherosclerotic lesions were quantified at the end of the experiment. The fecal microbiota was characterized by enumerating the Lactobacillus spp., Bifidobacterium spp., Enterococcus spp., Enterobacteria and Clostridium spp. populations.

RESULTS

After 60 days of the experiment, intake of the probiotic soy product was correlated with significant increases (P < 0.05) on Lactobacillus spp., Bifidobacterium spp. and Enterococcus spp. and a decrease in the Enterobacteria population. A strong correlation was observed between microbiota composition and lipid profile. Populations of Enterococcus spp., Lactobacillus spp. and Bifidobacterium spp. were negatively correlated with total cholesterol, non-HDL-cholesterol, autoantibodies against oxidized LDL (oxLDL Ab) and lesion size. HDL-C levels were positively correlated with Lactobacillus spp., Bifidobacterium spp., and Enterococcus spp. populations.

CONCLUSION

In conclusion, daily ingestion of the probiotic soy product, supplemented or not with isoflavones, may contribute to a beneficial balance of the fecal microbiota and this modulation is associated with an improved cholesterol profile and inhibition of atherosclerotic lesion development.

Lesser in vitro anaerobic cecal isoflavone disappearance was associated with greater apparent absorption of daidzein and genistein in Golden Syrian hamsters

Our hypothesis in this study was that in vitro disappearance of isoflavones from fecal or cecal contents of Golden Syrian hamsters paralleled the apparent absorption of these compounds, comparable with previous findings from in vitro human fecal incubations. Two studies were conducted to test this idea: one on in vitro fecal (study 1, n = 20/sex) and the other on in vitro cecal contents (study 2, n = 10/sex) ability to degrade isoflavones. According to HPLC analysis, urinary isoflavone excretion was significantly less by 2-4 fold in males compared with females in both studies. Fecal isoflavone excretion was not significantly different between sexes or isoflavones (study 1) and was <0.5% of ingested dose. In vitro anaerobic fecal isoflavone degradation rate constants from study 1 were minimal with no significant correlation between urinary and fecal isoflavone excretion. However, in vitro anaerobic cecal isoflavone degradation rate constants (study 2) were greater and significantly correlated with urinary excretion of daidzein (R = 0.90; p = 0.01) and genistein (R = 0.93; p = 0.004), but not glycitein (R = 0.50; p = 0.3). Both male and female hamsters showed a pattern of urinary isoflavone excretion similar to that found in humans (daidzein > genistein). Hamster in vitro cecal isoflavone degradation rate constants seemed to be analogous to human in vitro fecal isoflavone degradation rate constants for genistein and daidzein. The sex difference in isoflavone excretion in hamsters and the instability in glycitein excretion across studies coupled with the paucity of human data on this isoflavone deserve further investigation.

Effects of isoflavone-supplemented soy yogurt on lipid parameters and atherosclerosis development in hypercholesterolemic rabbits: a randomized double-blind study

BACKGROUND

There is increasing interest in natural treatments to control dyslipidemia and reduce the risk of cardiovascular disease. Previous studies have demonstrated the beneficial effects of soy yogurt fermented with Enterococcus faecium CRL 183 and of dietary isoflavones on the lipid profile. The purpose of the present study was to investigate the effects of isoflavone-supplemented soy yogurt, fermented with E. faecium CRL183, on lipid parameters and atherosclerosis development in rabbits with induced hypercholesterolemia.

METHODS

Forty-eight rabbits were randomly assigned to eight groups fed on the following diets for 60 days: C - control; IY - isoflavone-supplemented soy yogurt; H - hypercholesterolemic (1.0% cholesterol wt/wt diet); HY - hypercholesterolemic plus soy yogurt; HIY - hypercholesterolemic plus isoflavone-supplemented soy yogurt; HP - hypercholesterolemic plus placebo; HI - hypercholesterolemic plus isoflavone and HE - hypercholesterolemic plus pure culture of E. faecium CRL 183. Serum lipids and autoantibodies against oxLDL (oxLDL Ab) were analyzed on days 0, 30 and 60 of the treatment and the atherosclerotic lesions were quantified at the end of the experiment.

RESULTS

Soy yogurt, soy yogurt supplemented with isoflavones and placebo promoted significant reductions in total cholesterol level (38.1%, 27.0% and 26.6%, respectively). Significant increases in serum HDL-C concentration relative to group H were detected in animals that ingested soy yogurt, with or without the isoflavone supplement (55.2%), E. faecium culture (43.3%) or placebo (35.8%). Intake of soy yogurt and soy yogurt supplemented with isoflavones prevented the rise of oxLDL Ab during the study period. The extent of atherosclerosis in the thoracic and abdominal aortas was reduced in the HIY, HY and HP groups. However, when the whole aorta was analyzed, animals treated with soy yogurt supplemented with isoflavones exhibited the greatest reduction (51.4%, P < 0.05) in atherosclerotic lesion area, compared to group H.

CONCLUSION

Soy yogurt could be consumed as an alternative means of reducing the risk of cardiovascular disease by improving the lipid profile and inhibiting oxLDL Ab formation. Our findings also suggest that isoflavone supplementation may enhance the antiatherosclerotic effect of soy yogurt.

Cholesterol-lowering properties of whole cowpea seed and its protein isolate in hamsters

Hypercholesterolemic hamsters were fed for 4 wk on diets rich in saturated fatty acids and cholesterol, differing only in protein source (20 %): casein (control group, HC), whole cowpea seed (HWS), and cowpea protein isolate (HPI). Hamsters fed on HWS and HPI presented significant reductions in plasma total cholesterol and non-HDL cholesterol. HPI and HC presented similar protein digestibility, which were significantly higher than that of HWS. Animals fed on HWS presented significantly higher levels of bile acids and cholesterol in feces than did the animals fed on casein or HPI diets. Histological analyses of the liver showed that HC diet resulted in steatosis widely distributed throughout the hepatic lobule, while HWS and HPI diets promoted reductions in liver steatosis. The effectiveness of HWS for modulating lipid metabolism was greater than that of HPI, as measured by plasma cholesterol reduction and liver steatosis.

Effects of probiotic bacteria, isoflavones and simvastatin on lipid profile and atherosclerosis in cholesterol-fed rabbits: a randomized double-blind study

Background

Much attention has been drawn to different alternative strategies for cardiovascular disease prevention. Objective: The aim of the present study was to observe and compare the effects of Enterococcus faecium CRL183 (probiotic microorganism), an isoflavones mixture and simvastatin (drug used to treat hypercholesterolemia) on lipid parameters and atherosclerosis development in rabbits with induced hypercholesterolemia.

Methods

The animals were randomly allocated to 5 experimental groups (n = 6) for 60 days: control (C) that did not consume cholesterol, hypercholesterolemic (H) that consumed an atherogenic diet (1.0% cholesterol wt/wt), hypercholesterolemic plus E. faecium (HE), hypercholesterolemic plus isoflavone (HI) and hypercholesterolemic plus simvastatin (HS). Total and HDL-cholesterol and triglycerides were determined by enzymatic methods; non-HDL-C was calculated by subtracting HDL-C from total cholesterol; and atherosclerosis was presented as the percentage of lesion area, relative to the total area from the aorta segment analyzed.

Results

Simvastatin significantly reduced the tot cholesterol (16%) and non-HDL-C level (17%) and increased the HDL-C (98%), compared to group H. E. faecium raised the HDL-C level by 43.3% (P < 0.05). Isoflavone decreased the total cholesterol and non-HDL-C concentrations (9%), but this effect was not statistically significant. At the end of the treatments, groups HE and HS had significantly lower levels of triglycerides in relation to H and HI. The atherosclerotic lesion area in the aortic arch was not different between groups. The extent of atherosclerosis in the thoracic and abdominal aorta was reduced in the groups HI and HS by 22.7% and 26.7% respectively, but this effect was not significant (P > 0.05).

Conclusion

The results indicated that probiotic microorganism E. faecium CRL 183 could be used to improve the lipid profile as an alternative or an adjuvant for drug therapy. The effectiveness of simvastatin in the management of blood lipid was confirmed. There were no effects of soy isoflavones, E. faecium and simvastatin on atherosclerosis development.

Hypocholesterolemic effects of dietary soybean vs. casein proteins in a crossed over diets in rat

To investigate the effects of dietary proteins on the level of serum total cholesterol (TC), triglyceride (TG) and high density lipoprotein (HDL), 32 male Wistar rats were randomly divided in control and 3 experimental groups (El, E2 and E3). The feeding regimes of rats were as follow: control, standard diet; E1, a cholesterol free diet containing 20% soybean protein; E2, a cholesterol free diet containing 20% casein and E3, a cholesterol free diet containing 10% soybean protein and 10% casein. The experimental period was 11 weeks but at the end of 7th week the diets of E1 and E2 groups were crossed over for the next 4 weeks. Blood samples were collected weekly, via the ophthalmic sinus and the serum levels TC, TG and HDL were measured. In comparison with control group, the results show that at the end of 7th week TC levels in E1 and E2 groups were significantly (p<0.05) increased while HDL level unchanged and the TC value of E2 was bigger (not significant) than E1. However by crossing over the diets, the TC level was significantly (p<0.05) diminished in E2 while TG value remarkably (p<0.05) increased. These results indicate that soybean protein may insert its hypocholesterolemic effect in hypercholestrolemic condition than in normolipidemic condition.

Novel black soy peptides with antiobesity effects: activation of leptin-like signaling and AMP-activated protein kinase

OBJECTIVE

To investigate the mechanisms underlying the antiobesity effects of a novel isoflavone-free peptide mixture (BSP) derived from black soybean.

DESIGN

Long-term effects of BSP were evaluated in diet-induced obese (DIO) mice fed a high-fat (HF) diet without or with BSP (2, 5 or 10% of energy) for 13 weeks, or for 8 weeks in combination with exercise. Acute effects of BSP on food intake and body weight in rats and leptin-deficient ob/ob mice were evaluated. Cell culture models or tissue extracts were used to investigate the mechanisms underlying the antiobesity effect.

MEASUREMENT

Total food intake, body weight gain, white adipose tissue (WAT) mass, plasma concentrations of leptin, adiponectin, cholesterol and triglyceride were measured. Janus kinase 2 (JAK2)-dependent signal transducers and activators of the transcription 3 (STAT3) phosphorylation and AMP-activated protein kinase (AMPK) activity were determined using Western-blot in cultured cells or tissue extracts.

RESULTS

DIO mice fed an HF diet with BSP (2, 5 or 10%) for 13 weeks gained less body weight (21.4, 19.8 or 17.1 g, respectively) than the mice fed an HF diet without BSP (22.6 g) concurrent with inhibition of total food intake in a dose-dependent manner. BSP also significantly decreased food intake in rats and leptin-deficient ob/ob mice. The highest dose of BSP (10%) significantly elevated the plasma adiponectin and decreased plasma triglyceride. BSP activated JAK2-dependent STAT3 in a cell model, and elevated the level of hypothalamic phospho-STAT3 in ob/ob mice. BSP also phosphorylated AMPK and acetyl-CoA carboxylase of C2C12 myocytes in a dose-dependent manner. The antiobesity effect was augmented by low-intensity wheel-based exercise. In exercised mice, BSP significantly decreased periepididymal WAT mass and body weight gain.

CONCLUSION

These results provided evidences that BSP decreased appetite and HF diet-induced body weight gain particularly in combination with exercise, through leptin-like STAT3 phosphorylation and AMPK activation.

Isoflavone glycitein diminished plasma cholesterol in female golden Syrian hamsters

The soybean isoflavones, daidzein, genistein, and glycitein, were hypothesized to act as cholesterol-lowering components, separate from soy protein. Pure synthetic daidzein, genistein, or glycitein (0.9 mmol/kg diet) or a casein-based control diet was fed to groups of 10 female Golden Syrian hamsters for 4 weeks. Hamsters fed glycitein had significantly lower plasma total (by 15%) and non-HDL (by 24%) cholesterol compared with those fed casein (P<0.05). Daidzein and genistein's effects on these lipids did not differ from the effects of either casein or glycitein. Plasma HDL cholesterol and triglyceride concentrations were not significantly affected by dietary treatments. The percentage of urinary recovery of the ingested dose of each isoflavone was glycitein>daidzein>genistein (33.2%, 4.6%, 2.2%, respectively), with the apparent absorption of glycitein significantly greater than that of the other isoflavones. These data suggest that glycitein's greater cholesterol-lowering effect was due to its greater bioavailability, as reflected in its urinary recovery compared with that of the other isoflavones.

Soy isoflavones reduce electronegative low-density lipoprotein (LDL(-)) and anti-LDL (-) autoantibodies in experimental atherosclerosis

BACKGROUND

Isoflavones present in soybean may contribute to soy atheroprotective effects.

AIM OF THE STUDY

To investigate the effect of soy isoflavones supplementation on the formation of electronegative LDL (LDL(-)) and its autoantibodies in blood plasma and aortic atheromas of rabbits fed an atherogenic casein-based diet enriched with isoflavones.

METHODS

New Zealand male rabbits (n = 15) were fed an atherogenic diet (27% casein) supplemented with isoflavones (0.73 or 7.3 mg of isoflavones/kg/day, Low and High Iso groups, respectively) for 180 days. Monthly, blood samples were collected after 12-15 h fasting and at 180 days of treatment all animals were sacrificed. Isoflavones were analyzed in plasma and urine samples by HPLC. LDL(-) in plasma and atheromas was detected by ELISA and immunohistochemistry, respectively, with a monoclonal antibody reactive to LDL(-). Autoantibodies reactive to LDL(-) were analyzed in plasma and aorta by ELISA.

RESULTS

Low and High Iso groups had decreased LDL-cholesterol, increased HDL-cholesterol and lower levels of LDL(-) in blood plasma and aortic atherosclerotic lesions than the non-supplemented Control group. IgG autoantibodies reactive to LDL(- )were higher in plasma of the Control group in comparison with the High and Low Iso groups. In contrast, the aortas from animals that consumed isoflavones showed higher levels of IgG reactive to LDL(- )than the Control group.

CONCLUSION

Soy isoflavones showed hypolipidemic effects and decreased the pro-inflammatory LDL(-) subfraction in blood plasma and aorta of hypercholesterolemic rabbits.

High urinary isoflavone excretion phenotype decreases plasma cholesterol in golden Syrian hamsters fed soy protein

Apparent absorption of isoflavones varies greatly among individuals but is relatively stable within an individual. We hypothesized that high urinary isoflavone excreters would show less plasma non-HDL cholesterol (non-HDL-C) than low isoflavone excreters after soy protein feeding. Fifty Golden Syrian hamsters were fed a high-fat/casein diet (n = 10) or a high-fat/soy protein diet (n = 40) for 4 wk. We identified 2 distinct urinary isoflavone excretion phenotypes based upon HPLC analysis of urinary glycitein using a pairwise correlation plots analysis, or based upon total urinary isoflavone using a hierarchical cluster test. High isoflavone excreters showed greater urinary isoflavones (P < 0.05) than did low isoflavone excreters at wk 1 and 4. The low urinary glycitein excretion phenotype was more stable than the high urinary glycitein excretion phenotype by McNemar's test. High urinary isoflavone excreters had significantly less non-HDL-C than did the low isoflavone excreters or casein-fed controls (P < 0.05). Plasma total and non-HDL-C were negatively correlated with urinary daidzein, glycitein, and total isoflavone excretion (r = -0.45 to -0.58, P < 0.05). Urinary isoflavone excretion phenotypes predicted the cholesterol-lowering efficacy of soy protein. Isoflavone absorbability, probably due to gut microbial ecology, is an important controllable variable in studies of effects of soy protein on blood lipids.

Oncogenicity evaluations of chemopreventive soy components in p53((+/-)) (p53 knockout) mice

Epidemiologic data suggest that soy consumption may protect against cancer induction in several tissues in humans. Although the soy components responsible for this activity remain unidentified, isoflavones (e.g., genistein) and protease inhibitors (e.g., Bowman-Birk inhibitor complex [BBIC]) demonstrate chemopreventive activity in several animal cancer models. As part of their preclinical development for cancer prevention, PTI G-2535 (a soy isoflavone mixture containing 45% genistein, 23% daidzein, and 4% glycitein) and BBIC were evaluated for oncogenicity in p53((+/-)) mice. In separate studies, groups of 25 p53((+/-)) mice/sex received daily gavage exposure to PTI G-2535 (0, 250, 1000, or 2500 mg/kg/day) or BBIC (0, 500, 1000, or 2000 mg/kg/day) for 6 months. The high doses of both PTI G-2535 and BBIC were limited by viscosity. p-Cresidine (400 mg/kg/day) served as a positive-control article in both studies. PTI G-2535 induced no gross toxicity in any animal, but did induce a dose-related suppression of body weight gain in male mice. Modest hematologic alterations and increased liver and spleen weights were seen in both sexes exposed to the isoflavone mixture. BBIC had no significant effect on body weight, food consumption, clinical pathology, or organ weights in either sex. Histopathologic evaluations demonstrated no increases in the incidence of either benign or malignant tumors in any group of p53((+/-)) mice exposed to PTI G-2535 or to BBIC. By contrast, the positive-control article, p-cresidine, induced urinary bladder cancers in both studies. Neither PTI G-2535 nor BBIC demonstrates any evidence of oncogenicity in the p53((+/-)) mouse model.

Soy protein isolate increases hepatic thyroid hormone receptor content and inhibits its binding to target genes in rats

Our previous studies showed that intake of 20% alcohol-washed soy protein isolate (SPI) significantly increased hepatic thyroid hormone receptor (TR) beta1 protein content in rats. However, whether SPI influences the binding ability of TR to its target genes is unknown. The purpose of this study was to examine the effect of increasing amounts of dietary SPI on hepatic TRbeta1 content and the binding of TR to thyroid hormone response element (TRE) in rats. Sprague-Dawley rats (28 d old) were fed diets containing casein (20%) with or without isoflavone supplementation (50 mg/kg diet) or alcohol-washed SPI (5, 10, or 20%) for 90 d. The hepatic TRbeta1 protein content was measured by Western blot, and the binding ability of TR to DNA was examined by electrophoretic mobility shift assay. Consumption of the 20% SPI diet increased pancreatic relative weight and decreased spleen relative weight. Intake of SPI markedly elevated TRbeta1 content in both male and female rats compared with a casein-based control diet. The increase in TRbeta1 in females was much higher than that in males. Interestingly, the binding abilities of TR to DNA were significantly inhibited by increasing amounts of dietary SPI in female rats. In conclusion, this study shows for the first time that dietary SPI increases hepatic TRbeta1 protein content and inhibits the binding of TR to target genes. Modulation of hepatic TRbeta1, a key regulator of gene expression involved in lipid metabolism, by SPI may be a novel mechanism by which soy components lower blood lipid level and exert their hypocholesterolemic actions.

Comparison of regulative functions between dietary soy isoflavones aglycone and glucoside on lipid metabolism in rats fed cholesterol

The effects of dietary soy isoflavones aglycone and glucoside on lipid metabolism were compared in male Sprague-Dawley rats (4 weeks old) given purified diets containing 0.3% cholesterol. The rats were fed a diet supplemented with either isoflavone aglycone-rich powder (IF-A group) or isoflavone glucoside-rich powder (IF-G group) or isoflavone-free diet (control group) for 40 days. The additional level of isoflavone aglycone moiety in the diet was prepared to the same level (approximately 0.096 g/100 g: approximately 0.1% in diet). The activity of hepatic cholesterol 7alpha-hydroxylase tended to be slightly higher in the rats fed isoflavones than in those fed the isoflavone-free diet. On the other hand, the activity of hepatic Delta6 desaturase in the IF-A group was lower than that of the control group. Reflecting this effect, the Delta6 desaturation indices [(20:3n-6+20:4n-6)/18:2n-6] in liver phospholipids of the IF-A group were lower than those in the control group. Liver and serum total cholesterol levels and liver TG level were also reduced by consumption of isoflavone aglycone. Moreover, serum TG level was lowered by consumption of both isoflavones aglycone and glucoside. The level of serum total isoflavones in the IF-A group was significantly higher than that in the IF-G group. Therefore, we speculate that the absorption speed of isoflavone aglycones might be faster than that of isoflavone glucosides in rats. This study suggests that dietary soy isoflavones, particularly their aglycone form, may exert a beneficial effect on lipid metabolism in rats fed cholesterol.

Soy, isoflavones and atherosclerosis

Consumption of soy protein is associated with a lower risk of cardiovascular disease in man, and reduced atherosclerosis in a variety of experimental animals. Although a portion of the cardiovascular protective effects appears to be due to reductions in plasma lipoprotein concentration, in most people the magnitude of this effect is relatively small. In many, but not all studies using animal models, the reduction in atherosclerosis is in part independent of changes in plasma lipids and lipoproteins. This implies that there may be a direct effect on the arterial wall of one or more of the components in soyprotein that reduces susceptibility to atherosclerosis. The most actively studied components of soy protein that may be responsible for these anti-atherogenic effects are the isoflavones and various protein factions. Extraction of isoflavones and other alcohol-soluble components from soy protein lowers, but does not eliminate its ability to reduce atherosclerosis. Surprisingly, in most studies, adding back the isoflavone-rich alcohol extract to the previously extracted soy protein, or to another protein, does not restore its lipoprotein lowering or anti-atherogenic properties. This implies that alcohol extraction either destroys an active component of soy, alters the structural integrity of the soy proteins, or disassociates a required isoflavone-soy protein complex. Understanding the mechanism of this effect is an important goal for future research. Likewise, the sites of action on the arterial wall, and the mechanisms by which various soy components act to reduce atherosclerosis are just now being studied. The recent demonstration that expression of estrogen receptor alpha is required for atheroprotection by soy protein provides important new mechanistic insight. Other properties of soy, including antioxidant, anti-inflammatory and potentially antithrombogenic properties need to be explored more mechanistically before the full potential of dietary soy protein for the protection from cardiovascular disease will be known.