A biochanin-enriched isoflavone from red clover lowers LDL cholesterol in men

Mechanisms Behind the Pharmacological Application of Biochanin-A: A review

This review was aimed at summarizing the cellular and molecular mechanisms behind the various pharmacological actions of biochanin-A. Many studies have been reported claiming its application in cancers, metabolic disorders, airway hyperresponsiveness, cardiac disorders, neurological disorders, etc. With regard to hormone-dependent cancers like breast, prostate, and other malignancies like pancreatic, colon, lung, osteosarcoma, glioma that has limited treatment options, biochanin-A revealed agreeable results in arresting cancer development. Biochanin-A has also shown therapeutic benefits when administered for neurological disorders, diabetes, hyperlipidaemia, and other chronic diseases/disorders. Isoflavones are considered phenomenal due to their high efficiency in modifying the physiological functions of the human body. Biochanin-A is one among the prominent isoflavones found in soy (glycine max), red clover (Trifolium pratense), and alfalfa sprouts, etc., with proven potency in modulating vital cellular mechanisms in various diseases. It has been popular for ages among menopausal women in controlling symptoms. In view of the multi-targeted functions of biochanin-A, it is essential to summarize it's mechanism of action in various disorders. The safety and efficacy of biochanin-A needs to be established in clinical trials involving human subjects. Biochanin-A might be able to modify various systems of the human body like the cardiovascular system, CNS, respiratory system, etc. It has shown a remarkable effect on hormonal cancers and other cancers. Many types of research on biochanin-A, particularly in breast, lung, colon, prostate, and pancreatic cancers, have shown a positive impact. Through modulating oxidative stress, SIRT-1 expression, PPAR gamma receptors, and other multiple mechanisms biochanin-A produces anti-diabetic action. The diverse molecular mechanistic pathways involved in the pharmacological ability of biochanin-A indicate that it is a very promising molecule and can play a major impact in modifying several physiological functions.

Biochanin A as a modulator of the inflammatory response: an updated overview and therapeutic potential

Uncontrolled inflammation and failure to resolve the inflammatory response are crucial factors involved in the progress of inflammatory diseases. Current therapeutic strategies aimed at controlling excessive inflammation are effective in some cases, though they may be accompanied by severe side effects, such as immunosuppression. Phytochemicals as a therapeutic alternative can have a fundamental impact on the different stages of inflammation and its resolution. Biochanin A (BCA) is an isoflavone known for its wide range of pharmacological properties, especially its marked anti-inflammatory effects. Recent studies have provided evidence of BCA's abilities to activate events essential for resolving inflammation. In this review, we summarize the most recent findings from pre-clinical studies of the pharmacological effects of BCA on the complex signaling network associated with the onset and resolution of inflammation and BCA's potential protective functionality in several models of inflammatory diseases, such as arthritis, pulmonary disease, neuroinflammation, and metabolic disease.

Chickpeas from a Chilean Region Affected by a Climate-Related Catastrophe: Effects of Water Stress on Grain Yield and Flavonoid Composition

The Valparaiso region in Chile was decreed a zone affected by catastrophe in 2019 as a consequence of one of the driest seasons of the last 50 years. In this study, three varieties (‘Alfa-INIA’, ‘California-INIA’, and one landrace, ‘Local Navidad’) of kabuli-type chickpea seeds produced in 2018 (control) and 2019 (climate-related catastrophe, hereafter named water stress) were evaluated for their grain yield. Furthermore, the flavonoid profile of both free and esterified phenolic extracts was determined using liquid chromatography-mass spectrometry, and the concentration of the main flavonoid, biochanin A, was determined using liquid chromatography with diode array detection. The grain yield was decreased by up to 25 times in 2019. The concentration of biochanin A was up to 3.2 times higher in samples from the second season (water stress). This study demonstrates that water stress induces biosynthesis of biochanin A. However, positive changes in the biochanin A concentration are overshadowed by negative changes in the grain yield. Therefore, water stress, which may be worsened by climate change in the upcoming years, may jeopardize both the production of chickpeas and the supply of biochanin A, a bioactive compound that can be used to produce dietary supplements and/or nutraceuticals.

A Graded Approach for Evaluating Health Claims about Plant-Based Food Supplements: Application of a Case Study Methodology

The implementation of REGULATION (EC) No 1924/2006 has led to the formation of a list of health claims that can be used in food supplements (EU 432/2012). However, such supplements are often composed of plant preparations with claims omitted from this list. The peculiarity of plants is related to their long history of use, that could allow claims based on traditionally recognized health effects. In addition, the scientific literature has been enriched over the years through clinical studies that have assessed the bioavailability and efficacy of bioactive components, and investigated their mechanisms of action. Based on existing recognized models which aim to classify research according to the level of scientific evidence, Synadiet developed a three-grade model (A, B or C) for assessing plants health claims. In this paper, the applicability of the model is illustrated through an example for which a Grade B health claim attesting the possible contribution of red clover isoflavones to the improvement of blood lipid levels in postmenopausal women has been attributed. The model appears able to be easily extrapolated to claims pertaining to other plants. If adopted by consensus at European level, this model could initiate the implementation of a positive list of health claims on plant preparations.

Metabolic Engineering of Isoflavones: An Updated Overview

Isoflavones are ecophysiologically active secondary metabolites derived from the phenylpropanoid pathway. They were mostly found in leguminous plants, especially in the pea family. Isoflavones play a key role in plant-environment interactions and act as phytoalexins also having an array of health benefits to the humans. According to epidemiological studies, a high intake of isoflavones-rich diets linked to a lower risk of hormone-related cancers, osteoporosis, menopausal symptoms, and cardiovascular diseases. These characteristics lead to the significant advancement in the studies on genetic and metabolic engineering of isoflavones in plants. As a result, a number of structural and regulatory genes involved in isoflavone biosynthesis in plants have been identified and characterized. Subsequently, they were engineered in various crop plants for the increased production of isoflavones. Furthermore, with the advent of high-throughput technologies, the regulation of isoflavone biosynthesis gains attention to increase or decrease the level of isoflavones in the crop plants. In the review, we begin with the role of isoflavones in plants, environment, and its benefits in human health. Besides, the main theme is to discuss the updated research progress in metabolic engineering of isoflavones in other plants species and regulation of production of isoflavones in soybeans.

Biochanin A alleviates gingival inflammation and alveolar bone loss in rats with experimental periodontitis

Biochanin A (BA) is an organic compound produced by Trifolium pretense and Arachis hypogaea with anti-inflammatory and antioxidative effects. The aim of the current study was to evaluate the effects of BA on gingival inflammation and alveolar bone destruction in rats with experimental periodontitis. Experimental rats (n=25) were distributed equally into five groups: i) Healthy control (control) group; ii) experimental periodontitis (ligation) group; and iii) and ligation plus low, medium and high dose of BA (12.5, 25 and 50 mg/kg/day, respectively) groups. A nylon ligature was inserted around rats' maxillary molars for 14 days to trigger the experimental periodontitis. BA was intravenous injected once daily for 4 weeks. After that, interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), reactive oxygen species (ROS) and osteocalcin (OCN) levels were determined in gingival and/or serum samples using ELISA or reverse transcription-quantitative PCR. Alveolar bone volume was assessed via hematoxylin and eosin staining and micro-computed tomography. Osteoclasts were identified by tartrate-resistant acid phosphatase staining, and the level of the nuclear factor erythroid-2 related factor 2 (Nrf2) was also detected by immunohistochemical staining. BA treatment groups showed alleviated alveolar bone resorption compared with the ligation group. Moreover, BA treatment significantly inhibited IL-1β, TNF-α, ROS levels, and reduced leukocyte acid phosphatase-positive cells, as well as increased OCN and Nrf2 levels compared with the ligation group. BA had beneficial effects on experimental periodontitis of rats. BA treatment inhibited inflammation, regulated unbalanced oxidative stress response and ameliorated the alveolar bone loss.

Biochanin A induces a brown-fat phenotype via improvement of mitochondrial biogenesis and activation of AMPK signaling in murine C3H10T1/2 mesenchymal stem cells

In this study, we investigated the effect of Biochanin A (BioA), an O-methylated isoflavone on the brown-fat phenotype formation and on the associated thermogenic program including mitochondrial biogenesis and lipolysis in C3H10T1/2 MSCs. Our data demonstrates that Treatment with BioA in an adipogenic differentiation cocktail induced formation of brown-fat-like adipocytes from C3H10T1/2 MSCs without treatment with a known browning inducer (rosiglitazone or T3) at an early stage of differentiation. The formation of brown-fat-like adipocytes by BioA treatment was evidenced by upregulation of key thermogenic markers: Ucp1, Pgc1α, Prdm16, and Pparγ. BioA also increased the expression of beige (Cd137 and Fgf21) and brown (Elovl3 and Zic1)-specific markers. Additionally, BioA treatment promoted mitochondrial biogenesis, judging by the upregulation of genes; Cox8b, Cidea, Dio2, Sirt1, Opa1, and Fis1. BioA treatment increased the amount of mitochondrial DNA and its encoded proteins: oxidative phosphorylation complexes (I-V); this change was associated with high oxygen consumption by C3H10T1/2 MSCs. A small-interfering-RNA-induced gene knockdown and experiments with dorsomorphin-driven competitive inhibition revealed that BioA exerts the thermogenic action via activation of AMPK signaling. Our study shows the mechanism of BioA-induced promotion of a brown-fat phenotype. Nonetheless, clinical research is necessary to validate BioA as a brown-fat-like signature inducer.

Effects of red clover on perimenopausal and postmenopausal women's blood lipid profile: A meta-analysis

The study aimed to perform a systematic review with meta-analysis of randomized controlled trials (RCTs) to access the effects of red clover isoflavones on the blood lipid profile of both perimenopausal and postmenopausal women. PubMed, Web of Science, Scopus, SciELO, and Cochrane Library were searched for the terms 'red clover', 'Trifolium pratense', and 'randomized controlled trial' during November 2017. Summary measures were reported as weighted mean differences (WMD) with 95% confidence interval (CI). Fixed or random effects models were used for meta-analyses, according to heterogeneity. Risk of bias was measured with the Cochrane tool. Twelve RCTs (totalizing 1284 perimenopausal and postmenopausal women receiving red clover isoflavones for 4 weeks-18 months) resulted in a significant decrease in total cholesterol (WMD = -12.34 mg/dl; 95% CI: -18.21, -6.48), low-density lipoprotein cholesterol (WMD = -10.61 mg/dl; 95% CI: -15.51, -5.72), and triglycerides (WMD = -10.18 mg/dl; 95% CI: -16.23, -4.13) together with a significant increase in high-density lipoprotein cholesterol (WMD = 1.60 mg/dl; 95% CI: 0.17, 3.03). In conclusion, the results demonstrate that the ingestion of red clover may have a beneficial effect on the lipid profile of perimenopausal and postmenopausal women.

Phytoestrogen isoflavone intervention to engage the neuroprotective effect of glutamate oxaloacetate transaminase against stroke

In the pathophysiologic setting of cerebral ischemia, excitotoxic levels of glutamate contribute to neuronal cell death. Our previous work demonstrated the ability of glutamate oxaloacetate transaminase (GOT) to metabolize neurotoxic glutamate in the stroke-affected brain. Here, we seek to identify small-molecule inducers of GOT expression to mitigate ischemic stroke injury. From a panel of phytoestrogen isoflavones, biochanin A (BCA) was identified as the most potent inducer of GOT gene expression in neural cells. BCA significantly increased GOT mRNA and protein expression at 24 h and protected against glutamate-induced cell death. Of note, this protection was lost when GOT was knocked down. To validate outcomes in vivo, C57BL/6 mice were intraperitoneally injected with BCA (5 and 10 mg/kg) for 4 wk and subjected to ischemic stroke. BCA levels were significantly increased in plasma and brain of mice. Immunohistochemistry demonstrated increased GOT protein expression in the brain. BCA attenuated stroke lesion volume as measured by 9.4T MRI and improved sensorimotor function-this protection was lost with GOT knockdown. BCA increased luciferase activity in cells that were transfected with the pERRE₃tk-LUC plasmid, which demonstrated transactivation of GOT. This increase was lost when estrogen-related receptor response element sites were mutated. Taken together, BCA represents a natural phytoestrogen that mitigates stroke-induced injury by inducing GOT expression.-Khanna, S., Stewart, R., Gnyawali, S., Harris, H., Balch, M., Spieldenner, J., Sen, C. K., Rink, C. Phytoestrogen isoflavone intervention to engage the neuroprotective effect of glutamate oxaloacetate transaminase against stroke.

Therapeutic Potential of Temperate Forage Legumes: A Review

The discovery of bioactive molecules from botanical sources is an expanding field, preferentially oriented to plants having a tradition of use in medicine and providing high yields and availability. Temperate forage legumes are Fabaceae species that include worldwide-important crops. These plants possess therapeutic virtues that have not only been used in veterinary and folk medicine, but have also attracted the interest of official medicine. We have examined here Medicago sativa (alfalfa), Trifolium pratense and T. repens (clovers), Melilotus albus and M. officinalis (sweet clovers), Lotus corniculatus (birdsfoot trefoil), Onobrychis viciifolia (sainfoin), Lespedeza capitata (roundhead lespedeza), and Galega officinalis (goat's rue). The phytochemical complexes of these species contain secondary metabolites whose pharmacological potentials deserve investigation. Major classes of compounds include alkaloids and amines, cyanogenic glycosides, flavonoids, coumarins, condensed tannins, and saponins. Some of these phytochemicals have been related to antihypercholesterolemia, antidiabetic, antimenopause, anti-inflammatory, antiedema, anthelmintic, and kidney protective effects. Two widely prescribed drugs have been developed starting from temperate forage legumes, namely, the antithrombotic warfarin, inspired from sweet clover's coumarin, and the antidiabetic metformin, a derivative of sainfoin's guanidine. Available evidence suggests that temperate forage legumes are a potentially important resource for the extraction of active principles to be used as nutraceuticals and pharmaceuticals.

The impact of equol-producing status in modifying the effect of soya isoflavones on risk factors for CHD: a systematic review of randomised controlled trials

Recent studies suggest that the ability to produce equol, a metabolite of the soya isoflavone daidzein, is beneficial to coronary health. Equol, generated by bacterial action on isoflavones in the human gut, is biologically more potent than dietary sources of isoflavones. Not all humans are equol producers. We investigated whether equol-producing status is favourably associated with risk factors for CHD following an intervention by dietary soya isoflavones. We systematically reviewed randomised controlled trials (RCT) that evaluated the effect of soya isoflavones on risk factors for CHD and that reported equol-producing status. We searched PubMed, EMBASE, Ovid Medline and the Cochrane Central Register for Controlled Trials published up to April 2015 and hand-searched bibliographies to identify the RCT. Characteristics of participants and outcomes measurements were extracted and qualitatively analysed. From a total of 1671 studies, we identified forty-two articles that satisfied our search criteria. The effects of equol on risk factors for CHD were mainly based on secondary analyses in these studies, thus with inadequate statistical power. Although fourteen out of the forty-two studies found that equol production after a soya isoflavone intervention significantly improved a range of risk factors including cholesterol and other lipids, inflammation and blood pressure variables, these results need further verification by sufficiently powered studies. The other twenty-eight studies primarily reported null results. RCT of equol, which has recently become available as a dietary supplement, on CHD and its risk factors are awaited.

Red clover isoflavones enriched with formononetin lower serum LDL cholesterol-a randomized, double-blind, placebo-controlled study

BACKGROUND

Although postmenopausal combined hormone replacement therapy reduces the risk of hip fracture, long-term use may be associated with an increased risk of breast cancer, and in women more than 10 years after menopause it is associated with an increased risk of cardiovascular disease. Isoflavones, because of preferential binding to estrogen receptor beta, may retain the beneficial effects on bone but lessen the adverse effects on the breast.

OBJECTIVE

The objective of this study was to study the effects of an isoflavone obtained from red clover (Rimostil) on bone mineral density, and on low-density lipoprotein (LDL) cholesterol.

DESIGN

In a double-blind, randomized, placebo-controlled trial, 50 mg of Rimostil was given to women who were menopausal for at least 1 year. Bone mineral density of the spine, femoral neck and forearm and serum LDL cholesterol were measured at baseline and at 6-month intervals. The duration of follow-up was 2 years.

RESULTS

There was no beneficial effect of Rimostil on bone density at any site. There was a 12% fall in serum LDL cholesterol in the Rimostil-treated arm, which was significantly greater than the 2% drop seen in the control arm (P=0.005).

MLK3 is a direct target of biochanin A, which plays a role in solar UV-induced COX-2 expression in human keratinocytes

Solar UV (sUV) is an important environmental carcinogen. Recent studies have shown that sUV is associated with numerous human skin disorders, such as wrinkle formation and inflammation. In this study, we found that the isoflavone, biochanin A, inhibited the expression of sUV-induced COX-2, which is a well-characterized sUV-induced enzyme, in both human HaCaT keratinocytes and JB6 P+ mouse skin epidermal cells. Several studies have demonstrated the beneficial effects of biochanin A. However, its direct molecular target is unknown. We found that biochanin A inhibited sUV-induced phosphorylation of MKK4/JNK/c-Jun and MKK3/6/p38/MSK1. Mixed-lineage kinase 3 (MLK3) is an upstream kinase of MKK4 and MKK3/6. Thus, we evaluated the effect of biochanin A on MLK3. We found that sUV-induced MLK3 phosphorylation was not affected, whereas MLK3 kinase activity was significantly suppressed by biochanin A. Furthermore, direct binding of biochanin A in the MLK3 ATP-binding pocket was detected using pull-down assays. Computer modeling supported our observation that MLK3 is a novel target of biochanin A. These results suggest that biochanin A exerts chemopreventive effects by suppressing sUV-induced COX-2 expression mediated through MLK3 inhibition.

Biochanin A protects against acute carbon tetrachloride-induced hepatotoxicity in rats

Biochanin A (BCA) is an isoflavone found in red clover possessing multiple pharmacological activities including antimicrobial, antioxidant, and anticancer ones. The present study aimed to assess its hepatoprotective potential at different doses in a carbon tetrachloride (CCl4)-induced hepatotoxicity model in rats. The effects on hepatic injury were explored by measuring serum levels of alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase. Furthermore, the serum levels of glucose, urea, creatinine, total bilirubin, total proteins, triglycerides, and total cholesterol were determined. The metabolic capacity of the liver was assessed by measuring changes in cytochrome P450 2E1 activity. The underlying mechanisms were substantiated by measuring oxidative stress markers as catalase, superoxide dismutase, glutathione peroxidase, glutathione transferase, glutathione reductase, reduced glutathione, total antioxidant capacity, and lipid peroxidation, as well as inflammation markers such as nitric oxide, inducible nitric oxide synthase, cyclooxygenase2, tumor necrosis factor-α, and leukocyte-common antigen. The results were confirmed by histopathological examination, and the median lethal dose was determined to confirm the safety of the drug. BCA successively protected against CCl4-induced damage, normalizing many parameters to that of the control group. The study indicates that BCA possesses multimechanistic hepatoprotective activity that can be attributed to its antioxidant, anti-inflammatory, and immunomodulatory actions.

Distribution of isoflavones and coumestrol in neglected tropical and subtropical legumes

BACKGROUND

Isoflavones and coumestrol from dietary legumes are plant constituents showing multiple beneficial effects on humans. Owing to their ability to bind with mammalian estrogenic receptors and thereby intervention in several kinds of hormone-related cancers, they have received much attention. Soybean (Glycine max) is currently the major source of isoflavonoids in human diet. However, dozens of tropical and subtropical leguminous species remain unexplored for their isoflavonoids content.

RESULTS

We have analyzed 55 extracts from 41 tropical and subtropical legume species used either in human or animal diet by high-performance liquid chromatography for the content of soy isoflavones, biochanin A, daidzein, daidzin, formononetin, genistein, genistin, sissotrin, ononin and the coumestan coumestrol. Genistein and biochanin A were the most abundant compounds. The highest content of genistein was found in aerial parts of Andira macrothyrsa, seeds of Pachyrhizus tuberosus and aerial parts of Calopogonium mucunoides (598, 250 and 184 µg g(-1), respectively) and biochanin A in aerial parts of Cratylia argentea, C. mucunoides and flowers of A. macrothyrsa (76, 53 and 40 µg g(-1), respectively).

CONCLUSION

None of the samples tested was richer overall source of soy isoflavones and coumestrol than soybean; nevertheless several species (C. mucunoides or A. macrothyrsa) may serve as a promising source of individual compounds.

Trifolium species-derived substances and extracts--biological activity and prospects for medicinal applications

BACKGROUND

Despite of the fact that clovers (family: Fabaceae; genus: Trifolium) have been known for many centuries as important forage plants and valuable herbs in folk medicine, their phytochemical characteristics and biological activity remain only partly established.

AIM OF THE STUDY

The presentation of the current knowledge of physiological effects, therapeutic action, new trends in the investigation of Trifolium plants and suggestions for the future applications of these herbs in therapy of various disorders.

METHODS

A critical review of literature on the biological activity of Trifolium plants, with the indication on important gaps, was performed. The compilation of existing information on physiological effects and medicinal value of clovers, derived from both traditional medicine recommendations and scientific reports, is presented.

RESULTS

The available data indicate on the abundance of biologically active substances in Trifolium plants, including numerous flavonoids, saponins, clovamides and phenolic acids. The best known clover - Trifolium pratense L. (red clover) - is used for the production of herbal medicines, an alternative to the conventional hormonal replacement therapy. The biological activity and potential therapeutic effects of other Trifolium species have gained a considerable scientific interest; extracts obtained from various clovers have been shown to possess antioxidative and antiinflammatory activities, inhibiting angiogenesis and displaying anti-cancer properties.

CONCLUSIONS

Clovers other than T. pratense also seem to be a promising source of valuable phytochemicals, such as isoflavones and various flavonoids. However, the therapeutic use of these Trifolium species is significantly limited by the lack of clinical evidence; thus further studies are needed.

High-Throughput Screening of Chemical Libraries for Modulators of Gene Promoter Activity ofHLA-B2705: Environmental Pathogenesis and Therapeutics of Ankylosing Spondylitis

Objective.

Ankylosing spondylitis (AS) is a highly heritable disease withHLA-B27being the strongest susceptible gene. In order to survey the environmental triggers for arthritis development, we used a high-throughput technique to screen the effects of 12,264 chemicals on theHLA-B27gene promoter.

Methods.

Promoter reporter transfectants 293T-HLA-B27 and HeLa-HLA-B27 were tested using robotics with 12,264 chemicals. Chemicals that modulatedHLA-B27promoter activity > 150% or < 40% were selected for further evaluation of IC50/EC50 and cell viability.

Results.

The primary screening using the 293T-HLA-B27 promoter reporter cell line yielded 5.1% hits that either suppressed (556 chemicals) or enhanced (68 chemicals) theHLA-B27promoter activity. A secondary reconfirmation screening was carried out with these 624 candidates using HeLa-HLA-B27 promoter reporter cells under several different culture conditions. The yield of positive candidates was 130, of which 47 were derived from natural products. Based on the bio-information of those positive natural products, 21 chemicals were selected for analysis by dose-response IC50/EC50 experiments. Eight compounds showed potential pharmacological activities. Two suppressors are both derived from an herbal medicine (lei gong teng) that has been used for decades to treat immune diseases. The 6 activators all belonged to a group of chemicals known as flavonoids, widely distributed among dietary fruits and vegetables.

Conclusion.

Several common dietary products that contain certain flavonoids might be environmental risk factors for AS; the Chinese traditional herblei gong tengmight be a potential drug for patients who areHLA-B27-positive. These results provide new research directions for the pathogenesis and therapeutics of AS.

Soy-derived isoflavones treatment in children with hypercholesterolemia: a pilot study

AIMS

To evaluate for the first time in children the effect of soy-derived isoflavones on lipid profile and insulin resistance.

METHODS

Twelve hypercholesterolemic children (8 females) aged 5.3 to 11.2 years have completed a prospective, controlled pilot study. After a low-fat diet for 12 weeks, children who maintained high cholesterol and low-density lipoprotein-cholesterol (LDL-C) levels were randomly assigned to three intervention periods of either placebo or low and high dose isoflavone (16 or 48 mg) consumption, each period lasting 8 weeks.

RESULTS

The diet significantly reduced LDL-C and apolipoprotein B (Apo B) levels. However, isoflavones had no effect on cholesterol, LDL-C, high-density lipoprotein-cholesterol (HDL-C), triglycerides, lipoprotein (a), Apo B, or insulin resistance, at either low or high doses. Isoflavones had no effect on sex hormones, gonadotropins, sex-hormone binding globulin and thyroid hormones.

CONCLUSIONS

The results of this pilot study do not suggest a beneficial role of an isoflavone-enriched diet in children with hypercholesterolemia.

In Vitro Production of Radiolabeled Red Clover (Trifolium pratense) Isoflavones

Red clover isoflavones are increasingly used in dietary supplements for their purported estrogenic effects. However, little is known about their metabolism in animals due to a lack of commercially available isotopically-labeled tracers. The goal of this research was to establish red clover cell culturing methodology for (14)C-biolabeling of isoflavones. When root, leaf, and petiole-derived suspension cultures were grown in darkness or light, dark-grown, petiole-derived solution cultures produced the highest concentrations of the two major red clover isoflavones, formononetin (0.67 mg/g FM inoculum) and biochanin A (0.13 mg/g FM inoculum). Varying levels and timing of copper chloride elicitor did not significantly affect isoflavone accumulation. Approximately 38% of the (14)C-sucrose dose accumulated in the cells. Eighteen percent of the initial labeled dose was detected in the isoflavone-rich methanolic extract and of that, 22% accumulated in isoflavones.

Effect of Trifolium pratense-derived isoflavones on the lipid profile of postmenopausal women with increased body mass index

BACKGROUND

Since current clinical evidence indicates that conventional estrogen hormone therapy (HT) increases cardiovascular risk, alternatives to estrogens are growing in popularity, especially among high-risk populations.

OBJECTIVE

To determine the effect of Trifolium pratense-derived isoflavone supplementation on the lipid profile of postmenopausal women with increased body mass index (BMI).

METHODS

Sixty postmenopausal women aged > 40 years, HT non-users, were randomly assigned to one of two groups: either two capsules of T. pratense (80 mg red clover isoflavones) daily for a 90-day period or placebo of equal design. After a 7-day washout period, medication was crossed-over for another 90 days. Total cholesterol (TC), triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C) and lipoprotein A (LpA) levels were assessed at baseline, 90 and 180 days. Women were divided into two groups: those with increased BMI (>or=25 kg/m(2)) and those with BMI < 25 kg/m(2).

RESULTS

Fifty-three women (88.3%) completed the trial. T. pratense isoflavone supplementation had a positive effect on the lipid profile of women with increased BMI, evidenced by a significant decrease in TC, LDL-C and LpA levels.

CONCLUSIONS

Isoflavones derived from T. pratense are an attractive alternative therapeutic option for high-risk populations such as postmenopausal women with increased BMI and abnormal lipid profile.

Clinical studies of red clover (Trifolium pratense) dietary supplements in menopause: a literature review

Red clover (Trifolium pratense L., Fabaceae) botanical dietary supplements have received much attention recently for their potential use in the treatment of menopause symptoms, maintenance/improvement of bone and cardiovascular health, and reported benign effects on the breast and endometrium. Literature searches of four computerized databases were run to identify clinical studies of red clover botanical dietary supplements. The manufacturer of the red clover products used in the majority of the studies was contacted for unpublished information and/or clarification regarding the chemical content of their products. Red clover studies were reviewed that pertained to women's health or menopause. Clinical evidence is presently lacking to support the efficacy of semipurified red clover isoflavone extracts for alleviation of climacteric vasomotor symptoms or reduction of low-density lipoprotein levels in the blood. Furthermore, the safety of use of red clover isoflavone supplements in patients with breast or endometrial cancer has not been established. Limited evidence suggests possible efficacy in maintenance of bone health and improvement of arterial compliance, a risk factor for atherosclerosis. This literature review covers red clover botanical dietary supplement clinical studies having a possible impact on the health care of mature and menopausal women, and provides historical perspective regarding the traditional uses of red clover.

Pharmacokinetics and bioavailability of the isoflavone biochanin A in rats

Biochanin A (BCA) is a dietary isoflavone present in legumes, most notably red clover, and in many herbal dietary supplements. BCA has been reported to have chemopreventive properties and is metabolized to the isoflavone genistein (GEN), BCA conjugates, and GEN conjugates. The metabolites may contribute to the chemopreventive effects of BCA. The absorption, metabolism, and disposition of BCA have not been determined in rats. Our objective was to evaluate the pharmacokinetics and metabolism of BCA in rats. Male Sprague-Dawley rats were administered BCA by intravenous injection (1 and 5 mg/kg), by intraperitoneal injection (5 and 50 mg/kg), and orally (5 and 50 mg/kg). Plasma and bile samples were enzymatically hydrolyzed in vitro to determine conjugate concentrations for BCA and GEN. Equilibrium dialysis was used to determine protein binding. The BCA and GEN concentrations in plasma, urine, and bile were determined by liquid chromatography-tandem mass spectrometry (LC/MS/MS). The pharmacokinetic parameters of BCA were analyzed by noncompartmental analysis. Significant levels of BCA conjugates and GEN conjugates were detected in plasma and bile. Both BCA and GEN were found to have a high clearance and a large apparent volume of distribution; the bioavailability of both was poor (<4%). Reentry peaks were evident after oral administration of both BCA and GEN, suggesting enterohepatic cycling. The free fraction of BCA in rat plasma was 1.5%. A 2-compartment model that included both linear and nonlinear clearance terms and enterohepatic recirculation best described the plasma data. This represents the first evaluation of the dose-dependent pharmacokinetics and metabolism of BCA in rats.

Differential effects of isoflavones, from Astragalus membranaceus and Pueraria thomsonii, on the activation of PPARalpha, PPARgamma, and adipocyte differentiation in vitro

Compounds that target the peroxisome proliferator-activated receptors PPARalpha and PPARgamma are used to correct dyslipidemia and to restore glycemic balance, respectively. Because the majority of diabetic patients suffer from atherogenic lipid abnormalities, in addition to insulin resistance, ligands are required that can activate both PPARalpha and PPARgamma. In this study, we used chimeric PPARalpha/gamma reporter-gene bioassays to screen herbal extracts with purported antidiabetic properties. Extracts of Astragalus membranaceus and Pueraria thomsonii significantly activated PPARalpha and PPARgamma. Bioassay-guided fractionation resulted in the isolation of the isoflavones, formononetin, and calycosin from Astragalus membranaceus, and daidzein from Pueraria thomsonii as the PPAR-activating compounds. We investigated the effects of these and 2 common isoflavones, genistein and biochanin A, using chimeric and full-length PPAR constructs in vitro. Biochanin A and formononectin were potent activators of both PPAR receptors (EC50 = 1-4 micromol/L) with PPARalpha/PPARgamma activity ratios of 1:3 in the chimeric and almost 1:1 in the full-length assay, comparable to those observed for synthetic dual PPAR-activating compounds under pharmaceutical development. There was a subtle hierarchy of PPARalpha/gamma activities, indicating that biochanin A, formononetin, and genistein were more potent than calycosin and daidzein in chimeric as well as full-length receptor assays. At low doses, only biochanin A and formononetin, but not genistein, calycosin, or daidzein, activated PPARgamma-driven reporter-gene activity and induced differentiation of 3T3-L1 preadipocytes. Our data suggest the potential value of isoflavones, especially biochanin A and their parent botanicals, as antidiabetic agents and for use in regulating lipid metabolism.

Clinical review: a critical evaluation of the role of soy protein and isoflavone supplementation in the control of plasma cholesterol concentrations

CONTEXT

The purpose of this review was to critically evaluate current research on the effect of soy protein and isoflavone supplements on plasma lipoproteins and place the potential role of soy in the prevention of coronary artery disease (CAD) into a clinical perspective.

EVIDENCE ACQUISITION

An extensive literature search was performed using a variety of medical and scientific databases including Medline, PubMed, Science Direct, Ovid, NIST, and Infotrac to identify relevant articles. Journal articles were cross-referenced for additional sources of information. Articles were evaluated based on level of experimental control as well as statistical, quantitative, and clinical analysis.

EVIDENCE SYNTHESIS

Soy and soy isoflavones have been the object of extensive research investigating their potential hypocholesterolemic effects and possible role in the prevention of CAD. It has been suggested that soy, especially the isoflavones contained in soy, improves lipoprotein levels, thus reducing the risk for CAD. This belief, however, is not uniformly accepted. Moreover, the experimental evidence in support of this notion is not as overwhelming as generally perceived, and the current available data reveal that the discrepancies observed are primarily statistical in nature rather than reflecting actual quantitative differences in the hypocholesterolemic effects detected.

CONCLUSIONS

A critical analysis of the investigations to date indicates the data are not quantitatively impressive and raises substantial questions about the clinical importance of the hypocholesterolemic effects observed.

The effect of red clover isoflavones on menopausal symptoms, lipids and vaginal cytology in menopausal women: a randomized, double-blind, placebo-controlled study

BACKGROUND

The unexpected results of the Women's Health Initiative study have decreased the use of conventional hormone therapy (HT), changing physicians' and patients' attitudes towards HT and increasing their interest in alternative options.

OBJECTIVE

The present study aimed to evaluate the effect of isoflavones contained in red clover extracts (Trifolium pratense) on menopausal symptoms, lipids and vaginal cytology in menopausal women.

METHODS

Sixty postmenopausal women aged >40 years, non-users of HT, with Kupperman index score 15, were double-blindly randomized to receive either a commercially available red clover isoflavone supplement (80 mg/day) or placebo for 90 days. Subsequently, after a 7-day washout period, subjects switched to receive the opposite treatment for a further 90 days. Kupperman index score was determined and fasting blood and vaginal cytologic sampling performed at baseline, 90 and 180 days.

RESULTS

Fifty-three women (88.3%) completed the trial. Mean age was 51.3 +/- 3.5 years, 69.7% of the women were aged 50 years or more. There was no significant effect on body mass index, weight or blood pressure after either treatment phase. Baseline Kupperman index score decreased significantly after each treatment phase, with the decrease more pronounced after the isoflavone phase (baseline: 27.2 +/- 7.7; after isoflavone: 5.9 +/- 3.9; after placebo: 20.9 +/- 5.3, p < 0.05). Red clover isoflavone supplementation significantly decreased the rate of menopausal symptoms and had a positive effect on vaginal cytology as expressed by improvement in karyopyknotic, cornification and basal cell maturation indices. Mean total cholesterol, low-density lipoprotein-cholesterol and triglyceride levels also decreased; however, only the latter was significantly lower compared with placebo.

CONCLUSIONS

Compared with placebo, red clover isoflavone supplementation in postmenopausal women significantly decreased menopausal symptoms and had a positive effect on vaginal cytology and triglyceride levels.

Polyphenols and prevention of cardiovascular diseases

PURPOSE OF REVIEW

Polyphenols are the most abundant dietary antioxidants and research on their role in the prevention of degenerative diseases has developed quickly over these last few years. This paper reviews the recent studies on the prevention of cardiovascular diseases by polyphenols, focusing on human studies.

RECENT FINDINGS

A large number of recent intervention studies have shown that several biomarkers of cardiovascular risk are influenced by the consumption of polyphenol-rich foods. Effects on biomarkers of oxidative stress, lipemia and inflammation appear so far inconclusive. More consistent effects have been observed on endothelial function and haemostasis and support a reduction of risk by polyphenols in agreement with the few epidemiological studies already published. All clinical studies have used foods or beverages containing a mixture of different polyphenols and the exact nature of the most active compounds remains largely unknown. Absorption, metabolism and elimination vary widely between polyphenols. These data on bioavailability should be taken into account to improve the experimental design and the interpretation of the observed effects.

SUMMARY

Future intervention studies should include a detailed assessment of the bioavailability of polyphenols. Beyond clinical trials carried out with polyphenol-rich foods, more studies with pure polyphenols will also be needed to establish their role in the prevention of cardiovascular diseases.