Preventive effects of Pueraria mirifica on bone loss in ovariectomized rats

The potential mechanism of the microbiota-gut-bone axis in osteoporosis: a review

Osteoporosis is the prevalent metabolic bone disease characterized by a decrease in bone quantity and/or quality and an increase in skeletal fragility, which increases susceptibility to fractures. Osteoporotic fractures severely affect the patients' quality of life and mortality. A plethora of evidences have suggested that the alterations in gut microbiome are associated with the changes in bone mass and microstructure. We summarized pre-clinical and clinical studies to elucidate the underlying mechanism of gut microbiota in osteoporosis. Probiotics, prebiotics, and traditional Chinese medicine may reverse the gut microbiota dysbiosis and consequently improve bone metabolism. However, the causality of gut microbiota on bone metabolism need to be investigated more in depth. In the present review, we focused on the potential mechanism of the microbiota-gut-bone axis and the positive therapeutic effect of probiotics, prebiotics, and traditional Chinese medicine on osteoporosis. Overall, the current scientific literatures support that the gut microbiota may be a novel therapeutic target in treatment of osteoporosis and fracture prevention.

Bioimprinting as a Receptor for Detection of Kwakhurin

Bioimprinting was performed against ovalbumin (OVA) to confer its binding cavities for kwakhurin (Kwa), an isoflavonoid, produced solely by Pueraria candollei var. mirifica (P. candollei). The characterization of bioimprinted-OVA (biOVA), evaluated by an enzyme-linked immunosorbent assay (ELISA), revealed that it functioned as a specific receptor for Kwa. Using biOVA, two systems, i.e., an indirect competitive ELISA (icELISA) and the even simpler and more rapid competitive enzyme-linked bioimprinted-protein assay (cELBIA), were developed as novel techniques for the quantitative analysis of Kwa in P. candollei and its related products. The two analysis methods were found to have limits of detection (LOD) of 4.0 and 2.5 µg/mL, respectively. The high reliability of the developed icELISA and cELBIA using biOVA was also demonstrated by various validation analyses. Subsequently, bioimprinting was performed using eight other proteins to investigate them as candidate scaffolds for the generation of binding cavities for Kwa. Interestingly, two bioimprinted-IgG monoclonal antibodies (biMAbs) recognized Kwa, but their original binding affinity to hapten was lost. That is, the MAbs obtained a new binding ability to Kwa in exchange for their original binding affinity, raising the possibility that biMAb could be alternatively used as a probe for the quantitative analysis of Kwa as well as biOVA. This is the first report of small molecules recognition by MAbs used as proteins for bioimprinting.

Permeation, stability and acute dermal irritation of miroestrol and deoxymiroestrol from Pueraria candollei var. mirifica crude extract loaded transdermal gels

In this study, permeation behaviors and chemical stability of miroestrol and deoxymiroestrol from Pueraria candollei var. mirifica (PM), Thai traditional medicine, crude extract containing transdermal gels were firstly evaluated. Three different PM extract containing gels were formulated, including hydroalcoholic and microemulsion gels using carbomer, and silicone gel using silicone elastomer. In vitro permeation through porcine ear skin demonstrated that the flux and 24 h cumulative permeation of miroestrol and deoxymiroestrol were in the order of hydroalcoholic > silicone > microemulsion gels. Hydroalcoholic gel provided the highest partition coefficient from gel onto skin, and thus the skin permeability coefficient. After 24 h permeation, no miroestrol and deoxymiroestrol remained deposited in the skin. Accelerated study using heating-cooling revealed insignificant difference between the remaining percentages of miroestrol and deoxymiroestrol in aqueous and non-aqueous based gels. Long-term stability study showed that miroestrol contents remained constant for 90 d and 30 d under 5 ± 3 °C and 30 ± 2 °C, 75 ± 5%RH, respectively; whereas the percentage of deoxymiroestrol decreased significantly after 30 d storage, irrespective of storage conditions. Acute dermal irritation test on New Zealand White rabbits showed that PM hydroalcoholic gels were non-irritant, with no signs of erythema or oedema.[Figure: see text].

A fraction of Pueraria tuberosa extract, rich in antioxidant compounds, alleviates ovariectomized-induced osteoporosis in rats and inhibits growth of breast and ovarian cancer cells

Pueraria tuberosa (Roxb. ex Willd.) DC., known as Indian Kudzu belongs to family Fabaceae and it is solicited as “Rasayana” drugs in Ayurveda. In the present study, we analyzed the efficacy of an ethyl acetate fraction from the tuber extract of Pueraria tuberosa (fraction rich in antioxidant compounds, FRAC) against menopausal osteoporosis, and breast and ovarian cancer cells. The FRAC from Pueraria tuberosa was characterized for its phenolic composition (total phenolic and flavonoid amount). Antioxidant property (in vitro assays) of the FRAC was also carried out followed by the analysis of the FRAC for its antiosteoporotic and anticancer potentials. The antiosteoporotic activity of FRAC was investigated in ovariectomy-induced osteoporosis in rats. The cytotoxicity effect was determined in breast and ovarian cancer cells. Gas chromatography/mass spectrometry (GC/MS) analysis of the FRAC was performed to determine its various phytoconstituents. Docking analysis was performed to verify the interaction of bioactive molecules with estrogen receptors (ERs). The FRAC significantly improved various biomechanical and biochemical parameters in a dose-dependent manner in the ovariectomized rats. FRAC also controlled the increased body weight and decreased uterus weight following ovariectomy in rats. Histopathology of the femur demonstrated the restoration of typical bone structure and trabecular width in ovariectomized animals after treatment with FRAC and raloxifene. The FRAC also exhibited in vitro cytotoxicity in the breast (MCF-7 and MDA-MB-231) and ovarian (SKOV-3) cancer cells. Furthermore, genistein and daidzein exhibited a high affinity towards both estrogen receptors (α and β) in the docking study revealing the probable mechanism of the antiosteoporotic activity. GC/MS analysis confirmed the presence of other bioactive molecules such as stigmasterol, β-sitosterol, and stigmasta-3,5-dien-7-one. The FRAC from Pueraria tuberosa has potential for treatment of menopausal osteoporosis. Also, the FRAC possesses anticancer activity.

A fraction of Pueraria tuberosa extract, rich in antioxidant compounds, alleviates ovariectomized-induced osteoporosis in rats and inhibits growth of breast and ovarian cancer cells

Pueraria tuberosa (Roxb. ex Willd.) DC., known as Indian Kudzu belongs to family Fabaceae and it is solicited as "Rasayana" drugs in Ayurveda. In the present study, we analyzed the efficacy of an ethyl acetate fraction from the tuber extract of Pueraria tuberosa (fraction rich in antioxidant compounds, FRAC) against menopausal osteoporosis, and breast and ovarian cancer cells. The FRAC from Pueraria tuberosa was characterized for its phenolic composition (total phenolic and flavonoid amount). Antioxidant property (in vitro assays) of the FRAC was also carried out followed by the analysis of the FRAC for its antiosteoporotic and anticancer potentials. The antiosteoporotic activity of FRAC was investigated in ovariectomy-induced osteoporosis in rats. The cytotoxicity effect was determined in breast and ovarian cancer cells. Gas chromatography/mass spectrometry (GC/MS) analysis of the FRAC was performed to determine its various phytoconstituents. Docking analysis was performed to verify the interaction of bioactive molecules with estrogen receptors (ERs). The FRAC significantly improved various biomechanical and biochemical parameters in a dose-dependent manner in the ovariectomized rats. FRAC also controlled the increased body weight and decreased uterus weight following ovariectomy in rats. Histopathology of the femur demonstrated the restoration of typical bone structure and trabecular width in ovariectomized animals after treatment with FRAC and raloxifene. The FRAC also exhibited in vitro cytotoxicity in the breast (MCF-7 and MDA-MB-231) and ovarian (SKOV-3) cancer cells. Furthermore, genistein and daidzein exhibited a high affinity towards both estrogen receptors (α and β) in the docking study revealing the probable mechanism of the antiosteoporotic activity. GC/MS analysis confirmed the presence of other bioactive molecules such as stigmasterol, β-sitosterol, and stigmasta-3,5-dien-7-one. The FRAC from Pueraria tuberosa has potential for treatment of menopausal osteoporosis. Also, the FRAC possesses anticancer activity.

Metabolomics strategy reveals the osteogenic mechanism of yak (Bos grunniens) bone collagen peptides on ovariectomy-induced osteoporosis in rats

Our previous work demonstrated that yak bone collagen peptides (YBP) possessed excellent osteogenic activity in vitro. However, associations between YBP and osteoporosis were less established, and the positive effect and underlying mechanism of YBP in the treatment of osteoporotic rats in vivo remained unclear. Herein, ovariectomized rats were intragastrically administered with YBP or 17β-estradiol for 12 weeks. Bone turnover markers, bone biomechanical parameters and bone microarchitecture were investigated to identify the specific changes of potential antagonistic effects of YBP on ovariectomized rats. Then, serum samples were analyzed by UPLC/Q-TOF-MS to identify metabolites. The results showed that YBP treatment remarkably altered the content of serum bone turnover markers and prevented the ovariectomy-induced deterioration of bone mechanical and microarchitecture characteristics. A total of forty-one biomarkers for which levels changed markedly upon treatment have been identified based on non-targeted metabolomics. Among them, twenty-one metabolites displayed a downward expression level, while twenty metabolites showed an upward expression level in the YBP group and finally were selected as potential biomarkers. The levels of these biomarkers displayed significant alterations and a tendency to be restored to normal values in YBP treated osteoporotic rats. A systematic network analysis of their corresponding pathways delineated that the protective or recovery effect of YBP on osteoporosis occurred primarily by regulating the amino acid metabolism and lipid metabolism (especially unsaturated fatty acid). Collectively, these findings highlight that such peptides hold promise in further advancement as a natural alternative for functional and health-promoting foods, which could be potentially used in mediated treatment of osteoporosis.

Kwakhurin-magnetic particles conjugates enable fast enzyme immunoassay for the detection of kwakhurin in Pueraria candollei

INTRODUCTION

Kwakhurin (Kwa) is one of the unique isoflavonoids produced in Pueraria candollei var. mirifica (P. candollei), which has long been used as folk medicine for rejuvenation in Thailand. Recently, the use of P. candollei-derived products has widely spread among Japanese women for cosmetic purposes. Correspondingly, there has been an increase in the number of reports regarding possible health hazards caused by estrogenic activity inherent to the plant; thus, the need for a detailed evaluation of the phytoestrogen content of P. candollei-derived products has gained a sense of urgency in recent years.

OBJECTIVE

This study aims to develop a rapid enzyme immunoassay that can be applied to the quantitative analysis of Kwa in P. candollei and its derived products.

MATERIAL AND METHOD

A rapid and sensitive immunoassay was developed with a combination of Kwa-specific monoclonal antibody (MAb 11F) and Kwa-magnetic particles (MPs) conjugates, which increased the surface area of the solid phase, resulting in a decrease in the immunoreaction time.

RESULT

This novel MPs-based enzyme immunoassay (MPs-EIA) was used to determine Kwa concentration in the range from 2.44 to 78.1 ng/mL with a limit of detection of 1.90 ng/mL. Validation analyses revealed that the proposed MPs-EIA protocol was sufficiently precise and accurate for effective quantitative analysis of Kwa in P. candollei and its derived products.

Puerarin improves the bone micro-environment to inhibit OVX-induced osteoporosis via modulating SCFAs released by the gut microbiota and repairing intestinal mucosal integrity

SCOPE

Half of women over the age of 50 will experience a fracture related osteoporosis in their lifetime. The common treatment is estrogen replacement therapy, which can cause many side effects. Puerarin as a phytoestrogen has been proven to improve postmenopausal osteoporosis. However, the mechanisms of anti-osteoporosis remain unclear due to its low bioavailability. The aim of this study is to investigate whether the anti-osteoporosis effects of puerarin are related to modulations in the gut microbiota and focus on the mechanism of gut / bone axis.

METHODS

We established ovariectomized (OVX) rats as osteoporosis model. The femur was analyzed by microcomputed tomography (μ-CT) and we measured serum biochemical indices and inflammatory factors. 16S rRNA sequencing was employed to evaluate the gut microbiota composition in the fecal samples. Short-chain fatty acids (SCFAs) was analyzed by GC. The expression of intestinal inflammatory factors and adhesion proteins was confirmed by western blotting and qPCR.

RESULTS

Puerarin increased the BMD and improved the intestinal mucosal integrity to reduce the systemic inflammation. The disorder of gut microbiota was improved and its metabolites SCFAs were elevated. Metabolic pathways such as amino acid metabolism, LPS biosynthesis and butyrate metabolism were enriched.

CONCLUSION

Puerarin treatment modulated the gut microbiota disorder to elicit the anti-osteoporosis effects in OVX rats, by improving the bone micro-environment via regulating the SCFAs levels and repairing the intestinal mucosal integrity.

Puerarin inhibits the migration of osteoclast precursors and osteoclastogenesis by inhibiting MCP-1 production

Puerarin inhibits osteoclastogenesis and cells migration. This study aims to explore whether puerarin prevents osteoclastogenesis by inhibiting osteoclast precursors (OCPs) migration. The results showed that puerarin reduced MCP-1 production in OCPs, while inhibiting OCPs migration based on MCP-1. Puerarin reversed MCP-1-promoted osteoclastogenesis. CCR2 overexpression didn't increase osteoclastogenesis with puerarin. Therefore, puerarin prevents OCPs migration by reducing MCP-1, whereby inhibiting osteoclastogenesis.

Puerarin inhibits the osteoclastogenesis by inhibiting RANKL-dependent and -independent autophagic responses

Background

Puerarin exerts therapeutic effect on osteoporosis due to its inhibitory effect on the formation of osteoclasts. Puerarin is also widely established as an autophagy inhibitor. The study aimed to investigate the significance of autophagy in Puerarin-treated osteoclast formation.

Methods

Osteoclast precursors (OCPs) derived from bone marrow-derived macrophages (BMMs) were treated with Puerarin along with RANKL or without RANKL, and then the autophagic parameters of OCPs (including autophagic proteins, LC3 transformation, autophagosome or LC3-puncta) were observed through Western Blotting, Transmission Electron Microscopy and Immunofluorescence assays. Next, after using overexpression vectors of autophagic genes (Atg7, Atg5 and BECN1) to alter autophagy activity, OCP proliferation was measured by Ethynyl deoxyuridine (EdU) assays and Cell Counting Kit-8 (CCK-8) kit, and osteoclast differentiation was assessed by Tartrate-resistant acid phosphatase (TRAP) staining.

Results

The results showed that Puerarin could directly inhibit the autophagy and proliferation of OCPs. Importantly, overexpression of autophagic genes Atg5, Atg7 and BECN1 reversed Puerarin-inhibited OCP autophagy and proliferation. What’s more, RANKL could promote the autography of OCPs, which was recovered by Puerarin treatment. Interestingly, different from single-Puerarin treatment, we found that in the presence of RANKL, only BECN1 overexpression significantly reversed Puerarin-inhibited osteoclast differentiation and OCP autophagy.

Conclusion

In conclusion, Puerarin could inhibit the OCP autophagy in the presence or absence of RANKL, which blocked the OCP proliferation and osteoclast differentiation respectively. Moreover, BECN1 plays an essential role in Puerarin-inhibited osteoclastogenesis. Our study provides potential clue to further complete the intrinsic mechanism of Puerarin in treating osteoporosis.

Pueraria mirifica inhibits 17β-estradiol-induced cell proliferation of human endometrial mesenchymal stem cells

OBJECTIVE

The notion that the human endometrium may contain a population of stem cells has recently been proposed. The mesenchymal stem cells (MSCs) in the endometrium are believed to be responsible for the remarkable regenerative ability of endometrial cells. Estrogens influence the physiological and pathological processes of several hormone-dependent tissues, such as the endometrium. Pueraria mirifica (PM) is a herbal plant that contains several phytoestrogens, including isoflavones, lignans, and coumestans, and is known to exert an estrogenic effect on animal models. The present study investigated the effects of PM on the proliferation of human endometrial MSCs (hEN-MSCs).

MATERIALS AND METHODS

The hEN-MSCs were isolated from human endometrial tissue. The surface markers of these hEN-MSCs were identified through reverse transcription-polymerase chain reaction analysis. The proliferation potential of hEN-MSCs was measured through a cell proliferation assay. Multilineage differentiation ability was confirmed through Oil red O and von Kossa staining.

RESULTS

This study demonstrated that 17β-estradiol-responsive MSCs with Oct-4, CD90, and CD105 gene expression can be derived from the human endometrium and that PM exerts biological effects on hEN-MSCs, specifically, enhanced cell growth rate, through the estrogen receptor. Furthermore, PM at 1500 and 2000 μg/mL significantly increased cell proliferation compared with the vehicle control, and PM concentration at 1000 μg/mL significantly inhibited the enhanced cell growth rate induced by 17β-estradiol in hEN-MSCs.

CONCLUSION

This study provides new insights into the possible biological effects of PM on the proliferation of hEN-MSCs.

Absolute oral bioavailability and disposition kinetics of puerarin in female rats

Background

Pueraria candollei var. mirifica is a medicinal plant that is promoted as a “Champion Product” by the Government of Thailand. This plant has been reported to relieve postmenopausal symptoms, prevent and reverse bone loss, inhibit the growth of breast cancer, and alleviate cardiovascular diseases in preclinical and clinical studies. However, there is little information on the oral bioavailability and tissue distribution of puerarin with respect to its pharmacodynamic activities. Therefore, the aim of this study was to determine the pharmacokinetics of puerarin, including absorption, distribution, metabolism, and elimination, in rats. Moreover, this is the first study to examine the tissue distribution of puerarin in the hippocampus, femur, tibia, and mammary gland.

Methods

Adult female rats were administered puerarin at 1 mg/kg intravenously or 5 and 10 mg/kg orally. Blood, tissue, urine, and feces were collected and analyzed by liquid chromatography–tandem mass spectrometry.

Results

Puerarin reached a maximum concentration in the blood of 140–230 μg/L within 1 h of oral dosing, and had an absolute oral bioavailability of approximately 7%. Following intravenous administration, puerarin was widely distributed in several tissues, including the hippocampus, heart, lung, stomach, liver, mammary gland, kidney, spleen, femur, and tibia. Approximately 50% of the intravenous dose was excreted as glucuronide metabolites via the urinary route.

Conclusions

The absolute oral bioavailability of puerarin was approximately 7% at doses of 5 and 10 mg/kg. Puerarin was widely distributed to several organs related to the diseases of aging, including the hippocampus, femur, tibia, and mammary gland. Glucuronides were the major metabolites of puerarin and were mainly excreted in the urine. These results are useful for the development of puerarin and Pueraria candollei var. mirifica as phytopharmaceutical products.

A pilot pharmacokinetic study of miroestrol and deoxymiroestrol on rabbit sera using polyclonal antibody-based icELISA analysis

Miroestrol (ME) and deoxymiroestrol (DME) are the most potent phytoestrogens and bioactive markers in Pueraria candollei var. mirifica tuberous roots. To understand their pharmacokinetic profiles, a pharmacokinetic study of ME and DME, at 0.43 and 0.21 mg per kg body weight, respectively, in three rabbits was performed after orally administering a single dose of P. candollei var. mirifica enriched fraction extract. Two established polyclonal antibody-based indirect competitive enzyme-linked immunosorbent assays were validated to determine ME and DME in rabbit sera. In rabbits, the area under the 0- to 48-hr concentration-time curve of ME and DME were 854.92 and 1,692.84 ng·h/ml, respectively. The maximum concentration of ME was measured 1 hr after administration as 69.62 ± 8.28 ng/ml, and the maximum concentration of DME was measured at 3 hr as 81.8 ± 5.43 ng/ml. These results provide an initial approach for designing and studying the relationship between the ME and DME levels and their therapeutic effects based on their pharmacokinetic profiles.

Puerarin promotes the proliferation and differentiation of MC3T3-E1 cells via microRNA-106b by targeting receptor activator of nuclear factor-κB ligand

Puerarin, an isoflavone-C-glucoside extracted from the root of Pueraria Labata (Willd.) Ohwi, is one of the most important crude herbs used in Chinese medicine for various medicinal purposes. Accumulating evidence has indicated that puerarin suppresses bone resorption and promotes bone formation. However, the molecular mechanism involved in puerarin-associated bone formation is unclear. The present study aimed to investigate the molecular mechanism of puerarin-induced osteoblast proliferation and differentiation. The study showed that puerarin treatment differentially affected cell proliferation in a time-dependent manner. Notably, at a concentration of 20 µM, puerarin significantly promoted cell proliferation in comparison with the control (P<0.01). Furthermore, puerarin promoted MC3T3-E1 cell differentiation at an appropriate concentration. In addition, miR-106b was significantly upregulated in MC3T3-E1 cells following treatment with 20 µM puerarin (P<0.01), and a known target for miR-106b, receptor activator of nuclear factor-κB ligand (RANKL) was demonstrated using the luciferase reporter assay. Furthermore, inhibition of miR-106b significantly reversed the promotion of cell differentiation induced by puerarin in MC3T3-E1 cells (P<0.01). In conclusion, the present study demonstrated that puerarin exerts its role in MC3T3-E1 osteogenesis through miR-106b by targeting RANKL. The findings suggest that puerarin may be considered a promising anti-osteoporotic agent for the treatment of osteoporosis.

Pueraria mirifica alleviates cortical bone loss in naturally menopausal monkeys

Since the in vitro and in vivo anti-osteoporotic effects of Pueraria mirifica (PM) in rodents have been verified, its activity in menopausal monkeys was evaluated as required before it can be applicable for human use. In this study, postmenopausal osteoporotic monkeys were divided into two groups (five per group), and fed daily with standard diet alone (PMP0 group) or diet mixed with 1000 mg/kg body weight (BW) of PM powder (PMP1000 group) for 16 months. Every 2 months, the bone mineral density (BMD), bone mineral content (BMC) and bone geometry parameters (cortical area and thickness and periosteal and endosteal circumference) at the distal radius and proximal tibia were determined using peripheral quantitative computed tomography together with plasma and urinary bone markers. Compared with the baseline (month 0) values, the cortical, but not trabecular, BMDs and BMCs and the cortical area and thickness at the metaphysis and diaphysis of the radius and tibia of the PMP0 group continuously decreased during the 16-month study period. In contrast, PMP1000 treatment ameliorated the bone loss mainly at the cortical diaphysis by decreasing bone turnover, as indicated by the lowered plasma bone-specific alkaline phosphatase and osteocalcin levels. Generally, changes in the cortical bone geometry were in the opposite direction to the cortical bone mass after PMP1000 treatment. This study indicated that postmenopausal monkeys continuously lose their cortical bone compartment, and they have a higher possibility for long bone fractures. Oral PMP treatment could improve both the bone quantity (BMC and BMD) and quality (bone geometry).

Puerarin attenuates glucocorticoid-induced apoptosis of hFOB1.19 cells through the JNK- and Akt-mediated mitochondrial apoptotic pathways

Puerarin is an active component of Pueraria lobata, which is a commonly used Chinese herbal medicine for the treatment of osteoporosis. The present study aimed to evaluate the osteoprotective effect of puerarin on glucocorticoid (GC)-induced apoptosis of osteoblasts in vitro. The effects of puerarin on dexamethasone (DEX)-induced cell apoptosis were assessed using enzyme-linked immunosorbent assay and a terminal deoxynucleotidyl transferase dUTP nick-end labeling assay, and found that the viability of hFOB1.19 cells was significantly increased following exposure to between 10⁻⁶ and 10⁻¹⁰ M puerarin, with a maximal anti-apoptotic effect at a concentration of 10⁻⁸ M. In addition, compared with the control group, puerarin upregulated the transcription and protein levels of B-cell lymphoma-2 and downregulated B-cell-associated X protein in the hFOB1.19 cells. Puerarin attenuated the DEX-induced release of cytochrome c and cleavage of caspase-3, and treatment with puerarin inhibited the c-Jun N-terminal kinase (JNK) pathway and activated the phosphoinositide 3-kinase (PI3K)/Akt pathway in the hFOB1.19 cells. Furthermore, the Akt inhibitor, LY294002, partly eliminated the protective effect of puerarin on DEX-induced apoptosis, and puerarin combined with the JNK inhibitor, SP600125, suppressed DEX-induced apoptosis to a lesser extent than in the cells treated with SP600125 alone. These results suggested that the JNK and PI3K/Akt signaling pathways mediate the inhibitory effects of puerarin on apoptosis in the hFOB1.19 cells. In conclusion, puerarin prevented DEX-induced apoptosis of hFOB1.19 cells via inhibition of the JNK pathway and activation of the PI3K/Akt signaling pathway in the cells, dependent on the mitochondrial apoptotic pathway. These results support puerarin as a promising target in the treatment of GC-induced osteoporosis.

Kefir improves bone mass and microarchitecture in an ovariectomized rat model of postmenopausal osteoporosis

SUMMARY

Kefir treatment in ovariectomized (OVX) rats could significantly decrease the levels of bone turnover markers and prevent OVX-induced bone loss, deterioration of trabecular microarchitecture, and biomechanical dysfunction that may be due to increase intracellular calcium uptake through the TRPV6 calcium channel.

INTRODUCTION

Osteoporosis is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to an increased fracture risk. The incidence of osteoporosis increases with age and occurs most frequently in postmenopausal women due to estrogen deficiency, as the balance between bone resorption and bone formation shifts towards increased levels of bone resorption. Among various methods of prevention and treatment for osteoporosis, an increase in calcium intake is the most commonly recommended preventive measure. Kefir is a fermented milk product made with kefir grains that degrade milk proteins into various peptides with health-promoting effects, including immunomodulating-, antithrombotic-, antimicrobial-, and calcium-absorption-enhancing bioactivities.

METHODS

The aim of this study is to investigate the effect of kefir on osteoporosis prophylaxis in an ovariectomized rat model. A total of 56 16-week-old female Sprague-Dawley (SD) rats were divided into 7 experimental groups: sham (normal), OVX/Mock, OVX/1X kefir (164 mg/kg BW/day), OVX/2X kefir (328 mg/kg BW/day), OVX/4X kefir (656 mg/kg BW/day), OVX/ALN (2.5 mg/kg BW/day), and OVX/REBONE (800 mg/kg BW/day). After 12-week treatment with kefir, the bone physiology in the OVX rat model was investigated. Accordingly, the aim of this study was to investigate the possible transport mechanism involved in calcium absorption using the Caco-2 human cell line.

RESULTS

A 12-week treatment with kefir on the OVX-induced osteoporosis model reduced the levels of C-terminal telopeptides of type I collagen (CTx), bone turnover markers, and trabecular separation (Tb. Sp.). Additionally, treatment with kefir increased trabecular bone mineral density (BMD), bone volume (BV/TV), trabecular thickness (Tb. Th), trabecular number (Tb. N), and the biomechanical properties (hardness and modulus) of the distal femur with a dose-dependent efficacy. In addition, in in vitro assay, we found that kefir increased intracellular calcium uptake in Caco-2 cell through TRPV6 calcium channels and not through L-type voltage-operated calcium channels.

CONCLUSION

The protective effect of kefir in the OVX rat model may occur through increasing intracellular calcium uptake through the TRPV6 calcium channel.

Puerarin attenuates calcification of vascular smooth muscle cells

Several studies demonstrate that estradiol can prevent arterial calcification. However, little is known regarding the effect of puerarin, a phytoestrogen extracted from Radix Puerariae, on arterial calcification. The aim of the present study was to determine whether puerarin reduced osteoblastic differentiation of calcifying vascular smooth muscle cells (CVSMCs). The CVSMCs were isolated from mice aorta and treated with different concentrations of puerarin. The alkaline phosphatase (ALP) activity, osteocalcin secretion and Runx2 expression were determined. To examine whether estrogen receptors (ERs) PI3K and Akt play a role in this effect, ICI182789, phosphoinositide 3-kinase (PI3K) inhibitor, LY294002, or the Akt inhibitor, 1L-6-hydroxymethyl-chiro-inositol 2-(R)-2-O-methyl-3-O-octadecylcarbonate (HIMO) was used. Our results showed puerarin could inhibit ALP activity, osteocalcin secretion and Runx2 expression in CVSMCs. Puerarin could induce the activation of Akt. Furthermore, pretreatment of ICI182780, LY294002, HIMO could abolish the effect of puerarin on ALP activity in CVSMCs. Our experiment demonstrated that puerain could attenuate the osteoblastic differentiation of VSMCs through the ER/PI3K-Akt signal pathway.

Pueraria mirifica extract and puerarin enhance proliferation and expression of alkaline phosphatase and type I collagen in primary baboon osteoblasts

Phytoestrogen-rich Pueraria mirifica (PM) tuberous extract is a promising candidate for the development of anti-osteoporosis drugs for postmenopausal women, but its action has never been validated in humans or in non-human primates, which are more closely related to humans than rodents. In vitro study of non-human primate osteoblasts is thus fundamental to prepare for in vivo studies of phytoestrogen effects on primate bone. This study aimed to establish a culture system of baboon primary osteoblasts and to investigate the effects of PM extract and its phytoestrogens on these cells. Primary osteoblasts from adult baboon fibulae exhibited osteoblast characteristics in regard to proliferation, differentiation, mineralization, and estrogen receptor expression. They responded to 17β-estradiol by increased proliferation rate and mRNA levels of alkaline phosphatase (ALP), type I collagen, and osteocalcin. After being exposed for 48 h to 100 μg/ml PM extract, 1000 nM genistein, or 1000 nM puerarin, primary baboon osteoblasts markedly increased the rate of proliferation and mRNA levels of ALP and type I collagen without changes in Runx2, osterix, or osteocalcin expression. PM extract, genistein, and puerarin also decreased the RANKL/OPG ratio, suggesting that they could decrease osteoclast-mediated bone resorption. However, neither PM extract nor its phytoestrogens altered calcium deposition in osteoblast culture. In conclusion, we have established baboon primary osteoblast culture, which is a new tool for bone research and drug discovery. Furthermore, the present results provide substantial support for the potential of PM extract and its phytoestrogens to be developed as therapeutic agents against bone fragility.

Medicinal herbs in the prevention and treatment of osteoporosis

Osteoporosis is a common disease with wide prevalence, especially in the elderly population. Osteoporosis induced fractures not only decrease the patient's life quality, but also cause heavy financial burden to the society. Although current medications for osteoporosis are effective, numerous adverse effects have been observed accompanying their clinical applications. Effective prevention and therapy strategies with high safety are critical, which benefit both individual patients and the whole society. Traditional Chinese medicines have been used for thousands of years to treat bone related diseases in China and a number of modern preparations have been developed that are currently commercially available. In addition, several medicinal herbs demonstrated therapeutic effects against osteoporosis in animal models. This paper reviewed the anti-osteoporotic effects of traditional Chinese formulas, medicinal herbs and bioactive constituents based on clinical trials and in vivo animal studies. Due to the lack of rigorous studies to compare the effectiveness with conventional interventions, traditional formulas are recommended as alternative medications or supplements to treat osteoporosis at the current stage. Although there are abundant natural resources with anti-osteoporotic effects, either in the form of medicinal herbs or bioactive components, much work need to be accomplished before they are developed into potential drugs.

Puerarin concurrently stimulates osteoprotegerin and inhibits receptor activator of NF-κB ligand (RANKL) and interleukin-6 production in human osteoblastic MG-63 cells

Puerarin, a daidzein-8-C-glucoside, is the major isoflavone glycoside found in the Chinese herb radix of Pueraria lobata (Willd.) Ohwi, and has received increasing attention because of its possible role in the prevention of osteoporosis. In our previous studies, puerarin reduced the bone resorption of osteoclasts and promoted long bone growth in fetal mouse in vitro. Further study confirmed that puerarin stimulated proliferation and differentiation of osteoblasts in rat. However, the mechanisms underlying its actions on human bone cells have remained largely unknown. Here we show that puerarin concurrently stimulates osteoprotegerin (OPG) and inhibits receptor activator of nuclear factor-κB ligand (RANKL) and Interleukin-6 (IL-6) production by human osteoblastic MG-63 cells containing two estrogen receptor (ER) isotypes. Treatment with the ER antagonist ICI 182,780 abrogates the above actions of puerarin on osteoblast-derived cells. Using small interfering double-stranded RNAs technology, we further demonstrate that the effects of puerarin on OPG and RANKL expression are mediated by both ERα and ERβ but those on IL-6 production primarily by ERα. Moreover, we demonstrate that puerarin may promote activation of the classic estrogen response element (ERE) pathway through increasing ERα, ERβ and steroid hormone receptor coactivator (SRC)-1 expression. Therefore, puerarin will be a promising agent that prevents or retards osteoporosis.

Improvements of vaginal atrophy without systemic side effects after topical application of Pueraria mirifica, a phytoestrogen-rich herb, in postmenopausal cynomolgus macaques

The estrogenic efficacy of topical vaginal application of Pueraria mirifica extract (PM) on the restoration of vaginal atrophy, and the presence of any systemic side effects, were investigated in postmenopausal cynomolgus macaques. Twelve postmenopausal cynomolgus macaques, with complete cessation of menstruation for at least 5 years before start of this experiment, were divided into three groups. They received a topical vaginal application daily of 0.1 or 1% (w/w) PM cream or a conjugated equine estrogen (CEE) cream (a mixture of estrone, equilin, 17β-dihydroequilin, 17α-estradiol and 17α-dihydroequilin at 0.625 mg total estrogen/g cream) for 28 days. Estrogenic efficacy was assessed weekly by vaginal cytology assay and vaginal pH measurement, whilst the plasma luteinizing hormone (LH) and sex skin coloration levels were determined at the end of each treatment period to evaluate the systemic side effects. PM significantly increased the proportion of superficial cells in a dose-dependent manner, with a similar efficacy between 1% (w/w) PM and CEE. Together with increased vaginal maturation, PM decreased the vaginal pH to acidic levels, as observed in the CEE group. PM induced no detected systemic side effects, whilst CEE decreased the plasma LH level and increased the reddish color of the sex skin during the posttreatment period. Topical vaginal treatment with PM stimulated the maturation of the vaginal epithelium without causing systemic side effects in postmenopausal monkeys. The implication is that PM could be a safer alternative to treat vaginal atrophy in postmenopausal women.

Puerarin stimulates proliferation and differentiation and protects against cell death in human osteoblastic MG-63 cells via ER-dependent MEK/ERK and PI3K/Akt activation

Puerarin, the main isoflavone glycoside found in the Chinese herb radix of Pueraria lobata (Willd.) Ohwi, has received increasing attention because of its possible role in the prevention of osteoporosis. Previously, we showed that puerarin could inhibit the bone absorption of osteoclasts and promote long bone growth in fetal mouse in vitro. Further study confirmed that puerarin stimulated proliferation and differentiation of osteoblasts in rat. However, the mechanisms underlying its actions on human bone cells have not been well defined. Here we show that puerarin increases proliferation and differentiation and opposes cisplatin-induced apoptosis in human osteoblastic MG-63 cells containing two estrogen receptor (ER) isoforms. Puerarin promotes proliferation by altering cell cycle distribution whereas puerarin-mediated survival may be associated with up-regulation of Bcl-xL expression. Treatment with the ER antagonist ICI 182,780 abolishes the above actions of puerarin on osteoblast-derived cells. Using small interfering double-stranded RNA technology, we further demonstrate that the effects of puerarin on proliferation, differentiation and survival are mediated by both ERα and ERβ. Moreover, we also demonstrate that puerarin functions at least partially through activation of MEK/ERK and PI3K/Akt signaling. This agent also shows much weaker effect on breast epithelial cell growth than that of estrogen. Therefore, puerarin will be a promising agent that prevents or retards osteoporosis.

Potential antiosteoporotic agents from plants: a comprehensive review

Osteoporosis is a major health hazard and is a disease of old age; it is a silent epidemic affecting more than 200 million people worldwide in recent years. Based on a large number of chemical and pharmacological research many plants and their compounds have been shown to possess antiosteoporosis activity. This paper reviews the medicinal plants displaying antiosteoporosis properties including their origin, active constituents, and pharmacological data. The plants reported here are the ones which are commonly used in traditional medical systems and have demonstrated clinical effectiveness against osteoporosis. Although many plants have the potential to prevent and treat osteoporosis, so far, only a fraction of these plants have been thoroughly investigated for their physiological and pharmacological properties including their mechanism of action. An attempt should be made to highlight plant species with possible antiosteoporosis properties and they should be investigated further to help with future drug development for treating this disease.

Upregulation of osteoblastic differentiation marker mRNA expression in osteoblast-like UMR106 cells by puerarin and phytoestrogens from Pueraria mirifica

Phytoestrogens have attracted attention for their potential in the prevention of postmenopausal osteoporosis. Recently, phytoestrogen-rich herb Pueraria mirifica has been demonstrated to possess an osteogenic effect on bone in ovariectomized rats, but its underlying cellular mechanism was not known. Here, we investigated the effects of P. mirifica extract and its major isoflavone compound, puerarin, on cell viability, cell proliferation and the expression of differentiation markers in rat osteoblast-like UMR106 cells. After exposure to 17β-estradiol (E2), genistein, P. mirifica extract and puerarin, proliferation but not viability of UMR106 cells was markedly decreased. Quantitative real-time PCR revealed that P. mirifica extract and puerarin significantly increased the mRNA expression of alkaline phosphatase (ALP) and osteoprotegerin, but not Runx2, osterix or osteocalcin. Puerarin also decreased the mRNA expression of receptor activator of nuclear factor-κB ligand, an osteoclastogenic factor, suggesting that it could induce bone gain by enhancing osteoblast differentiation and suppressing osteoclast function. Furthermore, after an exposure to high affinity estrogen receptor (ER) antagonist (ICI182780), the E2-, genistein-, P. mirifica extract- and puerarin-induced upregulation of ALP expressions were completely abolished. It could be concluded that P. mirifica extract and puerarin induced osteoblast differentiation rather than osteoblast proliferation in an ER-dependent manner. The present findings, therefore, corroborated the potential benefit of P. mirifica extract and puerarin in the prevention and treatment of postmenopausal osteoporosis.

Puerarin stimulates osteoblasts differentiation and bone formation through estrogen receptor, p38 MAPK, and Wnt/β-catenin pathways

Puerarin is an isoflavone extracted from Radix Puerariae, a traditional Chinese herb used to treat many diseases such as osteoporosis. In this study, puerarin was shown to stimulate alkaline phosphatase (ALP) activity, type I collagen (Col I) secretion, and mineralized nodules formation of primary osteoblasts. Whereas the estrogen receptor (ER) antagonist ICI 182780 was able to reduce the increase in ALP activity and Col I secretion induced by puerarin. Furthermore, puerarin was shown to elevate levels of phospho-p38 mitogen-activated protein kinase (MAPK) and β-catenin proteins in a time-dependent manner. Pretreatment of osteoblasts with ICI 182780 can reduce this elevation, whereas pretreatment with p38 MAPK inhibitor SB 203580 did not affect the increase of β-catenin protein. Meanwhile, intragastric administration of puerarin protected against reduction in bone mineral density and bone mineral content in ovariectomized rats, and improved femur trabecular bone structure. Taken together, ER, p38 MAPK, and Wnt/β-catenin pathways were involved in puerarin-stimulated osteoblasts differentiation and bone formation.

Medical applications of phytoestrogens from the Thai herb Pueraria mirifica

Pueraria mirifica Airy Shaw et Suvatabandhu is a medicinal plant endemic to Thailand. It has been used in Thai folklore medicine for its rejuvenating qualities in aged women and men for nearly one hundred years. Indeed, it has been claimed that P. mirifica contains active phytoestrogens (plant substances with estrogen-like activity). Using high performance liquid chromatography, at least 17 phytoestrogens, mainly isoflavones, have been isolated. Thus, fairly considerable scientific researches, both in vitro in cell lines and in vivo in various species of animals including humans, have been conducted to date to address its estrogenic activity on the reproductive organs, bones, cardiovascular diseases and other climacteric related symptoms. The antioxidative capacity and antiproliferative effect on tumor cell lines have also been assessed. In general, P. mirifica could be applicable for preventing, or as a therapeutic for, the symptoms related to estrogen deficiency in menopausal women as well as in andropausal men. However, the optimal doses for each desirable effect and the balance to avoid undesired side effects need to be calculated before use.

Osteoblast response to puerarin-loaded porous titanium surfaces: an in vitro study

Recent studies demonstrate puerarin stimulates bone formation, suggesting its potential application in dental implantology field. The aim of this study was to investigate effects of puerarin-loaded titanium surfaces on the promotion of osteogenesis in preosteoblasts (MC3T3-E1). Puerarin was prepared onto titanium surfaces with varying concentration (10(-9) M, 10(-8) M, 10(-7) M, and 10(-6) M) by biomimetic calcium phosphate deposition process. Surface characteristics were performed by field-emission scanning electron microscope (FSEM), X-ray diffractometer (XRD), and Fourier transform infrared spectroscopy (FTIR). Puerarin concentration in the coatings was performed by High-performance liquid chromatograph (HPLC) analyses. FSEM observation showed puerarin concentration influenced formation of sharp flakes in the coating. The size of flakes decreased with increase of puerarin concentrations. XRD and FTIR examinations demonstrated the puerarin concentration did not affect the chemical compositions of coatings, which composed of octacalcium phosphate (OCP). Puerarin concentration on the surfaces of 10(-8) M group was 10.22 ± 0.32 ng/cm(2) . Puerarin had an increased effect on MC3T3-E1 ALP activities. Significant differences were found in 10(-8) and 10(-7) M groups on day 4, 10(-8) , 10(-7) , and 10(-6) M groups on day 7, and 10(-8) on day 14. In Type I collagen synthesis assay, 10(-9) and 10(-8) M on day 7, 10(-8) on day 14 showed significant differences compared with control group. Furthermore, this stimulatory effect of puerarin was also observed in osteocalcin release assay (p < 0.05, at 10(-8) M and 10(-7) M, maximal at 10(-8) M). These results indicate puerarin-loaded titanium surfaces promote accelerated osteogenic differentiation of preosteoblasts, which has the potential to improve the nature of osseointegration.

Anti-osteoporosis activity of Cibotium barometz extract on ovariectomy-induced bone loss in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Recent research has confirmed that Cibotium barometz could inhibits osteoclast formation with no affect on BMM cell viability. However, the influence of Cibotium barometz on osteoporosis in animals is relatively unknown. The purpose of this study is to systemically investigate the effects of Cibotium barometz extract (CBE) on ovariectomy-induced osteoporosis in rats.

MATERIALS AND METHODS

A total of Seventy-two 3-month-old female Sprague-Dawley rats were used and randomly divided into sham-operated group and five ovariectomized (OVX) groups: OVX with vehicle; OVX with 17β-estradiol (E2, 25 μg/kg/day); OVX with CBE of graded doses (100, 300, or 500 mg/kg/day). Daily oral administration of E2 or CBE began 4 weeks after the surgery and lasted for 16 weeks. Bone mass, bone turnover and strength were analyzed by DEXA, biochemical markers and three-point bending test. The trabecular bone microarchitecture was evaluated by MicroCT.

RESULTS

CBE prevented total BMD decrease in the femur induced by OVX, which was accompanied by a significant decrease in skeletal remodeling, as was evidenced by the decreased levels of the bone turnover markers, such as osteocalcin (OC), alkaline phosphatese (ALP), deoxypyridinoline (DPD), and urinary Ca and P excretions. The treatment could also enhance the bone strength and prevent the deterioration of trabecular microarchitecture.

CONCLUSIONS

The present study indicated that Cibotium barometz extract might be a potential alternative medicine for the prevention and treatment of postmenopausal osteoporosis.

A protective effect of Curcuma comosa Roxb. on bone loss in estrogen deficient mice

ETHNOPHARMACOLOGICAL RELEVANCE

Curcuma comosa Roxb. or Wan chak motluk is an indigenous medicinal herb and has traditionally been used among postmenopausal women for relief of unpleasant menopausal symptoms.

AIM OF THE STUDY

Estrogen deficiency is a causative factor in the development of osteoporosis in menopausal women. Phytoestrogens, non-steroidal plant-derived compounds which have an array of beneficial effects, are considered as an effective alternative compound in preventing bone loss caused by the deficiency of estrogen. The present study determined the potential effect of Curcuma comosa Roxb. (C. comosa) hexane extract containing phytoestrogens in protecting bone loss induced by ovariectomy in mice.

MATERIALS AND METHODS

Mature Swiss albino female mice were ovariectomized and treated with the C. comosa extract for 5 weeks. Bone calcium content, bone mass density, histology, and bone markers were evaluated.

RESULTS

The ovariectomized mice showed a marked decrease in total bone calcium content and bone mass density of lumbar vertebrae 5-6, femur and tibia bone in comparison with the intact control mice. Bone histology demonstrated the poor development of endochondral bone formation in ovariectomized mice which correlated with a decrease in plasma bone alkaline phosphatase activity. Treatment with C. comosa protected against the loss of total bone calcium content and bone mass density in both trabecular and cortical bones, similar to results observed with estrogen treatment. In addition, C. comosa treatment resulted in less increase in uterine weight compared to estrogen treatment.

CONCLUSION

Our results suggest that C. comosa prevents bone loss induced by estrogen deficiency. Therefore, C. comosa would be a potential alternative treatment for prevention of postmenopausal osteoporosis.

Tracking deposition of a 14C-radiolabeled kudzu hairy root-derived isoflavone-rich fraction into bone

Hairy roots were induced in four genotypes from three kudzu species (Pueraria montana var. lobata, P. lobata and P. phaseoloides) in vitro using Agrobacterium rhizogenes to stimulate rapid secondary metabolite synthesis. Hairy roots from P. montana var. lobata (United States Department of Agriculture no. PI 434246) yielded the highest puerarin and total isoflavone content and the greatest new biomass per growth cycle among the genotypes evaluated. Hairy roots from this genotype were selected for radiolabeling using (14)C-sucrose as a carbon source. Isoflavones from radiolabeled kudzu hairy root cultures were extracted with 80% methanol, partitioned by solvent extraction, and then subfractionated by Sephadex LH-20 gel filtration. Radiolabeled isoflavones were isolated in a highly enriched fraction, which contained predominantly puerarin, daidzin and malonyl-daidzin and had an average radioactivity of 8.614 MBq/g (232.8 μCi/g) dry fraction. The (14)C-radiolabeled, isoflavone-rich fraction was orally administered at a dose of 60 mg/kg body weight to male Sprague-Dawley rats implanted with a jugular catheter, a subcutaneous ultrafiltrate probe and a brain microdialysate probe. Serum, interstitial fluid, brain microdialysate, urine and feces were collected using a Culex(®) Automated Blood Collection System for 24 h. At the end of this period, rats were sacrificed and major tissues were collected. Analysis by a scintillation counter confirmed that a bolus dose of (14)C-radiolabeled, isoflavone-rich kudzu fraction reached bone tissues, which accumulated 0.011%, 0.09% and 0.003% of the administered dose in femur, tibia and vertebrae, respectively. Femurs extracted with 80% methanol were analyzed by high-performance liquid chromatography with electrospray ionization-mass spectrometry and were found to contain trace quantities of puerarin, daidzein and puerarin glucuronide. This study demonstrates that kudzu isoflavones and metabolites are capable of reaching bone tissues, where they may contribute to the prevention of osteoporosis and the promotion of bone health.

Telmisartan alleviates rosiglitazone-induced bone loss in ovariectomized spontaneous hypertensive rats

In the present study, we systematically examined telmisartan, an angiotensin AT(1) receptor antagonist, on rosiglitazone-induced bone loss in ovariectomized spontaneously hypertensive rats. Telmisartan (5 mg/kg/d, 90 days) was found to be able to significantly alleviate rosiglitazone (10 mg/kg/d, 90 days)-induced decrease in BMD of femur and lumbar vertebrae. The BMD changes were associated with positive biomechanical changes of lumbar vertebrae, improvements in microarchitecture of tibial metaphysic and normalized serum osteocalcin (OC) levels and urinary deoxypyridinoline/creatinine (DPD/Cr) ratio. MicroCT analysis of the tibial metaphysis showed that telmisartan significantly prevented the decreases in bone volume/tissue volume (BV/TV), connect density (Conn. D.), trabecular number (Tb. N.) and trabecular thickness (Tb. Th.), and increase in trabecular separation (Tb. Sp.) induced by rosiglitazone. Histomorphometric analysis also showed that telmisartan had protective effects on rosiglitazone-reduced bone formation indices such as histomorphometric bone volume fraction (BV/TV-Histo), mineralizing surface/bone surface (MS/BS), mineral apposition rate (MAR) and bone formation rate (BFR/BS). Our study clearly showed that telmisartan alleviated rosiglitazone-induced bone loss in ovariectomized spontaneous hypertensive rats. The relief of bone loss provides a possible therapeutic application of telmisartan with rosiglitazone for the treatment of elderly women patients afflicted with metabolic syndrome.

The mutagenic and antimutagenic effects of the traditional phytoestrogen-rich herbs, Pueraria mirifica and Pueraria lobata

Pueraria mirifica is a Thai phytoestrogen-rich herb traditionally used for the treatment of menopausal symptoms. Pueraria lobata is also a phytoestrogen-rich herb traditionally used in Japan, Korea and China for the treatment of hypertension and alcoholism. We evaluated the mutagenic and antimutagenic activity of the two plant extracts using the Ames test preincubation method plus or minus the rat liver mixture S9 for metabolic activation using Salmonella typhimurium strains TA98 and TA100 as indicator strains. The cytotoxicity of the two extracts to the two S. typhimurium indicators was evaluated before the mutagenic and antimutagenic tests. Both extracts at a final concentration of 2.5, 5, 10, or 20 mg/plate exhibited only mild cytotoxic effects. The plant extracts at the concentrations of 2.5, 5 and 10 mg/plate in the presence and absence of the S9 mixture were negative in the mutagenic Ames test. In contrast, both extracts were positive in the antimutagenic Ames test towards either one or both of the tested mutagens 2-(2-furyl)-3-(5-nitro-2-furyl)-acrylamide and benzo(a)pyrene. The absence of mutagenic and the presence of anti-mutagenic activities of the two plant extracts were confirmed in rec-assays and further supported by a micronucleus test where both plant extracts at doses up to 300 mg/kg body weight (equivalent to 16 g/kg body weight plant tuberous powder) failed to exhibit significant micronucleus formation in rats. The tests confirmed the non-mutagenic but reasonably antimutagenic activities of the two plant extracts, supporting their current use as safe dietary supplements and cosmetics.

Differential binding with ERalpha and ERbeta of the phytoestrogen-rich plant Pueraria mirifica

Variations in the estrogenic activity of the phytoestrogen-rich plant, Pueraria mirifica, were determined with yeast estrogen screen (YES) consisting of human estrogen receptors (hER) hERalpha and hERbeta and human transcriptional intermediary factor 2 (hTIF2) or human steroid receptor coactivator 1 (hSRC1), respectively, together with the beta-galactosidase expression cassette. Relative estrogenic potency was expressed by determining the beta-galactosidase activity (EC(50)) of the tuber extracts in relation to 17beta-estradiol. Twenty-four and 22 of the plant tuber ethanolic extracts interacted with hERalpha and hERbeta, respectively, with a higher relative estrogenic potency with hERbeta than with hERalpha. Antiestrogenic activity of the plant extracts was also determined by incubation of plant extracts with 17beta-estradiol prior to YES assay. The plant extracts tested exhibited antiestrogenic activity. Both the estrogenic and the antiestrogenic activity of the tuber extracts were metabolically activated with the rat liver S9-fraction prior to the assay indicating the positive influence of liver enzymes. Correlation analysis between estrogenic potency and the five major isoflavonoid contents within the previously HPLC-analyzed tuberous samples namely puerarin, daidzin, genistin, daidzein, and genistein revealed a negative result.

In vivo metabolic tracking of 14C-radiolabelled isoflavones in kudzu (Pueraria lobata) and red clover (Trifolium pratense) extracts

Absorption, distribution and elimination of 14C-labelled isoflavone-containing extracts from kudzu (Pueraria lobata) root culture and red clover (Trifolium pratense) cell culture were investigated in an in vivo rat model. The predominant isoflavones in the kudzu extract were the glycosides puerarin, daidzin and malonyl daidzin, while in the red clover extract, the major isoflavones were formononetin and its derivatives, genistein and biochanin A, with radioactivities of 3.770 and 7.256 MBq/g, respectively. Male Sprague-Dawley rats, implanted with a jugular catheter and a subcutaneous ultrafiltrate probe, were orally administered with 14C-labelled isoflavone extracts from either kudzu or clover cell cultures. Serum, interstitial fluid (ISF), urine and faeces were collected using a Culex Automated Blood Collection System for 24 h. Analysis of bone tissues revealed that radiolabel accumulated in the femur, tibia and vertebrae at 0.04, 0.03 and 0.01 % of the administered dose, respectively, in both kudzu and red clover treatments. The liver accumulated the greatest concentration of radiolabel among the tissues tested, at 1.99 and 1.54 % of the administered kudzu and red clover extracts, respectively. Serum and ISF analysis showed that both extracts were rapidly absorbed, distributed in various tissues, and largely eliminated in the urine and faeces. Urine and faeces contained 8.53 and 9.06 % of the kudzu dose, respectively, and 3.60 and 5.64 % of the red clover dose, respectively. Serum pharmacokinetics suggest that extracts from kudzu may undergo enterohepatic circulation.