Puerarin exhibits weak estrogenic activity in female rats

Puerarin Ameliorated PCOS through Preventing Mitochondrial Dysfunction Dependent on the Maintenance of Intracellular Calcium Homeostasis

Polycystic ovarian syndrome (PCOS) is the major cause of infertility in reproductive women, but no universal drug is feasible. Although puerarin clinically treats cerebrovascular and cardiovascular diseases, its curative effect on PCOS remains elusive. The present study discovered that administration of puerarin restored estrous cycle of PCOS mice and diminished the number of cystic follicles with the concomitant recovery for circulating testosterone, LH and FSH levels, and LH/FSH ratio, indicating the therapeutic role of puerarin in PCOS. KEGG analysis of differential genes between PCOS and control revealed the enrichment in MAPK and calcium signaling pathway. Application of puerarin restricted the phosphorylation of ERK1/2 and JNK, whose activation neutralized the improvement of puerarin on the secretory function and apoptosis of ovarian granulosa cells (GCs). Meanwhile, puerarin alleviated the accumulation of cytosolic Ca2+ through restricting the opening of Ryr and Itpr channels, but this effectiveness was counteracted by the activatory ERK1/2 and JNK. Attenuation of cytosolic Ca2+ counteracted the antagonistic effects of ERK1/2 and JNK activation on puerarin's role in rescuing the calcineurin and Nfatc. Further analysis manifested that Mcu had been authenticated as a direct downstream target of Nfatc to mediate the amelioration of puerarin on mitochondrial Ca2+ uptake. Moreover, puerarin prevented the disorder of ATP content, mitochondrial membrane potential, and mitochondrial permeability transition pore opening through maintaining mitochondrial Ca2+ homeostasis. Collectively, puerarin might ameliorate the symptoms of PCOS mice through preventing mitochondrial dysfunction that is dependent on the maintenance of intracellular Ca2+ homeostasis after inactivation of ERK1/2 and JNK.

Anti-Inflammatory and Anti-oxidative Effects of Puerarin in Postmenopausal Cardioprotection: Roles of Akt and Heme Oxygenase-1

During menopause, the sharp decline in estrogen levels leads to an increased risk of cardiovascular disease in women. The inflammatory response and oxidative stress are reportedly involved in the development of cardiovascular disorders postmenopause. In this study, we evaluated the cardioprotective effects of puerarin, a phytoestrogen derived from the root of Pueraria lobate, and investigated its underlying molecular mechanisms. Puerarin alleviated cytotoxicity and the production of reactive oxygen species (ROS) in lipopolysaccharide (LPS)- and hydrogen peroxide-stimulated H9c2 cardiomyoblasts. Puerarin scavenges free radicals and reduces apoptosis, thereby suppressing NADPH oxidase-1 and Bax activation to attenuate the production of ROS and restore Bcl-2 expression. Additionally, puerarin inhibited the expression of inducible nitric oxide synthase, cyclooxygenase-2, and nitric oxide production and decreased the hypertrophic phenotype under LPS stimulation. Treatment with puerarin reduced the levels of malondialdehyde and restored glutathione levels when facing oxidative stress. Mechanistically, puerarin inhibited both the LPS-induced Toll-like receptor 4/NF-[Formula: see text]B and mitogen-activated protein kinase signaling pathways. Furthermore, it reversed both the LPS-mediated downregulation of Akt activation and heme oxygenase-1 (HO-1) expression. The cardioprotective effects of puerarin were abolished by inhibitors of Akt and HO-1 and the estrogen receptor antagonist fulvestrant (ICI). This indicated that the estrogen receptor mediated by these two molecules plays important roles in conferring the anti-inflammatory and anti-oxidative functions of puerarin. These results demonstrate the therapeutic potential of puerarin for treating heart disease in postmenopausal women through Akt and HO-1 activation.

Flavonoids and Other Phenolic Compounds from Medicinal Plants for Pharmaceutical and Medical Aspects: An Overview

Phenolic compounds as well as flavonoids are well-known as antioxidant and many other important bioactive agents that have long been interested due to their benefits for human health, curing and preventing many diseases. This review attempts to demonstrate an overview of flavonoids and other phenolic compounds as the interesting alternative sources for pharmaceutical and medicinal applications. The examples of these phytochemicals from several medicinal plants are also illustrated, and their potential applications in pharmaceutical and medical aspects, especially for health promoting e.g., antioxidant effects, antibacterial effect, anti-cancer effect, cardioprotective effects, immune system promoting and anti-inflammatory effects, skin protective effect from UV radiation and so forth are highlighted.

Effects of puerarin on estrogen-regulated gene expression in gonadotropin-releasing hormone pulse generator of ovariectomized rats

Effects of puerarin on the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator function is investigated, for the first time, in ovariectomized rats at the level of mRNA expression of estrogen-responsive genes, e.g., estrogen receptor (ER), GnRH and its receptor (GnRHR). Rats were treated orally for 90 days either with a soy-free diet containing two different doses of puerarin (low dose of 600 mg/kg and high dose of 3000 mg/kg) or estradiol benzoate (E2B) at either low dose (4.3 mg/kg) or high dose (17.3 mg/kg). Levels of mRNA expression in the medial preoptic area/anterior hypothalamus (MPOA/AH), mediobasal hypothalamus/median eminence (MBH/ME) and adenohypophysis were measured by quantitative TaqMan® real-time RT-PCR. Plasma levels of luteinizing hormone (LH) and prolactin (PRL) were measured by radioimmunoassay. In the MPOA/AH, both puerarin and E2B decreased ERα mRNA levels without any significant changes in ERβ and GnRH mRNA levels. Both puerarin and E2B did not significantly alter the expression levels of ERα, ERβ and GnRHR in the MBH/ME. E2B exerted significant effects on the down-regulation of adenohypophyseal GnRHR mRNA transcripts and serum LH levels. Puerarin did not cause significant changes in pituitary GnRHR mRNA transcripts and serum LH and PRL levels. This is the first study to demonstrate that in ovariectomized rat models of ovarian hormone deprivation, puerarin acted as a weak estrogen-active compound in the hypothalamic GnRH pulse generator through the downregulation of MPOA/AH ERα mRNA expression.

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.

Puerarin promotes MIN6 cell survival by reducing cellular reactive oxygen species

Type 1 diabetes is caused by destruction of the pancreatic β‑cells and, to date, no cure has been developed. Promoting the survival of pancreatic β‑cells may be beneficial for patients with type 1 diabetes. Puerarin is an estrogen analogue that been demonstrated in previous studies to be able to decreased blood glucose in patients with type 1 diabetes. Similar results were demonstrated in previous studies which additionally demonstrated that puerarin was able to decreased blood glucose in type 1 diabetic mice by protecting pancreatic β‑cells. However, the mechanism underlying the function of puerarin in pancreatic β‑cells remains unclear. Therefore, the present study sought to investigate the detailed function of puerarin in pancreatic β‑cells. In the present study, H2O2 was used to induce apoptosis. It was observed that puerarin significantly decreased H2O2‑induced apoptosis in mouse insulinoma MIN6 cells. It was additionally observed that puerarin decreased the levels of intracellular reactive oxygen species and mitochondrial superoxide in MIN6 cells. The protective effect of puerarin was markedly decreased by 6‑aminonicotinamide, an inhibitor of glucose‑6‑phosphate dehydrogenase (G6PD). In conclusion, the results of the present study suggested that puerarin may increase the activity of G6PD, decreased the level of oxidative stress in MIN6 cells, protect mitochondria and promote MIN6 cell survival. Investigating the mechanism underlying the effect of puerarin in MIN6 cells may provide a novel approach for development of a cure for type 1 diabetes.

Evaluation of in vivo estrogenic potency of natural estrogen-active chemical, puerarin, on pituitary function in gonadectomized female rats

AIMS

Previous research has revealed that puerarin, the major phytoestrogen in tuberous roots of Pueraria lobata and Pueraria mirifica, acts as a selective estrogen receptor modulator that displays predominantly estrogenic potential for health benefit. However, little is known about the estrogenic potency of puerarin in pituitary, especially in the rat model of postmenopausal females.

MAIN METHODS

Plasma prolactin and growth hormone levels as well as mRNA expression levels of pituitary estrogen-regulated genes, such as estrogen receptor (ER) subtypes alpha (ERα) and beta (ERβ), truncated ER product-1 (TERP-1) and -2 (TERP-2) and gonadotropin alpha subunit, were examined using radioimmunoassay and TaqMan® real-time PCR, respectively. The effects were compared with the potent ER agonist, 17β-estradiol-3-benzoate (E2B), and both substances were supplemented at low and high doses, i.e., 0.6 or 3g puerarin and 0.0043 or 0.0173g E2B per kilogram of phytoestrogens-free rat chow, and applied to ovariectomized rats (five groups; 11-12 rats per group) for 12weeks.

KEY FINDINGS

Puerarin possessed weak E2B-like activities on pituitary function by acting as ERβ and TERP-1/-2 agonists, which resulted in the downregulation and upregulation of ERβ and TERP-1/-2 mRNA expressions, respectively, and elevation of growth hormone levels. There were trends of decreased levels of alpha subunit mRNA transcripts and increased levels of prolactin in puerarin-treated rats as observed in E2B-treated animals.

SIGNIFICANCE

This is the first report in ovariectomized rats the effects of puerarin on somatotropes and pituitary estrogen-responsive mRNA expressions, which are very weakly estrogenic by acting through ERβ- and TERP-1/-2 mediated pathways.

Neurotherapeutic Effects of Pueraria mirifica Extract in Early- and Late-Stage Cognitive Impaired Rats

We determined the neurotherapeutic effects of Pueraria mirifica extract (PME) and pure puerarin (PU) in comparison with 17β-estradiol (E2 ) in early- and late-stage cognitive impaired rats. Rats were ovariectomized (OVX), kept for 2 and 4 months to induce early- and late-stage cognitive impairment, respectively, and divided into four groups that were treated daily with (i) distilled water, (ii) 100 mg/kg of PME, (iii) 7 mg/kg of PU, and (iv) 80 µg/kg of E2 for 4 months. The estrogen deficiency symptoms of OVX rats were abrogated by treatment with E2 or PME, but not by treatment with PU. The mRNA level of genes associated with amyloid production (App and Bace1) and hyperphosphorylated Tau (Tau4) were upregulated together with the level of impaired cognition in the 2- and 4-month OVX rats. Treatment with E2 reduced the level of cognitive impairment more than that with PME and PU, and 2-month OVX rats were more responsive than 4-month OVX rats. All treatments down-regulated the Bace1 mRNA level in 2-month OVX rats, while PU and PME also decreased the App mRNA level in 2- and 4-month OVX rats, respectively. Only PU suppressed Tau4 expression in 2-month OVX rats. Thus, PME and PU elicit neurotherapeutic effects in different pathways, and earlier treatment is optimal. Copyright © 2016 John Wiley & Sons, Ltd.

Dynamics of phytoestrogen, isoflavonoids, and its isolation from stems of Pueraria lobata (Willd.) Ohwi growing in Democratic People's Republic of Korea

Four isoflavonoids were isolated from stems of Pueraria lobata (Willd.) Ohwi growing in Democratic People’s Republic of Korea and identified as daidzein (1), genistin (2), daidzin (3), and puerarin (4), structures, which were elucidated by means of spectroscopic analysis. Isoflavonoids were isolated using silica gel chromatography and purified with organic solvents. Isoflavonoid contents in P. lobata were determined using reliable high-performance liquid chromatography. The results indicated that the contents of puerarin and genistin in the roots are higher than those in the stems (6.19% and 0.04% vs. 1.15% and 0.02%), whereas the stems have higher contents of daidzin and daidzein than the roots (3.17% and 0.06% vs. 1.72% and 0.05%). Accordingly, the root part of the plant is useful for the isolation of puerarin and the stem part for daidzin. This study suggests that the stem of P. lobata is useful as an alternative source of puerarin, daidzin, genistin, and daidzein. In addition, collection of the stem will not sacrifice the plant and thus is beneficial to the natural ecosystems.

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: a review of pharmacological effects

Puerarin is the major bioactive ingredient isolated from the root of the Pueraria lobata (Willd.) Ohwi, which is well known as Gegen (Chinese name) in traditional Chinese medicine. As the most abundant secondary metabolite, puerarin was isolated from Gegen in the late 1950s. Since then, its pharmacological properties have been extensively investigated. It is available in common foods and is used in alternative medicine. It has been widely used in the treatment of cardiovascular and cerebrovascular diseases, diabetes and diabetic complications, osteonecrosis, Parkinson's disease, Alzheimer's disease, endometriosis, and cancer. The beneficial effects of puerarin on the various medicinal purposes may be due to its wide spectrum of pharmacological properties such as vasodilation, cardioprotection, neuroprotection, antioxidant, anticancer, antiinflammation, alleviating pain, promoting bone formation, inhibiting alcohol intake, and attenuating insulin resistance. However, the direct molecular mechanisms and targets remain unclear. This review provides a comprehensive summary of the pharmacological effects of puerarin.

Simple, sensitive and reliable in vivo assays to evaluate the estrogenic activity of endocrine disruptors

Purpose

We compared three in vivo assays, determining changes of body weight, and uterotropic and vaginal cytology assays, for the evaluation of estrogenic activity of an estrogen disrupting compound, Pueraria mirifica (PM), in comparison with 17β-estradiol (E).

Methods

Female rats were ovariectomized and gavaged with distilled water, 0.01, 0.1, 1, 10 and 20 mg/kg BW/day of E and 100 and 1,000 mg/kg BW/day of PM for 14 days. Body weights were measured weekly, and vaginal epithelium cells were monitored daily. The uterus was dissected at the end of the treatment period, weighed and examined for histomorphometry.

Results

There were a decrease in body weight and an increase in uterine weight, uterine, endometrium and myometrium areas, uterine gland numbers, and percent of cornified cell which were dependent on doses of E and PM treatments.

Conclusions

Of the three assays proposed, although all are reliable and had critical read-out, measurements of body and uterine weights is likely convenient and simple, but the uterotropic assay needs to kill the animals. Vaginal cytology assay appears most promising for sensitivity and shortening the duration of the assay. Compared to those of E, the estrogenic activity of PM at concentrations of 100 and 1,000 mg/kg BW was in the range of 14 to >20 mg/kg BW.

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.

Metabolic profile of puerarin in rats after intragastric administration of puerarin solid lipid nanoparticles

Puerarin has multiple pharmacological effects and is widely prescribed for patients with cardiovascular diseases including hypertension, cerebral ischemia, myocardial ischemia, diabetes mellitus, and arteriosclerosis. We have successfully prepared puerarin-loaded solid lipid nanoparticles (Pue-SLNs) for oral administration. Pue-SLNs are prepared using monostearin, soya lecithin, and poloxamer 188. SLNs may alter the course of puerarin absorption predominantly to and through lymphatic routes and regions, presumably following a transcellular path of lipid absorption, especially by enterocytes and polar epithelial cells of the intestine. The alteration of absorption might influence the metabolic profile of puerarin when incorporated into SLNs. In the present study, we investigated the metabolic profile of puerarin in rat plasma and urine using rapid resolution liquid chromatography–tandem mass spectrometry after a single-dose intragastric administration of Pue-SLNs in comparison with puerarin suspension. Two glucuronidated metabolites of puerarin, puerarin-4′-O-glucuronide and puerarin-7-O-glucuronide, were detected in rat plasma and urine after intragastric administration of Pue-SLNs, with the latter acting as the major metabolite. Similar results were found in rat plasma and urine after intragastric administration of puerarin suspension. The results suggest that incorporation of puerarin into SLNs does not change either the position of glucuronidation or the metabolic pathway of puerarin in rats.

Optimization of ionic liquid based ultrasonic assisted extraction of puerarin from Radix Puerariae Lobatae by response surface methodology

Ionic liquid (IL) based ultrasonic assisted extraction (ILUAE) was developed for the effective extraction of puerarin from Radix Puerariae Lobatae (RPL). The ILUAE parameters including the type of ILs, IL concentration, RPL amount, ultrasonic power and time were optimized by single-factor experiment and response surface methodology. Under the optimized experimental conditions, the best results were obtained using RPL amount 0.43 g in 10 mL 1.06 molL(-1) 1-butyl-3-methylimidazolium bromide aqueous solution, ultrasonic time 27.43 min and ultrasonic power 480 W. Scanning electron microscope images of RPL samples were obtained to provide visual evidence of the sonication effect. Compared with the conventional ultrasonic assisted extraction and refluent extraction, the proposed ILUAE offered shorter extraction time and remarkable higher efficiencies due to the higher penetration ability and solubility of IL and the cavitation phenomenon produced in the solvent by the passage of an ultrasonic wave, which further supported the suitability of the proposed approach.

UDP-glucuronosyltransferase 1A1 is the principal enzyme responsible for puerarin metabolism in human liver microsomes

Puerarin has multiple pharmacological effects and is widely prescribed for patients with cardiovascular diseases, including hypertension, cerebral ischemia, myocardial ischemia, diabetes mellitus, and arteriosclerosis. While puerarin is a useful therapeutic agent, its mechanisms of action have not been well defined. Understanding puerarin metabolism, in particular its interactions with metabolizing enzymes, will contribute to our understanding of its toxic and therapeutic effects and may help to elucidate potential negative drug-drug interactions. In this study, the major metabolite of puerarin was obtained from the urine of rats administered puerarin, by a semi-preparative high-performance liquid chromatography method. The major metabolite was identified as puerarin-7-O-glucuronide. In vitro, we used a UDP-glucuronosyltransferase (UGT) reaction screening method with 12 recombinant human UGTs to demonstrate that formation of puerarin-7-O-glucuronide was catalyzed by UGT1A1, 1A9, 1A10, 1A3, 1A6, 1A7, and 1A8. UGT1A1, 1A9, and 1A10 significantly catalyzed puerarin-7-O-glucuronide formation, and the activity of UGT1A1 was significantly higher than those of 1A9 and 1A10. The V (max) of UGT1A1 was two- to threefold higher than the levels of UGT1A9 or 1A10, with a lower K ( m ) value and a higher V (max)/K ( m ) value. The kinetics of puerarin-7-O-glucuronide formation catalyzed by UGT1A1 were similar to those of the pooled human liver microsomes (HLMs), with V (max) values of 186.3 and 149.2 pmol/min/mg protein, and K ( m ) values of 811.3 and 838.9 μM, respectively. Furthermore, bilirubin and β-estradiol, probe substrates for UGT1A1, significantly inhibited the formation of puerarin-7-O-glucuronide in HLMs.

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.

Dynamic oxidative stress and DNA damage induced by oestrogen deficiency and protective effects of puerarin and 17β-oestradiol in ovariectomized rats

Oxidative stress plays an essential role in the pathogenesis of cardiovascular diseases and osteoporosis resulting from oestrogen deficiency in the postmenopausal period. In this report, we observed a dynamic change of oxidative stress and DNA damage after ovariectomy in female rats. We then compared phytoestrogen puerarin and 17β-oestradiol (E₂) in their effects on oestrogen deficiency-induced oxidative stress and DNA damage. Serum total antioxidant capacity (TAC), malondialdehyde (MDA) and lymphocytes DNA damage (comet%) were measured. There was a gradual increase in oxidative stress in the ovariectomized (OVX) rats over time after ovariectomy, as compared to rats receiving sham operation. OVX rats that were on puerarin and E₂ showed increased TAC and decreased MDA in the serum, as well as decreased lymphocytes comet%. Puerarin appeared to have a more powerful protective effect on DNA oxidative damage than E₂. The study indicates that postmenopausal women may benefit from phytoestrogen puerarin.

Pharmacokinetics, tissue distribution and relative bioavailability of puerarin solid lipid nanoparticles following oral administration

Puerarin has various pharmacological effects; however, poor water-solubility and low oral bioavailability limit its clinical utility. A delivery system of solid lipid nanoparticles could enhance its oral absorption. The objective of this study was to investigate the pharmacokinetics, tissue distribution and relative bioavailability of puerarin in rats after a single dose intragastric administration of puerarin solid lipid nanoparticles (Pue-SLNs). The puerarin concentrations in plasma and tissues were determined by rapid resolution liquid chromatography electrospray ionization-tandem mass spectrometry. The C(max) value of puerarin after the administration of Pue-SLNs was significantly higher than that obtained with puerarin suspension (0.33±0.05 μg/mL vs. 0.16±0.06 μg/mL, P<0.01). The T(max) value after the administration of the Pue-SLNs was significantly shorter than that after puerarin suspension administration (40±0 min vs. 110±15.49 min, P<0.01). The AUC(0→t) values of puerarin were 0.80±0.23 mg h/L, and 2.48±0.30 mg h/L after administration of the puerarin suspension and Pue-SLNs, respectively. Following administration of the Pue-SLNs, tissue concentrations of puerarin also increased, especially in the target organs such as the heart and brain. These data suggest that SLNs are a promising delivery system to enhance the oral bioavailability of puerarin.

Puerarin improves insulin resistance and modulates adipokine expression in rats fed a high-fat diet

The link between obesity and insulin resistance largely accounts for the pathogenesis of metabolic syndrome and diabetes mellitus, in which adipokine expression plays a key role. Puerarin, a major active isoflavone extracted from the traditional Chinese medicine Radix Puerariae, has been studied for its comprehensive biological actions. However, its effect on high-fat diet (HFD)-induced insulin resistance and adipokine expression in rat has not been well investigated. In the present study, male Sprague-Dawley rats were fed on a normal control diet (NCD) or HFD for 6 weeks, followed by administration of puerarin (100 and 200 mg/kg) for up to 8 weeks. Compared to NCD, HFD feeding for 6 weeks led to increased body weight gain and impaired glucose/insulin tolerance manifested by oral glucose/intraperitoneal insulin tolerance tests in rats. These exacerbations prolonged through HFD feeding, but were effectively reversed by puerarin administration. Enzyme-linked immunosorbent assay demonstrated that, serum levels of leptin and resistin, but not that of adiponectin, were markedly augmented by HFD and retarded by puerarin treatment. Real-time reverse transcription polymerase chain reaction results showed that, in agreement with the circulating levels, mRNA expression of leptin and resistin in epididymal white adipose tissue was modified by HFD and improved by puerarin in the same pattern. Collectively, we revealed that puerarin could improve body weight gain, glucose/insulin intolerance and adipokine expression in HFD-induced insulin resistant rats, indicating its potential value for treatment of metabolic syndrome.

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.