tetrahydroxystilbene-2-O-β-D-glucoside Research Articles

Tetrahydroxystilbene Glucoside Attenuates Neuroinflammation through the Inhibition of Microglia Activation

Neuroinflammation is closely implicated in the pathogenesis of neurological diseases. The hallmark of neuroinflammation is the microglia activation. Upon activation, microglia are capable of producing various proinflammatory factors and the accumulation of these factors contribute to the neuronal damage. Therefore, inhibition of microglia-mediated neuroinflammation might hold potential therapy for neurological disorders. 2,3,5,4′-Tetrahydroxystilbene-2-O-β-D-glucoside (TSG), an active component extracted from Polygonum multiflorum, is reported to be beneficial for human health with a great number of pharmacological properties including antioxidant, free radical-scavenging, anti-inflammation, antilipemia, and cardioprotective effects. Recently, TSG-mediated neuroprotective effects have been well demonstrated. However, the neuroprotective actions of TSG on microglia-induced neuroinflammation are not known. In the present study, microglia BV2 cell lines were applied to investigate the anti-neuroinflammatory effects of TSG. Results showed that TSG reduced LPS-induced microglia-derived release of proinflammatory factors such as TNFα, IL-1β, and NO. Moreover, TSG attenuated LPS-induced NADPH oxidase activation and subsequent reactive oxygen species (ROS) production. Further studies indicated that TSG inhibited LPS-induced NF-κB signaling pathway activation. Together, TSG exerted neuroprotection against microglia-mediated neuroinflammation, suggesting that TSG might present a promising benefit for neurological disorders treatment.

Tetrahydroxystilbene glucoside antagonizes age-related α-synuclein overexpression in the hippocampus of APP transgenic mouse model of Alzheimer's disease

To investigate the mRNA and protein alterations of α-synuclein in the brain of Alzheimer's disease-like mouse model at the different ages, and to evaluate the effects of 2,3,5,4'-tetrahydroxy stilbene-2-O-β-D-glucoside (TSG) on α-synuclein expression. TSG (120 or 240 μmol kg(-1)d(-1)) was intragastrically administered to APPV717I transgenic (Tg) mice at 4- or 10-month-old for 6 months. mRNA expression of α-synuclein increased in hippocampus in 4 month to 16 month old Tg mice compared with age-matched control. α-synuclein protein expression in hippocampus also increased in 4 month to 16 month old Tg mice significantly. Significant down-regulation of α-synuclein mRNA and protein expression in hippocampus was found after treatment of TSG for 6 months in both 10- and 16-month-old Tg mice. Production of dimer and tetramer of α-synuclein protein in Tg mice was inhibited after treatment with TSG. The expression and aggregation of α-synuclein was age-dependently increased in Tg mice. TSG not only prevents over-expression of α-synuclein at an early stage, but also reverses the increased expression of α-synuclein and inhibits the aggregation at the late stage of Tg mice. TSG may have potential to the prevention and treatment of Alzheimer's diseases.

Proteomic analysis for anti-atherosclerotic effect of tetrahydroxystilbene glucoside in rats

2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (TSG) extracted from Polygonum multiflorum (a traditional Chinese medicinal herb) has been proved to exhibit significant anti-atherosclerotic activity. In this study, we firstly used proteomic analyses to investigate the molecular events occurring in the atherosclerotic rats after TSG treatment. Aortic samples were collected from the atherosclerotic rat group and the TSG-treated group, and its proteome was analyzed by two-dimensional gel electrophoresis (2-DE). Proteins showing significant changes in expression were identified and analyzed by matrix-assisted desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). As a result, 21 protein spots were found with significant differential expression after the treatment with TSG. A total of 18 spots were identified by database searching, and 17 spots matched with known proteins. Among these proteins (11 proteins up-regulated and six proteins down-regulated), five proteins were mainly involved in inflammation, cholesterol transport, cell apoptosis and adhesion. TSG treatment enhanced the expression of HSP 70, lipocortin 1 and Apo A-I, and inhibited the expression of calreticulin, vimentin. Furthermore, we randomly selected four proteins and confirmed the results of proteomic analysis by RT-PCR and western blotting. In conclusion, TSG treatment suppresses atherosclerosis by altering the expression of different proteins. Calreticulin, vimentin, HSP 70, lipocortin 1, and Apo A-I, are key proteins that may be novel molecular targets responsible for atherogenesis suppression induced by TSG treatment.

Tetrahydroxystilbene glucoside improves the learning and memory of amyloid-β1–42-injected rats and may be connected to synaptic changes in the hippocampus

The aim of this study was to evaluate the protective effects of 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (TSG), an active component extracted from Polygonum multiflorum, on learning/memory deficits in Alzheimer's disease (AD). We randomly divided 24 male Sprague-Dawley rats among 4 groups: (i) the sham-operated group (control); (ii) sham-operated group also treated with TSG (sham+TSG); (iii) beta amyloid treated group (Aβ); and (iv) Aβ treatment group also treated with TSG (Aβ+TSG). Rats in the Aβ and Aβ+TSG groups were treated with Aβ₁₋₄₂ intracerebroventricularly, whereas the control and sham+TSG groups were given phosphate-buffered saline. Rats in the sham+TSG and Aβ+TSG groups were then treated intragastrically with TSG (50 mg·(kg body mass)⁻¹·day⁻¹) for 4 weeks, and rats in the Aβ and control groups were treated with saline. The results from Morris water maze tests, electron microscopy, real-time polymerase chain reaction, and Western blotting demonstrated that Aβ₁₋₄₂ induced impairment in learning and memory, degeneration in synaptic structures, and downregulation of Src and NR2B at the gene and protein level, respectively. These alterations were reversed by the administration of TSG, suggesting that TSG exerts anti-AD properties by protecting synaptic structure and function. TSG-induced upregulation of Src and NR2B may be responsible for this process.

2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside ameliorates vascular senescence and improves blood flow involving a mechanism of p53 deacetylation

Background and aims2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside (THSG), a resveratrol analog with glucoside, has been shown in various studies to inhibit proliferation of vascular smooth muscle cells, attenuate inflammation, and prevent vascular endothelial dysfunction. In the study, we examined the effects of THSG on vascular senescence and blood flow. Methods and resultsOral administration of THSG for 14 weeks, resulted in notable increases in blood flow in spontaneously hypertensive rats (SHRs); and effective inhibition of vascular senescence as indicated by senescence-associated β-galactosidase (SA-β-gal) staining, phosphorylation of γH2AX observed by stain analysis of immunofluorescence, and K373 acetylation of p53 in the aortic arches of SHRs. Oral administration of THSG also induced eNOS expression and urinary NOx production. THSG weekly activated SIRT1 activity, stimulated eNOS promoter reporter gene activity, and ameliorated H2O2-induced cellular senescence and K373 acetylation of p53 in cultured human umbilical vein endothelial cells (HUVECs). ConclusionsTHSG improves blood flow and ameliorates vascular senescence by increasing eNOS expression and Sirt1 activity and decreasing acetylation of p53 at K373 site, at least in part, both in vitro and in vivo.

Protective effect of tetrahydroxystilbene glucoside against hydrogen peroxide-induced dysfunction and oxidative stress in osteoblastic MC3T3-E1 cells

Oxidative stress can induce apoptosis and decrease activities of osteoblasts. 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside (TSG), is a potent antioxidant derived from a Chinese herb Polygonum multiflorum Thunb. To evaluate the protective effect provided by TSG to osteoblastic MC3T3-E1 cells, the cells were pretreated with TSG for 24h before being treated with 0.3mM hydrogen peroxide (H2O2) for 24h, then some markers of osteoblast function and oxidative damage of the cells were examined. Our data demonstrated that TSG significantly (P< 0.05) increased cell survival, alkaline phosphatase (ALP) activity, calcium deposition, and the mRNA expression of ALP, collagen I (COL-I) and osteocalcin (OCN) in the presence of H2O2. In addition, TSG decreased the production of receptor activator of nuclear factor-κB ligand (RANKL), interleukin-6 (IL-6), intracellular reactive oxygen species and malondialdehyde (MDA) of osteoblastic MC3T3-E1 cells induced by H2O2. Taken together, these results demonstrated that the protective effect provided by TSG to osteoblastic MC3T3-E1 cells was mediated, at least in part, via inhibition of the release of bone-resorbing mediators and oxidative damage of the cells. Our results indicated that TSG may be effective in providing protection against osteoporosis associated with oxidative stress.

Comparison of laxative and antioxidant activities of raw, processed and fermented Polygoni Multiflori Radix

Aim To observe the anti-oxidative activity and adverse laxative effect of raw, traditional processed and fermented products of Polygoni Multiflori Radix (PMR), and furthermore, to evaluate the fermentation method used in the processing procedure of PMR. Methods In vitro ferric reducing antioxidant power (FRAP) assay was carried out to evaluate the anti-oxidative activity. Modulation of normal defecation and effect on gastrointestinal motility in mice were carried out to investigate their adverse laxative effect. Results Fermented PMR induced less severe laxative adverse effect than Polygoni Multiflori Radix Praeparata (PMRP). PMR fermented with Rhizopus sp. (FB) could modulate the defecation significantly. The gastrointestinal motility was inhibited by PMRP and PMR fermented with Rhizopus oryzae (FA). FA and FB showed better antioxidant activity than PMRP in 50% and 95% ethanol group. Contents of 2, 3, 5, 4′-tetrahydroxy-stilbene-2- O-β-D-glucoside (TSG) were reduced significantly after traditional processing but maintained after fermentation. Emodin and physcion were increased after traditional processing and fermented with Rhizopus oryzae. Conclusion All processing procedure, including fermentation, might reduce its anti-oxidative activity. However, most of the processed products could lessen the adverse effect on gastrointestinal tract compared to PMR. Fermentation with Rhizopus oryzae was considered as a promising processing method of PMR.

Lipid regulation effects of Polygoni Multiflori Radix, its processed products and its major substances on steatosis human liver cell line L02

Ethnopharmacological relevanceRaw and processed Polygoni Multiflori Radix (PMR) are used in the prevention and treatment of non-alcoholic fatty liver disease (NAFLD), hyperlipidemia or related diseases. However, few researches compared the activities of raw and processed PMR on lipid metabolism regulation. Moreover, the active substances of Polygonum multiflorum are still not clearly elucidated. Materials and methodsIn this research, a sensitive, accurate and rapid in vitro model, steatosis hepatic L02 cell, was applied to compare the relative activities of raw and processed PMR on lipid metabolism regulation. Furthermore, the lipid regulation activities of emodin, physcion and 2,3,5,4′-tetrahydroxy-stilbene-2-O-β-d-glucoside (TSG) were evaluated. The steatosis L02 cells were obtained after cultured with 1% fat emulsion–10% fetal bovine serum (FBS)–RPMI 1640 medium for 48h. Contents of total cholesterol (TC), triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C) in L02 cells are evaluated after exposure. ResultsThe intracellular TG contents were increased from 16.50±1.29mmol/L to 34.40±1.36mmol/L in steatosis L02 cells, while the intracellular contents of TC were increased from 5.07±1.80mmol/L to 11.79±0.54mmol/L. Water extract of raw PMR showed much remarkable TG-regulation and TC-regulation effects than its processed products. Emodin displayed the best TG regulation activity while TSG showed the best TC regulation activity. At the same time, the exposure of emodin and physcion could reduce the LDL-C contents in steatosis L02 cells. ConclusionsOn account of these in vitro results, raw PMR might have more satisfactory effects in clinic treatment of NAFLD or hyperlipidemia characterized by the elevation of cholesterol than processed PMR.

Tetrahydroxystilbene glucoside improves learning and (or) memory ability of aged rats and may be connected to the APP pathway.

The aim of this study is to evaluate the protective effects of 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside (TSG) on learning and (or) memory deficit in aged rats, as well as to explore the possible connection between TSG and the β-amyloid precursor protein (APP) pathway. Sprague-Dawley rats were randomly divided into a young control group (age, 4months), an aged control group (age, 22months), and a TSG-treated group (age, 22months). TSG at doses of 50mg·kg(-1)·day(-1) was intragastrically administered to 22-month-old rats for 4weeks. The learning and (or) memory ability was measured using the Morris water maze (MWM) test, and the mRNA and protein expression of APP pathway proteins was measured by real-time polymerase chain reaction (RT-PCR) and Western blot, respectively. The aged rats exhibited obvious learning and (or) memory deficit when compared with the young rats, but TSG treatment significantly improved the learning and (or) memory ability in the aged rats, as noted from the MWM test. RT-PCR and Western blot analysis showed an increase in the expression of beta-site APP cleaving enzyme 1 (BACE1) and A Disintegrin And Metalloproteinase 17 (ADAM17) in aged rats, and a decrease in ADAM10; however, TSG treatment significantly increased the mRNA and protein expression of ADAM10 (p< 0.01, compared with aged control rats). These results provide solid evidence for the therapeutic effect of TSG on age-related cognitive impairment, especially spatial learning and memory deficit. TSG might exert this effect through the APP pathway, although further studies on the topic are required.

Protective effect of tetrahydroxystilbene glucoside on 6-OHDA-induced apoptosis in PC12 cells through the ROS-NO pathway.

Oxidative stress plays an important role in the pathogenesis of neurodegenerative diseases, such as Parkinson's disease. The molecule, 2,3,5,4′-tetrahydr- oxystilbene-2-O-β-D-glucoside (TSG), is a potent antioxidant derived from the Chinese herb, Polygonum multiflorum Thunb. In this study, we investigated the protective effect of TSG against 6-hydroxydopamine-induced apoptosis in rat adrenal pheochromocytoma PC12 cells and the possible mechanisms. Our data demonstrated that TSG significantly reversed the 6-hydroxydopamine-induced decrease in cell viability, prevented 6-hydroxydopamine-induced changes in condensed nuclei and decreased the percentage of apoptotic cells in a dose-dependent manner. In addition, TSG slowed the accumulation of intracellular reactive oxygen species and nitric oxide, counteracted the overexpression of inducible nitric oxide syntheses as well as neuronal nitric oxide syntheses, and also reduced the level of protein-bound 3-nitrotyrosine. These results demonstrate that the protective effects of TSG on rat adrenal pheochromocytoma PC12 cells are mediated, at least in part, by the ROS-NO pathway. Our results indicate that TSG may be effective in providing protection against neurodegenerative diseases associated with oxidative stress.

Hepatoxicity of major constituents and extractions of Radix Polygoni Multiflori and Radix Polygoni Multiflori Praeparata

Ethnopharmacological relevanceRadix Polygoni Multiflori (RPM) and Radix Polygoni Multiflori Praeparata (RPMP) were traditionally widely used as Chinese herbal medicine. However, liver adverse reactions caused by RPM or RPMP were frequently reported all around the world recent years. The aim of this study was to study the cytotoxicities of RPM, RPMP and their major constituents on human liver cell L-02 simultaneously. Materials and methodsMulti-assays, including MTT assay, neutral red uptake (NRU) assay, LDH leakage percentage and liver enzyme secretion (AST, ALT and ALP) were used. Cytotoxicities of major chemical constituents of RPM, 2, 3, 5, 4′-tetrahydroxy-stilbene-2-O-β-D-glucoside (TSG), physcion and emodin, were tested. The cytotoxicities of water, 50% ethanol and 95% ethanol extractions of RPM and RPMP were tested. HPLC-DAD analysis was carried to reveal the content change of TSG, physcion and emodin after the processing procedure. ResultsThe TD50 of TSG, physcion and emodin in MTT assay were >10,000μM, 2853.61μM and 520.37μM. In the NRU assay, the TD50 of TSG, physcion and emodin were much smaller (1401.53μM, 1140.00μM, and 3.80μM). Emodin induced much severe liver enzyme secretion than TSG and physcion. Cell proliferation and LDH leakage rate showed no difference between RPM and RPMP extractions, but ALP, AST and ALT secretions in RPMP extractions were significant lower than that of PMR groups. Water extractions of RPM and RPMP were less toxic than any other solvent in most of the assays. Positive correlation was found between the TSG/emodin ratio and MTT survival rate. The emodin/physcion ratio also showed positive correlation with the LDH leakage percentage. ConclusionsIn conclusion, Radix Polygonum multiflorum and Radix Polygonum multiflorum Praeparata were not liver injure inducing in our in vitro assays. However, the processing produce of RPM could reduce its effect on both cell proliferation and enzyme secretion of liver cell. Judging from cell proliferation, integrity of cell membrane and enzyme secretion, three major chemical constituents of RPM: TSG, physcion and emodin showed no, moderate and severe cytotoxicity against human liver cell line L-02 respectively. Chemical constituents-cytotoxicity relationship investigation revealed that TSG and physcion probably had attenuating effect to emodin. The attenuating mechanisms were still under investigation.

Tetrahydroxystilbene glucoside protects human neuroblastoma SH-SY5Y cells against MPP+-induced cytotoxicity

1-Methyl-4-phenylpyridinium (MPP+), an inhibitor of mitochondrial complex I, has been widely used as a neurotoxin for inducing a cell model of Parkinson's disease. This study aimed to evaluate the effects of 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside (TSG), an active component extracted from Polygonum multiflorum, on MPP+-induced cytotoxicity in human dopaminergic neuroblastoma SH-SY5Y cells. The results from the MTT and lactate dehydrogenase (LDH) assays showed that incubating cells with 500μM MPP+ for 24h decreased cell viability and increased LDH leakage, whereas preincubating cells with 3.125 to 50μM TSG for 24h protected the cells against MPP+-induced cell damage. Using 2′,7′-dichlorofluorescin diacetate (DCFH-DA) and rhodamine 123, respectively, we found that TSG inhibited both the elevation of intracellular reactive oxygen species and the disruption of mitochondrial membrane potential induced by MPP+. In addition, TSG suppressed both the upregulation of the ratio of Bax to Bcl-2 and the activation of caspase-3 induced by MPP+, and TSG inhibited apoptosis as detected by flow cytometric analysis using Annexin-V and propidium (PI) label. These results suggest that TSG may protect neurons against MPP+-induced cell death through improving mitochondrial function, decreasing oxidative stress and inhibiting apoptosis, and this may provide a potentially new strategy for preventing and treating neurodegenerative disorders such as Parkinson's disease.

Protection by tetrahydroxystilbene glucoside against neurotoxicity induced by MPP+: The involvement of PI3K/Akt pathway activation

Oxidative stress plays an important role in the pathogenesis of Parkinson's disease (PD). 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside (TSG), which is an active component of the rhizome extract from polygonum multiflorum, shows potent antioxidant properties. In this paper, the neuroprotective effects of TSG on 1-methyl-4-phenylpyridinium (MPP+)-induced apoptosis in PC12 cells were investigated. Pretreatment with TSG markedly attenuated MPP+-induced loss of cell viability and release of lactate dehydrogenase (LDH), and reduced MPP+-induced apoptotic cell death in a dose-dependent manner. The anti-apoptotic effects of TSG were probably mediated by the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway since TSG failed to rescue cells from MPP+ injury in the presence of the PI3K inhibitor, LY294002. These results indicate that TSG affords a significant neuroprotective effect against MPP+-induced damage and apoptosis in PC12 cells. The PI3K/Akt signaling pathway might be involved in the TSG-mediated anti-apoptotic effects.

Tetrahydroxystilbene glucoside, a plant-derived cognitive enhancer, promotes hippocampal synaptic plasticity

Plant or food derived polyphenols have received a great deal of attention due to their biological properties including anti-oxidative effects, neuroprotection and memory enhancement. Here, we investigated the roles of 2,3,5,4′-tetrahydroxystilbene-2-O-β- d-glucoside (TSG), an active component of the rhizome extracted from Polygonum multiflorum, in the regulation of hippocampal synaptic plasticity in normal mice as well as the underlying mechanisms. It was shown that TSG promoted the differentiation of PC12 cells and increased the intracellular calcium level in hippocampal neurons. TSG facilitated high-frequency stimulation (HFS)-induced hippocampal long-term potentiation (LTP) in a bell-shaped manner. The facilitation of LTP induction by TSG required calcium/calmodulin-dependent protein kinase II (CaMKII) and extracellular signal-regulated kinase (ERK) activation. Taken together, our data demonstrate that TSG promotes LTP induction and this effect may contribute to the enhancement of learning and memory seen in animal models.

Tetrahydroxystilbene glucoside ameliorates diabetic nephropathy in rats: Involvement of SIRT1 and TGF-β1 pathway

Oxidative stress caused by hyperglycaemia is believed to be a major molecular mechanism underlying diabetic nephropathy. 2,3,5,4′-tetrahydroxystilbene-2-O-β- d-glucoside (TSG), an active component extract from Polygonum multiflorum Thunb, exhibits antioxidative and anti-inflammatory effects. Possible protective mechanisms of TSG on diabetic nephropathy were investigated in rats and cultured rat mesangial cells. Total cholesterol and triglyceride levels of diabetic rats were clearly increased and these increases were diminished by treatment with TSG. Treatment of diabetic rats with TSG also significantly reduced blood urea nitrogen, creatinine, 24 h urinary protein levels, and kidney weight/body weight. The activities of superoxide dismutase and glutathione peroxidase in renal homogenate were increased markedly, whereas malonaldehyde levels were decreased significantly in TSG-treated diabetic rats. TSG dramatically inhibited diabetes-induced overexpression of TGF-β1 and COX-2, and restored the decrease of SIRT1 expression in diabetic rats. High glucose-induced overexpression of TGF-β1 in cultured mesangial cells was significantly inhibited, whereas the decease of SIRT1 expression was restored by pretreatment of TSG. Nicotinamide, the inhibitor of SIRT1, partially relieved the inhibitory effect of TSG on TGF-β1 expression under high glucose condition. These findings indicate that the protective mechanisms of TSG on diabetic nephropathy are involved in the alleviation of oxidative stress injury and overexpression of COX-2 and TGF-β1, partially via activation of SIRT1.

Tetrahydroxystilbene glucoside attenuates MPP +-induced apoptosis in PC12 cells by inhibiting ROS generation and modulating JNK activation

It is known that oxidative stress plays a major role in the progression of Parkinson's disease (PD). Previous studies have suggested that 2,3,5,4′-tetrahydroxystilbene-2-O-β- d-glucoside (TSG), an active component extracted from a traditional Chinese herb Polygonum multiflorum Thunb., has significant antioxidant and free radical-scavenging activities. This is the first study that investigated the protective effects of TSG against MPP +-induced apoptosis in PC12 cells and determined the underlying mechanism. The results showed that incubation of PC12 cells with TSG before exposing them to MPP + could significantly decrease cell viability loss and reverse cell apoptosis in a dose-dependent manner. The anti-apoptotic effects of TSG were probably mediated via the inhibition of ROS generation and modulation of JNK activation because TSG blocked ROS increase and JNK phosphorylation induced by MPP +. Taken together, these results indicated that TSG may provide a useful therapeutic strategy for the treatment of neurodegenerative diseases such as PD.

Inhibitory Effects of Stilbene Glucoside Isolated from the Root of Polygonum multiflorum on Tyrosinase Activity and Melanin Biosynthesis

As part of efforts to discover phytochemicals that inhibit melanin biosynthesis, we screened (E)-2,3,5,4′-tetrahydroxystilbene-2-O-β-D-glucoside (THSG) isolated from Polygonum multiflorum. THSG dose-dependently inhibited tyrosinase activity, with an ID50 value of 100 μg/mL. THSG also potently inhibited melanin production in B16 melanoma cells induced by forskolin, an inducer of melanogenesis, with ID50 of 1–10 μg/mL. THSG may therefore reduce melanogenesis.

UPLC-PDA Analysis for Simultaneous Quantification of Four Active Compounds in Crude and Processed Rhizome of Polygonum multiflorum Thunb

A novel, rapid and specific ultra performance liquid chromatography-photo diode array detection method was developed for the simultaneous determination of 2,3,5,4′-tetrahydroxystilbene-2-O-β-d-glucoside (TSG), emodin-8-O-β-d-glucoside (EMG), emodin (EM) and physcion (PS). The chromatographic separation was performed on an Acquity BEH C18 column (100 × 2.1 mm i.d., 1.7 μm). The mobile phase was a mixture of 0.3% acetic acid–water and 0.3% acetic acid–acetonitrile employing gradient elution at the flow rate of 0.4 mL min−1. The four compounds behaved linearly in the concentration range between 60.80–3040.00 μg mL−1 (TSG), 0.50–25.00 μg mL−1 (EMG), 2.16–108.00 μg mL−1 (EM) and 1.56–78.00 μg mL−1 (PS), respectively with correlation coefficients >0.999. The precision of the method were below 5% RSD. Recoveries of the four compounds ranged from 95.71 to 102.97%, with RSD values less than 2%.

2, 3, 5, 4′-tetrahydroxystilbene-2-O-β- d-glucoside (THSG) induces melanogenesis in B16 cells by MAP kinase activation and tyrosinase upregulation

Aims The 2, 3, 5, 4′-tetrahydroxystilbene-2-O-β- d-glucoside (THSG), a water-soluble active component extracted from dried tuber root of Polygonum multiflorum, has been found to induce pigmentation in B16 cells, but the details of the underlying mechanism remain unknown. The present study was conducted to investigate the mechanism of stimulatory effect of THSG on melanogenesis using B16F1 melanoma cells. Main methods Several experiments were performed in B16F1 melanoma cells. We studied melanin content, tyrosinase activity, cell viability, and performed reverse transcription polymerase chain reaction and Western blots for proteins involved in melanogenesis. Key findings THSG increased the melanin content and tyrosinase activity in a concentration-dependent manner and treatment with 10 µg/ml THSG enhanced the expression of tyrosinase time-dependently in B16 cells. We then investigated whether THSG influences the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. THSG was found to induce sustained MITF up-regulation and cAMP response element (CRE) binding protein (CREB) activation, suggesting that THSG-mediated MITF activation may be cAMP dependent. Furthermore, Western blot analysis revealed that THSG elevated the level of phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) significantly at 1–6 h; a p38 MAPK inhibitor, SB203580, almost completely attenuated the THSG-mediated up-regulation of melanin synthesis and induction of MITF and tyrosinase expression. Significance THSG exerts its stimulatory effect on melanogenesis by MAP kinase activation and MITF-induction of tyrosinase.

Protection by tetrahydroxystilbene glucoside against cerebral ischemia: involvement of JNK, SIRT1, and NF-κB pathways and inhibition of intracellular ROS/RNS generation

Many natural polyphenolic compounds have been shown to attenuate reactive oxygen/nitrogen species (ROS/RNS) formation and protect against ischemia/reperfusion injury both in vitro and in vivo. 2,3,5,4′-tetrahydroxystilbene-2- O-β- d-glucoside (TSG), an active component of the rhizome extract from Polygonum multiflorum, exhibits antioxidative and anti-inflammatory effects. Here, we used an in vitro ischemic model of oxygen–glucose deprivation followed by reperfusion (OGD-R) and an in vivo ischemic model of middle cerebral artery occlusion (MCAO) to investigate the neuroprotective effects of TSG on ischemia/reperfusion brain injury and the related mechanisms. We demonstrated that OGD-R-induced neuronal injury, intracellular ROS generation, and mitochondrial membrane potential dissipation were reversed by TSG. The elevation of H 2O 2-induced [Ca 2+] i was also attenuated by TSG. Inhibition of the c-Jun N-terminal kinase (JNK) and Bcl-2 family-related apoptotic signaling pathway was involved in the neuroprotection afforded by TSG. Meanwhile, TSG inhibited iNOS mRNA expression induced by OGD-R, which may be mediated by the activation of SIRT1 and inhibition of NF-κB activation. In vivo studies further demonstrated that TSG significantly reduced the brain infarct volume and the number of positive cells by TUNEL staining in the cerebral cortex compared to the MCAO group. Our study indicates that TSG protects against cerebral ischemia/reperfusion injury through multifunctional cytoprotective pathways.