Gou-teng (from Uncaria rhynchophylla Miquel)-induced endothelium-dependent and -independent relaxations in the isolated rat aorta

Gene coexpression networks allow the discovery of two strictosidine synthases underlying monoterpene indole alkaloid biosynthesis in Uncaria rhynchophylla

Plant-derived monoterpene indole alkaloids (MIAs) from Uncaria rhynchophylla (UR) have huge medicinal properties in treating Alzheimer's disease, Parkinson's disease, and depression. Although many bioactive UR-MIA products have been isolated as drugs, their biosynthetic pathway remains largely unexplored. In this study, untargeted metabolome identified 79 MIA features in UR tissues (leaf, branch stem, hook stem, and stem), of which 30 MIAs were differentially accumulated among different tissues. Short time series expression analysis captured 58 pathway genes and 12 hub regulators responsible for UR-MIA biosynthesis and regulation, which were strong links with main UR-MIA features. Coexpression networks further pointed to two strictosidine synthases (UrSTR1/5) that were coregulated with multiple MIA-related genes and highly correlated with UR-MIA features (r > 0.7, P < 0.005). Both UrSTR1/5 catalyzed the formation of strictosidine with tryptamine and secologanin as substrates, highlighting the importance of key residues (UrSTR1: Glu309, Tyr155; UrSTR5: Glu295, Tyr141). Further, overexpression of UrSTR1/5 in UR hairy roots constitutively increased the biosynthesis of bioactive UR-MIAs (rhynchophylline, isorhynchophylline, corynoxeine, etc), whereas RNAi of UrSTR1/5 significantly decreased UR-MIA biosynthesis. Collectively, our work not only provides candidates for reconstituting the biosynthesis of bioactive UR-MIAs in heterologous hosts but also highlights a powerful strategy for mining natural product biosynthesis in medicinal plants.

Safety and biological activity evaluation of Uncaria rhynchophylla ethanolic extract

Uncaria rhynchophylla (UR) belongs to the Rubiaceae family, and its dried hooks are usually used in traditional medicine. It is effective in treating diseases related to the central nervous system. This study aimed to evaluate the safety of UR extract, investigate its antimutagenic and antioxidative activities, and elucidate its active components. Extraction and fractionation of the UR extract resulted in yields of 6.71%, 0.037%, 0.042%, 0.152%, 0.332%, and 5.132%, for hexane, ether, DCM, EtOAC, and aqueous fractions, respectively. The four indole alkaloids, total phenolic content (TPC), and total flavonoid content (TFC) of UR extract and its subfractions were measured. Alkaloid content was highest in the UR extract. TPC was the highest in the EtOAC fraction (373.7 ± 20.9 mg gallic acid equivalent (GAE)/g), whereas TFC was the highest in the UR extract (33.5 ± 2.4 mg quercetin equivalent (QE)/g). To assess the safety of UR extract mutagenicity, cytotoxicity, and oxidative stress inducibility assays were performed. The UR extract (2000 µg/plate) showed excellent antimutagenic activity (above 90%) against BaP in both TA98 and TA100 strains. The UR extract exhibited efficient DPPH (RC₅₀ 239.2 ± 16.5 µg/mL) and ABTS scavenging activity (RC₅₀ 458.7 ± 25.0 µg/mL). The UR extract (150 µg/mL) showed cytoprotective activity (65.6% ± 9.2%) against t-BHP. Among the subfractions, the EtOAC fraction possessed the strongest activities, overall. UR generally showed excellent biological activity at nontoxic concentrations (determined in vitro in current work), although the chemical composition of UR requires further investigation prior to its potential future use.

Natural plant products in treatment of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a severe disease characterized by progressive remodeling of distal pulmonary arteries and persistent elevation of pulmonary vascular resistance (PVR), which leads to right ventricular dysfunction, heart failure, and eventually death. Although treatment responsiveness for this disease is improving, it continues to be a life-threatening condition. With the clinical efficacy of natural plant products being fully confirmed by years of practice, more and more recognition and attention have been obtained from the international pharmaceutical industry. Moreover, studies over the past decades have demonstrated that drugs derived from natural plants show unique advantages and broad application prospects in PAH treatment, not to mention the historical application of Chinese traditional medicine in cardiopulmonary diseases. In this review, we focus on summarizing natural plant compounds with therapeutic properties in PAH, according to the extracts, fractions, and pure compounds from plants into categories, hoping it to be helpful for basic research and clinical application.

Rhynchophylline Ameliorates Endothelial Dysfunction via Src-PI3K/Akt-eNOS Cascade in the Cultured Intrarenal Arteries of Spontaneous Hypertensive Rats

Objectives: To examine the protective effect of Rhynchophylline (Rhy) on vascular endothelial function in spontaneous hypertensive rats (SHRs) and the underlying mechanism. Methods: Intrarenal arteries of SHRs and Wistar rats were suspended in myograph for force measurement. Expression and phosphorylation of endothelial nitric oxide (NO) synthase (eNOS), Akt, and Src kinase (Src) were examined by Western blotting. NO production was assayed by ELISA. Results: Rhy time- and concentration-dependently improved endothelium-dependent relaxation in the renal arteries from SHRs, but had no effect on endothelium-independent relaxation in SHR renal arteries. Wortmannin (an inhibitor of phosphatidylinositol 3-kinase) or PP2 (an inhibitor of Src) inhibited the improvement of relaxation in response to acetylcholine by 12 h-incubation with 300 μM Rhy. Western blot analysis revealed that Rhy elevated phosphorylations of eNOS, Akt, and Src in SHR renal arteries. Moreover, wortmannin reversed the increased phosphorylations of Akt and eNOS induced by Rhy, but did not affect the phosphorylation of Src. Furthermore, the enhanced phosphorylations of eNOS, Akt, and Src were blunted by PP2. Importantly, Rhy increased NO production and this effect was blocked by inhibition of Src or PI3K/Akt. Conclusion: The present study provides evidences for the first time that Rhy ameliorates endothelial dysfunction in SHRs through the activation of Src-PI3K/Akt-eNOS signaling pathway.

Novel rhynchophylline analogues as microvascular relaxation agents for the treatment of microvascular dysfunction caused by diabetes

Dysfunction in vascular reactivity in the micro- and macrocirculation is well established in cardiovascular disease. However, little is known about methods that may improve vascular reactivity in patients likely to develop microvascular dysfunction. One of the racemic analogues of rhynchophylline (G2) and its stereoisomers (G2-a and G2-b) were synthesized to address this knowledge gap. The preliminary pharmaceutical studies on the relaxation of the rat thoracic aorta showed that G2 and its stereoisomers are more potent (at least 30-fold) than the natural product rhynchophylline, which encouraged us to further investigate their functions and mechanisms as treatments for microvascular dysfunction caused by diabetes. G2-a displayed the best microvascular relaxation activity on rat mesenteric arteries among the three compounds, and G2 or G2-a caused relaxation in an endothelium-dependent manner. In ex vivo tests, G2 and G2-a exhibited a weaker potency in inducing microvascular relaxation in mesenteric arteries from diabetic rats than from normal rats, most likely, due to microvascular endothelium damage caused by diabetes. However, based on the animal studies, G2 ameliorated diabetes-induced endothelial dysfunction in rat mesenteric arteries in vivo. Further investigations of the mechanism showed that G2 mainly induced the recovery of endothelial function by upregulating endothelial nitric oxide synthase (eNOS) expression and further increasing the concentration of nitric oxide (NO), which is required for vascular relaxation.

Neuroprotective effect of 1-methoxyoctadecan-1-ol from Uncaria sinensis on glutamate-induced hippocampal neuronal cell death

ETHNOPHARMACOLOGICAL RELEVANCE

We isolated a single compound, 1-methoxyoctadecan-1-ol (MOD), from dried hooks and stems of Uncaria sinensis, which is used in traditional Korean medicine to provide relief from various nervous related symptoms.

MATERIALS AND METHODS

Neuroprotective effects of MOD against glutamate-induced oxidative stress in HT22 cells were investigated by analyzing cell viability, lactate dehydrogenase, flow cytometry, reactive oxygen species (ROS) and Western blot assays.

RESULTS

Exposure to glutamate alone resulted in remarkable hippocampal neuronal cell death; however, pretreatment with MOD resulted in suppression of neuronal death and ROS accumulation in connection with cellular Ca2+ level after exposure to glutamate. Stimulation by glutamate also caused significant protein level of phosphorylated p38 mitogen-activated protein kinases (MAPK), and dephosphorylated phosphatidylinositol-3 kinase (PI3K), however, pretreatment with MOD resulted in inhibition of these changes in protein level. Treatment with glutamate alone led to suppressed protein level of mature brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element binding protein (CREB); however, pretreatment with MOD resulted in significant enhancement of this level of protein. Anti-oxidant N-acetyl-L-cysteine and both Ca2+ inhibitors, BAPTA and EGTA, showed effects similar to those of MOD in all proteins examined, except mature BDNF.

CONCLUSIONS

Our results suggest that MOD mainly exerted neuroprotective effects in suppression of ROS accumulation and up-regulation of mature BDNF in association with p38 MAPK and PI3K signaling in hippocampal neuronal cells.

Hexane extract from Uncaria sinensis exhibits anti-apoptotic properties against glutamate-induced neurotoxicity in primary cultured cortical neurons

We explored the neuroprotective effects of a hexane extract from Uncaria sinensis (HEUS) against glutamate-induced toxicity focusing on its anti-apoptotic mechanism in primary cultured cortical neurons. Pretreatment with HEUS resulted in significantly reduced glutamate-induced toxicity in a dose-dependent manner with a decrease in the release of lactate dehydrogenase. Morphological assay and flow cytometry were performed for determination of the type of cell death; according to the results, treatment with HEUS resulted in a significant reduction of glutamate-induced apoptotic cell death. We examined the anti-apoptotic mechanism of HEUS; treatment with HEUS resulted in markedly decreased expression of death receptor (DR)4, which was induced by glutamate stimulation. In contrast, treatment with HEUS resulted in significantly enhanced levels of expression of glutamate-attenuated XIAP and Bcl-2, as well as marked blockade of glutamate-induced Bid cleavage, which inhibits both extrinsic and intrinsic apoptosis pathways. In addition, pretreatment with HEUS resulted in almost complete blockade of glutamate-induced activation of caspases-8, -9 and -3, as well as cleavage of poly (ADP-ribose) polymerase. These findings suggest that the neuroprotective effects of HEUS against glutamate-induced toxicity occur via inhibition of DR4 and expression of anti-apoptotic proteins XIAP and Bcl-2 resulting in effective abrogation of the activation of caspase cascades and promotion of cell survival.

Uncaria rhynchophylla (Miq) Jack Plays a Role in Neuronal Protection in Kainic Acid-Treated Rats

Uncaria rhynchophylla (Miq) Jack (UR) is one of many Chinese herbs. Our previous studies have shown that UR has both anticonvulsive and free radical-scavenging activities in kainic acid (KA)-treated rats. The aim of the present study was to use the effect of UR on activated microglia, nitric oxide synthase, and apoptotic cells to investigate its function in neuroproction in KA-treated rats. UR of 1.0 or 0.5 g/kg was orally administered for 3 days (first day, second day, and 30 min prior to KA administration on the third day), or 10 mg/kg (intraperitoneal injection, i.p.) N-nitro-L-arginine methyl ester (L-NAME) 30 min prior to KA (2 μg/2 μl) was injected into the right hippocampus region of Sprague-Dawly rats. ED1 (mouse anti rat CD68), neuronal nitric oxide synthase (nNOS), inducible nitric oxide synthase (iNOS) immunoreactive cells and apoptotic cells were observed in the hippocampus region. The results indicated that 1.0 g/kg, 0.5 g/kg of UR and 10 mg/kg of L-NAME reduced the counts of ED1, nNOS, iNOS immunoreactive cells and apoptotic cells in KA-treated rats. This study demonstrates that UR can reduce microglia activation, nNOS, iNOS and apoptosis, suggesting that UR plays a neuro-protective role against neuronal damage in KA-treated rats.

Anti-inflammatory effects of rhynchophylline and isorhynchophylline in mouse N9 microglial cells and the molecular mechanism

Excessive production of nitric oxide (NO) and proinflammatory cytokines from activated microglia contributes to human neurodegenerative disorders. Our previous study demonstrated the potent inhibition of lipopolysaccharide (LPS)-induced NO production in rat primary microglial cells by rhynchophylline (RIN) and isorhynchophylline (IRN), a pair of isomeric alkaloids of Uncaria rhynchophylla (Miq.) Jacks. that has been used in China for centuries as a "cognitive enhancer" as well as to treat strokes. We further investigated whether RIN and IRN effectively suppress release of proinflammatory cytokines in LPS-activated microglial cells and the underling molecular mechanism for the inhibition of microglial activation. RIN and IRN concentration-dependently attenuated LPS-induced production of proinflammatory cytokines such as TNF-alpha and IL-1beta as well as NO in mouse N9 microglial cells, with IRN showing more potent inhibition of microglial activation. The western blotting analysis indicated that the potential molecular mechanism for RIN or IRN-mediated attenuation was implicated in suppressions of iNOS protein level, phosphorylation of ERK and p38 MAPKs, and degradation of IkappaBalpha. In addition, the differential regulation of the three signaling pathways by two isomers was shown. Our results suggest that RIN and IRN may be effective therapeutic candidates for use in the treatment of neurodegenerative diseases accompanied by microglial activation.

Endothelium-dependent induction of vasorelaxation by the butanol extract of Phellinus igniarius in isolated rat aorta

The butanol extract of Phellinus igniarius (BPI) induced relaxation of the phenylephrin e-precontracted rat aorta in a dose-dependent manner, and its effect was abolished by the removal of functional endothelium. Pretreatment of the aortic tissues with N(G)-nitro-L-arginine methyl ester (L-NAME), methylene blue, or 1H-[1,2,4]-oxadiazole-[4,3-alpha]-quinoxalin1-one (ODQ) inhibited the vascular relaxation induced by BPI. BPI-induced vascular relaxations were also markedly attenuated by the addition of verapamil or diltiazem, while the relaxant effect of BPI was not blocked by pretreatment with indomethacine, glibenclamide, tetraethylammonium (TEA), atropine, or propranolol. Incubation of endothelium-intact rat aorta with BPI increased the production of cGMP in a dose-dependent manner. These results suggest that BPI dilates vascular smooth muscle via endothelium-dependent nitric oxide-cGMP signaling pathway, with the possible involvement of L-type Ca(2+) channels.

Vascular relaxation by the methanol extract of Sorbus cortex via NO-cGMP pathway

The methanol extract of Sorbus commixta cortex (MSC) induced relaxation of the phenylephrine-precontracted aorta in a dose-dependent manner, which was disappeared by removal of functional endothelium. Pretreatment of the aortic tissues with N(G)-nitro-L-arginine methyl ester (L-NAME), methylene blue, or 1H-[1,2,4]-oxadiazole-[4,3-alpha]-quinoxalin-1-one (ODQ) inhibited the vascular relaxation induced by MSC. MSC-induced vascular relaxations were also markedly attenuated by addition of verapamil or diltiazem, while the relaxant effect of MSC was not blocked by pretreatment with indomethacine, glibenclamide, tetraethylammonium (TEA), atropine, or propranolol, respectively. Incubation of endothelium-intact carotid arteries or of human umbilical vein endothelial cells (HUVECs) with MSC increased the production of guanosine 3',5'-cyclic monophosphate (cGMP). Moreover, MSC-induced cGMP production was effect was blocked by pretreatment with L-NAME or ODQ. These results suggest that MSC dilates vascular smooth muscle via endothelium-dependent nitric oxide-cGMP signaling pathway, possible involvement of L-type Ca(2+) channel.

Monoamine oxidase B (MAO-B) inhibition by active principles from Uncaria rhynchophylla

Attenuation of monoamine oxidase B (MAO-B) activity may provide protection against oxidative neurodegeneration. For this reason, inhibition of MAO-B activity is used as part of the treatment of Parkinson's and Alzheimer's patients. The hook of Uncaria rhynchophylla (Miq.) Jacks. (Rubiaceae) is a traditional Chinese herbal drug that is generally used to treat convulsive disorders. In this study, the fractionation and purification of Uncaria rhynchophylla extracts using a bioguided assay isolated two known compounds, (+)-catechin and (-)-epicatechin. The compounds inhibited MAO-B, as measured by an assay of rat brain MAO-B separated by electrophoresis on a 7.5% native polyacrylamide gel. The IC(50) values of (+)-catechin and (-)-epicatechin were 88.6 and 58.9 microM, respectively, and inhibition occurred in a dose-dependent manner, as measured by the fluorescence method. The Lineweaver-Burk plot revealed K(i) values for (+)-catechin and (-)-epicatechin of 74 and 21 microM, respectively. This suggests that these two compounds, isolated here for the first time from Uncaria rhynchophylla, might be able to protect against neurodegeneration in vitro, and, therefore, the molecular mechanism deserves further study. This finding may also increase interest in the health benefits of Uncaria rhynchophylla.

Neuroprotective herbs for stroke therapy in traditional eastern medicine

Traditional Eastern Medicine (TEM) has a long history in stroke therapy and its therapeutic efficacy has been confirmed by clinical studies. Extensive experience and abundant clinical data on TEM in stroke treatment have been accumulated over the past thousand years. Basic and clinical research in TEM constitutes a potentially rich source for new drug discovery and development with the integration of TEM and Western pharmacology. In recent years, many attempts have been made to document research data from extracts of composite formulas, single herbs, or single compounds from TEM herbs, according to orthodox pharmacological actions. This article reviews herbs and prescriptions that have been documented to have a neuroprotective effect in in vitro and in vivo ischemic model systems, and the neuroprotective compounds isolated from them. I also discuss the neuroprotective mechanisms of prescriptions, herbs, and single compounds relevant to the treatment of brain ischemia, including anti-oxidant, anti-excitotoxic, and anti-inflammatory effects.

Screening of vasorelaxant activity of some medicinal plants used in Oriental medicines

Hexane, ethylacetate (EtOAC), and n-butanol (n-BuOH) extracts of medicinal plants traditionally used in the East Asia, such as China, Korea, and Japan were screened for their vasorelaxant activity using isolated rat aorta. Among the 60 solvent-extracts from 20 medicinal plants, hexane and n-BuOH extracts of Diospyros kaki and Polygonum aviculare, hexane, EtOAC, and n-BuOH extracts of Magnolia liliflora, n-BuOH extract of Sorbus commixta, and EtOAC and n-BuOH extracts of Selaginella tamariscina were found to exhibit distinctive vasorelaxant activity. The activity disappeared by removal of functional endothelium or pre-treatment of the aortic tissues with N(G)-nitro-L-arginine methyl ester (L-NAME), which is an inhibitor of nitric oxide synthase. These findings suggest that the medicinal plants relax vascular smooth muscle via endothelium-dependent nitric oxide. These results will be useful to further analyze those medicinal plants that contain the vasorelaxant activity in order to identify the active principles.

Vitamins, Supplements, Herbal Medicines, and Arrhythmias

Nutritional and herbal supplements may have harmful or beneficial effects on arrhythmias. Potential supplements that may have antiarrhythmic activity include omega-3 polyunsaturated fatty acids (N-3 PUFA), coenzyme Q10, and carnitine. Clinical studies show that N-3 PUFA or fish oil supplementation appears to reduce mortality and sudden death. Coenzyme Q10, used in treatment of heart failure, and carnitine and its derivatives may have beneficial effects on arrhythmias, although clinical studies have been limited. Antioxidant supplements may be beneficial, but large studies with vitamin E have been disappointing in that it does not reduce mortality. Correction of electrolyte disturbances has been long advised and magnesium supplementation has been beneficial in the treatment of torsades de pointes and in some studies after cardiac surgery. However, routine electrolyte supplementation with empiric potassium or magnesium in non-deficient patients has not been convincingly beneficial. Several herbal supplements have also been promoted to have antiarrhythmic activity. However, clinical studies are lacking to support routine use of these herbal medications. In addition, some herbal supplements may cause serious proarrhythmia, and many supplements significantly interact with warfarin and digoxin.

Effects of bulbus Fritillaria water extract on blood pressure and renal functions in the L-NAME-induced hypertensive rats

A pharmacological inhibition of nitric oxide synthase (NOS) in rats produces renal vasoconstriction, renal dysfunction, and hypertension. The present study was aimed at investigating whether Bulbus Fritillaria water extract (BFWE) ameliorates NG-nitro-L-arginine methylester (L-NAME)-induced hypertension. Treatment of rats with L-NAME (60 mg/l drinking water, 4 weeks) caused a sustained increase in systolic blood pressure (SBP). The NO concentration in plasma and NO productions in the vascular tissues of the L-NAME-treated group were significantly reduced as compared with those in the control, whereas the expressions of NOS proteins were not altered. BFWE restored SBP to normal level in the L-NAME-treated hypertensive rats. Moreover, BFWE was able to preserve the vascular NO production and plasma NO metabolites concentration without changes of the expression NOS proteins. The renal functional parameters including urinary volume, sodium excretion, and creatinine clearance (Ccr) were significantly restored in rats co-treated with BFWE and L-NAME compared to the L-NAME-treated group. Taken together, these results suggest that BFWE prevents the increase of SBP in the L-NAME-induced hypertension that may have been caused by enhanced generation of vascular NO and amelioration of renal functions.

In vitro vasodilator mechanisms of the indole alkaloids rhynchophylline and isorhynchophylline, isolated from the hook of Uncaria rhynchophylla (Miquel)

Rhynchophylline (Rhy) and isorhynchophylline (Isorhy), indole alkaloids from Uncaria hooks, reportedly exert hypotensive and vasodilatory effects, but the mechanism of action is unclear. We therefore investigated the relaxant effects of these two isomeric alkaloids in rat arteries in vitro, in particular in respect of the various functional Ca2+ pathways. Both Rhy and Isorhy relaxed aortic rings precontracted with phenylephrine (PE, 1 microM) in a dose-dependent manner (3-300 microM). Removal of endothelium and preincubation with L-NAME (300 microM) slightly inhibited but did not prevent the relaxant response. These results indicate that Rhy and Isorhy act largely in an endothelium-independent manner. Unlike nicardipine, both alkaloids not only inhibited the contraction induced by 60 mM KCl (IC50 20-30 microM), but also that induced by PE and U46619, albeit to a lesser extent (IC50 100 and 200 microM, respectively). These results suggest that Rhy and Isorhy may act via multiple Ca2+ pathways. In contrast to their inhibitory effects on KCl-induced and receptor-mediated contractions, where both isomers were comparably potent, Rhy was more potent than Isorhy at higher concentrations (>100 microM) in inhibiting both caffeine (25 mM)- and cyclopiazonic acid (CPA, 30 microM)-induced contractions. Similar results observed with caffeine in Ca2+-containing medium were also observed in Ca2+-free medium. However, 0.1-0.3 microM nicardipine (which completely inhibited KCl-induced contraction) had no significant inhibitory effect on CPA-induced contractions. Taken together, these results indicate discrimination between these two isomers with respect to Ca2+-induced Ca2+ release and non-L-type Ca2+ channel, but not for IP3-induced Ca2+ release and L-type Ca2+ channels. Similar relaxant responses to KCl- and caffeine-induced contractions were seen when these two alkaloids were tested on the smaller mesenteric and renal arteries. In conclusion, the vasodilatory effects of Rhy and Isorhy are largely endothelium independent and are mediated by L-type Ca2+ channels. At higher concentrations, they also affect other Ca2+-handling pathways, although to a lesser extent. While there is no discrimination between the two isomers with respect to the contraction induced by KCl or agonists (PE and U46619), differential effects between Rhy and Isorhy were seen on caffeine- and CPA-induced contractions.

Choto-san prevents occurrence of stroke and prolongs life span in stroke-prone spontaneously hypertensive rats

The effects of long-term oral administration of choto-san (diao-teng-san in Chinese) extract on the occurrence of stroke and life span were investigated in stroke-prone spontaneously hypertensive rats (SHR-SPs). Twenty-four rats were ramdomized into three groups. From 8 weeks of age, 0.1% and 0.3% choto-san groups were given water containing 0.1% (150 mg/kg/day) and 0.3% (450 mg/kg/day) choto-san extract, respectively. A control group was given only water. The mean survival times of the control group, 0.1% and 0.3% choto-san groups were 122.1, 159.8 and 176.8 days, respectively. The percent survivals of both the 0.1% and 0.3% choto-san groups were significantly enhanced compared to the control (Kaplan-Meier analysis followed by log-rank test; 0.1% choto-san: p < 0.05; 0.3% choto-san: p < 0.05). Furthermore, the cumulative percent occurrence of neurological and behavioral signs accompying stroke in the 0.3% choto-san group was significantly inhibited compared to the control (p < 0.05). These results suggested that choto-san prevents the occurrence of stroke and prolongs the life span of SHR-SPs.

Effects of Cudrania tricuspidata water extract on blood pressure and renal functions in NO-dependent hypertension

A pharmacological inhibition of nitric oxide synthase (NOS) in rats for 4-6 weeks produces renal vasoconstriction, renal dysfunction, and severe hypertension. The present study was aimed at investigating whether Cudrania tricuspidata (C. tricuspidata) water extract ameliorates N(G)-Nitro-L-arginine methylester (L-NAME)-induced hypertension. Treatment of L-NAME (60 mg/L drinking water, 4 weeks) causes a sustained increase in systolic blood pressure (SBP). The concentration of plasma NO metabolites and NO/cGMP productions in the vascular tissues of the L-NAME-treated group were significantly reduced as compared with those in the control. C. tricuspidata water extract blocked increase of SBP in the L-NAME-treated group and restored SBP to normal level. Futhermore, C. tricuspidata water extract was able to preserve the vascular NO/cGMP production and plasma NO metabolites concentration. However, there are no changes in the expression of ecNOS and iNOS of thoracic aorta among the rats of control, L-NAME-treated group, and L-NAME and C. tricuspidata water extract co-treated group. The urinary sodium level, urine volume, and creatinine clearance were significantly higher in rats co-treated with C. tricuspidata water extract and L-NAME than in L-NAME-treated group. Taken together, these results suggest that C tricuspidata water extract prevents the increase of SBP in the L-NAME-induced hypertension that may have been caused by enhanced generation of vascular NO/cGMP.

Geissoschizine methyl ether, an indole alkaloid extracted from Uncariae Ramulus et Uncus, is a potent vasorelaxant of isolated rat aorta

Effects of geissoschizine methyl ether, an indole alkaloid isolated from the hook of Uncariae Ramulus et Uncus, on vascular responses were examined using isolated strips of rat aorta. Geissoschizine methyl ether (10(-7)-10(-4) M) relaxed norepinephrine (5x10(-8) M)-induced contraction in a dose-dependent manner. The potency (50% efficacy concentration, EC(50)=0.744 microM) was approximately 14 times greater than that (EC(50)=10.6 microM) of hirsutine, one of the indole alkaloids isolated from Uncariae Ramulus et Uncus that demonstrates a vasorelaxant effect by Ca(2+)-channel blocking. The vasorelaxant effect of geissoschizine methyl ether found at the lower concentrations (10(-7)-3x10(-6) M) on the norepinephrine-induced contraction was abolished by pretreatment with N(G)-nitro-L-arginine (10(-4) M), an inhibitor of nitric oxide synthesis, or by denuding aortas of endothelium, while the effects at the higher concentrations (10(-5)-10(-4) M) were not completely prevented by either N(G)-nitro-L-arginine and deendothelialization. Furthermore, geissoschizine methyl ether did not relax high K(+)-, Ca(2+)- and a Ca(2+)-channel agonist Bay K8644-induced contractions at the lower concentrations that markedly relaxed the norepinephrine-induced contractions, while the higher concentrations of geissoschizine methyl ether relaxed the high K(+)-, Ca(2+)- and Bay K8644-induced contractions. These results suggest that the vasorelaxant effect of geissoschizine methyl ether is composed of two different mechanisms: endothelial dependency with nitric oxide and endothelial independency with voltage-dependent Ca(2+)-channel blocking.

Neuroprotection by methanol extract of Uncaria rhynchophylla against global cerebral ischemia in rats

In traditional Oriental medicine, Uncaria rhynchophylla has been used to lower blood pressure and to relieve various neurological symptoms. However, scientific evidence related to its effectiveness or precise modes of action has not been available. Thus, in the current study, we evaluated neuroprotective effects of U. rhynchophylla after transient global ischemia using 4-vessel occlusion model in rats. Methanol extract of U. rhynchophylla administered intraperitoneally (100-1000 mg/kg at 0 and 90 min after reperfusion) significantly protected hippocampal CA1 neurons against 10 min transient forebrain ischemia. Measurement of neuronal cell density in CA1 region at 7 days after ischemia by Nissl staining revealed more than 70% protection in U. rhynchophylla-treated rats compared to saline-treated animals. In U. rhynchophylla-treated animals, induction of cyclooxygenase-2 in hippocampus at 24 hr after ischemia was significantly inhibited at both mRNA and protein levels. Furthermore, U. rhynchophylla extract inhibited TNF-alpha and nitric oxide production in BV-2 mouse microglial cells in vitro. These anti-inflammatory actions of U. rhynchophylla extract may contribute to its neuroprotective effects.

Effects of Choto-san on hemorheological factors and vascular function in stroke-prone spontaneously hypertensive rats

Choto-san is a formula used for the treatment of headache and vertigo. Recently it has often also been used for hypertension and dementia. One of the mechanisms involved is thought to be the improvement of blood circulation, but the details are still unclear. In this study, the effect of Chotosan was studied on nitric oxide (NO) function, hemorheological factors and endothelial function in stroke-prone spontaneously hypertensive rats (SHR-SP). Rats were given Choto-san in drinking water for eight weeks. Body weight, blood pressure, serum NO2-/NO3-, lipid peroxides, blood viscosity, erythrocyte deformability and endothelium-dependent/-independent relaxation were measured. The results indicated that Choto-san caused a decrease in blood pressure and an increase in erythrocyte deformability and NO function. Blood viscosity was not changed. Furthermore, endothelium-dependent relaxation by acetylcholine was significantly increased as compared to control. In this study, it was supposed that Choto-san had a protective effect on the endothelium. SHR-SP is a useful model for human brain stroke, and Choto-san showed a protective effect against cerebral vascular injury in the susceptible rat.

Effects of Choto-san on microcirculation, serum nitric oxide and lipid peroxides in patients with asymptomatic cerebral infarction

The effects of Choto-san on microcirculation, serum nitric oxide and lipid peroxides were investigated. Fifteen patients with asymptomatic cerebral infarction were investigated before and after a four-week administration of Choto-san. The variables of microcirculation of the bulbar conjunctiva, which were the internal diameter of vessels, flow velocity and flow volume rate, were increased. Serum NO2(-)/NO3(-) tended to increase and lipid peroxides were decreased. Total serum cholesterol was also decreased. These results suggest that Choto-san may improve microcirculation affected by endothelial function and fat metabolism.

Vasodilator effect of extract prepared from Uncariae ramulus on isolated rat aorta

Uncariae ramulus et Uncus (URE) has a vasodilator effect. Its mechanism consists of not only endothelium-independent relaxation with Ca2+ channel blocking effect but also endothelium-dependent relaxation with nitric oxide. The active components are alkaloids and tannin contained in Uncariae ramulus et Uncus. They also show a superoxide dismutase-like effect and suppressed vasocontraction induced by xanthine and xanthine oxidase. These mechanisms may also influence vasodilatation by Uncariae ramulus et Uncus in vivo.

Effect of Uncariae ramulus et Uncus on endothelium in spontaneously hypertensive rats

The protective effect of the extract of Uncariae ramulus et Uncus (URE) against endothelium disorder due to hypertension was investigated. We administered low (150 mg/kg/day) and high (450 mg/kg/day) doses of URE orally to spontaneously hypertensive rats for 8 weeks. Endothelium dependent vasodilatation by acetylcholine increased significantly in the high URE group compared with the control group. Endothelium dependent vasocontraction by xanthine oxidase decreased significantly in the high URE group compared with the control group. Serum NO2-/NO3- were tended to increase in the high URE group. It is suggested that URE may have a protective effect for the endothelium against the influence of hypertension.

Anticonvulsive and free radical scavenging actions of two herbs, Uncaria rhynchophylla (MIQ) Jack and Gastrodia elata Bl., in kainic acid-treated rats

Uncaria rhynchophylla (Miq.) Jack (UR) and Gastrodia elata BI. (GE) are traditional Chinese herbs that are usually used in combination to treat convulsive disorders, such as epilepsy, in China. The aim of this study was to compare the anticonvulsive and free radical scavenging activities of UR alone and UR in combination with GE in rats. For the in vitro studies, brain tissues from 6 male Sprague-Dawley (SD) rats were treated with 120 microg/ml kainic acid (KA), with or without varied concentrations of UR or UR plus GE. For the in vivo studies, male SD rats (6 per group) received intraperitoneal (i.p.) injection of KA 12 mg/kg to induce epileptic seizures and generation of free radicals, with or without oral administration of UR 1 g/kg alone or UR 1 g/kg plus GE 1 g/kg. Epileptic seizures were verified by behavioral observations, and electroencephalography (EEG) and electromyography (EMG) recordings. These results showed that UR alone decreased KA-induced lipid peroxide levels in vitro, whereas UR plus GE did not produce a greater effect than UR alone. UR significantly reduced counts of wet dog shakes (WDS), paw tremor (PT) and facial myoclonia (FM) in KA-treated rats and significantly delayed the onset time of WDS, from 27 min in the control group to 40 min in the UR group. UR plus GE did not inhibit seizures more effectively than UR alone, but did further prolong the onset time of WDS to 63 min (P < 0.05 vs. UR alone). UR alone reduced the levels of free radicals in vivo, as measured by lipid peroxidation in the brain and luminol-chemiluminescence (CL) counts and lucigenin-CL counts in the peripheral whole blood, but the combination of GE and UR did not reduce free radical levels more markedly than UR alone. In conclusion, our results indicate that UR has anticonvulsive and free radical scavenging activities, and UR combined with GE exhibit greater inhibition on the onset time of WDS than UR alone. These findings suggest that the anticonvulsive effects of UR and GE may be synergistic. However, the mechanism of interaction between UR and GE remains unknown.

Efficacy of Choto-san on vascular dementia and the protective effect of the hooks and stems of Uncaria sinensis on glutamate-induced neuronal death

Two different multicenter studies on the efficacy of Choto-san on patients with vascular dementia, one a well-controlled but non-double blind (60 patients), the other a double-blind controlled study (139 patients), were performed. In the well-controlled study, Choto-san was superior in global improvement rating, utility rating and improvement of subjective symptoms, psychiatric symptoms and disturbance in daily living activities. In the double-blind study, with more objective criteria than the well-controlled study, Choto-san was also superior in global improvement rating, utility rating and improvement of subjective symptoms, psychiatric symptoms and disturbance in daily living activities. These results suggest that Choto-san is effective in the treatment of vascular dementia. Uncaria sinensis (OLIV.) HAVIL. (US) is the main medicinal plant composing Choto-san. Glutamate-induced cell death of cultured cerebellar granule cells was protected by the application of water extract of US in a dose-dependent manner, and concentrations of 10(-5) to 10(-4) g/ml had a significant effect compared to exposure to glutamate only. Further, the increase of 45Ca2+ influx into cells by glutamate was also blocked by the water extract in a dose-dependent manner. These results suggest that US has a protective effect on glutamate-induced neuronal death in cultured cerebellar granule cells through the inhibition of Ca2+ influx.

Evaluation of the protective effects of alkaloids isolated from the hooks and stems of Uncaria sinensis on glutamate-induced neuronal death in cultured cerebellar granule cells from rats

We have previously shown that an aqueous extract of the hooks and stems of Uncaria sinensis (Oliv.) Havil., Uncariae Uncus Cum Ramulusis, protects against glutamate-induced neuronal death in cultured cerebellar granule cells by inhibition of Ca2+ influx. Because it is not known which components of Uncaria sinensis are active, in this study we have evaluated, by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) staining, the neuroprotective effects of the oxyindole alkaloids corynoxeine, rhynchophylline, isorhynchophylline and isocorynoxeine, and the indole alkaloids geissoschizine methyl ether, hirsuteine and hirsutine, isolated from the hooks and stems of Uncaria sinensis, on glutamate-induced cell death. We also investigated the inhibitory effects of the compounds on 45Ca2+ influx in cultured rat cerebellar granule cells. Cell viability evaluated by the MTT assay was significantly increased by application of rhynchophylline (10(-3) M), isorhynchophylline (10(-4)-10(-3) M), isocorynoxeine (10(-4)-10(-3) M), hirsuteine (10(-4)-3 x 10(-4) M) or hirsutine (10(-4)-3 x 10(-4) M) compared with exposure to glutamate only, with the effect of isorhynchophylline being the strongest. The increased 45Ca2+ influx into cells induced by glutamate was significantly inhibited by administration of rhynchophylline (10(-3) M), isorhynchophylline (3 x 10(-4)-10(-3) M), isocorynoxeine (3 x 10(-4)-10(-3) M), geissoschizine methyl ether (10(-3) M), hirsuteine (3 x 10(-4)-10(-3) M) or hirsutine (3 x 10(-4)-10(-3) M). These results suggest that oxyindole alkaloids such as isorhynchophylline, isocorynoxeine and rhynchophylline and indole alkaloids such as hirsuteine and hirsutine are the active components of the hooks and stems of Uncaria sinensis which protect against glutamate-induced neuronal death in cultured cerebellar granule cells by inhibition of Ca2+ influx.