Content Determination and Release Characteristics of Six Components in the Different Phases of "Glycyrrhizaglabra-Nux vomica" Decoction by UPLC-MS/MS.

The decoction turns into a complex multiphase system following exposure to high temperature and a complex chemical environment. However, the differences in the concentration of key active ingredients in different phase states and the release of drugs in sedimentary phase have yet to be elucidated. A simple ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the simultaneous quantitative determination of brucine, strychnine, liquiritin, isoliquiritin, isoliquiritigenin and glycyrrhizic acid concentrations and it was applied to compare the content of different phases and measure the release characteristics of the sedimentary phase in "Glycyrrhiza glabra-Nux vomica" decoction (NGD). The results show that the method's selectivity, precision (intraday and interday ≤ 2%), matrix effect (101-108%), recovery and stability results were acceptable according to the guidelines. The method is sensitive and reliable. The content determination results show that the most toxic strychnine in the sedimentary phase accounted for 75.70% of the total components. The different components exhibited differential release in different media, and its components were released in the artificial intestinal fluid up to 81.02% in 12 h. Several components conformed to the primary kinetic model and the Ritger-Peppas model, and the most toxic compound exhibited slow release, thus conforming to the Ritger-Peppas model. This study provides a standard of reference for studies investigating reduction in toxicity of the combination of Glycyrrhiza glabra (Glycyrrhiza glabra L.) and Nux vomica (Strychnos nux-vomica L.).

Alkaloids from nux vomica suppresses colon cancer cell growth through Wnt/ß-catenin signaling pathway.

Brucine and Strychnine are alkaloids isolated from the seeds of Strychnos nux vomica L., which have long been used as a traditional medicine for the treatment of tumor. However, the effect of Brucine and Strychnine on colorectal cancer (CRC) and the underlying molecular mechanism remain unclear. In the present study, Brucine and Strychnine displayed profound inhibitory effects on the growth of human colon cancer cells. The results of flow cytometric analysis demonstrated that the two alkaloids induced cellular apoptosis. Moreover, the growth of DLD1 xenografted tumors in nude mice was significantly suppressed in the Brucine or Strychnine treated group. Mechanistically, the Wnt/ß-catenin is involved in this phenomenon, which is characterized by significantly increased expression of DKK1 and APC, whereas decreased expression of ß-catenin, c-Myc, and p-LRP6 in CRC cells as well as tumor tissues. Collectively, Brucine and Strychnine have targeted inhibition for colon cancer proliferation both in vitro and in vivo, and it is valuable for future exploitation and utilization as an antitumor agent of CRC.

Brucine Suppresses Vasculogenic Mimicry in Human Triple-Negative Breast Cancer Cell Line MDA-MB-231.

Vasculogenic mimicry (VM) with the pattern of endothelial independent tubular structure formation lined by aggressive tumor cells mimics regular tumor blood vessels to ensure robust blood supply and correlates with the proliferation, invasion, metastasis, and poor prognosis of malignant tumors, which was demonstrated to be a major obstacle for resistance to antiangiogenesis therapy. Therefore, it is urgent to discover methods to abrogate the VM formation of tumors, which possesses important practical significance for improving tumor therapy. Brucine is a traditional medicinal herb extracted from seeds of Strychnos nux-vomica L. (Loganiaceae) exhibiting antitumor activity in a variety of cancer models. In the present study, the effect of brucine on vasculogenic mimicry and the related mechanism are to be investigated. We demonstrated that, in a triple-negative breast cancer cell line MDA-MB-231, brucine induced a dose-dependent inhibitory effect on cell proliferation along with apoptosis induction at higher concentrations. The further study showed that brucine inhibited cell migration and invasion with a dose-dependent manner. Our results for the first time indicated that brucine could disrupt F-actin cytoskeleton and microtubule structure, thereby impairing hallmarks of aggressive tumors, like migration, invasion, and holding a possibility of suppressing vasculogenic mimicry. Hence, the inhibitory effect of brucine on vasculogenic mimicry was further verified. The results illustrated that brucine significantly suppressed vasculogenic mimicry tube formation with a dose-dependent effect indicated by the change of the number of tubules, intersections, and mean length of tubules. The in-depth molecular mechanism of vasculogenic mimicry suppression induced by brucine was finally suggested. It was demonstrated that brucine inhibited vasculogenic mimicry which might be through the downregulation of erythropoietin-producing hepatocellular carcinoma-A2 and matrix metalloproteinase-2 and metalloproteinase-9.

Virtual screening of natural anti-filarial compounds against glutathione-S-transferase of Brugia malayi and Wuchereria bancrofti.

Glutathione-S-transferase also referred as GST is one of the major detoxification enzymes in parasitic helminths. The crucial role played by GST in various chronic infections has been well reported. The dependence of nematodes on detoxification enzymes to maintain their survival within the host established the crucial role of GST in filariasis and other related diseases. Hence, this well-established role of GST in filariasis along with its greater nonhomology with its human counterpart makes it an important therapeutic drug target. Here in this study, we have tried to explore the inhibitory potential of some of the well-reported natural ant-filarial compounds against the GST from Wuchereria bancrofti (W.bancrofti) and Brugia malayi (B.malayi). In silico virtual screening, approach was used to screen the selected natural compounds against GST from W.bancrofti and B.malayi. On the basis of our results, here we are reporting some of the natural compounds which were found to be very effective against GSTs. Along with we have also revealed the characteristic of the active site of BmGST and WbGST and the role of important active site residues involve in the binding of natural compounds within the active site of GSTs. This information will oped doors for using natural compounds as anti-filarial therapy and will also be helpful for future drug discovery.

In vivo Antimalarial and Antitrypanosomal Activity of Strychnogucine B, a Bisindole Alkaloid from Strychnos icaja.

Strychnogucine B is a bisindole alkaloid previously isolated from Strychnos icaja that possesses promising in vitro antiplasmodial properties. This compound was synthesized in four steps from (-)-strychnine. As no acute toxicity was observed at the highest tested cumulative dose of 60 mg/kg, its in vivo antimalarial activity was determined intraperitoneally at 30 mg/kg/d in a Plasmodium berghei murine model. In the Peters's 4-d suppressive test, this alkaloid suppressed the parasitaemia by almost 36% on day 5 and 60% on day 7 compared to vehicle-treated mice. In addition to this interesting antimalarial activity, it showed moderate in vitro antitrypanosomal activity but no in vivo activity in an acute Trypanosoma brucei model. It was also inactive in vitro on Leishmania mexicana promastigotes. This highlights its selective antimalarial efficacy and leads to further investigation to assess its potential as new antimalarial lead compound.

Microdialysis combined with RRLC-MS/MS for the pharmacokinetics of two major alkaloids of Bi qi capsule and the potential roles of P-gp and BCRP on their penetration.

Bi qi capsule (BQC) is a traditional Chinese medicine prescription that is clinically used for the treatment of rheumatoid arthritis. Strychnine and brucine, as two typical kinds of alkaloids, are the primary active and neurotoxic constituents of BQC. In this study, a sensitive and reliable rapid resolution liquid chromatography-tandem mass spectrometry (RRLC-MS/MS) quantitative method was used to determine the concentrations of brucine and strychnine in rat brain and blood dialysates. The blood-brain barrier (BBB) penetration of free brucine and strychnine and their pharmacokinetic characteristics were investigated by the validated RRLC-MS/MS method coupled with in vivo microdialysis for the first time. The dialysate brain-blood AUC ratios of brucine were 0.098, 0.44 and 0.40 respectively at 0.4, 0.8 and 1.6 g kg-1 doses of BQC, and the dialysate brain-blood AUC ratios of strychnine were 0.20, 1.25 and 2.06 respectively at 0.4, 0.8 and 1.6 g kg-1 doses of BQC. The high brain-blood AUC ratios of brucine and strychnine were observed in medium and high dose groups of BQC. In addition, the effects of P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) on brucine and strychnine across BBB were also studied using the above method as well as molecular docking. The results prompted that brucine was the substrate of P-gp, and strychnine might be the inhibitor of P-gp. Brucine and strychnine showed high brain penetration, so it is very important to well control the clinic dosage of BQC and manufactory quality for avoiding the side effects and obtaining good therapeutic efficacy. Our study could be further used in investigating BBB penetration for other drugs caused neurotoxicity.

Brucine suppresses breast cancer metastasis via inhibiting epithelial mesenchymal transition and matrix metalloproteinases expressions.

OBJECTIVE: To examine the effect of brucine on the migration, invasion, adhesion and expressions of epithelial-to-mesenchymal transition (EMT) markers and matrix metalloproteinases (MMPs) in the highly metastatic breast cancer cell lines MDA-MB-231 and Hs578-T. METHODS: MDA-MB-231 and Hs578-T cells were divided to 4 groups: the control group (0.1% DMSO), and 25, 50 and 100 µmol/L brucine groups. The cell viability was determined using a CellTiter-Glo® luminescent cell viability. The scratch wound healing assay and tanswell migration assay were used to determine the migration ability of these cells treated by different concentrations of brucine. The proliferation rate, invasive potential and adhesive ability were respectively performed by colony formation assay, transwell invasion assay and adhension assay. The protein and mRNA expressions of EMT biomarkers, MMP-2 and MMP-9 were investigated by real-time reverse transcription polymerase chain reaction and Western blot. RESULTS: Compared with the control group, brucine had little effect on cell viability or proliferation (P>0.05), but led to a dose-dependent decrease on migration, invasion, adhension of MDA-MB-231 and Hs578-T cells (P<0.01). Furthermore, brucine increased the protein and mRNA levels of EMT markers such as E-cadherin and ß-catenin in MDA-MB-231 and Hs578-T cells, and decreased the protein and mRNA levels of mesenychmal markers such as vimentin and fibronectin, as well as the expressions of MMP-2 and MMP-9 (all P<0.01). CONCLUSION: Brucine inhibited triple negative breast cancer cells metastasis potentially through EMT reversion and MMP-2 and MMP-9 inhibition.

An LC-MS/MS method for determination of bioactive components of liquorice and Semen Strychni in rat plasma: Application to a pharmacokinetics study.

Semen Strychni is known for its treatment of rheumatic arthritis with a low therapeutic index. Liquorice contributes a lot in herb detoxification according to the traditional Chinese medicine theory. A simple, rapid, and sensitive liquid chromatography-mass spectrometric method (LC-MS) was developed and validated for simultaneous determination of main bioactive ingredients in liquorice and Semen Strychni in rat plasma. Using moclobemide and cyproterone acetate as the internal standards, the analytes were pretreated via protein precipitation with methanol. An Ultimate AQ-C18 column (3.0 µm, 3.0 × 100 mm) was employed for chromatographic separation, combining with gradient elution. The mobile phase consisted of 0.07% formic acid and 0.12% ammonium acetate in aqueous phase (A) and acetonitrile in organic phase (B). The elution program was as follows: 0-0.5 min, 20% B; 0.5-1 min, 20-60% B; 1-7 min, 60-85% B; and 7-7.5 min, returned to 20% B, then continued to 12 min. Selected reaction monitoring was performed in both positive and negative ESI. Positive mode was adopted for detection of strychnine, brucine, and moclobemide, while negative mode was used for glycyrrhizic acid, glycyrrhetinic acid, liquiritigenin, isoliquiritigenin, liquiritin, and cyproterone acetate. The method was validated for specificity, linearity, matrix effect, recovery, precision, accuracy, and stability. The results show that this method is sensitive, accurate and robust for biological matrix analysis. Moreover, the proposed method was applied to a pharmacokinetic study in Sprague-Dawley rats for investigating the mechanism of which liquorice detoxifies Semen Strychni.

Exploring ß-Tubulin Inhibitors from Plant Origin using Computational Approach.

INTRODUCTION: ß-Tubulin is an important target for the binding of anti-cancer drugs, in particular, paclitaxel (taxol), vinblastine and epothilone. However, mutations in ß-tubulin structure give resistance to chemotherapeutic agents. Notably, mutations at R306C, F270 V, L217R, L228F, A185T and A248V positions in ß-tubulin give high resistance for paclitaxel binding. OBJECTIVE: To discover novel inhibitors of ß-tubulin from natural sources, particularly alkaloids, using a virtual screening approach. METHODOLOGY: A virtual screening approach was employed to find potent lead molecules from the Naturally-occurring Plant-based Anti-cancer Compound-activity Target (NPACT) database. Alkaloids have great potential to be anti-cancer agents. Therefore, we have screened all alkaloids from a total of 1574 molecules from the NPACT database for our study. Initially, Molinspiration and DataWarrior programs were utilised to calculate pharmacokinetics and toxicity risks of the alkaloids, respectively. Subsequently, AutoDock algorithm was employed to understand the binding efficiency of alkaloids against ß-tubulin. The binding affinity of the docked complex was confirmed by means of an intermolecular interaction study. Moreover, oral toxicity was predicted by using ProTox program. Further, metabolising capacity of drugs was studied by using SmartCYP software. Additionally, scaffold analysis was done with the help of scaffold trees and dendrograms, providing knowledge about the building blocks for parent-compound synthesis. RESULTS: Overall, the results of our computational analysis indicate that isostrychnine, obtained from Strychnosnux-vomica, satisfies pharmacokinetic and bioavailability properties, binds efficiently with ß-tubulin. Thus, it could be a promising lead for the treatment of paclitaxel resistant cancer types. CONCLUSION: This is the first observation of inhibitory activity of isostrychnine against ß-tubulin and warrants further experimental investigation. Copyright © 2016 John Wiley & Sons, Ltd.

Determination of strychnine, brucine, strychnine N-oxide, and brucine N-oxide in plasma samples after the oral administration of processed semen strychni extract by high-performance liquid chromatography with ultrasound-assisted mixed cloud point extraction.

A sensitive and efficient mixed cloud point extraction combined with high-performance liquid chromatography was developed for the simultaneous separation and determination of four alkaloids (strychnine, strychnine N-oxide, brucine, and brucine N-oxide) in plasma after the oral administration of processed semen strychni extract. Tergitol TMN-6 and cetyl-trimethyl ammonium bromide were chosen as the mixed surfactants, and ultrasound was employed to enhance the extraction efficiency. Some important parameters affecting the mixed cloud point extraction efficiency, such as the content of Tergitol TMN-6 and cetyl-trimethyl ammonium bromide, pH, salt effect, extraction temperature, and ultrasound time were studied and optimized. Under optimum conditions, the linear range of four alkaloids was from 1.0 to 1000 ng/mL. All correlation coefficients of the calibration curves were higher than 0.9993. The intraday and interday precision were below 8.65% and the limits of detection for the four alkaloids were less than 1.0 ng/mL (S/N = 3).

Effects of pulsatile electrical stimulation of the round window on central hyperactivity after cochlear trauma in guinea pig.

Partial hearing loss induced by acoustic trauma has been shown in animal models to result in an increased spontaneous firing rate in central auditory structures. This so-called hyperactivity has been suggested to be involved in the generation of tinnitus, a phantom auditory sensation. Although there is no universal cure for tinnitus, electrical stimulation of the cochlea, as achieved by a cochlear implant, can result in significant reduction of the tinnitus percept. However, the mechanism by which this tinnitus suppression occurs is as yet unknown and furthermore cochlear implantation may not be an optimal treatment option for tinnitus sufferers who are not profoundly deaf. A better understanding of the mechanism of tinnitus suppression by electrical stimulation of the cochlea, may lead to the development of more specialised devices for those for whom a cochlear implant is not appropriate. This study aimed to investigate the effects of electrical stimulation in the form of brief biphasic shocks delivered to the round window of the cochlea on the spontaneous firing rates of hyperactive inferior colliculus neurons following acoustic trauma in guinea pigs. Effects during the stimulation itself included both inhibition and excitation but spontaneous firing was suppressed for up to hundreds of ms after the cessation of the shock train in all sampled hyperactive neurons. Pharmacological block of olivocochlear efferent action on outer hair cells did not eliminate the prolonged suppression observed in inferior colliculus neurons, and it is therefore likely that activation of the afferent pathways is responsible for the central effects observed.

Preparation of molecularly imprinted polymers for strychnine by precipitation polymerization and multistep swelling and polymerization and their application for the selective extraction of strychnine from nux-vomica extract powder.

Monodisperse molecularly imprinted polymers for strychnine were prepared by precipitation polymerization and multistep swelling and polymerization, respectively. In precipitation polymerization, methacrylic acid and divinylbenzene were used as a functional monomer and crosslinker, respectively, while in multistep swelling and polymerization, methacrylic acid and ethylene glycol dimethacrylate were used as a functional monomer and crosslinker, respectively. The retention and molecular recognition properties of the molecularly imprinted polymers prepared by both methods for strychnine were evaluated using a mixture of sodium phosphate buffer and acetonitrile as a mobile phase by liquid chromatography. In addition to shape recognition, ionic and hydrophobic interactions could affect the retention of strychnine in low acetonitrile content. Furthermore, molecularly imprinted polymers prepared by both methods could selectively recognize strychnine among solutes tested. The retention factors and imprinting factors of strychnine on the molecularly imprinted polymer prepared by precipitation polymerization were 220 and 58, respectively, using 20 mM sodium phosphate buffer (pH 6.0)/acetonitrile (50:50, v/v) as a mobile phase, and those on the molecularly imprinted polymer prepared by multistep swelling and polymerization were 73 and 4.5. These results indicate that precipitation polymerization is suitable for the preparation of a molecularly imprinted polymer for strychnine. Furthermore, the molecularly imprinted polymer could be successfully applied for selective extraction of strychnine in nux-vomica extract powder.

Zebrafish model for assessing induced organ toxicity by Strychnos nux-vomica.

OBJECTIVE: To assess the acute organ toxicity of Strychnos nux-vomica with zebrafish model visually. METHODS: To assess acute toxicity, we initially determined the lethal concentration after Strychnos nux-vomica treatment for 24 h. Zebrafish was treated with five concentrations ≦ LC10 for 24 h, and the effects of Strychnos nux-vomica on morphology, function of heart, central nervous system, liver, kidney and organ-specific cell death were assessed. Next, we assessed the reversibility of toxic effect. RESULTS: Strychnos nux-vomica has an effect on the different organs of zebrafish, including heart, central nervous system, liver, and kidney, and cadiotoxicity induced by Strychnos nux-vomica was reversible to some extent. CONCLUSION: Zebrafish model is suitable for confirming the toxic target organs for Chinese traditional medicine.

Isostrychnine synthesis mediated by hypervalent iodine reagent.

Althought there are several reported synthetic routes to strychnine, one of the most widely recognized alkaloids, we report an unexplored route with an oxidative dearomatizing process mediated by hypervalent iodine as the key step. The new syntheses of isostrychnine and strychnine have been achieved from an readily available phenol in nine and ten steps. In addition to the key step, these syntheses involve an aza Michael-ether-enol tandem transformation, two heck type cyclizations, a reductive isomerization, and a double reductive amination in cascade leading to the alkaloid main core.

Brucine suppresses ethanol intake and preference in alcohol-preferring Fawn-Hooded rats.

AIM: Brucine (BRU) extracted from the seeds of Strychnos nux-vomica L is glycine receptor antagonist. We hypothesize that BRU may modify alcohol consumption by acting at glycine receptors, and evaluated the pharmacodynamic profiles and adverse effects of BRU in rat models of alcohol abuse. METHODS: Alcohol-preferring Fawn-Hooded (FH/Wjd) rats were administered BRU (10, 20 or 30 mg/kg, sc). The effects of BRU on alcohol consumption were examined in ethanol 2-bottle-choice drinking paradigm, ethanol/sucrose operant self-administration paradigm and 5-d ethanol deprivation test. In addition, open field test was used to assess the general locomotor activity of FH/Wjd rats, and conditioned place preference (CPP) was conducted to assess conditioned reinforcing effect. RESULTS: In ethanol 2-bottle-choice drinking paradigm, treatment with BRU for 10 consecutive days dose-dependently decreased the ethanol intake associated with a compensatory increase of water intake, but unchanged the daily total fluid intake and body weight. In ethanol/sucrose operant self-administration paradigms, BRU (30 mg/kg) administered before each testing session significantly decreased the number of lever presses for ethanol and the ethanol intake, without affecting the number of sucrose (10%) responses, total sucrose intake, and the number of lever presses for water. Acute treatment with BRU (30 mg/kg) completely suppressed the deprivation-induced elevation of ethanol consumption. Treatment with BRU (10, 20, and 30 mg/kg) did not alter locomotion of FH/Wjd rats, nor did it produce place preference or aversion. CONCLUSION: BRU selectively decreases ethanol consumption with minimal adverse effects. Therefore, BRU may represent a new pharmacotherapy for alcoholism.

Pharmacological evaluation of total alkaloids from nux vomica: effect of reducing strychnine contents.

The aim of the study was to investigate the possibility of improving the therapeutic efficacy of the total alkaloid fraction (TAF) extracted from processed nux vomica by reducing the strychnine contents. Most strychnine was removed from TAF to obtain the modified total alkaloid fraction (MTAF). The toxicity and pharmacokinetics of TAF and MTAF were further investigated and compared besides their antitumor, analgesic and anti-inflammatory activities. The results showed that the ratios of brucine to strychnine were 1:2.05 and 2.2:1 for TAF and MTAF, respectively, and the toxicity of TAF was about 3.17-fold higher than that of MTAF. Compared to brucine alone, the elimination of brucine was found to be inhibited by other alkaloids in TAF or MTAF except strychnine. Significantly increased pharmacological activities when administered by the oral route were obtained with MTAF in comparison to TAF and nux vomica powder (NVP). In summary, MTAF might replace NVP and TAF in the clinical application of Chinese medicine to obtain much higher efficacy.

Brucine-loaded liposomes composed of HSPC and DPPC at different ratios: in vitro and in vivo evaluation.

OBJECTIVE: The objective of this study is to test the hypothesis that the phase transition temperature (T(m)), the main property of liposomes, can be easily controlled by changing the molar ratio of hydrogenated soy phosphatidylcholine (HSPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphacholine (DPPC) after drug encapsulation. MATERIALS AND METHODS: Brucine, an antitumor alkaloid, was encapsulated into the liposomes with different HSPC/DPPC compositions. The T(m)s of the brucine-loaded liposomes (BLs) were determined by differential scanning calorimetry (DSC). Then the physicochemical properties and pharmacokinetics of the BLs with different HSPC/DPPC compositions were investigated and compared. RESULTS: The results of DSC revealed that HSPC and DPPC can combine into one phase. The findings of molecular modeling study suggested that HSPC interacts with DPPC via electrostatic interaction. The molar ratio of HSPC/DPPC influenced the sizes of BLs but had little effect on the entrapment efficiency (EE). The stability of BLs was improved with the increase of the HSPC ratios, especially with the presence of plasma. Following i.v. administration, it was found that AUC values of BLs in vivo were directly related to the HSPC/DPPC ratios of BLs, namely the T(m)s of BLs. DISCUSSION: The behavior of liposomes, especially in vivo pharmacokinetic behavior, can be controlled by the modification of T(m). CONCLUSION: The characterization of BLs in vitro and in vivo had demonstrated that the Tm could be flexibly modified for liposomes composed of both HSPC and DPPC. Using HSPC/DPPC composition may be an efficient strategy to control the T(m), thus control the in vivo pharmacokinetic behavior, of BLs.

In vitro metabolism of brucine by human liver microsomes and its interactions with CYP substrates.

Brucine, one of the main active ingredients in semen Strychni, has been included in many oral prescriptions of traditional Chinese medicine. In this study, we investigated the in vitro metabolism of brucine by human liver microsomes (HLMs) and the metabolic interactions of brucine with the substrates of cytochrome P450 (CYP450). Brucine was incubated with HLMs or CYP3A4 and then analysed by Liquid chromatography/mass spectrometry. The Km and Vmax values for HLMs were 30.53±3.14µM and 0.08±0.0029nmol/mg protein/min, respectively, while the corresponding values for CYP3A4 were 20.12±3.05µM and 6.40±0.21nmol/nmol P450/min. CYP3A4 may be the major enzyme responsible for brucine metabolism in HLMs, other human isoforms of CYP showed minimal or no effect on brucine metabolism. The inhibitory action of brucine was observed in CYP3A4 for the 1'-hydroxylation of midazolam, with inhibitory concentration 50 (IC50) of 8.4-fold higher than specific inhibitors in HLMs. Furthermore, brucine significantly inhibited the CYP3A4-catalyzed midazolam 1'-hydroxylation (Ki=2.14µM) at a concentration lower than 10µM, but no obvious inhibitory effects were observed on other CYP substrates (IC50>50µM). These results suggest that brucine has the potential to interact with a wide range of xenobiotics and endogenous chemicals especially CYP3A4 substrates.

[Brucine chitosan thermosensitive hydrogel for intra-articular injection].

The aim of this study was to develop a sustained release converse thermosensitive hydrogel for intra-articular injection using chitosan-glycerol-borax as matrix, its physical properties and biocompatibility were investigated. Taking gelation time and gelation condition as index, the influence of concentration of chitosan, ratio of chitosan to glycerol, pH on physical properties of hydrogel were investigated. And then the in vitro drug release, rheological properties and biocompatibility were studied. The thermosensitive hydrogel flows easily at room temperature and turns to gelation at body temperature, which can certainly prolong the release of drug and has good biocompatibility.

A new method for the simultaneous analysis of strychnine and brucine in Strychnos nux-vomica unprocessed and processed seeds using a carbon-paste electrode modified with multi-walled carbon nanotubes.

INTRODUCTION: Strychnos nux-vomica L. (Loganiaceae), widely used in folk medicine, is grown extensively in southern Asian countries. Its major bioactive constituents are strychnine and brucine, which are frequently used in traditional herbal medicines for treatment of nervous diseases, vomiting and traumatic pain. OBJECTIVE: A new method using a carbon-paste electrode modified with multi-walled carbon nanotubes (CNT/CPE) was developed and validated for single or simultaneous determination of strychnine and brucine in Strychnos nux-vomica seeds. Additionally, an environmentally friendly method was successfully applied to reduce the levels of strychnine and brucine in seeds. MATERIALS AND METHODS: Cyclic voltammetry, chronocoulometry and differential pulse voltammetry were used with multi-walled carbon nanotube modified carbon-paste electrodes. RESULTS: The peak currents increase linearly with the strychnine and brucine concentrations in the ranges of 50-1000 and 5-355 µ m, and the detection limits for strychnine and brucine were 0.43 and 0.28 µ m, respectively. Of the processing methods used, the greatest reduction in the strychnine and brucine levels was observed in samples processed using milk and saltwater. CONCLUSION: A new, sensitive and selective method was developed for the measurement of strychnine and brucine. This method was successfully applied to the determination of strychnine and brucine in unprocessed and processed Strychnos nux-vomica seed.