brucine-n-oxide and brucine

Brucine (BRU) and brucine N-oxide (BNO) are prominent, bioactive, and toxic alkaloids in crude and processed Semen Strychni. Studies have demonstrated that BRU and BNO possess comprehensive pharmacological activities, such as anti-inflammatory and analgesic. In this context, a comparative study of BRU and BNO was performed by combination analysis of in silico ADMET prediction, in vivo toxicity evaluation, and potential action mechanism exploration. ADMET prediction showed that BRU and BNO might induce liver injury, and BRU may have a stronger hepatoxic effect. The prediction was experimentally verified using the zebrafish model. The BRU-induced hepatotoxicity of zebrafish larvae had a dose-response relationship. The mechanism of BRU-induced hepatotoxicity might relate to phosphorylation, kinase activity, and signal transduction. By comparison, signal transduction and gap junctions might involve BNO-induced hepatotoxicity. Our results provided a better understanding of BRU- and BNO-induced hepatotoxicity. We also built a foundation to elucidate the material base of the hepatotoxicity of traditional Chinese medicine Semen Strychni.

Topics: Animals; Chemical and Drug Induced Liver Injury; Drugs, Chinese Herbal; Strychnine; Zebrafish

A rapid, simple and sensitive UHPLC-MS/MS method was developed and validated for the simultaneous determination of brucine, strychnine and brucine N-oxide in rat plasma using huperzine A as an internal standard (IS) after protein precipitation with methanol. The analytes were separated on a Purospher® STAR RP18 UHPLC column (2 µm, 2.1 × 100 mm) by gradient elution using a mobile phase composed of methanol and water (containing 0.1% formic acid) at a flow rate of 0.3 mL/min. Brucine, strychnine, brucine N-oxide and IS were detected in positive ion multiple reaction monitoring mode by means of an electrospray ionization interface (m/z 395.2 → 324.1, m/z 335.2 → 184.1, m/z 411.2 → 394.2, m/z 243.1 → 226.1). The calibration curve was linear over the range of 1-500 ng/mL for brucine and strychnine and 0.2-50 ng/mL for brucine N-oxide. The intra- and inter-day precisions of these analytes were all within 15% and the accuracy ranged from 85 to 115%. The stability experiment indicated that the plasma samples at three concentration levels were stable under different conditions. The developed method was successfully applied for the first time to pharmacokinetic studies of brucine, strychnine and brucine N-oxide following a single oral and intravenous administration of modified total alkaloid fraction in rats. Copyright © 2016 John Wiley & Sons, Ltd.

Topics: Animals; Chromatography, High Pressure Liquid; Cyclic N-Oxides; Limit of Detection; Rats; Reproducibility of Results; Strychnine; Tandem Mass Spectrometry

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).

Topics: Administration, Oral; Chromatography, High Pressure Liquid; Cyclic N-Oxides; Drugs, Chinese Herbal; Humans; Plant Extracts; Strychnine; Ultrasonic Waves

A liquid chromatography-electrospray ionization-ion trap mass spectrometry (LC-ESI-ITMS) method was developed for the simultaneous analysis of strychnine, brucine and their major metabolites. Strychnine and brucine were individually incubated with rat liver S9 fraction. The incubation samples were pooled together and analyzed with LC-ESI-ITMS in positive ion and full-scan detection mode. The calibration curves of strychnine and brucine in rat liver showed good linearity in ranges of 0.020 to 8.0 µg/mL for strychnine and 0.020 to 8.5 µg/mL for brucine. The limits of detections were both 0.008 µg/mL and the recoveries were 88.3 and 83.2% for strychnine and brucine, respectively. Two metabolites were identified as strychnine N-oxide and brucine N-oxide by comparing the molecular mass, retention time, full-scan mass spectra, tandem MS and MS(3) spectra with those of strychnine and brucine. The developed method provided high sensitivity and selectivity for the determination of poisonous alkaloids and their major metabolites and can be applied in the determination of samples in forensic and clinically toxicological cases.

Topics: Analgesics; Animals; Cyclic N-Oxides; Forensic Toxicology; Limit of Detection; Liver; Male; Poisons; Rats; Rats, Sprague-Dawley; Ribosomal Protein S9; Ribosomal Proteins; Spectrometry, Mass, Electrospray Ionization; Strychnine; Substance Abuse Detection; Tandem Mass Spectrometry

To study the cytotoxicity of four alkaloids: brucine, strychnine, brucine N-oxide and isostrychnine from nux vomica on SMMC 7721 cells and their possible mechanisms, MET assay was used to examine the growth inhibitory effects of these alkaloids. Brucine revealed the strongest growth inhibitory effect on SMMC-7721 cells. Furthermore, as directly observed under an inverted microscope, fluorescent microscope and transmission electronic microscope, brucine caused SMMC-7721 cell shrinkage, membrane blobbing, formation of apoptotic body as well as nucleus condensation, all of which are typical characteristics of apoptotic programmed cell death. In addition, brucine dose-dependently caused SMMC-7721 cells apoptosis via formation of subdipolid DNA and phosphatidylserine externalization, as evidenced by flow cytometry analysis. The brucine-induced apoptosis was partially attributed to the activation of caspase 3 as well as cyclooxygenase 2 inhibition, since neither caspase 3 specific inhibitor, z-DEVD-fmk nor was exogenous addition of prostaglandin E(2) able to completely abrogate the brucine-induced SMMC 7721 cell apoptosis. In sum, this paper indicate that the major alkaloids present in the seed of Strychnos nux-vomica are effective against SMMC-7721 cells proliferation, among which brucine proceeds SMMC-7721 cells death via apoptosis, probably through the participation of caspase 3 and cyclooxygenase 2.

Topics: Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Cell Line, Tumor; Cell Proliferation; Cyclic N-Oxides; Cyclooxygenase 2; Dose-Response Relationship, Drug; Enzyme Activation; Flow Cytometry; Humans; Liver Neoplasms; Seeds; Strychnine; Strychnos nux-vomica

To screen the anti-tumor effects of the four alkaloids: brucine, strychnine, brucine N-oxide and isostrychnine from the seed of Strychnos nux-vomica, MTT assay was used to examine the growth inhibitory effects of these alkaloids on human hepatoma cell line (HepG2). Brucine, strychnine and isostrychnine revealed significant inhibitory effects against HepG2 cell proliferation, whereas brucine N-oxide didn't have such an effect. In addition, brucine caused HepG2 cell shrinkage, membrane blebbing, apoptotic body formation, all of which are typical characteristics of apoptotic programmed cell death. The results of flow cytometric analysis demonstrated that brucine caused dose-dependent apoptosis of HepG2 cells through cell cycle arrest at G0/G1 phase, thus preventing cells entering S or G2/M phase. Immunoblot results revealed that brucine significantly decreased the protein expression level of cyclooxygenase-2, whereas increased the expression caspase-3 as well as the caspase-3-like protease activity in HepG2 cells, suggesting the involvement of cyclooxygenase-2 and caspase-3 in the pro-apoptotic effects exerted by brucine. Therefore, this paper indicate that the major alkaloids present in the seed of Strychnos nux-vomica are effective against HepG2 cells proliferation, among which brucine proceed HepG2 cells death via apoptosis, probably through the participation of caspase-3 and cyclooxygenase-2.

Topics: Alkaloids; Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Caspase 3; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Cell Shape; Cyclic N-Oxides; Cyclooxygenase 2; Dose-Response Relationship, Drug; Humans; Liver Neoplasms; Seeds; Strychnine; Strychnos nux-vomica

In an attempt to dissect the mechanism of Strychnos nux-vomica, a commonly used Chinese folk medicine in the therapy of liver cancer, the cytotoxic effects of four alkaloids in Strychnos nux-vomica, brucine, brucine N-oxide, strychnine, and isostrychnine, on human hepatoma cells (HepG2) were screened by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrasolium bromide (MTT) assay. Brucine, among the four alkaloids, exhibited the strongest toxic effect, the mechanism of which was found to cause HepG2 cell apoptosis, since brucine caused HepG2 cell shrinkage, the formation of apoptotic bodies, DNA fragmentation, cell cycle arrest, as well as phosphatidylserine externalization, all of which are typical characteristics of apoptotic programmed cell death. Brucine-induced HepG2 cell apoptosis was caspase dependent, with caspase-3 activated by caspase-9. Brucine also caused the proteolytic processing of caspase-9. In addition, brucine caused depolarization of the mitochondrial membrane of HepG2 cells, the inhibition of which by cyclosporine A completely abrogated the activation of casapses and release of cytochrome c in brucine-treated HepG2 cells. These findings suggested a pivotal role of mitochondrial membrane depolarization in HepG2 cell apoptosis elicited by brucine. Furthermore, brucine induced a rapid and sustained elevation of intracellular [Ca2+], which compromised the mitochondrial membrane potential and triggered the process of HepG2 cell apoptosis. Finally, Bcl-2 was found to predominately control the whole event of cell apoptosis induced by brucine. The elevation of [Ca2+]i caused by brucine was also suppressed by overexpression of Bcl-2 protein in HepG2 cells. From the facts given above, Ca2+ and Bcl-2 mediated mitochondrial pathway were found to be involved in brucine-induced HepG2 cell apoptosis.

Topics: Apoptosis; Calcium; Carcinoma, Hepatocellular; Caspase 3; Caspases; Cell Line, Tumor; Cyclic N-Oxides; Cytochromes c; Enzyme Activation; Humans; Liver Neoplasms; Mitochondria, Liver; Proto-Oncogene Proteins c-bcl-2; Seeds; Strychnine; Strychnos nux-vomica

To further understand the purpose of the traditional processing method of the seeds of Strychnos nux-vomica L. (Loganiaceae) as well as analgesic and anti-inflammatory activities of brucine and brucine N-oxide extracted from this medicinal plant, various pain and inflammatory models were employed in the present study to investigate their pharmacological profiles. Both brucine and brucine N-oxide revealed significant protective effects against thermic and chemical stimuli in hot-plate test and writhing test. However, on different phases they exerted analgesic activities in formalin test. Brucine N-oxide showed stronger inhibitory effect than brucine in carrageenan-induced rat paw edema, both of them significantly inhibited the release of prostaglandin E2 in inflammatory tissue, reduced acetic acid-induced vascular permeability and the content of 6-keto-PGF1a in Freund's complete adjuvant (FCA) induced arthritis rat's blood plasma. In addition, brucine and brucine N-oxide were shown to reduce the content of 5-hydroxytryptamine (5-HT) in FCA-induced arthritis rat's blood plasma, while increase the content of 5-hydroxytryindole-3-acetic acid (5-HIAA) accordingly. These results suggest that central and peripheral mechanism are involved in the pain modulation and anti-inflammation effects of brucine and brucine N-oxide, biochemical mechanisms of brucine and brucine N-oxide are different even though they are similar in chemical structure.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Arthritis, Experimental; Capillary Permeability; Cyclic N-Oxides; Disease Models, Animal; Edema; Female; Male; Mice; Mice, Inbred ICR; Pain; Plant Extracts; Rats; Rats, Sprague-Dawley; Seeds; Serotonin; Strychnine; Strychnos nux-vomica

To study the pharmacokinetic process about the concentration in rat plasma of the alkaloids from processed seeds of Strychnos nux-vomica with RP-HPLC method.. Hypersil BDS C18 column was used and the mobile phase consisted of acetonitrile-water at the flow rate of 0.8 mL.min-1. The UV detection wave length was 254 nm.. The concentration-time data of strychnine, brucine, strychnine N-oxide and brucine N-oxide were all in accordance with an open two-compartment model after i.v. alkaloids. Their parameters were as follows: T1/2 alpha were (8 +/- 5), (4 +/- 3), (6.2 +/- 1.7) and (3.0 +/- 0.8) min, T1/2 beta were (262 +/- 125), (416 +/- 131), (285 +/- 50) and (342 +/- 141) min, CL were (17 +/- 4), (21 +/- 12), (1.9 +/- 1.8) and (2.8 +/- 1.1) mL.min-1, Vc were (1.4 +/- 0.5), (1.7 +/- 1.1), (0.24 +/- 0.16) and (0.23 +/- 0.06) L.kg-1, Vd were (6.0 +/- 1.2), (12 +/- 7), (0.8 +/- 0.6) and (1.5 +/- 0.6) L.kg-1, AUC were (57,578 +/- 25,578), (35,240 +/- 15,616), (93,088 +/- 22,375) and (177,712 +/- 120,110) h.microgram.L-1, respectively.. The method is a good reference for pharmacokinetics in human bodies.

Topics: Alkaloids; Animals; Cyclic N-Oxides; Drugs, Chinese Herbal; Female; Hot Temperature; Male; Plants, Medicinal; Rats; Rats, Sprague-Dawley; Seeds; Strychnine; Strychnos nux-vomica; Technology, Pharmaceutical

In radioligand binding studies, it has been reported that brucine, N-chloromethyl brucine, and brucine N-oxide increased the affinity of acetylcholine for M1, M3, and M4 muscarinic receptors, respectively, in a manner consistent with the predictions of the ternary complex allosteric model. We now demonstrate an equivalent ability of these three allosteric agents to modulate the actions of acetylcholine in functional studies in membranes and in whole cells. The enhancing actions of brucine and brucine N-oxide on acetylcholine (ACh) potency at M1 and M4 receptors respectively have been confirmed in guanosine-5'-O-(3-[35S]thio)triphosphate, GTPase, cAMP, and intracellular Ca2+ mobilization assays of function. In general, neither the basal nor the maximally stimulated response to ACh is affected. The subtype-selective allosteric effects of N-chloromethyl brucine on M2 and M3 receptors were shown to be qualitatively and quantitatively the same in guanosine-5'-O-(3-[35S]thio)triphosphate functional assays, in terms of both its affinity and cooperativity with ACh, as those found in binding assays. Neutral cooperativity of N-chloromethyl brucine with ACh on M4 receptor function was also observed, thereby demonstrating its "absolute subtype selectivity": a lack of action at any concentration at M4 receptors and an action at M2 and M3 receptors. The enhancing action of N-chloromethyl brucine on neurogenically released ACh binding at M3 receptors was also detected in whole tissue as an increased contraction of the isolated guinea pig ileum to submaximal electrical stimulation. In conclusion, these functional studies confirm that brucine analogs are allosteric enhancers of ACh affinity at certain muscarinic receptor subtypes.

Topics: Acetylcholine; Allosteric Regulation; Animals; Cell Membrane; CHO Cells; Cricetinae; Cyclic N-Oxides; Guinea Pigs; Humans; Male; Receptor, Muscarinic M1; Receptor, Muscarinic M3; Receptor, Muscarinic M4; Receptors, Muscarinic; Strychnine