Summary: An alkaloid found in the seeds of STRYCHNOS NUX-VOMICA. It is a competitive antagonist at glycine receptors and thus a convulsant. It has been used as an analeptic, in the treatment of nonketotic hyperglycinemia and sleep apnea, and as a rat poison.

Top Publications

  1. Trailović S, Varagic V. The effect of ivermectin on convulsions in rats produced by lidocaine and strychnine. Vet Res Commun. 2007;31:863-72 pubmed mechanism; therefore, the anticonvulsive effect of ivermectin against convulsions caused by lidocaine and strychnine was evaluated...
  2. Wang F, Xiao C, Ye J. Taurine activates excitatory non-synaptic glycine receptors on dopamine neurones in ventral tegmental area of young rats. J Physiol. 2005;565:503-16 pubmed
    ..In voltage-clamped neurones, taurine induced a current which was antagonized by strychnine and by picrotoxin, but not by bicuculline...
  3. Qin X, Yuan Y, Liu C, Wang Q, Shen X, Yang B. Preparation of liposomal brucine and its pharmaceutical/pharmacodynamic characterization. Acta Pharmacol Sin. 2007;28:1851-8 pubmed
    ..It can be proposed that LB prepared here could represent a safe, effective and promising transdermal formulation for analgesic and anti-inflammatory effects. ..
  4. Dhalwal K, Shinde V, Namdeo A, Mahadik K, Kadam S. Development and validation of a TLC-densitometric method for the simultaneous quantitation of strychnine and brucine from Strychnos spp. and its formulations. J Chromatogr Sci. 2007;45:706-9 pubmed
    ..specific thin-layer chromatography densitometric method has been developed for the simultaneous quantitation of strychnine and brucine...
  5. Agrawal S, Saraswati S, Mathur R, Pandey M. Cytotoxic and antitumor effects of brucine on Ehrlich ascites tumor and human cancer cell line. Life Sci. 2011;89:147-58 pubmed publisher
    ..Our findings suggest that BRU possesses antitumor and anti-angiogenic activities in vitro and in vivo. The above results showed that BRU can be used as a potential anticancer agent as an antimetastatic and anti-angiogenic agent. ..
  6. Sebe J, van Brederode J, Berger A. Inhibitory synaptic transmission governs inspiratory motoneuron synchronization. J Neurophysiol. 2006;96:391-403 pubmed
    ..Further, the time course of synaptic GABAergic currents is a determinant of oscillation frequency. ..
  7. Molander A, Söderpalm B. Accumbal strychnine-sensitive glycine receptors: an access point for ethanol to the brain reward system. Alcohol Clin Exp Res. 2005;29:27-37 pubmed
    ..We recently demonstrated that strychnine-sensitive glycine receptors (GlyRs) are present in the nAc and that they are involved in regulating ..
  8. Renna J, Strang C, Amthor F, Keyser K. Strychnine, but not PMBA, inhibits neuronal nicotinic acetylcholine receptors expressed by rabbit retinal ganglion cells. Vis Neurosci. 2007;24:503-11 pubmed
    b>Strychnine is considered a selective competitive antagonist of glycine gated Cl- channels (Saitoh et al...
  9. Salceda R, Aguirre Ramirez M. Characterization of strychnine-sensitive glycine receptor in the intact frog retina: modulation by protein kinases. Neurochem Res. 2005;30:411-6 pubmed
    We studied 3H-glycine and 3H-strychnine specific binding to glycine receptor (GlyR) in intact isolated frog retinas...

More Information


  1. Rao P, Ramanadham M, Prasad M. Anti-proliferative and cytotoxic effects of Strychnos nux-vomica root extract on human multiple myeloma cell line - RPMI 8226. Food Chem Toxicol. 2009;47:283-8 pubmed publisher
    ..The anti-proliferative and cytotoxic activity could be due to the alkaloids strychnine and brucine, which have been identified by LC-mass spectral analysis of the SN-extract in comparison to the ..
  2. Ericson M, Clarke R, Chau P, Adermark L, Söderpalm B. beta-Alanine elevates dopamine levels in the rat nucleus accumbens: antagonism by strychnine. Amino Acids. 2010;38:1051-5 pubmed publisher
    ..In line with previous observations investigating ethanol, glycine and taurine, the competitive GlyR antagonist strychnine completely blocked the dopamine elevation...
  3. Brams M, Pandya A, Kuzmin D, van Elk R, Krijnen L, Yakel J, et al. A structural and mutagenic blueprint for molecular recognition of strychnine and d-tubocurarine by different cys-loop receptors. PLoS Biol. 2011;9:e1001034 pubmed publisher
    ..b>Strychnine and d-tubocurarine (d-TC) are neurotoxins that have been highly instrumental in decades of research on glycine ..
  4. Ericson M, Molander A, Stomberg R, Söderpalm B. Taurine elevates dopamine levels in the rat nucleus accumbens; antagonism by strychnine. Eur J Neurosci. 2006;23:3225-9 pubmed
    ..It was recently suggested that strychnine-sensitive glycine receptors (GlyR) in the nAcc regulate both basal and ethanol-induced mesolimbic DA activity ..
  5. Chen Y, Dai T, Zeng Y. Strychnine-sensitive glycine receptors mediate the analgesic but not hypnotic effects of emulsified volatile anesthetics. Pharmacology. 2007;80:151-7 pubmed
    The present study was designed to investigate the role of strychnine-sensitive glycine receptors in hypnosis and analgesia induced by emulsified volatile anesthetics...
  6. McCool B, Chappell A. Strychnine and taurine modulation of amygdala-associated anxiety-like behavior is 'state' dependent. Behav Brain Res. 2007;178:70-81 pubmed
    b>Strychnine-sensitive glycine receptors are expressed in many adult forebrain regions, yet the biological function of these receptors outside the spinal cord/brainstem is poorly understood...
  7. Raafat K, Breitinger U, Mahran L, Ayoub N, Breitinger H. Synergistic inhibition of glycinergic transmission in vitro and in vivo by flavonoids and strychnine. Toxicol Sci. 2010;118:171-82 pubmed publisher
    ..Here, inhibition of recombinant human ?1 GlyRs in HEK 293 cells by genistein, quercetin, and strychnine was studied using whole-cell recording techniques...
  8. Deng X, Yin W, Li W, Yin F, Lu X, Zhang X, et al. The anti-tumor effects of alkaloids from the seeds of Strychnos nux-vomica on HepG2 cells and its possible mechanism. J Ethnopharmacol. 2006;106:179-86 pubmed
    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 ..
  9. Li Y, He X, Qi S, Gao W, Chen X, Hu Z. Separation and determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation by nonaqueous capillary electrophoresis. J Pharm Biomed Anal. 2006;41:400-7 pubmed
    An easy, rapid method for simultaneous determination of strychnine and brucine in Strychnos nux-vomica L. and its preparation was developed by nonaqueous capillary electrophoresis (NACE) without pretreatment for the first time...
  10. Miller P, Da Silva H, Smart T. Molecular basis for zinc potentiation at strychnine-sensitive glycine receptors. J Biol Chem. 2005;280:37877-84 pubmed
    The divalent cation Zn(2+) is a potent potentiator at the strychnine-sensitive glycine receptor (GlyR). This occurs at nanomolar concentrations, which are the predicted endogenous levels of extracellular neuronal Zn(2+)...
  11. Chen J, Hou T, Fang Y, Chen Z, Liu X, Cai H, et al. HPLC determination of strychnine and brucine in rat tissues and the distribution study of processed semen strychni. Yakugaku Zasshi. 2011;131:721-9 pubmed
    ..and low-cost HPLC method with UV absorbance detection was developed and validated to simultaneously determine strychnine and brucine, the most abundant alkaloids in the processed Semen Strychni, in rat tissues (kidney, liver, spleen, ..
  12. Chen J, Xiao H, Hu R, Hu W, Chen Z, Cai H, et al. Pharmacokinetics of brucine after intravenous and oral administration to rats. Fitoterapia. 2011;82:1302-8 pubmed publisher
    ..The results of dose-dependent pharmacokinetic behavior under different administration routes may account for the significantly different toxicities of brucine between intravenous and oral administration. ..
  13. Mueller P, Foley C, Vogl H, Hay M, Hasser E. Cardiovascular response to a group III mGluR agonist in NTS requires NMDA receptors. Am J Physiol Regul Integr Comp Physiol. 2005;289:R198-208 pubmed mimic sympathoinhibitory responses to L-AP4, even in the presence of the inhibitory glycine antagonist, strychnine (3 mM)...
  14. Jakubik J, Krejci A, Dolezal V. Asparagine, valine, and threonine in the third extracellular loop of muscarinic receptor have essential roles in the positive cooperativity of strychnine-like allosteric modulators. J Pharmacol Exp Ther. 2005;313:688-96 pubmed
    We have investigated allosteric interactions of four closely related strychnine-like substances: Wieland-Gumlich aldehyde (WGA), propargyl Wieland-Gumlich aldehyde, strychnine, and brucine with N-methylscopolamine (NMS) on M(3) subtype of ..
  15. Yin W, Deng X, Yin F, Zhang X, Cai B. The cytotoxicity induced by brucine from the seed of Strychnos nux-vomica proceeds via apoptosis and is mediated by cyclooxygenase 2 and caspase 3 in SMMC 7221 cells. Food Chem Toxicol. 2007;45:1700-8 pubmed
    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 ..
  16. Grudzinska J, Schemm R, Haeger S, Nicke A, Schmalzing G, Betz H, et al. The beta subunit determines the ligand binding properties of synaptic glycine receptors. Neuron. 2005;45:727-39 pubmed
    ..Because the beta subunit anchors GlyRs at synaptic sites, our results have important implications for the biosynthesis, clustering, and pharmacology of synaptic GlyRs. ..
  17. Maksay G, Bíró T, Laube B, Nemes P. Hyperekplexia mutation R271L of alpha1 glycine receptors potentiates allosteric interactions of nortropeines, propofol and glycine with [3H]strychnine binding. Neurochem Int. 2008;52:235-40 pubmed
    ..alpha1(R271L) glycine receptors (GlyRs) were transiently expressed in human embryonic kidney 293 cells for [3H]strychnine binding. Binding parameters were determined using a ternary allosteric model...
  18. Venard C, Boujedaini N, Belon P, Mensah Nyagan A, Patte Mensah C. Regulation of neurosteroid allopregnanolone biosynthesis in the rat spinal cord by glycine and the alkaloidal analogs strychnine and gelsemine. Neuroscience. 2008;153:154-61 pubmed publisher
    ..The alkaloid strychnine, well-known as a glycine receptor (Gly-R) antagonist, blocked glycine stimulatory effect on 3alpha,5alpha-THP ..
  19. Ahrens J, Leuwer M, Stachura S, Krampfl K, Belelli D, Lambert J, et al. A transmembrane residue influences the interaction of propofol with the strychnine-sensitive glycine alpha1 and alpha1beta receptor. Anesth Analg. 2008;107:1875-83 pubmed publisher
  20. Chen J, Lin A, Chen Z, Wang W, Zhang T, Cai H, et al. Ammonium sulfate gradient loading of brucine into liposomes: effect of phospholipid composition on entrapment efficiency and physicochemical properties in vitro. Drug Dev Ind Pharm. 2010;36:245-53 pubmed publisher
    ..We developed a novel liposome-based brucine formulation that was composed of soybean phosphatidylcholine (SPC) and hydrogenated soybean phosphatidylcholine (HSPC)...
  21. Wegner F, Kraft R, Busse K, Hartig W, Ahrens J, Leffler A, et al. Differentiated human midbrain-derived neural progenitor cells express excitatory strychnine-sensitive glycine receptors containing ?2? subunits. PLoS ONE. 2012;7:e36946 pubmed publisher
    ..Whole-cell recordings demonstrate the ability of NPCs to express functional strychnine-sensitive glycine receptors after differentiation for 3 weeks in vitro...
  22. Li P, Zhang M, Ma W, Sun X, Jin F. Effects of brucine on vascular endothelial growth factor expression and microvessel density in a nude mouse model of bone metastasis due to breast cancer. Chin J Integr Med. 2012;18:605-9 pubmed publisher
    ..05). Brucine could inhibit the growth of breast cancer to bone metastases, possibly by inhibiting tumor angiogenesis. ..
  23. Brockhoff A, Behrens M, Massarotti A, Appendino G, Meyerhof W. Broad tuning of the human bitter taste receptor hTAS2R46 to various sesquiterpene lactones, clerodane and labdane diterpenoids, strychnine, and denatonium. J Agric Food Chem. 2007;55:6236-43 pubmed
    ..of its agonist pattern, we characterized hTAS2R46 as a bitter receptor broadly tuned to sesquiterpene lactones and to clerodane and labdane diterpenoids as well as to the unrelated bitter substances strychnine and denatonium.
  24. Makarovsky I, Markel G, Hoffman A, Schein O, Brosh Nissimov T, Tashma Z, et al. Strychnine--a killer from the past. Isr Med Assoc J. 2008;10:142-5 pubmed
  25. Cheng W, Yin Q, Cheng M, Chen H, Wang S, Feng T, et al. Intracerebroventricular or intrathecal injection of glycine produces analgesia in thermal nociception and chemical nociception via glycine receptors. Eur J Pharmacol. 2009;614:44-9 pubmed publisher
    ..Glycine was injected intracerebroventricularly or intrathecally and strychnine, a glycine receptor antagonist, was injected intracerebroventricularly or intrathecally before glycine injection...
  26. Williamson R, Buevich A, Martin G. Experimental and theoretical investigation of 1J(CC) and (n)J(CC) coupling constants in strychnine. Org Lett. 2012;14:5098-101 pubmed publisher
    ..A generalized protocol for the measurement of (1)J(CC) and (3)J(CC) couplings using a 4.6 mg sample of strychnine as a model compound is described, and the utility of DFT calculations for the prediction of these useful ..
  27. Saraswati S, Agrawal S. Brucine, an indole alkaloid from Strychnos nux-vomica attenuates VEGF-induced angiogenesis via inhibiting VEGFR2 signaling pathway in vitro and in vivo. Cancer Lett. 2013;332:83-93 pubmed publisher
    ..Taken together, our study suggests that brucine potently suppresses angiogenesis by targeting VEGFR2 activation and may be a viable drug candidate in anti-angiogenesis and anti-cancer therapies. ..
  28. Saraswati S, Agarwal S. Strychnine inhibits inflammatory angiogenesis in mice via down regulation of VEGF, TNF-? and TGF-?. Microvasc Res. 2013;87:7-13 pubmed publisher
    b>Strychnine is known to possess anti-inflammatory and antitumour activity, but its roles in tumour angiogenesis, the key step involved in tumour growth and metastasis, and the involved molecular mechanism are still unknown...
  29. Chen Y, Dai T, Zeng Y. Strychnine-sensitive glycine receptors mediate analgesia induced by emulsified inhalation anaesthetics in thermal nociception but not in chemical nociception. Basic Clin Pharmacol Toxicol. 2007;100:165-9 pubmed
    The present study was designed to investigate the role of strychnine-sensitive glycine receptors in analgesia induced by emulsified inhalation anaesthetics...
  30. Ataka T, Gu J. Relationship between tonic inhibitory currents and phasic inhibitory activity in the spinal cord lamina II region of adult mice. Mol Pain. 2006;2:36 pubmed
    ..The prominent charge transfer by tonic inhibitory currents and their synaptic activity dependency suggest a significant role of tonic inhibition in sensory processing. ..
  31. Santos S, Rebelo S, Derkach V, Safronov B. Excitatory interneurons dominate sensory processing in the spinal substantia gelatinosa of rat. J Physiol. 2007;581:241-54 pubmed
    ..We conclude that sensory integration in the intrinsic SG neuronal network is dominated by excitatory interneurons. Such organization of neuronal circuitries in the spinal SG can be important for nociceptive encoding. ..
  32. Gomeza J, Hülsmann S, Ohno K, Eulenburg V, Szoke K, Richter D, et al. Inactivation of the glycine transporter 1 gene discloses vital role of glial glycine uptake in glycinergic inhibition. Neuron. 2003;40:785-96 pubmed vitro respiratory activity is strikingly reduced but normalized by the glycine receptor (GlyR) antagonist strychnine. Conversely, glycine or the GlyT1 inhibitor sarcosine suppress respiratory activity in slices from wild-type ..
  33. Degtyarenko A, Kaufman M. Bicuculline and strychnine suppress the mesencephalic locomotor region-induced inhibition of group III muscle afferent input to the dorsal horn. Neuroscience. 2003;118:779-88 pubmed
    We examined the effect of iontophoretic application of bicuculline methiodide and strychnine hydrochloride on the mesencephalic locomotor region (MLR)-induced inhibition of dorsal horn cells in paralyzed cats...
  34. Chattipakorn S, McMahon L. Strychnine-sensitive glycine receptors depress hyperexcitability in rat dentate gyrus. J Neurophysiol. 2003;89:1339-42 pubmed
    Previously we have shown that strychnine-sensitive glycine-gated chloride channels (GlyRs) are functionally expressed by CA1 pyramidal cells and GABAergic interneurons in mature rat hippocampal slices...
  35. Rodriguez Ithurralde D, Maruri A, Rodriguez X. Motor neurone acetylcholinesterase release precedes neurotoxicity caused by systemic administration of excitatory amino acids and strychnine. J Neurol Sci. 1998;160 Suppl 1:S80-6 pubmed
    ..p.), or blockade of glycine receptors with strychnine (STRY, 2 mg/kg, i.p.)...
  36. Yamashina S, Konno A, Wheeler M, Rusyn I, Rusyn E, Cox A, et al. Endothelial cells contain a glycine-gated chloride channel. Nutr Cancer. 2001;40:197-204 pubmed
    ..Furthermore, the inhibitory effects of glycine were prevented by 1 microM strychnine, a glycine receptor antagonist, or when cells were incubated in Cl(-)-free buffer...
  37. Asaoka K. Deficiency of gustatory sensitivity to some deterrent compounds in "polyphagous" mutant strains of the silkworm, Bombyx mori. J Comp Physiol A. 2000;186:1011-8 pubmed
    ..By contrast, the deterrent cells of all strains responded similarly to strychnine nitrate in a dose-dependent manner...
  38. Akagi H, Hirai K, Hishinuma F. Functional properties of strychnine-sensitive glycine receptors expressed in Xenopus oocytes injected with a single mRNA. Neurosci Res. 1991;11:28-40 pubmed
    ..The electrophysiological properties of the wild-type receptor and some mutant receptors produced by site-directed mutagenesis were analyzed. ..
  39. Grenningloh G, Rienitz A, Schmitt B, Methfessel C, Zensen M, Beyreuther K, et al. The strychnine-binding subunit of the glycine receptor shows homology with nicotinic acetylcholine receptors. Nature. 1987;328:215-20 pubmed
    We have cloned and sequenced cDNAs of the strychnine-binding subunit of the rat glycine receptor, a neurotransmitter-gated chloride channel protein of the CNS...
  40. Di Fabio R, Capelli A, Conti N, Cugola A, Donati D, Feriani A, et al. Substituted indole-2-carboxylates as in vivo potent antagonists acting as the strychnine-insensitive glycine binding site. J Med Chem. 1997;40:841-50 pubmed
    ..3-[2-[(Phenylamino)carbonyl]ethenyl]-4,6-dichloroindole-2-carboxyl ic acid (8) was an antagonist at the strychnine-insensitive glycine binding site (noncompetitive inhibition of the binding of [3H]TCP, pA2 = 8...
  41. Sorkin L, Puig S. Neuronal model of tactile allodynia produced by spinal strychnine: effects of excitatory amino acid receptor antagonists and a mu-opiate receptor agonist. Pain. 1996;68:283-92 pubmed
    Touch evoked agitation (allodynia) can be induced by spinal delivery of strychnine and this effect is antagonized by intrathecal NMDA and non-NMDA receptor antagonists, but not by mu-opiate receptor agonists...
  42. McCool B, Botting S. Characterization of strychnine-sensitive glycine receptors in acutely isolated adult rat basolateral amygdala neurons. Brain Res. 2000;859:341-51 pubmed
    ..In addition to its cytoprotective and osmoregulatory roles, taurine may also serve as an agonist at GABA(A)- and strychnine-sensitive glycine receptors...
  43. Wang J, Wang X, Irnaten M, Venkatesan P, Evans C, Baxi S, et al. Endogenous acetylcholine and nicotine activation enhances GABAergic and glycinergic inputs to cardiac vagal neurons. J Neurophysiol. 2003;89:2473-81 pubmed
    ..Nicotinic facilitation of inhibitory neurotransmission to premotor cardiac parasympathetic neurons may be involved in generating respiratory sinus arrhythmia. ..
  44. Xu H, Zhou K, Huang Y, Chen L, Xu T. Taurine activates strychnine-sensitive glycine receptors in neurons of the rat inferior colliculus. Brain Res. 2004;1021:232-40 pubmed
    ..currents evoked by Tau at both low (1 mM) and high (10 mM) concentrations were almost completely inhibited by strychnine, a glycine receptor antagonist...
  45. Zhou Z. A critical role of the strychnine-sensitive glycinergic system in spontaneous retinal waves of the developing rabbit. J Neurosci. 2001;21:5158-68 pubmed
    ..perinatal rabbit retinal preparation, this study demonstrates that, in addition to the cholinergic system, a strychnine-sensitive system in the inner retina plays an obligatory and developmentally regulated role in the initiation ..
  46. Sergeeva O, Haas H. Expression and function of glycine receptors in striatal cholinergic interneurons from rat and mouse. Neuroscience. 2001;104:1043-55 pubmed
    ..We demonstrate interspecies differences and heterogeneity in expression and function of glycine receptors within the same neuronal population in the neostriatum. ..
  47. Loomis C, Khandwala H, Osmond G, Hefferan M. Coadministration of intrathecal strychnine and bicuculline effects synergistic allodynia in the rat: an isobolographic analysis. J Pharmacol Exp Ther. 2001;296:756-61 pubmed
    ..t.) strychnine (STR) or bicuculline (BIC), respectively...
  48. Rasmussen H, Rasmussen T, Triller A, Vannier C. Strychnine-blocked glycine receptor is removed from synapses by a shift in insertion/degradation equilibrium. Mol Cell Neurosci. 2002;19:201-15 pubmed
    The long-term inhibition by strychnine of glycine receptor activity in neurons provokes the receptor's selective intracellular accumulation and disappearance from synapses...
  49. Darstein M, Landwehrmeyer G, Kling C, Becker C, Feuerstein T. Strychnine-sensitive glycine receptors in rat caudatoputamen are expressed by cholinergic interneurons. Neuroscience. 2000;96:33-9 pubmed
    b>Strychnine-sensitive glycine receptors are ligand-gated anion channels widely expressed in spinal cord and brainstem...
  50. Bradaia A, Trouslard J. Fast synaptic transmission mediated by alpha-bungarotoxin-sensitive nicotinic acetylcholine receptors in lamina X neurones of neonatal rat spinal cord. J Physiol. 2002;544:727-39 pubmed, rapidly desensitizing inward current, which was fully blocked by alpha-bungarotoxin (alpha-BgT; 50 nM) and strychnine (1 microM), two antagonists of alpha7*nAChRs...
  51. Hussy N, Deleuze C, Pantaloni A, Desarmenien M, Moos F. Agonist action of taurine on glycine receptors in rat supraoptic magnocellular neurones: possible role in osmoregulation. J Physiol. 1997;502 ( Pt 3):609-21 pubmed
    ..acutely dissociated from adult rats, using whole-cell voltage clamp, (ii) studied the effects of taurine and strychnine in vivo by extracellular recordings of supraoptic vasopressin neurones in anaesthetized rats, and (iii) measured ..
  52. Llanos M, Ronco A, Aguirre M. Specific strychnine binding sites on acrosome-associated membranes of golden hamster spermatozoa. Biochem Biophys Res Commun. 2003;306:376-81 pubmed
    ..vesicles originated from the hamster sperm head after the occurrence of the acrosome reaction, possess specific strychnine binding sites...
  53. Choi Y, Sohn Y, Kim C, Oh K, Kim J. Analysis of strychnine from detoxified Strychnos nux-vomica [corrected] seeds using liquid chromatography-electrospray mass spectrometry. J Ethnopharmacol. 2004;93:109-12 pubmed
    The content of strychnine from Strychnos nux-vomica [corrected] seeds was analyzed and compared to processed seeds by the HPLC-ESI/MS method. Using this technique, levels as low as 1 ng of strychnine were detected...