The action of the alkaloids from yew (Taxus baccata) on the action potential in theXenopus medullated axon

Smythies, J. R.; Benington, F.; Morin, R. D.; Al-Zahid, G.; Schoepfle, Gordon M.

doi:10.1007/bf01922572

Cited by 11 publications

(3 citation statements)

References 5 publications

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“…Extraction of taxine: The extraction procedure was essentially the same as that described by Smythies et al (10) with some modifications. Twigs were stripped and the leaves were dried below 40° C until they lost approximately 60% of their weight.…”

Section: Facultymentioning

confidence: 99%

Negative Chronotropic and Atrioventricular Blocking Effects of Taxine on Isolated Frog Heart and Its Acute Toxicity in Mice

Tekol¹

1985

Planta Med

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The alkaloid mixture of yew ( TAXUS BACCATA) was converted to sulphate salt and this salt form of the drug was used throughout the experiments. The median lethal doses (LD50) and their 19/20 confidence limits of two samples of the drug, the freshly prepared and the stored taxine sulphate, were determined on mice (s. c.) and found as 12.96 (11.37-14.77) and 13.09 (11.73-14.61) mg/kg, respectively. There was no significant difference between these values. Results show that taxine in salt form can be preserved for long periods without loosing its properties. The cardiac actions of the drug (10-100 microg/ml) were determined on isolated frog heart. It was found that the drug slows both atrial and ventricular rate dose-dependently, however, the rate-depressing effect was more prominent on the ventricle, e.g., in the highest concentration, the observed percent changes in cardiac rate (mean +/- S.E.M.) were 38.29 +/- 4.13 for atrium and 1.71 +/- 0.80 for ventricle, indicating that the atrioventricular conduction is more susceptible to the drug. The effect of the drug on the heart could be removed partially by washing. At the end of this procedure, the atrial and ventricular rates reached 56.63 +/- 5.44 and 51.35 +/- 5.54 that of control rates, respectively. From these findings and those observed by previous authors, it is deduced that the actions of taxine on heart might result from its Ca (2+) antagonizing properties, but electrophysiological studies are necessary for a definitive conclusion.

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Section: Facultymentioning

confidence: 99%

Negative Chronotropic and Atrioventricular Blocking Effects of Taxine on Isolated Frog Heart and Its Acute Toxicity in Mice

Tekol¹

1985

Planta Med

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“…In a study of isolated guinea pig hearts, Taxine B was found to be the most potent taxine alkaloid in T. baccata to attenuate cardiac electrical (A-V conduction time, QT interval, and QRS complex duration), and physiological (contractile activity, beating frequency, and coronary flow) activity [4]. Electrophysiological studies in Xenopus axons demonstrated inhibition of sodium channels [12]. A study in cells isolated from rabbit aorta, atrium, and jejunum identified calcium channel inhibition mediated decreases in contractions with the greatest effects occurring in the heart cells [13].…”

Section: Taxus Baccata Contains Different Taxine Alkaloids Namely Taxinementioning

confidence: 99%

Fatal ingestion ofTaxus baccata: English yew

Brooks-Lim

Mérette²,

Hawkins

et al. 2021

Journal of Forensic Sciences

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Poisoning from consumption of foraged alternative medicine products is an uncommon yet recognized occurrence. Here, presented is the case of a 40-year-old woman who was witnessed to collapse with labored breathing and subsequently died despite emergency medical personnel attendance and resuscitation efforts. Autopsy revealed the presence of plant matter that was visually identified as leaves from Taxus baccata -the English Yew. Isolation of alkaloids from the plant material and subsequent identification of the same alkaloids in the decedent's blood by liquid chromatographytandem mass spectrometry indicated a toxicological cause of death. This case illustrates a collaborative team approach among subject matter experts to unexpectedly discover and then confirm the sudden death of this woman from T. baccata toxicity.

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“…In vivo, taxines markedly slow atrial and especially ventricular rates, the ventricles eventually stopping in diastole at death (Bryan -Brown 1932;Tekol 1985). Thus, the effects seem to be mainly AV conduction interference possibly via inhibition of sodium and calcium currents in cardiac cells and/or possible potassium channel effects (Smythies et al 1975;Tekol and Kameyama 1987). This seems to be borne out by the marked slowing of the heart and distinctive widening of the QRS complexes (Frohne and Pribilla 1965;Schulte 1975;von Dach and Streuli 1988;Nora et al 1993).…”

Section: Taxaceae Agraymentioning

confidence: 99%