Chemical Properties
Off-White to Tan Crystalline Solid
Uses
antiinflammatory, respiratory stimulant
Uses
Toxic priniciple in seed of Laburnum anagyroides and other Leguminosae. A neuronal nicotinic acetylcholine agonist
Definition
ChEBI: An organic heterotricyclic compound that is the toxic principle in Laburnum seeds and is found in many members of the Fabaceae (legume, pea or bean) family. An acetylcholine agonist, it is widely used throughout Eastern Europe as
n aid to giving up smoking.
Biological Activity
A potent, selective agonist at neuronal nicotinic receptors. Acts as a partial agonist at β 2-containing nicotinic receptors.
Physical properties
Appearance: white or yellow powder. Solubility: soluble in water, pyridine, acetone, ethanol, and methanol and only slightly soluble in benzene but insoluble in petroleum ether. Melting point: 154–156?°C. Specific optical rotation: ?114.0 to ?116.0° (C?=?0.1, H2O). Toxic, stable under room temperature, and should be kept in a dry and dark place.
History
The largest amount of cytisine (about 1–5%) is also found in the seeds of common garden decorative plant Du-Dou 毒豆 (Laburnum anagyroides). In the early twentieth century, cytisine was identified as the toxic component of this plant. The extracts of Laburnum seeds or flowers have been used in traditional medicine for hundreds of years. In the Second World War, the leaves of Laburnum anagyroides were used as a tobacco substitute by soldiers. In 1960s, cytisine was firstly used as a smoking cessation aid in Bulgaria. The pharmacological and clinical studies of cytisine were also conducted in other Eastern European countries such as Poland and Russia. These results were promising. Stoyanov S. and Yanachkova M. studied 70 volunteers with a long experience in smoking. They found that 57% volunteers stopped smoking and 31.4% volunteers decreased cigarettes: reduction of the cigarettes smoked from 20–30 to 3–4 a day. Cytisine was developed and marked as Tabex? (Sopharma, Bulgaria), which has been widely distributed in the Eastern Europe .
Indications
It is the first effective medicine in the world for smoking cessation, which does not contain nicotine and antidepressants. It is administered perorally according to the following schedule:
First 3 days: one tablet six times daily (every 2 h) with a parallel reduction of the
number of cigarettes smoked.
If the result is unsatisfactory, the treatment is discontinued, and a new therapy
can be resumed after 2–3 months. In case of good effect, the treatment should continue according to the following schedule:
Fourth to 12th day: one tablet every 2 and 1/2 h (five tablets daily)
Thirteenth to 16th day: one tablet every 3 h (four tablets daily)
Seventeenth to 20th day: one tablet every 5 h (three tablets daily)
Twenty-first to 25th day: one to two tablets daily
General Description
Cystine ((1R,5S)-1,2,3,4,5,6-hexahydro-1,5-methano-8H-pyrido[1,2a][1,5]diazocin-8-one) displays classical antidepressant action in various animal models of antidepressant efficacy. Infrared and Raman spectral studies suggest that it has two stable conformers.
Health Hazard
Cytisine is highly toxic to humans and ani mals. Ingestions may cause nausea, vomiting,and convulsions. Death may occur from respiratory failure
LD50 value, oral (rats): 101 mg/kg.
Biochem/physiol Actions
Potent agonist at α3β4 and α7 nicotinic acetylcholine receptors and partial agonist at α4β2 nicotinic acetylcholine receptors.
Pharmacology
Tobacco smoking is one of the main threats to human health. Nicotine is responsible for the dependence of tobacco, and it is commonly accepted that nicotine addiction results from its interaction with neuronal nicotinic acetylcholine receptors (nAChRs). Cytisine has a similar chemical structure to that of nicotine, and in?vitro binding assays showed that cytisine possesses selective binding affinity for nAChRs, which is superior to that of nicotine and many other nAChR agonists. In vivo studies indicated that cytisine moderately increased the dopamine level in the mesolimbic system and attenuate the withdrawal symptoms.
Clinical Use
Cytisine has been used in the Eastern European countries for many years because of its proven benefits and low cost as compared with other cessation medications. A recent clinical trial in New Zealand found that at 1?month, continuous abstinence from smoking was reported for 40% of participants receiving cytisine (264 of 655)
and 31% of participants receiving nicotine replacement therapy (203 of 655) .
The available data indicates that cytisine is generally well-tolerated in human.
However, high dosages of cytisine can be toxic.
Purification Methods
Crystallise cytisine from acetone and sublime it in a vacuum. Its solubilities are: 77% (H2O), 7.7% (Me2CO), 28.6% (EtOH), 3.3% (*C6H6), 50% (CHCl3) but it is insoluble in pet ether. The tartrate has m 206-207o [] D +45.9o, the N-tosylate has m 206-207o, and the N-acetate has m 208o. [Bohlmann et al. Angew Chem 67 708 1955, van Tamelen & Baran J Am Chem Soc 77 4944 1955, Isolation: Ing J Chem Soc 2200 1931, Govindachari et al. J Chem Soc 3839 1957, Abs config: Okuda et al. Chem Ind (London) 1751 1961, Beilstein 24 H 134, 24 I 244, 24 II 70, 24 III/IV 321.] TOXIC.
