Arecoline


Arecoline is a nicotinic acid-based alkaloid found in the areca nut, the fruit of the areca palm. It is an odourless oily liquid. It can bring a sense of euphoria and relaxation.

Chemistry

Arecoline is a base, and its conjugate acid has a pKa ~ 6.8.
Arecoline is volatile in steam, miscible with most organic solvents and water, but extractable from water by ether in presence of dissolved salts. Being basic, arecoline forms salts with acids. The salts are crystalline, but usually deliquescent: the hydrochloride, arecoline•HCl, forms needles, m.p. 158 °C; the hydrobromide, arecoline•HBr, forms slender prisms, mp. 177–179 °C from hot alcohol; the aurichloride, arecoline•HAuCl4, is an oil, but the platinichloride, arecoline2•H2PtCl6, mp. 176 °C, crystallizes from water in orange-red rhombohedrons. The methiodide forms glancing prisms, mp. 173-174 °C.

Pharmacology

Arecoline is the primary active ingredient responsible for the central nervous system effects of the areca nut. Arecoline has been compared to nicotine; however, nicotine acts primarily on the nicotinic acetylcholine receptor. Arecoline is known to be a partial agonist of muscarinic acetylcholine M1, M2, M3 receptors and M4, which is believed to be the primary cause of its parasympathetic effects. Arecoline also acts on nicotinic receptor

Effects on nervous system

Arecoline promotes excitation and decreases sleeping time. It also enhances learning and memory. Intraperitoneal administration of arecoline decreases locomotor activity dose dependently. Arecoline reversed scolopamine induced memory loss. It could also decrease symptoms of depression and schizophrenia

Effects on cardiovasular system

AN is a vasodilator mainly due to presence of arecoline. It also have anti-thrombosis and anti-atherogenic effects by increasing plasma nitric oxide, eNos and mRNA expression and decreasing IL-8 along with other downregulations.

Effects on endocrine system

It increases level of testosterone by stimulating Leydig's cells as well as levels of FSH and LH. It also activates HPA axis and stimulates CRH release.It prevents dysfunction of B cells of pancreas from high fructose intake.

Effects on digestive system

Arecoline has the ability to stimulate digestive system through activation os musacarinic receptors. Areca nut water extract could increase the contractions of gastric smooth muscle and muscle strips of duodenum, ileum and colon significantly. This activity could be caused my arecoline.

Uses

Owing to its muscarinic and nicotinic agonist properties, arecoline has shown improvement in the learning ability of healthy volunteers. Since one of the hallmarks of Alzheimer's disease is a cognitive decline, arecoline was suggested as a treatment to slow down this process and arecoline administered intravenously did indeed show modest verbal and spatial memory improvement in Alzheimer's patients, though due to arecoline's possible carcinogenic properties, it is not the first drug of choice for this degenerative disease.In many Asian cultures, the areca nut is chewed along with betel leaf to obtain a stimulating effect.
Arecoline has also been used medicinally as an antihelmintic.
Arecoline also increase testosterone in low doses

Toxicity

Current science is confident that areca nut chewing is carcinogenic. Research suggests this is probably at least partly because of arecoline itself, although it could also be from the other constituents of the nut as well, some of which are precursors to nitrosamines that form in the mouth during chewing. Section 5.5 Evaluation on page 238 of IARC Monograph 85-6 states the following:

  • There is sufficient evidence in humans for the carcinogenicity of betel quid without tobacco. Betel quid without tobacco causes oral cancer.
  • There is sufficient evidence in experimental animals for the carcinogenicity of betel quid without tobacco.
  • There is sufficient evidence in experimental animals for the carcinogenicity of betel quid with tobacco.
  • There is sufficient evidence in experimental animals for the carcinogenicity of areca nut.
  • There is sufficient evidence in experimental animals for the carcinogenicity of areca nut with tobacco.
  • There is limited evidence in experimental animals for the carcinogenicity of arecoline.
  • There is inadequate evidence in experimental animals for the carcinogenicity of arecaidine.