Clinical pharmacokinetics of arecoline in subjects with Alzheimer's disease

Bis-piperidine alkaloids from the peels of Areca catechu

Four new alkaloids, arecatines A-D (1-4), were isolated from the peels of Areca catechu. Compound 1 is an unusual piperidine-pyridine hybrid alkaloid, whereas compounds 2-4 feature bis-piperidine alkaloids. Their structures were elucidated by UV, IR, HRESIMS, and NMR spectra analysis. The molecular docking analysis indicated that compound 3 exhibited the best binding affinity with the GABAA receptor, indicating its potential anti-epilepsy activity.

Metabolism of the areca alkaloids - toxic and psychoactive constituents of the areca (betel) nut

Areca nut (AN) is consumed by millions of people for its therapeutic and psychoactive effects, making it one of the most widely self-administered psychoactive substances in the world. Even so, AN use/abuse is associated with myriad oral and systemic side effects, affecting most organ systems in the body. Alkaloids abundant in the nut (e.g. arecoline, arecaidine, guvacoline, and guvacine), collectively called the areca alkaloids, are presumably responsible for the major pharmacological effects experienced by users, with arecoline being the most abundant alkaloid with notable toxicological properties. However, the mechanisms of arecoline and other areca alkaloid elimination in humans remain poorly documented. Therefore, the purpose of this review is to provide an in-depth review of areca alkaloid pharmacokinetics (PK) in biological systems, and discuss mechanisms of metabolism by presenting information found in the literature. Also, the toxicological relevance of the known and purported metabolic steps will be reviewed. In brief, several areca alkaloids contain a labile methyl ester group and are susceptible to hydrolysis, although the human esterase responsible remains presumptive. Other notable mechanisms include N-oxidation, glutathionylation, nitrosamine conversion, and carbon-carbon double-bond reduction. These metabolic conversions result in toxic and sometimes less-toxic derivatives. Arecoline and arecaidine undergo extensive metabolism while far less is known about guvacine and guvacoline. Metabolism information may help predict drug interactions with human pharmaceuticals with overlapping elimination pathways. Altogether, this review provides a first-of-its-kind comprehensive analysis of AN alkaloid metabolism, adds perspective on new mechanisms of metabolism, and highlights the need for future metabolism work in the field.

Role of Shankhpushpi (Convolvulus pluricaulis) in Neurological Disorders: An Umbrella Review Covering Evidence from Ethnopharmacology to Clinical Studies

C. pluricaulis Choisy (C. pluricaulis), a perennial herb aka C. microphyllus Sieb. and C. Prostratus Forsk. is being used as a traditional folk medicine for a variety of ailments. In this article, we collected information about C. pluricaulis through electronic search using PubMed, SciFinder, Google Scholar, and Web of Science as well as network pharmacology is done. This comprehensive review sheds light on the plant profile, phytochemistry, neuropharmacological, and toxicological data of C. pluricaulis. The crude herb and its metabolites have exhibited a wide range of in vitro and in vivo neuropharmacological effects, including memory enhancement, anxiolytic, tranquilizing, anti-depressant, anti-stress, neurodegenerative, anti-inflammatory, anti-oxidant, analgesic, sedative, anti-convulsant, and Alzheimer's disease-reversing effects. Network pharmacology results indicate that compounds from C. pluricaulis interact with various proteins, neuro synapses, signaling pathways, and serotonergic synapse which plays a crucial role in neurotransmission, Alzheimer's disease, long-term depression, addictions to alcohol, cognitive disorders, psychological conditions, and increasing serotonin concentration in synapses.

Chemical Composition, Pharmacological, and Toxicological Effects of Betel Nut

Betel nut, the fruit of Areca catechu L, has a long medical history in Southeast Asia. It is native to Malaysia and is cultivated and processed extensively in subtropical regions, such as South China and India. Betel nut almost appears as a "snack" in various occasions in most parts of China. Clinically, betel nut can play a certain pharmacology role and was used in malaria, ascariasis, arthritis, enterozoic abdominalgia, stagnation of food, diarrhea, edema, and beriberi. The nervous excitement of betel nut chewing has made it gradually become popular. However, chewing betel nut can induce oral submucosal fibrosis (OSF) and oral cancer (OC). At the same time, long-term chewing of betel nut also causes inhaled asthma, sperm reducing, betel quid dependence (BQD), and uterine and esophageal cancers. The main components of processed betel nut are the goal of this review. This study will mainly start from the pharmacological activity and toxicology study of betel nut in recent years, aiming to seek its advantages and disadvantages. In the meantime, this study will analyze and emphasize that betel nut and arecoline are the high-risk factors for oral cancer, which should arouse attention and vigilance of the public.

Cholinergic System and Its Therapeutic Importance in Inflammation and Autoimmunity

Neurological and immunological signals constitute an extensive regulatory network in our body that maintains physiology and homeostasis. The cholinergic system plays a significant role in neuroimmune communication, transmitting information regarding the peripheral immune status to the central nervous system (CNS) and vice versa. The cholinergic system includes the neurotransmitter\ molecule, acetylcholine (ACh), cholinergic receptors (AChRs), choline acetyltransferase (ChAT) enzyme, and acetylcholinesterase (AChE) enzyme. These molecules are involved in regulating immune response and playing a crucial role in maintaining homeostasis. Most innate and adaptive immune cells respond to neuronal inputs by releasing or expressing these molecules on their surfaces. Dysregulation of this neuroimmune communication may lead to several inflammatory and autoimmune diseases. Several agonists, antagonists, and inhibitors have been developed to target the cholinergic system to control inflammation in different tissues. This review discusses how various molecules of the neuronal and non-neuronal cholinergic system (NNCS) interact with the immune cells. What are the agonists and antagonists that alter the cholinergic system, and how are these molecules modulate inflammation and immunity. Understanding the various functions of pharmacological molecules could help in designing better strategies to control inflammation and autoimmunity.

Indian Medicinal Herbs and Formulations for Alzheimer's Disease, from Traditional Knowledge to Scientific Assessment

Cognitive impairment, associated with ageing, stress, hypertension and various neurodegenerative disorders including Parkinson's disease and epilepsy, is a major health issue. The present review focuses on Alzheimer's disease (AD), since it is the most important cause of cognitive impairment. It is characterized by progressive memory loss, language deficits, depression, agitation, mood disturbances and psychosis. Although the hallmarks of AD are cholinergic dysfunction, β-amyloid plaques and neurofibrillary tangle formation, it is also associated with derangement of other neurotransmitters, elevated levels of advanced glycation end products, oxidative damage, neuroinflammation, genetic and environmental factors. On one hand, this complex etiopathology makes a response to commonly used drugs such as donepezil, rivastigmine, galantamine and memantine less predictable and often unsatisfactory. On the other hand, it supports the use of herbal medicines due to their nonspecific antioxidant and anti-inflammatory activity and specific cholinesterase inhibitory activity. The popularity of herbal medicines is also increasing due to their perceived effectiveness, safety and affordability. In the present article, the experimental and clinical evidence have been reviewed for various Indian herbal medicines such as Centella asiatica, Bacopa monnieri, Curcuma longa, Clitoria ternatea, Withania somnifera, Celastrus paniculatus, Evolvulus alsinoides, Desmodium gangeticum, Eclipta alba, Moringa oleifera and Convolvulus pluricaulis, which have shown potential in cognitive impairment. Some commonly available herbal formulations for memory impairment in India have also been reviewed.

Genetic toxicology and toxicokinetics of arecoline and related areca nut compounds: an updated review

Areca nut (AN) is consumed by more than 600 million of individuals, particularly in some regions of South Asia, East Africa, and tropical Pacific, being classified as carcinogenic to humans. The most popular way of exposure consists of chewing a mixture of AN with betel leaf, slaked lime, and other ingredients that may also contain tobacco named betel quid (BQ). Arecoline is the principal active compound of AN, and, therefore, has been systematically studied over the years in several in vitro and in vivo genotoxicity endpoints. However, much of this information is dispersed, justifying the interest of an updated and comprehensive review article on this topic. In this sense, it is thus pertinent to describe and integrate the genetic toxicology data available as well as to address key toxicokinetics aspects of arecoline. This review also provides information on the effects induced by arecoline metabolites and related compounds, including other major AN alkaloids and nitrosation derivatives. The complexity of the chemicals involved renders this issue a challenge in genetic toxicology. Overall, positive results in several endpoints have been reported, some of them suggesting a key role for arecoline metabolites. Nevertheless, some negative genotoxicity findings for this alkaloid in short-term assays have also been reported in the literature. Finally, this article also collates information on the potential mechanisms of arecoline-induced genotoxicity, and suggests further approaches to tackle this important toxicological issue.

Betel Quid Health Risks of Insulin Resistance Diseases in Poor Young South Asian Native and Immigrant Populations

Betel quid, traditionally prepared with areca nut, betel leaf, and slaked lime, has been consumed for thousands of years, mainly in the form of chewing. Originally used for cultural, medicinal, and ceremonial purposes mainly in South Asian countries, its use has recently spread across the globe due to its psychoactive, euphoric, and aphrodisiac properties. Now it is widely used as a social lubricant and source of financial profit. Unfortunately, the profit motive has led to high rates of habitual consumption with eventual conversion to addiction among young girls and boys. Moreover, the worrisome practice of including tobacco in quid preparations has grown, particularly among pregnant women. Major health concerns include increased rates of malignancy, oral pathology, and cardiovascular, hepatic, fertility, metabolic, and neuropsychiatric disorders. Metabolic disorders and insulin resistance disease states such as type 2 diabetes, obesity, and metabolic syndrome contribute to cognitive decline and neurodegeneration. Mechanistically, the constituents of areca nut/betel quid are metabolized to N-nitroso compounds, i.e., nitrosamines, which are carcinogenic at high doses and cause insulin resistance following chronic low-level exposures. From an epidemiological perspective, the rising tide of insulin resistance diseases including obesity, diabetes, and dementias that now disproportionately burden poor countries has been propagated by rapid commercialization and enhanced access to betel quid. Public health measures are needed to impose socially and ethically responsible barriers to yet another cause of global health disparity.

Adverse Health Effects of Betel Quid and the Risk of Oral and Pharyngeal Cancers

Global reports estimate 600 million betel quid (BQ) chewers. BQ chewing has been demonstrated not only to be a risk factor for cancers of the oral cavity and pharynx and oral potentially malignant disorders (OPMD) but also to cause other cancers and adverse health effects. Herein, we summarized the international comparison data to aid in the understanding of the close relationship between the prevalence of BQ chewing, the occurrence of oral and pharyngeal cancers, and adverse health effects. Potential biomarkers of BQ carcinogens, such as areca nut, alkaloids, and 3-methylnitrosaminopropionitrile (MNPN), are closely associated with human health toxicology. Molecular mechanisms or pathways involving autophagy, hypoxia, COX-2, NF-κB activity, and stemness are known to be induced by BQ ingredients and are very closely related to the carcinogenesis of cancers of oral and pharynx. BQ abuse-related monoamine oxidase (MAO) gene was associated with the occurrence and progress of oral and pharyngeal cancers. In summary, our review article provides important insights into the potential roles of environmental BQ (specific alkaloid biomarkers and nitrosamine products MNPN) and genetic factors (MAO) and offers a basis for studies aiming to reduce or eliminate BQ-related OPMD and oral/pharyngeal cancer incidences in the future.

Pilot study of the pharmacokinetics of betel nut and betel quid biomarkers in saliva, urine, and hair of betel consumers

Approximately 600 million people worldwide practise the carcinogenic habit of betel nut/quid chewing. Carcinogenic N-nitroso compounds have been identified in saliva or urine of betel chewers and the betel alkaloid arecoline in hair from habitual betel quid chewers. However, the pharmacokinetic parameters of these compounds have been little explored. Assessment of betel use by biomarkers is urgently needed to evaluate the effectiveness of cessation programmes aimed at reducing betel consumption to decrease the burden of cancers in regions of high betel consumption. In the search for biomarkers of betel consumption, we measured by liquid chromatography-mass spectrometry (LC-MS) the appearance and disappearance of betel alkaloids (characteristic for betel nuts), N-nitroso compounds, and chavibetol (characteristic for Piper Betle leaves) in saliva (n=4), hair (n=2), and urine (n=1) of occasional betel nut/quid chewers. The betel alkaloids arecoline, guvacoline, guvacine, and arecaidine were detected in saliva of all four participants and peaked within the first 2 h post-chewing before returning to baseline levels after 8 h. Salivary chavibetol was detected in participants consuming Piper Betle leaves in their quid and peaked ~1 h post-chewing. Urinary arecoline, guvacoline, and arecaidine excretion paralleled saliva almost exactly while chavibetol glucuronide excretion paralleled salivary chavibetol. No betel nut related compounds were detected in the tested hair samples using various extraction methods. From these preliminary results, we conclude that betel exposure can only be followed on a short-term basis (≤8 h post-chewing) using the applied biomarkers from urine and saliva while the feasibility of using hair has yet to be validated. Copyright © 2015 John Wiley & Sons, Ltd.

Quantification of Salivary Arecoline, Arecaidine and N-Methylnipecotic Acid Levels in Volunteers by Liquid Chromatography-Tandem Mass Spectrometry

Relatively little is known about the metabolism of areca nut in human saliva. We here describe the simultaneous quantification of areca nut metabolites: arecoline, arecaidine and N-methylnipecotic acid in saliva samples after chewing one 5 g areca nut by using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Time courses of salivary areca nut metabolites in five adult male areca nut chewer volunteers were investigated. The limits of quantification were all 1.25 ng/mL for arecoline, arecaidine and N-methylnipecotic acid. Intra- and interday imprecisions were <4.2 and 13.6%, respectively. The within-day accuracy ranged from 82.2 to 116.7%, and the between-day accuracy ranged from 78.3 to 115.6%. Through areca nut chewing time course study, we found that salivary arecoline, arecaidine and N-methylnipecotic acid concentrations varied greatly over time between experiment individuals. Our findings suggest that arecoline might be metabolized slightly to arecaidine at 30 min after areca nut chewing and arecoline might be metabolized slightly to N-methylnipecotic acid at 25 min after areca nut chewing in the mouth. We first provide simultaneous quantification of human salivary arecoline, arecaidine and N-methylnipecotic acid levels using LC-MS-MS. This method may facilitate future research design in the pathogenic effects of areca nut exposure.

Formulation optimization of arecoline patches

The response surface methodology (RSM) including polynomial equations has been used to design an optimal patch formulation with appropriate adhesion and flux. The patch formulations were composed of different polymers, including Eudragit RS 100 (ERS), Eudragit RL 100 (ERL) and polyvinylpyrrolidone K30 (PVP), plasticizers (PEG 400), and drug. In addition, using terpenes as enhancers could increase the flux of the drug. Menthol showed the highest enhancement effect on the flux of arecoline.

Chewing betel quid and the risk of metabolic disease, cardiovascular disease, and all-cause mortality: a meta-analysis

Background

Betel nut (Areca nut) is the fruit of the Areca catechu tree. Approximately 700 million individuals regularly chew betel nut (or betel quid) worldwide and it is a known risk factor for oral cancer and esophageal cancer. We performed a meta-analysis to assess the influence of chewing betel quid on metabolic diseases, cardiovascular disease, and all-cause mortality.

Methodology/Principal Findings

We searched Medline, Cochrane Library, Web of Science, and Science Direct for pertinent articles (including the references) published between 1951 and 2013. The adjusted relative risk (RR) and 95% confidence interval were calculated using the random effect model. Sex was used as an independent category for comparison.

Results

Of 580 potentially relevant studies, 17 studies from Asia (5 cohort studies and 12 case-control studies) covering 388,134 subjects (range: 94 to 97,244) were selected. Seven studies (N = 121,585) showed significant dose-response relationships between betel quid consumption and the risk of events. According to pooled analysis, the adjusted RR of betel quid chewers vs. non-chewers was 1.47 (P<0.001) for obesity (N = 30,623), 1.51 (P = 0.01) for metabolic syndrome (N = 23,291), 1.47 (P<0.001) for diabetes (N = 51,412), 1.45 (P = 0.06) for hypertension (N = 89,051), 1.2 (P = 0.02) for cardiovascular disease (N = 201,488), and 1.21 (P = 0.02) for all-cause mortality (N = 179,582).

Conclusion/Significance

Betel quid chewing is associated with an increased risk of metabolic disease, cardiovascular disease, and all-cause mortality. Thus, in addition to preventing oral cancer, stopping betel quid use could be a valuable public health measure for metabolic diseases that are showing a rapid increase in South-East Asia and the Western Pacific.

Effect of Arecoline on Regeneration of Injured Peripheral Nerves

The present study provides in vitro and in vivo evaluation of arecoline on peripheral nerve regeneration. In the in vitro study, we found that arecoline at 50 μg/ml could significantly promote the survival and outgrowth of cultured Schwann cells as compared to the controls treated with culture medium only. In the in vivo study, we evaluated peripheral nerve regeneration across a 10-mm gap in the sciatic nerve of the rat, using a silicone rubber nerve chamber filled with the arecoline solution. In the control group, the chambers were filled with normal saline only. At the end of the fourth week, morphometric data revealed that the arecoline-treated group at 5 μg/ml significantly increased the number and the density of myelinated axons as compared to the controls. Immunohistochemical staining in the arecoline-treated animals at 5 μg/ml also showed their neural cells in the L4 and L5 dorsal root ganglia ipsilateral to the injury were strongly retrograde-labeled with fluorogold and lamina I–II regions in the dorsal horn ipsilateral to the injury were significantly calcitonin gene-related peptide-immunolabeled compared with the controls. In addition, we found that the number of macrophages recruited in the distal sciatic nerve was increased as the concentration of arecoline was increased. Electrophysiological measurements showed the arecoline-treated groups at 5 and 50 μg/ml had a relatively larger nerve conductive velocity of the evoked muscle action potentials compared to the controls. These results indicate that arecoline could stimulate local inflammatory conditions, improving the recovery of a severe peripheral nerve injury.

An update on Shankhpushpi, a cognition-boosting Ayurvedic medicine

Shankhpushpi is an Ayurvedic drug used for its action on the central nervous system, especially for boosting memory and improving intellect. Quantum of information gained from Ayurvedic and other Sanskrit literature revealed the existence of four different plant species under the name of Shankhpushpi, which is used in various Ayurvedic prescriptions described in ancient texts, singly or in combination with other herbs. The sources comprise of entire herbs with following botanicals viz., Convulvulus pluricaulis Choisy. (Convulvulaceae), Evolvulus alsinoides Linn. (Convulvulaceae), Clitoria ternatea Linn. (Papilionaceae) and Canscora decussata Schult. (Gentianaceae). A review on the available scientific information in terms of pharmacognostical characteristics, chemical constituents, pharmacological activities, preclinical and clinical applications of controversial sources of Shankhpushpi is prepared with a view to review scientific work undertaken on Shankhpushpi. It may provide parameters of differentiation and permit appreciation of variability of drug action by use of different botanical sources.

Monoamine oxidase A variants are associated with heavy betel quid use

Few studies have investigated whether genetic abnormalities predispose individuals to heavy betel quid (BQ) use. One of the major ingredients of BQ, arecoline, is known to affect the expression of monoamine oxidase A (MAO-A). We investigated the extent to which arecoline inhibits MAO-A expression and the role of MAO-A polymorphisms in BQ use in Taiwanese aborigines. Cytotoxicity assays, microarrays and quantitative reverse transcriptase-polymerase chain reaction were used to examine the effects of arecoline and areca nut extract (ANE) on cell viability and MAO-A expression in neuroblastoma SH-SY5Y cells. After identifying the effective concentrations of arecoline and ANE in vitro, we examined the in vivo effects of these compounds using a rat model system. Our results indicate that arecoline and ANE inhibit MAO-A expression both in vitro and in vivo. In addition, we examined the correlation between plasma MAO-A activity and cumulative exposure to BQ in humans. We recruited 1307 aborigines from a large-scale community-based survey to determine whether MAO-A variants were associated with high BQ use and a preference for use with smoking or alcohol and whether gender bias existed. MAO-A expression was significantly downregulated by arecoline and ANE at 100-200 µg/ml and in rat whole brains on days 30 and 45. MAO-A activity levels in human plasma were positively correlated with the extent of BQ exposure, and individuals with at-risk alleles exhibited lower activity, although this result did not reach statistical significance. We found two single nucleotide polymorphism (SNPs) in aboriginal males [rs2283725, odds ratio (OR) = 2.04; rs5953210, OR = 2.03] and females (rs2283725, OR = 1.54; rs5953210, OR = 1.59) that were associated with heavy BQ use. Those individuals carrying at-risk alleles who drank alcohol were twice as likely to be heavy BQ users. However, the effects of these SNPs on BQ use were significant even after controlling for alcohol use. Our results suggest that two specific loci may confer a susceptibility to BQ abuse and affect MAO-A enzymatic activity.

Potential action of betel alkaloids on positive and negative symptoms of schizophrenia: a review

BACKGROUND

The Areca catechu Linn. is the fourth most used drug in the world after nicotine, ethanol and caffeine. This plant contains nine alkaloids with muscarinic and nicotinic action, which could have an antipsychotic effect.

AIM

The aim of this work is reviewing literature data about the potential action of betel alkaloids on positive, negative and cognitive symptoms of schizophrenia.

METHOD

We reviewed the clinical literature data since 1980 via a PubMed search for the terms: arecoline, arecaidine, guvacine, guvacoline, betel, Areca catechu, positive and negative symptoms, cognitive symptoms, psychosis and schizophrenia in combination.

CONCLUSION

Male high consumption of betel had significantly lower positive symptoms than low consumers or non-betel users.

Arecoline, a major alkaloid of the areca nut, causes neurotoxicity through enhancement of oxidative stress and suppression of the antioxidant protective system

Arecoline, an areca nut alkaloid, has been noted for its potential cognition-enhancing effects in patients with Alzheimer dementia. However, it has been confirmed that areca nut use is associated with oral and pharyngeal cancers. In addition, arecoline is genotoxic and cytotoxic both in vitro and in vivo through oxidative stress-dependent mechanisms. The aim of this study was to investigate whether arecoline would interfere with the antioxidant defense system and induce cytotoxicity in rat primary cortical neurons. Results indicate that arecoline (50-200 μM) induces neuronal cell death, and catalase, NADPH oxidase inhibitors (diphenyleneiodonium chloride and apocynin), and a caspase inhibitor (z-VAD-fmk) can prevent arecoline-induced cell death. Furthermore, arecoline increased reactive oxygen species production and upregulated protein expression and mRNA levels of NADPH oxidase 2, which could be attenuated by catalase and NADPH oxidase inhibitors. Arecoline also attenuated neuronal antioxidant defense by decreasing glutathione (GSH) level and superoxide dismutase activity. In addition, arecoline enhanced the expression of proapoptotic proteins (cytochrome c, Bax, caspase-9, and caspase-3) and attenuated the expression of the antiapoptotic protein Bcl-2. Moreover, NADPH oxidase inhibitors could attenuate the arecoline-induced GSH depletion and reverse arecoline-induced changes in proapoptotic and antiapoptotic proteins. In conclusion, the results indicate that arecoline could induce neuronal apoptotic death by attenuating antioxidant defense and enhancing oxidative stress.

High-throughput simultaneous analysis of five urinary metabolites of areca nut and tobacco alkaloids by isotope-dilution liquid chromatography-tandem mass spectrometry with on-line solid-phase extraction

BACKGROUND

Areca nut and tobacco are commonly used drugs worldwide and have been frequently used in combination. We describe the use of on-line solid-phase extraction and isotope-dilution liquid chromatography-tandem mass spectrometry for the simultaneous measurement of five major urinary metabolites of both areca nut and tobacco alkaloids, namely, arecoline, arecaidine, N-methylnipecotic acid, nicotine, and cotinine.

METHODS

Automated purification of urine was accomplished with a column-switching device. After the addition of deuterium-labeled internal standards, urine samples were directly analyzed within 13 minutes. This method was applied to measure urinary metabolites in 90 healthy subjects to assess areca nut/tobacco exposure. Urinary time course of arecoline, arecaidine, and N-methylnipecotic acid was investigated in five healthy nonchewers after oral administration of areca nut water extracts.

RESULTS

The limits of detection were 0.016 to 0.553 ng/mL. Interday and intraday imprecision were <10%. Mean recoveries of five metabolites in urine were 97% to 114%. Mean urinary concentrations of arecoline, arecaidine, N-methylnipecotic acid, nicotine, and cotinine in regular areca nut chewers also smokers were 23.9, 5,816, 1,298, 2,635, and 1,406 ng/mg creatinine, respectively. Time course study revealed that after administration of areca nuts extracts, the major urinary metabolite was arecaidine with a half-life of 4.3 hours, followed by N-methylnipecotic acid with a half-life of 7.9 hours, and very low levels of arecoline with a half-life of 0.97 hour.

CONCLUSIONS

This on-line solid-phase extraction liquid chromatography-tandem mass spectrometry method firstly provides high-throughput direct analysis of five urinary metabolites of areca nut/tobacco alkaloids.

IMPACT

This method may facilitate the research into the oncogenic effects of areca nut/tobacco exposure.

Systemic conditions associated with areca nut usage: a literature review

AIM

The adverse effects of areca nut (AN) chewing habit on oral health have been reported. However, the hazards related to the habit are not restricted to the oral cavity but they can also jeopardise the systemic health. Since no review reporting the harmful effects of AN chewing on systemic health is yet available, the aim of the present study was to review the systemic conditions associated with AN usage.

METHODS

To address the focused question ''What are the deleterious effects of AN usage on systemic health?'', the MEDLINE PubMed databases were explored from 1966 up to and including May 2010. The eligibility criteria included: human studies, individuals using AN, use of controls, and articles published in English. Hand-searching was also performed. Unpublished data was excluded.

RESULTS

The review included 28 articles. Seven studies associated AN chewing with cardiovascular disorders and three studies related the habit with cerebrovascular disorders. Eight studies related AN chewing with obesity, hyperglycaemia, metabolic syndrome, and type 2 diabetes mellitus. Five studies related AN chewing with the development of hepatic disorders. Two studies associated the chewing habit with oesophageal inflammation and fibrosis. Three studies associated AN chewing with respiratory discomfort. Renal disorders were related with the chewing abuse in two studies. Two studies showed an adverse effect of AN chewing on birth outcome.

CONCLUSIONS

AN chewing adversely affects systemic health by damaging the vital organs.

Arecoline-induced growth arrest and p21WAF1 expression are dependent on p53 in rat hepatocytes

Betel-quid use is associated with the risk of liver cirrhosis and hepatocellular carcinoma and arecoline, the major alkaloid of betel-quid, is hepatotoxic in mice. Therefore, we studied the cytotoxic and genotoxic effects of arecoline in normal rat hepatocytes (Clone-9 cells). Arecoline dose-dependently (0.1-1mM) decreased cell cycle-dependent proliferation while inducing DNA damage at 24h. Moreover, arecoline (1mM)-induced apoptosis and necrosis at 24h. Arecoline dose-dependently (0.1-0.5mM) increased transforming growth factor-beta (TGF-beta) mRNA, gene transcription and bioactivity and neutralizing TGF-beta antibody attenuated arecoline (0.5mM)-inhibited cell proliferation at 24h. Arecoline (0.5mM) also increased p21(WAF1) protein expression and p21(WAF1) gene transcription. Moreover, arecoline (0.5mM) time-dependently (8-24h) increased p53 serine 15 phosphorylation. Pifithrin-alpha (p53 inhibitor) and the loss of the two p53-binding elements in the p21(WAF1) gene promoter attenuated arecoline-induced p21(WAF1) gene transcription at 24h. Pifithrin-alpha also attenuated arecoline (0.5mM)-inhibited cell proliferation at 24h. We concluded that arecoline induces cytotoxicity, DNA damage, G(0)/G(1) cell cycle arrest, TGF-beta1, p21(WAF1) and activates p53 in Clone-9 cells. Moreover, arecoline-induced p21(WAF1) is dependent on p53 while arecoline-inhibited growth is dependent on both TGF-beta and p53.

Ultrastructural and hormonal changes in the pineal-testicular axis following arecoline administration in rats

Arecoline is an alkaloid of betel nut of Areca catechu. Betel nut is chewed by millions of people in the world and it causes oral and hepatic cancers in human. It has therapeutic value for the treatment of Alzheimer and schizophrenia. Arecoline has immunosuppressive, mutagenic and genotoxic effects in laboratory animals. It also affects endocrine functions. The objective of this study was to investigate the effects of arecoline on pineal-testicular axis in rats. Since pineal activity is different between day and night, the current study is undertaken in both the photophase and scotophase. The findings were evaluated by ultrastructural and hormonal studies of pineal and testicular Leydig cells, with quantitations of fructose and sialic acid of sex accessories. Arecoline treatment (10 mg/kg body weight daily for 10 days) caused suppression of pineal activity at ultrastructural level by showing dilatation of the cisternae of the rough endoplasmic reticulum (RER), large autophagosome-like bodies with swollen mitochondrial cristae, numerous lysosomes, degenerated synaptic ribbons and reduced number of synaptic-like microvesicles. Moreover, pineal and serum N-acetylserotonin and melatonin levels were decreased with increased serotonin levels in both the gland and serum. In contrast, testicular Leydig cell activity was stimulated with abundance of smooth endoplasmic reticulum (SER), electron-dense core vesicles and vacuolated secretory vesicles, and increased testosterone level in the arecoline recipients. Consequently, the testosterone target, like prostate, was ultrastructurally stimulated with abundance of RER and accumulation of secretory vesicles. Fructose and sialic acid concentrations were also significantly increased respectively in the coagulating gland and seminal vesicle. These results were more significant in the scotophase than the photophase. The findings suggest that arecoline inhibits pineal activity, but stimulates testicular function (testosterone level) and its target organs presumably via muscarinic cholinergic receptor in rats.

Betel Nut Use among First and Second Generation Bangladeshi Women in London, UK

This study evaluated the effects of socio-economic variables and migration history on the prevalence of betel nut and smokeless tobacco use in both UK- and Bangladeshi born migrant women resident in London. No significant difference in betel nut use prevalence was found among women of different generations. However, in all groups betel nut users were significantly older and less educated than non-users. Among first generation women there was no effect of either length of time living in the UK or age at migration on use of betel nut, even after controlling for current age. No significant differences in prevalence use due to language spoken, occupation, marital status or borough of residence in London were found. We conclude that, although there are some indications of a change in behavior among younger individuals, betel nut chewing is a practice very much present among Bangladeshi women born and brought up in a bicultural context.

A metabolomic approach to the metabolism of the areca nut alkaloids arecoline and arecaidine in the mouse

The areca alkaloids comprise arecoline, arecaidine, guvacoline, and guvacine. Approximately 600 million users of areca nut products, for example, betel quid chewers, are exposed to these alkaloids, principally arecoline and arecaidine. Metabolism of arecoline (20 mg/kg p.o. and i.p.) and arecaidine (20 mg/kg p.o. and i.p.) was investigated in the mouse using a metabolomic approach employing ultra-performance liquid chromatography-time-of-flight mass spectrometric analysis of urines. Eleven metabolites of arecoline were identified, including arecaidine, arecoline N-oxide, arecaidine N-oxide, N-methylnipecotic acid, N-methylnipecotylglycine, arecaidinylglycine, arecaidinylglycerol, arecaidine mercapturic acid, arecoline mercapturic acid, and arecoline N-oxide mercapturic acid, together with nine unidentified metabolites. Arecaidine shared six of these metabolites with arecoline. Unchanged arecoline comprised 0.3-0.4%, arecaidine 7.1-13.1%, arecoline N-oxide 7.4-19.0%, and N-methylnipecotic acid 13.5-30.3% of the dose excreted in 0-12 h urine after arecoline administration. Unchanged arecaidine comprised 15.1-23.0%, and N-methylnipecotic acid 14.8%-37.7% of the dose excreted in 0-12 h urine after arecaidine administration. The major metabolite of both arecoline and arecaidine, N-methylnipecotic acid, is a novel metabolite arising from carbon-carbon double-bond reduction. Another unusual metabolite found was the monoacylglyceride of arecaidine. What role, if any, that is played by these uncommon metabolites in the toxicology of arecoline and arecaidine is not known. However, the enhanced understanding of the metabolic transformation of arecoline and arecaidine should contribute to further research into the clinical toxicology of the areca alkaloids.

Effects of arecoline in relaxing human umbilical vessels and inhibiting endothelial cell growth

This study investigated the effects of arecoline, an active ingredient of the areca nut, on the tone of human umbilical arteries and veins and on the eNOS expression and cell proliferation of human umbilical vein endothelial cells (HUVECs). We found that arecoline relaxes the human umbilical artery and vein rings in a concentration-dependent manner; the higher the concentration of arecoline, the greater the relaxation of the rings. However, the relaxation decreases after the endothelium was removed or pretreated with L-NAME, a nitric oxide synthase inhibitor. Moreover, arecoline increases in a dose-dependent way the cGMP levels of human umbilical arteries and veins. In HUVECs, arecoline also increases the eNOS expression. Therefore, the relaxant effects of arecoline on the umbilical artery and vein rings were endothelium-dependent through the NO-cGMP systems. In addition, arecoline at higher doses (100-1000 microM) inhibits endothelial cell proliferation; the exposure toarecoline (100-1000 microM) for 24 and 48 h induces G2/M cell cycle arrest of HUVECs. Our results indicate that arecoline would decrease vascular tone, in part mediated by NO. Higher doses of arecoline inhibit endothelial cell growth, which suggest that long-term use or high doses of areca nut might induce endothelial dysfunction and associated diseases.

Porcine vaginal mucosa as an in vitro permeability model for human vaginal mucosa

The availability of human tissue for experimental purposes is often problematical and use is thus made of animal tissue as models of the human tissue. In this study, porcine vaginal mucosa was used as an in vitro permeability model for human vaginal mucosa using tritium-labelled permeants (17beta-estradiol, r-arecoline, vasopressin, oxytocin and water). Fresh porcine and human vaginal tissues were frozen in liquid nitrogen and stored at -85 degrees C. In vitro permeability studies were performed using a flow-through diffusion apparatus (24 h, 20 degrees C, 1.5 ml/h). The mean steady state flux values for water, r-arecoline and vasopressin were approximately 4, 12 and 5% lower, while those for 17beta-estradiol and oxytocin were approximately 17 and 53% higher, through porcine vaginal mucosa as compared to human vaginal mucosa, respectively. Using a F-test (comparing whole curves), statistically significant differences in the diffusion of 17beta-estradiol, r-arecoline and oxytocin were indicated when comparing human and porcine vaginal mucosa. Generally, porcine vaginal mucosa seems a good in vitro permeability model for human vaginal mucosa. However, permeability of these two mucosa towards all permeants tested does not always correspond closely. These differences must always be considered when using porcine tissue as an in vitro permeability model for human vaginal mucosa.

Effects of aqueous extracts of "Betel quid" and its constituents on testosterone production by dispersed mouse interstitial cells

Betel quid (BQ) is a favorite chewing item among many communities in different parts of Asia where it is popular by different names. BQ is a unique combination of nut or fruit from the Areca catechu Linn. (AN) tree, leaf from the Piper betle Linn. (BL) vine, slaked lime, paste of bark from the Acacia catechu tree and other spices. AN has been used successfully in various traditional medicines by different civilizations over several ages. Initially condemned by the medical communities for its health hazards, identification and application of potent pharmacologically bioactive compounds from different constituents of BQ have rekindled growing interest in related investigations. Curious about the stimulating role of BQ, we investigated the potential steroidogenic activity of hot water extract from BQ and its constituents and arecoline on testosterone producing ability in an in vitro experiment. Enzyme dissociated interstitial cells from adult mouse testes (ICR strain) were cultured with/without different doses of the extracts and the level of testosterone produced was assayed by an enzyme immunoassay (EIA) technique. It was found that at lower doses of arecoline, AN and BL extracts had significantly stimulated testosterone production over the basal level (p < 0.05). BQ extract, on the other hand, did not show any significant effect on testosterone production. Combinations of arecoline at low doses with 10 ng/ml ovine leutinizing hormone (oLH) showed increases in testosterone produced, while cyclic adenosine monophosphate (cAMP) co-culture showed dose-related inhibition. Our current finding hints at the possible dose-dependent dualistic role of AN and BL extracts and arecoline for testosterone production employing possible non-cAMP-dependent pathway of steroidogenesis. However, the identity of the active compounds besides arecoline and the exact mechanism involved remains to be further investigated.

Psychotropic substance-seeking: evolutionary pathology or adaptation?

According to a conventional evolutionary perspective, the human propensity for substance use is the product of a 'mismatch' between emotional mechanisms that evolved in a past without pure drugs or direct routes of drug administration, and the occurrence of these phenomena in the contemporary environment. The primary purpose of this review is to assert that, contrary to the conventional view, humans have shared a coevolutionary relationship with psychotropic plant substances that is millions of years old. We argue that this 'deep time' relationship is self-evident both in the extant chemical-ecological adaptations that have evolved in mammals to metabolize psychotropic plant substances and in the structure of plant defensive chemicals that have evolved to mimic the structure, and interfere with the function, of mammalian neurotransmitters. Given this evidence, we question how emotional mechanisms easily triggered by plant toxins can have evolved. Our argument is also supported with archeological and historical evidence of substance use in antiquity suggesting that, for people in the past, psychotropic plant substances were as much a mundane everyday item as they are for many people today. Our second, and more speculative objective is to suggest provisional hypotheses of human substance-using phenomena that can incorporate the evolutionary implications of a deep time relationship between psychotropic substances and people. We discuss hypotheses of selective benefits of substance use, including the idea that neurotransmitter-analog plant chemicals were exploited as substitutes for costly, nutritionally constrained endogenous neurotransmitters. However, even if substance seeking was adaptive in the environment of our hominid ancestors, it may not still be so in the contemporary environment. Thus, the implications of our argument are not that the mismatch concept does not apply to human substance-using phenomena, but that it must be reconsidered and extended to incorporate the implications of a substance-rich, rather than substance-free, evolutionary past.

Anthropological perspectives on use of the areca nut

This paper first reviews the identity of historical and contemporary users of the areca nut. It then considers the reasons given by users for indulging in areca consumption, drawing upon historical, ethnographic and experimental sources of evidence for the effects which users have sought to derive from it. Particularly important is the social context in which consumption occurs, and the social meanings attached to areca use and exchange. Finally, a possible evolutionary hypothesis is postulated to explain the origins of areca use as a form of behaviour indicating reproductive availability. However, diverse culturally explicit reasons underlie usage and what may once have been a sufficient rationale for consumption may no longer justify this pattern of behaviour.

Effects of chewing betel nut (Areca catechu) on the symptoms of people with schizophrenia in Palau, Micronesia

BACKGROUND

Although millions of people with schizophrenia live in betel chewing regions, the effects of betel chewing on their symptoms are unknown. Betel nut alkaloids include potent muscarinic cholinomimetics: recent research suggests that these agents may be therapeutic in schizophrenia.

AIMS

To compare the primary and extrapyramidal symptom profiles and substance-using habits of betel chewing v. non-chewing people with schizophrenia.

METHOD

A cross-sectional study of 70 people with schizophrenia. Symptom ratings measured by the Positive and Negative Syndrome Scale (PANSS) and Extrapyramidal Symptom Rating Scale (ESRS), and demographic and substance-use data, were compared for 40 chewers and 30 non-chewers of betel nut.

RESULTS

Betel chewers with schizophrenia scored significantly lower on the positive (P = 0.001) and negative (P = 0.002) sub-scales of the PANSS than did non-chewers. There were no significant differences in extrapyramidal symptoms or tardive dyskinesia.

CONCLUSIONS

Betel chewing is associated with milder symptomatology and avoidance of more harmful recreational drugs. These initial results indicate that longitudinal research is merited.

Twenty years of cholinergic intervention in Alzheimer's disease: A tale of disappointment and ultimate confidence

The authors present an overview of drugs that operate on the basis of the cholinergic hypothesis, either currently available for the palliative treatment of Alzheimer's disease or in the later stages of clinical development. Of the many conceivable strategies that are being exploited, only inhibitors of acetylcholinesterase have been shown to have sufficient therapeutic potential and manageable side-effect profiles to be turned into broadly acknowledged drugs. These compounds, and others based on the modulation of cholinergic neurotransmission, are discussed and a differentiation of their clinical potential is attempted.

Arecoline via miniosmotic pump improves AF64A-impaired radial maze performance in rats: a possible model of Alzheimer's disease

Male Sprague-Dawley rats, preoperatively trained in a 1-h delay non-match-to-position radial maze task, received bilateral stereotaxic injections of a selective cholinotoxin, ethylcholine aziridinium ion (AF64A: 3 nmol/3 microliters/lateral ventricle). Animals treated with AF64A made significantly more total postdelay errors than vehicle controls. Sustained delivery, via miniosmotic pumps, of arecoline (0.1, 0.3, 1, 3, 10, or 30 mg/kg/day sc for 14 days) attenuated the AF64A-induced cognitive impairment in a dose-dependent manner, producing an inverted U-shaped dose-response function which was optimal at 1.0 mg/kg/day. Following these studies, choline acetyltransferase activity was significantly reduced in hippocampi extracted from the AF64A-treated rats, indicating successful cholinotoxicity. This paradigm may be useful as a possible screen for potential Alzheimer's disease therapeutic agents. This conclusion is supported by published reports of beneficial arecoline effects observed following 2-week intravenous infusions in patients with Alzheimer's disease (Soncrant, Raffaele, Asthana, Berardi, Morris, & Haxby, 1993).