Systemic administration of arecoline reduces ethanol-induced sleeping through activation of central muscarinic receptor in mice

Inhibition of cortical synaptic transmission, behavioral nociceptive, and anxiodepressive-like responses by arecoline in adult mice

Areca nut, the seed of Areca catechu L., is one of the most widely consumed addictive substances in the world after nicotine, ethanol, and caffeine. The major effective constituent of A. catechu, arecoline, has been reported to affect the central nervous system. Less is known if it may affect pain and its related emotional responses. In this study, we found that oral application of arecoline alleviated the inflammatory pain and its induced anxiolytic and anti-depressive-like behavior. Arecoline also increased the mechanical nociceptive threshold and alleviated depression-like behavior in naïve mice. In the anterior cingulate cortex (ACC), which acts as a hinge of nociception and its related anxiety and depression, by using the multi-electrode field potential recording and whole-cell patch-clamp recording, we found that the evoked postsynaptic transmission in the ACC of adult mice has been inhibited by the application of arecoline. The muscarinic receptor is the major receptor of the arecoline in the ACC. Our results suggest that arecoline alleviates pain, anxiety, and depression-like behavior in both physiological and pathological conditions, and this new mechanism may help to treat patients with chronic pain and its related anxiety and disorder in the future.

Comprehensive insights into areca nut: active components and omics technologies for bioactivity evaluation and quality control

Areca nut (AN), the fruit or seed of Areca catechu Linn, has many uses, including chewing and medicinal purposes. It has sparked worries about health due to the presence of alkaloids. Chewing AN may have a variety of negative consequences; however, the medicinal use of AN has no notable adverse effects. To completely understand and effectively use AN, researchers have investigated its chemical makeup or biological activity, analyzed the variations between different AN species and different periods, and improved extraction and processing procedures. Today, an increasing number of researchers are exploring the underlying reasons for AN variations, as well as the molecular mechanisms of biosynthesis of chemical components, to comprehend and change AN at the genetic level. This review presents an overview of the clinical study, pharmacology, and detection of the main bioactive components in AN, and the main factors influencing their content, delving into the omics applications in AN research. On the basis of the discussions and summaries, this review identifies current research gaps and proposes future directions for investigation.

Biological Effects and Biomedical Applications of Areca Nut and Its Extract

The dried, mature fruit of the palm tree species Areca catechu L. is known as the areca nut (AN) or betel nut. It is widely cultivated in the tropical regions. In many nations, AN is utilized for traditional herbal treatments or social activities. AN has historically been used to address various health issues, such as diarrhea, arthritis, dyspepsia, malaria, and so on. In this review, we have conducted a comprehensive summary of the biological effects and biomedical applications of AN and its extracts. Initially, we provided an overview of the constituents in AN extract. Subsequently, we summarized the biological effects of AN and its extracts on the digestive system, nervous system, and circulatory system. And we elucidated the contributions of AN and its extracts in antidepressant, anti-inflammatory, antioxidant, and antibacterial applications. Finally, we have discussed the challenges and future perspectives regarding the utilization of AN and its extracts as emerging pharmaceuticals or valuable adjuncts within the pharmaceutical field.

Short-term arecoline exposure affected the systemic health state of mice, in which gut microbes played an important role

Arecoline is a critical bioactive component in areca nuts with toxicity and pharmacological activities. However, its effects on body health remain unclear. Here, we investigated the effects of arecoline on physiologic and biochemical parameters in mouse serum, liver, brain, and intestine. The effect of arecoline on gut microbiota was investigated based on shotgun metagenomic sequencing. The results showed that arecoline promoted lipid metabolism in mice, manifested as significantly reduced serum TC and TG and liver TC levels and a reduction in abdominal fat accumulation. Arecoline intake significantly modulated the neurotransmitters 5-HT and NE levels in the brain. Notably, arecoline intervention significantly increased serum IL-6 and LPS levels, leading to inflammation in the body. High-dose arecoline significantly reduced liver GSH levels and increased MDA levels, which led to oxidative stress in the liver. Arecoline intake promoted the release of intestinal IL-6 and IL-1β, causing intestinal injury. In addition, we observed a significant response of gut microbiota to arecoline intake, reflecting significant changes in diversity and function of the gut microbes. Further mechanistic exploration suggested that arecoline intake can regulate gut microbes and ultimately affect the host's health. This study provided technical help for the pharmacochemical application and toxicity control of arecoline.

Oxidative Stress and Endoplasmic Reticulum Stress Contributes to Arecoline and Its Secondary Metabolites-Induced Dyskinesia in Zebrafish Embryos

Areca nut has been listed as one of the most addictive substances, along with tobacco, alcohol and caffeine. Areca nut contains seven psychoactive alkaloids; however, the effects of these alkaloids on embryonic development and motor behavior are rarely addressed in zebrafish embryo-larvae. Herein, we investigated the effects of exposure to three alkaloids (arecoline and secondary metabolites—arecaidine and arecoline N-oxide) on the developmental parameters, locomotive behavior, oxidative stress and transcriptome of zebrafish embryos. Zebrafish embryos exposed to different concentrations (0, 0.1, 1, 10, 100 and 1000 μM) of arecoline, arecaidine and arecoline N-oxide showed no changes in mortality and hatchability rates, but the malformation rate of zebrafish larvae was significantly increased in a dose-dependent manner and accompanied by changes in body length. Moreover, the swimming activity of zebrafish larvae decreased, which may be due to the increase in reactive oxygen species and the imbalance between oxidation and antioxidation. Meanwhile, transcriptome analysis showed that endoplasmic reticulum stress and the apoptosis p53 signaling pathway were significantly enriched after exposure to arecoline and arecoline N-oxide. However, arecaidine exposure focuses on protein synthesis and transport. These findings provide an important reference for risk assessment and early warning of areca nut alkaloid exposure.

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.

Pharmaceutical Assessment Suggests Locomotion Hyperactivity in Zebrafish Triggered by Arecoline Might Be Associated with Multiple Muscarinic Acetylcholine Receptors Activation

Arecoline is one of the nicotinic acid-based alkaloids, which is found in the betel nut. In addition to its function as a muscarinic agonist, arecoline exhibits several adverse effects, such as inducing growth retardation and causing developmental defects in animal embryos, including zebrafish, chicken, and mice. In this study, we aimed to study the potential adverse effects of waterborne arecoline exposure on zebrafish larvae locomotor activity and investigate the possible mechanism of the arecoline effects in zebrafish behavior. The zebrafish behavior analysis, together with molecular docking and the antagonist co-exposure experiment using muscarinic acetylcholine receptor antagonists were conducted. Zebrafish larvae aged 96 h post-fertilization (hpf) were exposed to different concentrations (0.001, 0.01, 0.1, and 1 ppm) of arecoline for 30 min and 24 h, respectively, to find out the effect of arecoline in different time exposures. Locomotor activities were measured and quantified at 120 hpf. The results showed that arecoline caused zebrafish larvae locomotor hyperactivities, even at a very low concentration. For the mechanistic study, we conducted a structure-based molecular docking simulation and antagonist co-exposure experiment to explore the potential interactions between arecoline and eight subtypes, namely, M1a, M2a, M2b, M3a, M3b, M4a, M5a, and M5b, of zebrafish endogenous muscarinic acetylcholine receptors (mAChRs). Arecoline was predicted to show a strong binding affinity to most of the subtypes. We also discovered that the locomotion hyperactivity phenotypes triggered by arecoline could be rescued by co-incubating it with M1 to M4 mAChR antagonists. Taken together, by a pharmacological approach, we demonstrated that arecoline functions as a highly potent hyperactivity-stimulating compound in zebrafish that is mediated by multiple muscarinic acetylcholine receptors.

The pharmacology, toxicology and potential applications of arecoline: a review

CONTEXT

Arecoline is an effective constituent of Areca catechu L. (Arecaceae) with various pharmacological effects. However, investigations also revealed that long use of arecoline could arouse some oral diseases.

OBJECTIVE

The present review gathers the fragmented information available in the literature (before 1 October 2015) regarding pharmacology and toxicology of arecoline. We also discussed the potential developments and applications of arecoline in the future.

METHODS

All the available information regarding the arecoline is compiled from scientific databases, including Science Direct, PubMed, Web of Science, Scopus, etc.

RESULTS

Previous research demonstrated that arecoline is one of the major effective constituents in A. catechu. Additionally, arecoline has a wide spectrum of pharmacological activities including effects on nervous, cardiovascular, digestive and endocrine systems and anti-parasitic effects. What's more, arecoline is reported to be the primary toxic constituent of A. catechu, and the main toxic effects include oral submucous fibrosis (OSF), oral squamous cell carcinoma (OSCC) and genotoxicity.

CONCLUSION

Arecoline has great potential to be a therapeutic drug for various ailments. However, further investigations are needed in the future to reduce or eliminate its toxicities before developing into new drug.