Mutual interactions among ingredients of betel quid in inducing genotoxicity on Chinese hamster ovary cells

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.

Plant-Derived Products for Treatment of Vascular Intima Hyperplasia Selectively Inhibit Vascular Smooth Muscle Cell Functions

Natural products are used widely for preventing intimal hyperplasia (IH), a common cardiovascular disease. Four different cells initiate and progress IH, namely, vascular smooth muscle, adventitial and endothelial cells, and circulation or bone marrow-derived cells. Vascular smooth muscle cells (VSMCs) play a critical role in initiation and development of intimal thickening and formation of neointimal hyperplasia. In this review, we describe the different originating cells involved in vascular IH and emphasize the effect of different natural products on inhibiting abnormal cellular functions, such as VSMC proliferation and migration. We further present a classification for the different natural products like phenols, flavonoids, terpenes, and alkaloids that suppress VSMC growth. Abnormal VSMC physiology involves disturbance in MAPKs, PI3K/AKT, JAK-STAT, FAK, and NF-κB signal pathways. Most of the natural isolate studies have revealed G1/S phase of cell cycle arrest, decreased ROS production, induced cell apoptosis, restrained migration, and downregulated collagen deposition. It is necessary to screen optimal drugs from natural sources that preferentially inhibit VSMC rather than vascular endothelial cell growth to prevent early IH, restenosis following graft implantation, and atherosclerotic diseases.

Toxicological Effects of Glycyrrhiza glabra (Licorice): A Review

Licorice (Glycyrrhiza glabra) has been considered as an herbal drug since ancient time. Nowadays, it is a well-known spice that possesses worth pharmacological effects. However, some relevant articles have revealed negative impacts of licorice in health. By considering the great wishes in using herbal medicine, it is important to show adverse effects of herbal medicine in health. At present, there are misunderstandings toward the safety of herbal medicines. Herein, we gathered scientific research projects on the toxicity effects of licorice and glycyrrhizin to highlight their safety. In this regards, we categorized our findings about the toxicity effects of licorice and glycyrrhizin in acute, sub-acute, sub-chronic, and chronic states. Besides, we discussed on the cytotoxicity, genotoxicity, mutagenicity, and carcinogenicity of licorice and glycyrrhizin as well as their developmental toxicity. This review disclosed that G. glabra and glycyrrhizin salts are moderately toxic. They need to be used with caution during pregnancy. G. glabra and glycyrrhizin possess selective cytotoxic effects on cancerous cells. The most important side effects of licorice and glycyrrhizin are hypertension and hypokalemic-induced secondary disorders. Licorice side effects are increased by hypokalemia, prolonged gastrointestinal transient time, decreased type 2 11-beta-hydroxysteroid dehydrogenase activities, hypertension, anorexia nervosa, old age, and female sex. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of arecoline on testosterone release in rats

Arecoline is one of the major components of betel nuts, which have been consumed as chewing gum in Southeast Asia. In this study, the effects of arecoline on testosterone (T) secretion were explored. Male rats were injected with human chorionic gonadotropin (hCG, 5 IU/kg) or arecoline (1 microg/kg) plus hCG via a jugular catheter. Blood samples were collected at several time intervals subsequent to the challenge. Rat anterior pituitary was treated with gonadotropin-releasing hormone in vitro with or without arecoline, and then the concentrations of luteinizing hormone (LH) in the medium were measured. Rat Leydig cells were purified by Percoll density gradient centrifugation and incubated with arecoline, hCG, forskolin, 8-bromo-cAMP (8-Br-cAMP), nifedipine, nimodipine, or tetrandrine at 34 degrees C for 1 h. A single intravenous injection of arecoline resulted in an increase of the hCG-induced level of plasma T. Administration of arecoline (10(-8) to 10(-6) M) in vitro increased T production in Leydig cells. The stimulatory effect of arecoline on T release in vitro was enhanced by hCG (0.001 IU/ml), forskolin (10(-6) M), or 8-Br-cAMP (10(-5) M). By contrast, nifedipine, nimodipine, or tetrandrine inhibited the increased T concentrations induced by arecoline. Western blot showed that arecoline increases steroidogenic acute regulatory (StAR) protein expression compared with vehicle. These results suggested that arecoline stimulates testosterone production by acting directly on Leydig cells via mechanisms involving an activation of L-type calcium channels, increasing the activity of 17beta-hydroxysteroid dehydrogenase and enhancing the expression of StAR.

In vitro effects of arecoline on sperm motility and cyclooxygenase-2 expression

Semen samples were obtained from 30 volunteers who had never consumed betel quid. Swim-up spermatozoa from the 30 seminal samples of non-betel quid chewers and also non-smokers, usually not exposed to passive smoking, were treated in vitro with arecoline at different concentrations to evaluate the action of these drugs on sperm motility. Highly motile sperms were collected and divided into 5 equal fractions. Four fractions were supplemented with various concentrations of arecoline and one as control. The study was carried out at time 0 and +1, +2, +3 and +4 hr of incubation. Sperm cells were also extracted and blotted with COX-2 antibody after arecoline treatment after 4 hr incubation. The sperm motility parameters, i.e., motility, average path velocity, curvilinear velocity, straight-line velocity and linearity, were significantly decreased after arecoline treatment. In vitro, arecoline induces the COX-2 expression of sperm cells in a dose-dependent manner. This is the first report to demonstrate that arecoline may mediate COX-2 expression in human sperms, resulting in inflammation response. This situation may act on the structure responsible for the flagellar motion and cause the reduction of sperm motility.

Elevated vimentin expression in buccal mucosal fibroblasts by arecoline in vitro as a possible pathogenesis for oral submucous fibrosis

Areca quid chewing is strongly correlated with oral submucous fibrosis (OSF) in Taiwan. The cytotoxicity of arecoline, a major areca nut alkaloid, on human oral fibroblasts has been extensively studied. To date, however, there has been little research exploring the possible effects of arecoline on cytoskeleton components. In this study, in addition to conducting a cytotoxicity assay, we examine the effect of arecoline on vimentin, an intermediate filament, and its expression in human buccal mucosal fibroblasts on exposure to various levels of arecoline (0-200 microg/ml) for 48 h. At a concentration above 50 microg/ml, arecoline demonstrated dose-dependent cytotoxicity (P<0.05) for cultured fibroblasts. Using sodium dodecyl sulphate-polyacrylamide gel electrophoresis, we demonstrated dose-dependent elevation of 57 kDa cytoskeletal-protein levels for arecoline. Evidence from immunoblotting assay indicated this 57 kDa cytoskeletal protein was vimentin. The increase in vimentin with arecoline exposure corresponded to that noted for fibroblasts cultured from OSF patients. Immunohistochemical assay also revealed that vimentin expression was much higher for OSF specimens than for normal buccal mucosa. We suggest these results may advance understanding of the possible pathogenesis for submucous fibrosis through the transformation of normal buccal mucosa as a result of areca quid chewing.

Synergistic effects of peroxynitrite on arecoline-induced cytotoxicity in human buccal mucosal fibroblasts

Epidemiological studies have demonstrated a clear association between betel nut chewing and an increased risk for oral mucosal lesions. Arecoline, the most abundant betel alkaloid, is considered the most important etiologic factor in betel nuts. In addition, most betel nut chewers are also smokers. In order to elucidate the potential toxicological implications of interactions of arecoline and peroxynitrite (a reaction product of cigarette smoking), cell viability, and cellular levels of glutathione (GSH) were investigated, using cultured human buccal mucosal fibroblasts. At a concentration higher than 0.8 mM, arecoline was cytotoxic to buccal mucosal fibroblasts in a concentration- and time-dependent manner. Arecoline also depleted intracellular GSH in a dose-dependent manner (P<0.05). The addition of extracellular peroxynitrite acted as a synergistic effect on the arecoline-induced cytotoxicity (P<0.05). Furthermore, at a concentration of 0.8 mM, arecoline depleted intracellular GSH by about 42%, while 2 mM peroxynitrite enhanced the arecoline-depleted GSH level further to 86% as compared with the control. During GSH depletion, arecoline may render the human buccal mucosal fibroblasts more vulnerable to other reactive agents within cigarette smoking. Taken together, we suggest that people who combine the habits of betel nut chewing with cigarette smoking could be more susceptible to oral mucosal damage than betel quid chewing alone.

Cytotoxic and non-genotoxic effects of arecoline on human buccal fibroblasts in vitro

Betel quid chewing has been linked to oral submucous fibrosis and oral cancer. Cytotoxicity and genotoxicity assays were used to investigate the pathobiological effects of arecoline on cultured human buccal fibroblasts. Arecoline increased double-stranded polynucleic acid at the concentration of 0.1 to 10 micrograms/ml in a concentration-dependent manner. At a concentration higher than 50 micrograms/ml, arecoline was cytotoxic to cultured fibroblasts and the cytotoxicity was dose-dependent. No genotoxicity for arecoline was found even at a concentration of 400 micrograms/ml. On the other hand, 600 micrograms/ml glutathione (GSH) and 200 micrograms/ml glycyrrhizin could prevent the arecoline-induced cytotoxicity. These results indicate that arecoline is a cytotoxic agent and no genotoxicity was found to human buccal fibroblasts. Furthermore, increasing consumption of GSH- and glycyrrhizin-rich foods may reduce the oral diseases associated with betel quid chewing.

Anthropometric status and resting metabolic rate in users of the areca nut and smokers of tobacco in rural Sarawak

The areca nut is chewed by many of the world's population, mainly in South and Southeast Asia. Anthropometric data for 458 Sarawaki adults aged over 24 years, measured both in 1990 and in 1996, were examined in relation to use of tobacco and areca nut. Compared to non-smokers, smoking men were significantly taller and slightly (not significantly) thinner in both years, while smoking women were thinner in 1990 and slightly (not significantly) thinner in 1996. In both sexes there was an increase in the mean and range of body mass index (BMI, W/H2) over the 6-year interval. Smoking women showed a significantly smaller increment in BMI after allowing for areca nut use, which was associated with a similar trend, and this finding depended on including areca use in the model. The trend for men was similar. Possible effects of areca use could reflect variation in 'affluence' or conservatism, or appetite suppression. However, resting metabolic rate in 54 men and 70 women aged 24-60 years was associated with areca use. This association appeared to be mediated by the maximum room temperature of the 24 h preceding measurement. In women, a significant curvilinear association of RMR with maximum temperature was found in users of areca nut but not in non-users. In men, RMR was 7% higher (p < 0.05) in users of areca nut than in non-users, after allowing for age, height, weight, the sum of four skinfold thicknesses, and haemoglobin, but the association with maximum temperature was similar in both groups. It is speculated that constituents of areca nut modulate thermoregulatory pathways, resulting in prolonged temperature-dependent and hyperthermic heat production in this population; that males are more responsive to this effect than females; and that by this mechanism, and possibly also through centrally mediated effects on appetite for food, areca use could contribute to long-term variation in energy balance represented by change in BMI.