A preliminary study of arecoline and guvacoline presence in the saliva of a "betel-quid" chewer using liquid-chromatography ion trap mass spectrometry

Simultaneous determination of areca nut- and tobacco-specific alkaloids in saliva by LC-MS/MS: Distribution and transformation of alkaloids in oral cavity

Areca nut and tobacco are frequently used in combination. Cigarette smoking and betel quid (BQ) chewing habits impose greater oral cancer risk than either habit alone. Saliva is a better noninvasive diagnostic material as it is in direct contact with oral mucosa and cancerous lesions. This study describes the application of isotope-dilution LC-MS/MS for simultaneous quantitation of five areca nut-specific alkaloids (ASAs) and three tobacco-specific alkaloids (TSAs) in human saliva. With this method, we demonstrate that the distribution of ASAs vary significantly in smokers who chew BQ habitually, due to the hydrolysis of ASAs and metabolic activity in the oral cavity. The alkaline condition formed due to slaked lime in BQ, plays an important role in the distribution of ASAs and TSAs, by catalyzing the hydrolysis of ester forms of ASAs to their respective carboxylic acid forms besides facilitating the TSA (i.e., nicotine) absorption in the oral cavity. Moreover, our results reveal that oral mucosa rather than saliva contributes to the metabolism of ASAs at oral cavity. Less than 2.1% of ASAs were metabolized by saliva, as determined by in vitro test. Our findings may provide a better insight into the pathobiology of oral carcinogenesis due to BQ chewing.

Molecular Mechanisms of Malignant Transformation of Oral Submucous Fibrosis by Different Betel Quid Constituents-Does Fibroblast Senescence Play a Role?

Betel quid (BQ) is a package of mixed constituents that is chewed by more than 600 million people worldwide, particularly in Asia. The formulation of BQ depends on a variety of factors but typically includes areca nut, betel leaf, and slaked lime and may or may not contain tobacco. BQ chewing is strongly associated with the development of potentially malignant and malignant diseases of the mouth such as oral submucous fibrosis (OSMF) and oral squamous cell carcinoma (OSCC), respectively. We have shown recently that the constituents of BQ vary geographically and that the capacity to induce disease reflects the distinct chemical composition of the BQ. In this review, we examined the diverse chemical constituents of BQ and their putative role in oral carcinogenesis. Four major areca alkaloids—arecoline, arecaidine, guvacoline and guvacine—together with the polyphenols, were identified as being potentially involved in oral carcinogenesis. Further, we propose that fibroblast senescence, which is induced by certain BQ components, may be a key driver of tumour progression in OSMF and OSCC. Our study emphasizes that the characterization of the detrimental or protective effects of specific BQ ingredients may facilitate the development of targeted BQ formulations to prevent and/or treat potentially malignant oral disorders and oral cancer in BQ users.

Fragmentation pattern of certain isatin–indole antiproliferative conjugates with application to identify their in vitro metabolic profiles in rat liver microsomes by liquid chromatography tandem mass spectrometry

The fragmentation pattern of certain isatin-based compounds was carried out using collision-induced dissociation inside the triple quadrupole mass analyzer. These data were used as a clue for the identification of metabolites of the recently reported isatin-based antiproliferative agent, namely, N′-[5-bromo-1-methyl-2-oxo-1,2-dihydro-3H-indol-3-ylidene]-5-methoxy-1H-indole-2-carbohydrazide (1) in rat liver microsomes (RLMs) using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Prediction of the vulnerable sites for metabolic pathways in compound 1 was performed by WhichP450 module of StarDrop software. In vitro metabolites for compound 1 were identified with the aid of rat liver microsomes. The in silico data were utilized as a guide for the practical work. Compound 1 was metabolized into three (hydroxylated, reduced and O-demethylated) metabolites in RLMs in the presence of NADPH. The chemical structures of those metabolites were elucidated, and the metabolic pathways were proposed by comparing the fragmentation pattern of the isatin–indole conjugates 1–7. The data presented in this paper provided useful information on the effect of different substituents on the ionization/fragmentation processes and can be used in the characterization of isatin derivatives. In silico toxicity assessments for the title compounds 1–7 and for the metabolites of compound 1 were conducted utilizing the deductive estimation of risk from existing knowledge (DEREK) module of StarDrop software.

Intoxication and substance use disorder to Areca catechu nut containing betel quid: A review of epidemiological evidence, pharmacological basis and social factors influencing quitting strategies

AIM

We present a systematic review of substance use disorder (SUD) to Areca catechu nut (AN) and AN containing betel quid (ANcBQ) with emphasis on dependence resulting from chewing of tobacco-free ANcBQ. We examined pharmacology of intoxication and addiction, and factors influencing quitting strategies.

METHODS

Epidemiological publications of SUD were included according to PRISMA criteria. Pharmacological publications were retrieved from the PUBMED database and websites of the WHO, United Nations, and Sigma-Aldrich.

RESULTS

Nine epidemiological studies show clear evidence of abuse and dependence in tobacco-free ANcBQ and/or ANcBQ+Tobacco chewers. Dependency is greater if ANcBQ contains tobacco. In both groups higher dependency scores were positively correlated with higher frequency of chewing. Dependency on AN+Lime is associated with altered brain morphology, resting state brain activity, neurochemistry and deterioration of working spatial memory. ANcBQ contains a complex mixture of neuroactive compounds that have the potential to act directly upon all major cerebral neurotransmitter systems. Of these compounds, only arecoline (muscarinic agonist) has been the focus of limited pharmacological investigation. In animal studies, arecoline increases dopamine transmission in the mesocorticolimbic circuit and this action may be one factor contributing to ANcBQ dependency in humans. Societal and familial acceptance of ANcBQ consumption is paramount for commencement and persistence of chewing.

CONCLUSIONS

ANcBQ SUD remains an orphan disease. The limited understanding of pharmacological basis of intoxication and SUD determines there are no pharmacological replacement therapies for ANcBQ SUD. The addictive properties of ANcBQ coupled with social acceptance of ANcBQ chewing limits the effectiveness of counseling-based quitting programs.

In vitro investigation of metabolic profiling of newly developed topoisomerase inhibitors (ethyl fluorescein hydrazones, EtFLHs) in RLMs by LC-MS/MS

Metabolic profiling of newly reported five topoisomerase inhibitors namely ethyl fluorescein hydrazones (EtFLHs) were studied in rat liver microsomes (RLMs) and the data were acquired in a liquid chromatography (LC) ion trap mass spectrometry. Hydroxyl group containing EtFLHs derivatives (1-3) were bio-transformed into hydrolyzed, mono-hydroxylated and hydrolyzed together with mono-hydroxylated metabolites. On the other hand, nitro and methoxy groups containing EtFLHs derivatives (4-5) were bio-transformed into hydrolyzed, hydrolyzed together with mono-hydroxylated and azo-reductive metabolites in the presence of NADPH. No metabolites were observed in the absence of either NADPH or microsomes for the compounds (1-5), indicating a likely involvement of CYP450 enzymes and cofactor NADPH in the metabolisms.