Flavonoids : old and new aspects of a class of natural therapeutic drugs

Oral submucous fibrosis: review on aetiology and pathogenesis.

In south-east Asia, Taiwan and Papua New Guinea, smoking, alcohol consumption and chewing of betel quid with or without tobacco or areca nut with or without tobacco are the predominant causes of oral cancer. In most areas, betel quid consists of a mixture of areca nut, slaked lime, catechu and several condiments according to taste, wrapped in a betel leaf. Almost all habitual chewers use tobacco with or without the betel quid. In the last few decades, small, attractive and inexpensive sachets of betel quid substitutes have become widely available. Aggressively advertised and marketed, often claimed to be safer products, they are consumed by the very young and old alike, particularly in India, but also among migrant populations from these areas world wide. The product is basically a flavoured and sweetened dry mixture of areca nut, catechu and slaked lime with tobacco (gutkha) or without tobacco (pan masala). These products have been strongly implicated in the recent increase in the incidence of oral submucous fibrosis, especially in the very young, even after a short period of use. This precancerous lesion, which has a high rate of malignant transformation, is extremely debilitating and has no known cure. The use of tobacco with lime, betel quid with tobacco, betel quid without tobacco and areca nut have been classified as carcinogenic to humans. As gutkha and pan masala are mixtures of several of these ingredients, their carcinogenic affect can be surmised. We review evidence that strongly supports causative mechanisms for genotoxicity and carcinogenicity of these substitute products. Although some recent curbs have been put on the manufacture and sale of these products, urgent action is needed to permanently ban gutkha and pan masala, together with the other established oral cancer-causing tobacco products. Further, education to reduce or eliminate home-made preparations needs to be accelerated.

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Alert for an epidemic of oral cancer due to use of the betel quid substitutes gutkha and pan masala: a review of agents and causative mechanisms

Role of areca nut in betel quid-associated chemical carcinogenesis: current awareness and future perspectives

Oral submucous fibrosis (OSF) is a chronic debilitating disease and a premalignant condition of the oral cavity. It is characterized by a generalized submucosal fibrosis. The pathogenesis of the disease is not well established. Epidemiological evidences strongly indicate the association of the betel quid (BQ) habit and OSF. Various findings indicate the disease to be a consequence of disturbances in the homeostatic equilibrium between synthesis and degradation of extracellular matrix (ECM), wherein collagen forms a major component, thus can be considered as a collagen-metabolic disorder. Transforming growth factor-beta (TGF-beta) is a potent stimulator of production and deposition of the ECM. The objectives of this review are to highlight the molecular events involved in the overproduction of insoluble collagen and decreased degradation of collagen occurring via exposure to BQ and stimulation of the TGF-beta pathway, and elucidate the cell signaling that is involved in the etiopathogenesis of the disease process.

Molecular pathogenesis of oral submucous fibrosis--a collagen metabolic disorder.

Stimulation of human buccal mucosa fibroblasts in vitro by betel-nut alkaloids

Treatment of reconstituted collagen fibrils and pieces of rat dermis with the crude extract, purified tannins or (+)-catechin from betel nut (Areca catechu) increases their resistance to both human and bacterial collagenases in a concentration-dependent manner. These tanning agents may stabilise collagen in vivo following damage to the oral epithelium and promote the sub-epithelial fibrosis which occurs in betel nut chewers.

J.P. Canniff

Papers

Stimulation of human buccal mucosa fibroblasts in vitro by betel-nut alkaloids

Stabilisation of collagen by betel nut polyphenols as a mechanism in oral submucous fibrosis.

An in-vitro comparison of human fibroblasts from normal and oral submucous fibrosis tissue

Inhibition of collagenase activity by areca nut tannins - a mechanism of collagen accumulation in oral submucous fibrosis (osf)

Metabolism of areca-catechu (betel nut) alkaloids by human buccal mucosa fibroblasts