**5.2 Oral squamous cell carcinoma (OSCC)**

Betel (areca nut) quid chewing is a widely prevalent habit correlated with a high incidence of oral cancer. A Previous study showed that the carcinogenic mechanism of action of betel quid chewing is caused by DNA damage induced by arecaidine and Cu (II). The Cu (II) is an important structural metal ion in chromatin; however, it is reported to be an important factor in DNA damage induced by many organic compounds. It was found that arecaidine alone had no significant effect on inducing DNA damage, but it caused significant DNA double strand breaks in the presence of Cu (II) ions under alkaline conditions. Further studies showed that reactive oxygen species were generated and Cu (II) was formed in the reaction. Areca nuts contain arecoline and arecaidine, both of which can cause mutation. When chewing areca nut, arecoline dissolves in saliva and its concentration can reach 140 g/mL. arecoline can cause cytotoxicity and genotoxicity for multicultured human cell lines and

*Antioxidant Activity of Areca Nut to Human Health: Effect on Oral Cancer Cell Lines… DOI: http://dx.doi.org/10.5772/intechopen.96036*

inhibits oral mucosal and gingival fibroblast which can cause epithelial damage and delayed wound healing.

The areca nut does not contain carcinogenic substances, but this carcinogenic effect is caused by nitrosamines product in the long term and uncontrollable. Nitrosamines are produced by nitrosation of the alkaloids in dried stored nuts, when in the mouth, and especially in the acid conditions of the stomach, in the presence of nitric oxide generated by bacteria [39]. The combination with nitric oxide, produced by bacteria, causes the production of methylnitrosaminoproprionitrile which is proved to cause carcinogenesis in animal studies [39]. This endogen nitrosation is higher significantly in a patient with bad oral hygiene [40]. If areca nut is combined with tobacco, then chewed by people with bad oral hygiene, there will be a very high accumulation of nitrosamines product [41]. This process usually occurs continuously for the long term because the seeds have addictive properties. Some studies also reported increased reactive oxygen species such as hydroxyl oxide in the oral cavity caused by a combination of polyphenol auto-oxidation from areca nut with high alkaline pH of slaked lime (Calcium hydroxide paste) [42]. If the areca nut is chewed with *Piper betel* and slaked lime, these two materials will cause mucous membrane erosion, so that carcinogenic substance could easily penetrate cells through the mucous membrane [43]. Some part of the community in India and Pakistan use industrial packaging areca nut called *gutka* and *pan masala*. *Gutka* contains areca nut, *Piper betel*, tobacco, and slaked lime, while *pan masala* was prepared without tobacco. Approximately 40% of *gutka* and *pan masala* packaging are contaminated with aflatoxin which has carcinogenic properties from *Aspergillus flavus*, *Aspergillus niger,* and *Rhizopus spp.*fungi [44]. The occurrence of the OSCC's risk depends greatly on the composition of the compound which determines the quality of the seeds, the method of using seeds which are associated with oral hygiene, duration of use, the presence or absence of toxin caused by fungi contamination in the seeds, and the presence or absence of other carcinogenic substances such as tobacco and slaked lime. The occurrence of OSCC could also be influenced by several factors such as intrinsic factors (tumor suppressor gene abnormality or mutation and oncogene) and extrinsic factors (tobacco smoking, vitamin A and iron deficiency, candidiasis, viral infection, and immunosuppression).

The dried areca nut, gambir, and calcium hydroxide wrapped in betel leaf are usually used as symbol of respect for guests in traditional ceremonies in Aceh, Indonesia.
