Ingredients Contribute to Variation in Production of Reactive Oxygen Species by Areca Quid

Abstract

Areca quid (AQ) chewing has been implicated an independent risk factor for the development of oral cancer. Taiwanese areca quid (AQ) refers to a combination of areca nut (AN), lime, and inflorescence of Piper betle Linn. (IPB) or Piper betle leaf (PBL). Studies of AQ in other countries reported that AN extract combined with lime generates reactive oxygen species (ROS), such as hydroxyl radical (HO^·), known to be a contributing factor in oral mucosa damage. To determine whether HO^· is formed in the oral cavity during AQ chewing, the formation of meta-tyrosine (m-Tyr) and ortho-tyrosine (o-Tyr) from _l-phenylalanine (Phe) was confirmed. It was demonstrated that combined aqueous extracts of AN, lime, metal ions (such as Cu²⁺ and Fe²⁺), and IPB or PBL produced HO^·. Thus, the yield of HO^· significantly increases when higher amounts of IPB or lime are added and also when Cu²⁺ and Fe²⁺ are increased. Further, the omission of any one of these ingredients significantly reduces the formation of HO^·. Our results found that chewing AQ with IPB generated significantly higher HO^· than chewing AQ with PBL, and may result in greater oxidative damage to the surrounding oral mucosa.

This study was supported by a grant from the Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Kaohsiung 807, Taiwan (NHRI-CN-IN-9006P).

Notes

This study was supported by a grant from the Division of Environmental Health and Occupational Medicine, National Health Research Institutes, Kaohsiung 807, Taiwan (NHRI-CN-IN-9006P).

^a Areca nut (AN).

^b Inflorescence of Piper betle Linn. (IPB).

^c Piper betle leaf (PBL).

^a The pH level of human saliva was assessed after chewing AQ for 15 min.

^b nd: m- and o-Tyr concentrations below detection limits (10 nM).

^c Significant at p < .05 as compared with the subjects chewing betel quid, by Mann–Whitney nonparametric test.