title: Use of the micronucleus test to monitor the effect of vitamin A, beta-carotene and canthaxanthin on the buccal mucosa of betel nut/tobacco chewers.
abstract: The frequency of exfoliated cells with micronuclei in buccal swabs was used to estimate the protective effect of vitamin A, beta-carotene and canthaxanthin (4,4'-diketo-beta-carotene) on the buccal mucosa of betel (areca) nut/tobacco chewers. Micronuclei were scored on exfoliated cells taken by swabbing and stained with the Feulgen reaction and fast green. The betel (areca) nut/tobacco chewers served as their own controls. Prior to the administration of vitamin A and beta-carotene, the examined betel quid chewers had elevated frequencies of micronucleated buccal mucosa cells, averaging 4.03% +/- 1.24 SD (n = 26) and 3.43% +/- 1.22 SD (n = 25), respectively. The frequency of micronucleated buccal mucosa cells in non-chewers and non-smokers was 0.51% (n = 52). Following a 9-week ingestion of vitamin A (150,000 IU/week) and beta-carotene (180 mg/week in 6 capsules), the frequency of micronucleated cells decreased significantly (p less than 0.001) to 1.70% and 1.16%, respectively. No significant shift in the frequencies of micronucleated cells was observed following the intake of canthaxanthin (180 mg/week in 6 capsules) for 9 weeks or that of a placebo. The lack of protective activity of canthaxanthin, which is a good trapper of oxygen singlets but cannot be converted into vitamin A, suggests that vitamin A and beta-carotene exert their inhibitory effect on the formation of micronuclei by a mechanism not involving the scavenging of free radicals. The efficacy of beta-carotene as an inhibitor of micronucleated cell formation, the lack of toxicity, and its availability from a multitude of dietary sources should focus attention on this carotenoid as a promising chemopreventive agent.
mesh_terms: D000328:Adult; D001114:Areca; D016644:Canthaxanthin; D002338:Carotenoids / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002467:Cell Nucleus / Q000187:drug effects; D002610:Cheek; D005260:Female; D006801:Humans; D008297:Male; D009061:Mouth Mucosa / Q000187:drug effects* / Q000648:ultrastructure; D009062:Mouth Neoplasms / Q000517:prevention & control; D009152:Mutagenicity Tests; D010946:Plants, Medicinal; D010947:Plants, Toxic; D014026:Nicotiana; D014801:Vitamin A / Q000494:pharmacology*; D019207:beta Carotene
chemical_list: D019207:beta Carotene; D014801:Vitamin A; D002338:Carotenoids; D016644:Canthaxanthin