Topical and oral administration of the natural water-soluble antioxidant from spinach reduces the multiplicity of papillomas in the Tg.AC mouse model

The Tg.AC mouse carrying the v-Ha-ras structural gene is a useful model for the study of chemical carcinogens, especially those acting via non-genotox ic mechanisms. This study evaluated the efficacy of the non-toxic, water-so luble antioxidant from spinach. natural antioxidant (NAO), in reducing skin papilloma induction in female hemizygous Tg.AC mice treated dermally five times over 2.5 weeks with 2.5 mug 13-O-tetradecanoylphorbol-13-acetate (TPA ). The TPA-only group was considered as a control; the other two groups rec eived, additionally: NAO topically (2 mg) or orally (100 mg/kg). 5 days/wee k For 5 weeks. Papilloma counts made macroscopically during the clinical ob servations showed a significant decrease in multiplicity (P<0.01) in the NA O topically treated group. According to histological criteria, papilloma mu ltiplicity were lower in both topical-NAG and oral-NAG groups. but signific antly so only in the oral-NAG mice (P < 0.01). The beneficial effect of NAG in the Tg.AC mouse is reported. (C) 2001 Elsevier Science ireland Ltd. All rights reserved.