Chemopreventive potential of Aloe vera against 7,12-dimethylbenz(a)anthracene-induced skin papillomagenesis in mice

The present investigation was undertaken to explore the antitumor-promoting activity of Aloe vera on 2-stage skin carcinogenesis, induced by a single topical application of 7,12-dimethylbenz(a)anthracene and promoted by treatment of croton oil for 16 weeks in Swiss albino mice. Oral administration of aloe leaf extract at a dose of 1000 mg/kg body weight/d and aloe gel treatment at a dose of I mL/ 9 Cm-2/mice/d was found to be effective in decreasing the number and size of the papillomas. A significant reduction in tumor incidence (40.00 +/- 5.10, 30.00 +/- 3.25, and 40.00 +/- 4.12 for aloe gel, aloe gel and aloe leaf extract combined, and aloe leaf extract alone, respectively) was observed in animals in the aloe extract- and aloe gel-treated groups compared with 100% tumor incidence in the control group. The cumulative number of papillomas during an observation period of 16 weeks was significantly reduced in the aloe-treated groups (8.0 +/- 0.34, 6.00 +/- 1.10, and 9.00 +/- 1.41 for aloe gel, aloe gel and leaf extract, and aloe leaf extract, respectively) compared with a 36 +/- 0.98 cumulative number of papillomas in the control group. The average latent period was significantly increased from 4.9 +/- 0.10 weeks in the control group to 6.37 +/- 0.12, 6.8 +/- 0.25, and 6.2 +/- 0.21 weeks in the aloe-treated groups, respectively. The tumor burden and tumor yield were significantly decreased (2.0 +/- 0.25, 2.00 +/- 0.30, and 2.25 +/- 0.2 and 0.8 +/- 0.25, 0.6 +/- 0.32, and 0.9 +/- 0.28, respectively) as compared with the 7,12-dhnediylbenz(a)anthracene-treated control group (3.6 +/- 0.10 and 3.6 +/- 0.19). Furthermore, treatment with aloe gel and/or extract by topical and/or oral administration resulted in a significant increase in the reduced glutathione (P <.05), DNA (P <.001), catalase (P <.05), and protein (P <.001) in the skin of mice. Conversely, lipid peroxidation levels were significantly decreased (P <.001) in the skin of mice.