Effect of green propolis on oral epithelial dysplasia in rats.

UNLABELLED Studies have demonstrated that flavonoid compounds of green propolis have antitumoral activity. STUDY DESIGN Experimental study. AIMS To evaluate the effect of a hydroalcoholic extract of green propolis (EPV) on chemically induced epithelial dysplasias in rat tongues. METHODS AND MATERIALS DMBA was brushed on the lingual dorsum of rats 3x/week on alternate days--100 (PROP1), 200 (PROP2) and 300 mg/kg (PROP3) EPV was administered orally for 20 weeks. EPV or DMBA were replaced by their vehicles and applied as positive (TUM1 and TUM2) and negative controls (CTR1 and CTR2), respectively. The lingual epithelium was histologically analyzed and graded according a binary system and the WHO classification; the data were compared using ANOVA (*p<0.05). RESULTS The EPV yield was 41% and the flavonoid yield was 0.95±0.44%. According to the Binary System, TUM1, TUM2 and PROP1 were considered high risk lesions, with significantly higher morphological alteration rates compared to the other groups (p<0.05), which were considered low risk lesions. Based on the WHO classification, moderate dysplasia was TUM1 and TUM2, mild dysplasia was PROP1, PROP2 and PROP3, and non-dysplastic epithelium was CTR1 and CTR2. CONCLUSION EPV seems to play an important protective role against chemically-induced lingual carcinogenesis in rats.