A composition is provided for chemoprevention of an oral cancer or precancerous condition, including an isolated berry preparation admixed with a bioadhesive carrier. The carrier may be a mucoadhesive gel. The berry preparation may be derived from one or more of strawberry, raspberry, red raspberry, and black raspberry. Methods for producing the compositions are provided also. There are also provided methods for chemoprevention of an oral cancer or precancerous condition, utilizing the compositions of the invention. Still further, methods for enhancing stability of an anthocyanin contained in the berry preparation of the invention are provided, along with methods for enhancing efficacy of the compositions.