Compounds of formula I: wherein X is selected from oxygen, nitrogen and sulfur； n is 0 or 1； R<；SUB>；1 <；/SUB>；is selected from alkyl, carboxylic acid, carboxylate, carboxamide, ester and combinations thereof； R<；SUB>；2 <；/SUB>；is selected from alkyl, substituted alkyl, carboxylic acid, carboxylate, carboxamide, sulfonyl, sulfonamide and combinations thereof； and derivatives and metabolites thereof. Further provided are methods of using a compound of formula I to prevent and/or treat a subject having a condition characterized by unwanted cell proliferation. Also provided are pharmaceutical compounds comprising one or more compounds of formula I, or derivatives or pharmaceutically acceptable salts thereof.
