The present invention relates to the polyprenylated phloroglucinol compounds of formulae I and II. The present invention also provides synthesis and p-glycoprotein induction activity of the alkyl- and acyl- polyprenylated phloroglucinol compounds. Further, use of the compounds as p-glycoprotein inducers and methods of treatment of Alzheimers disease using compounds of the invention are also provided.