There is provided compounds of Formula (I), or geometric isomers, stereoisomers, pharmaceutically acceptable salts or solvates thereof, for use in treating a cancer. Also provided are specific compounds of Formula (I), or geometric isomers, stereoisomers, pharmaceutically acceptable salts or solvates thereof. Also provided are specific compounds of Formula (I) isolated from propolis originating from plants of the Myoporum genus. Further provided is a compound of the following Formula for use in the preparation of a medicament for treating an autoimmune disease or a skin inflammatory disease or disorder.