Provided is a compound of the formula I or a pharmaceutically acceptable salt, solvate or stereoisomer thereof: wherein Ar represents R5, R6, R7, R8, R1′, R2′, R3′, R4′, R5′, R6′, R7′, R8′ independently represent H, OH, F, Cl, Br, C1 to C6 alkyl group, C1 to C6 alkoxy group, C2 to C6 alkenyl group, C2 to C6 alkenoxy group, C2 to C6 alkynyl group, C2 to C6 alkynoxy group, amine group, mono- or di-substituted amino group, cyclic C1 to C5 alkylamino group, imidazolyl group, morpholino group, piperazinyl group, optionally substituted with one or more hydroxy or halo; and X represents NH, O or S. The present invention also provides a composition comprising the compound of formula I. The compound and the composition in accordance with the present invention are effective on treating or alleviating a disease or disorder, such as malignant glioma.