Compounds of formula (I):[in which:X is a group of formula>；CR1R2or>；SO2；Y is a group of formula>；NH or>；CR1R2；Z is a group of formula>；C＝0 or>；CH2or a direct bond, R1is hydrogen and R2is hydrogen. carboxy or hydroxy；or R1and R2together represent an oxo group, a methylenedioxy group or a hydroxyimino group, R3is hydrogen or lower alkyl；R4represents two hydrogen atoms, or an oxo or hydroxyimino group；R5is hydrogen, lower alkyl or halogen；R6is hydrogen, lower alkoxy or carboxy；R7and R8are each hydrogen, lower alkyl or halogen；and pharmaceutically acceptable salts and esters thereof can be used for the treatment or prophylaxis of acute or chronic neu.rodegenerative diseases or conditions such as Alzheimer's Disease, Parkinson's Disease, Huntington's Chorea, Multiple Sclerosis or the sequela≧to acute ischaemic events such as heart attack, stroke or head injury and for protection against ischaemic damage to tissues of peripheral organs.一種式(I)之化合物： (I)；其中X為式>；CR1R2或>；SO2；Y為式>；NH或>；CR1R2；Z為式>；C=O、>；CH2或直接鍵結；R1為氫及R2可為氫、羧基或羥基；或R1及R2可一起代表側氧基、亞甲基二氧基或羥基亞胺基；R3為氫或短鏈烷基；R4代表二個氫原子、或側氧或羥基亞胺基；R5可為氫、短鏈烷基或鹵素；R6可為氫、短鏈烷氧基或羧基；R7及R8每個可為氫、短鏈烷基或鹵素；及其醫藥上可接受的鹽及酯；該化合物可使用來治療或預防急性或慢性神經變性疾病或症狀，諸如阿茲海默症、帕金森氏症、哈丁頓氏舞蹈症、多發性硬化，或急性絕血事件(諸如心臟病發作、中風或頭部損傷)的後遺症，且可用來保護對抗對周邊器官組織之絕血損傷。
