There are described compounds of general formula (I) and isomeric forms thereof wherein n is 0, 1, 2 or 3, saturated or unsaturated； most preferably at least one of R1 to R5 represents halogen； at least one of R1, R2, R3, R4 and R5 is selected from —S—R or —COOR, or two or more Of R1-R5 comprise a linking group such as —S—(CH2)mS—, where m is 1, 2 or 3 and R is selected from alkyl having 1 to 5 carbon atoms, cycloalkyl having 3-6 carbon atoms, hydroxy, and aryl having 6 to 10 carbon atoms, such groups being optionally substituted, and when R1 is selected from —S—R, then at least one of R2, R3 and R5 is most preferably selected from halogen； and R1, R2, R3, R4 and R5 are otherwise the same or different and are selected from hydrogen, halogen, alkyl having 1 to 5 carbon atoms, electron donor groups such as alkoxy having 1-5 carbon atoms or hydroxy, electron acceptor groups selected from cyano, nitro, trifluoroalkyl or amide； alkylamino, benzoyloxy, nitroxy, phenyl or sulpho； and pharmacologically acceptable salts thereof. Compounds described have activity on the melanocortin receptors and have application in the treatment of a wide range of inflammatory, arthritic or central nerve regeneration conditions.
