A compound of formula A, or a pharmaceutically acceptable salt, solvate, racemate, non-enantiomer or geometric isomer thereof ** (See formula) ** in which: R1 and R2, are the same or different, are selected between hydrogen； I rent； optionally substituted saturated hydrocarbon rings containing 1 to 3 rings and each ring contains 3 to 7 carbon atoms； alkoxyalkyl； alkylaminoalkyl； heterocycle； a straight chain or branched chain alkyl group having 1 to 4 ethylenic bonds containing 2 to 20 carbon atoms； and a straight chain or branched chain alkyl group with 1 to 4 acetylenic bonds containing 2 to 20 carbon atoms； where hydrocarbyl； alkoxyalkyl； alkylaminoalkyl and heterocycle are unsubstituted or optionally substituted, preferably substituted with halogen, hydroxy, alkoxy, alkyl, alkoxyalkyl, optionally substituted saturated hydrocarbon ring containing from 1 to 3 rings and each ring contains from 3 to 7 carbon atoms, and heterocycle ； provided that R1 or R2 do not contain any unsaturated bonds, or if R1 and / or R2 contain an unsaturated bond, the unsaturated bond atom cannot be connected directly to the nitrogen atom； R3 is selected from alkyl, an optionally substituted saturated hydrocarbon ring containing 1 to 3 rings and each ring contains 3 to 7 carbon atoms； R4 and R5, are the same or different, selected from: hydrogen； hydroxyl； I rent； optionally substituted saturated hydrocarbon rings containing 1 to 3 rings and each ring contains 3 to 7 carbon atoms； alkoxy； alkoxyalkyl； heterocycle； a straight chain or branched chain alkyl group having 1 to 4 ethylenic bonds containing 2 to 20 carbon atoms； a straight chain or branched chain alkyl group with 1 to 4 acetylenic bonds containing 2 to 20 carbon atoms； wherein alkyl, a straight chain or branched chain alkyl group with 1 to 4 ethylenic bonds containing 2 to 20 carbon atoms, a straight chain or branched chain alkyl group having 1 to 4 acetylenic bonds containing 2 to 20 carbon atoms, an optionally substituted satu
