The present invention relates to the compounds of formula (I), or its pharmacy or veterinarily acceptable salt, or the mixture of its stereoisomer or stereoisomer, wherein, R is the group in the group for select free style (A), formula (B), formula (C), formula (D) and formula (E) composition, and R1, R2 and R3 are as defined herein, are selected from the inhibitor by one of DNMT1, DNMT3A and DNMT3B group formed or a variety of DNMT. The invention further relates to the drug containing them or animal medicinal composition and its drug, particularly treatment and/or pre- anti-cancer, fibrosis and/or immunological regulation in application.