Dihydrofolate reductase inhibitors(叶酸拮抗剂 叶酸减少，白细胞减少，设计叶酸拮抗剂治疗白血病 Folic acid HO HO dihydrofolic acid DHFR H2N Thymine synthesis DNA synthesis CH3 MTX水溶解度差，酸碱两性，酰胺键易 在酸性溶液中水解失活 Methotrexate 甲氨蝶呤 对DHFR亲和力104X Dihydrofolate reductase inhibitors (叶酸拮抗剂) 叶酸减少，白细胞减少，设计叶酸拮抗剂治疗白血病 N N H N N NH O O O H2N NH O HO HO N N H N N H NH O O O H2N NH O HO HO DHFR N N H N H N H NH O O O H2N NH O HO HO Thymine synthesis / DNA synthesis N N N N NH N O O O NH2 H2N OH OH CH3 Folic acid dihydrofolic acid Methotrexate 甲氨蝶呤 对DHFR亲和力104X MTX水溶解度差，酸碱两性，酰胺键易 在酸性溶液中水解失活