中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
2-氨基-6-(羟基甲基)-7,8-二氢-1H-蝶啶-4-酮 | 6-hydroxymethyl-7,8-dihydropterin | 3672-03-5 | C7H9N5O2 | 195.181 |
7,8-二氢-D-新蝶呤 | 7,8-dihydroneopterin | 1218-98-0 | C9H13N5O4 | 255.233 |
中文名称 | 英文名称 | CAS号 | 化学式 | 分子量 |
---|---|---|---|---|
4-[(2-氨基-4-氧代-7,8-二氢-1H-蝶啶-6-基)甲基氨基]苯甲酸 | dihydropteroate | 2134-76-1 | C14H14N6O3 | 314.304 |
—— | dihydrofolic acid | 4033-27-6 | C19H21N7O6 | 443.419 |
—— | 2-Hydroxy-7,8-dihydropteroic acid | 52028-29-2 | C14H14N6O4 | 330.303 |
The mechanistic basis for the resistance of
Forty-four sulfa drugs were screened against crude preparations of recombinant Pneumocystis carinii dihydropteroate synthetase. The apparent Michaelis-Menten constants (Km) for p-aminobenzoic acid and 7,8-dihydro-6-hydroxymethylpterin pyrophosphate were 0.34 +/- 0.02 and 2.50 +/- 0.71 microM, respectively. Several sulfa drugs, including sulfathiazole, sulfachlorpyridazine, sulfamethoxypyridazine, and sulfathiourea, inhibited dihydropteroate synthetase approximately as well as sulfamethoxazole, as determined by the concentrations which cause 50% inhibition and/or by Ki. For all sulfones and sulfonamides tested, unsubstituted p-amino groups were necessary for activity, and sulfonamides containing an N1-heterocyclic substituent were found to be the most effective inhibitors. Folate biosynthesis in isolated intact P. carinii was approximately equally sensitive to inhibition by sulfamethoxazole, sulfachlorpyridazine, sulfamethoxypyridazine, sulfisoxazole, and sulfathiazole. Two of these drugs, sulfamethoxypyridazine and sulfisoxazole, are known to be less toxic than sulfamethoxazole and should be further evaluated for the treatment of P. carinii pneumonia.