sulforaphane-related compounds were positively identified in the chloroform extract, of which 5-methylsulfinylpentylnitrile was found in the greatest concentration (475.7 mg/kg of fresh sprouts), followed by sulforaphane (222.6 mg/kg) and 4-methylsulfinylbutylnitrile (63.0 mg/kg). Among 18 sulforaphane and relatedcompounds synthesized (6 amines, 6 isothiocyanates, and 6 nitriles), 2 amines, 6 isothiocyanates, and
Es werden die racemischen und optisch aktiven Formen des Methyl-allyl-sulfoxyds (I) und des Methyl-[buten-(3)-yl-(1)]-sulfoxyds (II) dargestellt und untersucht.
Synthesis of Novel Analogs of Acetyl Coenzyme A: Mimics of Enzyme Reaction Intermediates
作者:David P. Martin、Richard T. Bibart、Dale G. Drueckhammer
DOI:10.1021/ja00090a014
日期:1994.6
An improved method for the synthesis of analogs of coenzyme A (CoA) and its thioesters, which are modified in the thiol or thioester moiety, has been developed using a combination of chemical and enzymatic reactions, The enzymes catalyzing the last two steps of CoA biosynthesis were used to prepare a CoA analog (1c) in which an amide bond is replaced by a thioester bond and the thiol group is replaced by a methyl group. Reaction of 1c with a primary amine in aqueous solution results in aminolysis of the thioester linkage to form the desired CoA analog. Reaction with different amines permits the introduction of a variety of functional groups in place of the nor mal thiol or thioester group. This methodology has been used in the synthesis of five new analogs of acetyl-CoA in which the thioester sulfur is replaced by a methylene group and the acetyl group is replaced by carboxylate (14a), nitro (14b), carboxamide (14c), methyl sulfoxide (14d), and methyl sulfone (14e) groups. 14a-c were designed to mimic the possible enolate or enol intermediate in the reaction of citrate synthase and related enzymes. 14a and 14c are potent inhibitors of citrate synthase, with K-i values 1000- and 570-fold lower than the K-m for acetyl-CoA, respectively. CD titrations indicate that 14a and 14c have low affinity for citrate synthase in the absence of oxaloacetate, consistent with their recognition as enol or enolate analogs. 14b is a poor inhibitor of citrate synthase, with affinity slightly lower than that for acetyl-CoA. These results are consistent with generation of the enol form of acetyl-CoA as the nucleophilic intermediate in the reaction of citrate synthase. 14d and 14e were designed to mimic the tetrahedral intermediate or transition state in the reaction of chloramphenicol acetyltransferase and related acetyl-CoA-dependent acetyltransferases. Both compounds are poor inhibitors of chloramphenicol acetyltransferase, with affinities slightly lower than that of acetyl-CoA, indicating that these compounds are not good mimics of the enzyme-bound tetrahedral intermediate or transition state.
SCHULTZ; GLEIXNER, Archiv der Pharmazie, 1962, vol. 295 /67, p. 879 - 894
作者:SCHULTZ、GLEIXNER
DOI:——
日期:——
Squaramide-Based Pt(II) Complexes as Potential Oxygen-Regulated Light-Triggered Photocages
Two new squaramide-based platinum(II) complexes C1 and C2 have been synthesized and fully characterized. Their photoresponse has been assessed and is discussed. A remarkable enhancement in the DNA binding activity has been observed for both complexes, up on irradiation. For C2, the release of Pt(II) provoked by its irradiation has been studied. The response of C2 has been found to be regulated by the presence of oxygen. In vitro cytotoxicity tests show an enhancement in the activity of complex C2 after selective irradiation under hypoxic conditions. Resulting Pt(II) species have been isolated and characterized by various analytical methods establishing this type of squaramido-based complexes as a proof of concept for new Pt(II) photocages.