Synthesis and anticandidal activities of optimized analogs of antibiotic Sch 37137

Novel approaches in the rational design of antifungal agents of low toxicity

This paper presents an overview of studies on novel strategies for the rational design of antifungal agents of low toxicity and overcoming the multidrug resistance (MDR) of fungi. This goal was achieved both due to the introduction of a novel target, glucosamine-6-phosphate synthase, as well as to the recognition of molecular basis of selectivity of action of amphotericin B derivatives.

Amide and ester derivatives of N3-trans-epoxysuccinoyl-L-2,3-diaminopropanoic acid: inhibitors of glucosamine-6-phosphate synthase

Several analogs 5, 6, 7, 8, 10 and 11 of the C-terminal fragment of a peptide antibiotic Sch 37137 were designed and tested as inhibitors of glucosamine-6-phosphate synthase from Saccharomyces cerevisiae. From IC50 values and kinetic parameters of inhibition of glucosamine-6-phosphate synthase by compounds 5-11 it has been found that the inhibitory potency of these compounds follows the order: 6 > 5 > 8 > 9 > 7, 10, 11. This suggests that an inhibitor with a primary amido group binds better to the active site of the enzyme than other inhibitors. The order of reactivity of compounds 5-11 may be attributed to a steric inability of the inhibitor to fit into the active site of the enzyme and also indicates the importance of the chirality of trans-epoxysuccinic acid on the inhibitory properties of the synthesized compounds.

Constrained search of conformational hyperspace of inactivators of glucosamine-6-phosphate synthase

Glucosamine-6-phosphate (GlcN-6-P) synthase (EC 2.6.1.16) is a key enzyme in amino sugar metabolism in micro-organisms and its selective and irreversible inhibitors can become valuable antifungal drugs. We performed a constrained search of the conformational hyperspace of glutamine and of the set of specific inactivators of the enzyme, as well as of some non-specific inhibitors of many cysteine containing enzymes. From these calculations we obtained spatial relationships of functional groups, the presence and specific orientation of which in the active site of the enzyme is important for effective and selective action of the inhibitor. Subsequent quantum chemical calculations confirmed the correctness of the pharmacophore conformation we obtained. Pharmacophore conformation of FMDP molecule, the most potent inhibitor in the selective inhibitors group, is placed close to the energy minimum on the conformational energy map.