Seiji Iwama

An efficient synthesis of short-chain sphingomyelin analogs and their susceptibility to hydrolysis catalyzed by sphingomyelinase

Abstract An efficient synthesis of (D)- erythro -sphingomyelin analogs was achieved via highly stereoselective reduction of 3-benzyl-4-(alkynyloxo)-oxazolidinone with diisobutylaluminum phenoxide reagent. The initial velocities of the hydrolysis of the (D)- erythro -derivatives catalyzed by B. cereus sphingomyelinase were more than 10 times faster than those of the (D)- threo -isomers.

X-ray crystal structure determination and molecular dynamics simulation of prophospholipase A2 inhibited by amide-type substrate analogues.

X-ray crystal structures of bovine pancreas prophospholipase A2 (proPLA2) inhibited by two amide-type inhibitors, [(R)-2-dodecanoyl-amino-1-hexanolphosphocholine (DAHPc) and (R)-2-dodecanoylamino-1-hexanolphosphoglycol (DAHPg)], were determined to R = 0.208 and 0.215 using reflections with up to 2.1 A resolution, respectively. Both complex crystals lacked defined electron densities for the prosequence of the N-terminal and for a loop region consisting of residues 65-70, retaining the disordered feature observed in free proPLA2 despite stabilization due to complex formation. The polar and nonpolar moieties of the amide-type inhibitors were located in the calcium-binding pocket and in the N-terminal alpha-helical hydrophobic region of the enzyme, respectively. As for the amide group of the inhibitor, which is lacking in the true substrate, a strong hydrogen bond was formed between the NH of the inhibitor and the unprotonated N(delta1) atom of His-48, resulting in the tight binding of the inhibitor to proPLA2, as well as to PLA2. The 20-30 times more potent inhibitory activity of DAHPg than DAHPc toward PLA2 could be explained by hydrogen bond formation between the glycol OH of DAHPg and the carbonyl O of Asp-49. The seven residues of the N-terminal prosequence of proPLA2, though disordered, block the access of a water molecule to Ala-1 of PLA2 or change the hydrogen-bonding property of Ala-1 alpha-amino group, resulting in breakage of the water-mediated hydrogen-bond network which is commonly formed in PLA2. The results of molecular dynamics (MD) calculation in an aqueous solution at 300 K indicate that this, rather than the close contact between the prosequence and the residues 65-70 loop region, is the main reason why the latter region becomes flexible in proPLA2, compared with in PLA2.

A Novel αvβ3 Integrin Antagonist Suppresses Neointima Formation for More Than 4 Weeks After Balloon Injury in Rats

Objectives—We performed a detailed kinetic analysis in a rat balloon injury model to clarify the essential roles of αvβ3 integrin and endothelial cell (EC) regeneration in neointima formation. Using this model, we evaluated the antistenotic effect of Dainippon compound BS-1417, a novel αvβ3 integrin antagonist. Methods and ResultsKinetic analysis using RT-PCR showed that αvβ3 integrin-related genes are upregulated before neointima formation. Morphological and functional analyses revealed that EC regeneration requires >4 weeks after injury, and that recovery of EC normal function coincides with the arrest of neointima formation. Subcutaneous infusion of BS-1417 for 2, 4, 7, or 12 weeks after injury potently inhibited neointima formation without affecting EC regeneration. Although withdrawal of treatment with BS-1417 after short-term administration after injury resulted in catch-up growth of neointima, a long-term study suggested that this catch-up growth can be prevented by continuous administration of BS-1417 until EC regeneration. ConclusionWe clarified that αvβ3 integrin and EC regeneration play an essential role in neointima formation, and that continuous administration of BS-1417 potently and stably inhibits neointima formation without affecting EC regeneration. These findings suggest that BS-1417 might be useful as a novel systemic drug for the treatment of restenosis.

New entry for asymmetric deoxyazasugar synthesis: syntheses of deoxymannojirimycin, deoxyaltrojirimycin and deoxygalactostatin

Deoxyazasugars such as deoxymannojirimycin, deoxyaltrojirimycin and deoxygalactostatin were stereoselectively synthesized starting from (R)-(+)-4-methoxycarbonyloxazolidinone via a bicyclic oxazolidinylpiperidine as a common synthetic intermediate.

Synthesis of oxazolidinone phospholipid analogue as a new inhibitor of phospholipase A2

Abstract (S)- and (R)-3-dodecanoyl-4-phosphatidylcholinohydroxymethyl-2-oxazolidinone ( 1 ), which are cyclic analogues of the amide phospholipid 7 , were synthesized. The inhibitory activities of these analogues toward phospholipase A 2 were compared with that of the amide analogue 7 .

Design and synthesis of new secretory phospholipase A2 inhibitor of a phospholipid analog

All stereoisomers of N-acyl-4,5-disubstituted oxazolidinone phospholipid analogs were synthesized by regio and stereoselective epoxide ring opening accompanied by introduction of an amino group. The (4R,5S)-derivative showed stronger inhibitory activity toward type II phospholipase A2 than the 4-substituted oxazolidinone phospholipid analog previously reported.

New phospholipase A2 inhibitor: Synthesis and inhibition mechanism of oxazolidinone phospholipid analog

(R)-3-Dodecanoyl-4-phosphatidylcholino-hydroxymethyl-2-oxazolidino ne (7), which is a new glycerophospholipid analog, was synthesized starting from (S)-glycidol through a 4-alkylsilyoxymethyl derivative and N-acyl-4-hydroxymethyl derivative. The cyclic amide analog 7 showed strong inhibitory activity toward both Group I and II PLA25, but the inhibitory potency of 7 was slightly weaker than that of the linear amide analog (R)-1, which had been developed by de Haas et al. (Biochem. Biophys. Acta 1990, 1043, 67). The interactions of 7 with human secretory PLA2 was investigated by computer modeling in comparison with those of the linear amide analog 1. The results of the computer modeling were very compatible with those of the inhibitory activities toward PLA2S, and the both results showed that the binding mode of the oxazolidinone analog 7 was very similar to that of the genuine substrate and was different from that of the linear amide analog 1.

Simple N,N-dimethyl phenylsulfonamides show potent anticonvulsant effect in two standard epilepsy models.

Optimization of the previously reported benzothiazine analogue A led to the identification of compound 1, which showed anti-convulsant activity in two golden standard animal models of seizure, the MES and scPTZ models. Structure-activity relationship investigation of compound 1 revealed compounds 2, 6 and 19 as attractive anti-epileptic drug (AED) candidates with potent anticonvulsant effect in both the MES and scPTZ models. As these compounds are structurally different from existing AEDs, determination of their mechanism of actions could provide clues to understanding current therapy-resistant seizures. Moreover, these simple phenylsulfoneamide compounds could be good starting points for searching broad spectrum AEDs by such in vivo screening.

N-alkyl-[1,1′-biphenyl]-2-sulfonamide derivatives as novel broad spectrum anti-epileptic drugs with efficacy equivalent to that of sodium valproate

In order to develop phenyl sulfonamides as a novel class of anti-epileptic drugs (AED) for both general and partial seizure, we initiated in vivo screening of our chemical library in the mice MES and sc-PTZ models and found compounds 1 and 2 as lead compounds. Optimization of 1 and 2 led to the discovery of compound 21, which showed potent anticonvulsant effect in MES, scPTZ and rat amygdala kindling models. These findings indicate that compound 21 could be a useful new broad spectrum AED like sodium valproate and provide an opportunity to struggle current therapy-resistant epilepsy.