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ABSTRACT: Conjugates of HIV protease inhibitors with a reverse transcriptase inhibitor were synthesized, which expressed excellent antiviral activity compared with that of the individual components. The remarkable antiviral activity of the conjugated compounds may be due to their penetration into the cell and later splitting into two different classes of anti-HIV agents.
Bioorganic & Medicinal Chemistry Letters 04/1999; 9(6):803-6. · 2.55 Impact Factor
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ABSTRACT: The human immunodeficiency virus (HIV) codes for an aspartic protease known to be essential for retroviral maturation and replication. HIV protease is formed from two identical 99 amino acid peptides. We synthesized [(NHCH2CH2-S-CH2CO)51-52, Ala67,95]HIV-1 protease using the thioether chemical ligation method, and then prepared the [(NHCH2CH2-S-CH2CO)51-52, Ala67,95, Cys98]HIV-1 protease dimer analogue covalently linked by a disulfide bridge. These HIV-1 protease analogues effectively cleaved the Tyr-Phe-type substrate, but had weak affinity to the Tyr-Pro-type substrate. Consequently, the molecular recognition of the protease analogues differs from that of the wild-type enzyme. Based on the substrate transition state, we designed and synthesized a novel class of HIV protease inhibitors containing an unnatural amino acid, (2S, 3S)-3-amino-2-hydroxy-4-phenylbutyric acid, named allophenylnorstatine, with a hydroxymethylcarbonyl (HMC) isostere. The stereochemistry of the hydroxyl group was significant for the enzyme inhibition and the HMC group interacted excellently with the aspartic acid carboxyl groups of HIV protease active site in the essentially same hydrogen-bonding mode as the transition state. Small dipeptide-based HIV protease inhibitors containing the HMC isostere were studied as advantageous compounds. Among them, a dipeptide-based HIV protease inhibitor, KNI-577, exhibited potent antiviral activities, low cytotoxicity, and good pharmacokinetic properties.
Biopolymers 02/1999; 51(1):59-68. · 2.87 Impact Factor
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Archiv der Pharmazie 04/1998; 331(3):87-9. · 1.71 Impact Factor
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H Michibata,
M Mukoyama,
I Tanaka,
S Suga,
M Nakagawa,
R Ishibashi,
M Goto, K Akaji,
Y Fujiwara,
Y Kiso,
K Nakao
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ABSTRACT: Adrenomedullin (AM), a potent vasorelaxant and natriuretic peptide isolated from human pheochromocytoma, is present in the kidney and secreted from endothelial cells (EC) and vascular smooth muscle cells (VSMC), but the functional role of AM is still unclear. To clarify the significance of AM as a local regulator, we investigated its secretion and action in cultured cells, and examined the effects of neutralization using a specific monoclonal antibody against AM. The prepared antibody directed against the ring structure showed a high affinity for human and rat AM. Using radioimmunoassay with this antibody, we found significant secretion from cultured rat mesangial cells (MC) of a 6-kDa mature form of AM as seen from EC and VSMC. The addition of AM into cultured cells dose-dependently increased cAMP production and potently inhibited PDGF-stimulated thymidine incorporation. Pretreatment with the monoclonal antibody completely abolished cAMP increase induced by exogenous AM. Moreover, antibody neutralization of endogenously secreted AM in cultured EC, but not in MC or VSMC, markedly (by approximately 70%) reduced basal cAMP production and significantly (1.7-fold) enhanced DNA synthesis. These results indicate that AM, acting as an autocrine/paracrine regulator, exerts an antiproliferative action on EC and MC, and suggest its role as a local modulator of endothelial and mesangial function.
Kidney International 04/1998; 53(4):979-85. · 6.61 Impact Factor
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ABSTRACT: A reductive acidolysis final deprotection strategy in solid phase peptide synthesis was developed using a new safety-catch type of semi-permanent protecting groups and new linkers which were derived from 4-methylsulfinylbenzyl protection. This new strategy was based on a two-dimensional protection scheme employing acid-labile temporary and acid-stable but reductive acidolysis-cleavable semi-permanent protecting groups. By using this strategy, we successfully synthesized four model peptides, of which two contained C-terminal amide.
CHEMICAL & PHARMACEUTICAL BULLETIN 02/1997; 45(1):18-26. · 1.59 Impact Factor
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ABSTRACT: Human C-type natriuretic peptide 22 (hCNP22), the third member of the natriuretic peptide family, was efficiently synthesized by Fmoc-based peptide chain construction on a 2-chlorotrityl (Clt) resin, followed by deprotection using tetrafluoroboric acid (HBF4). The use of Clt resin was effective in suppressing racemization at the C-terminal cysteine residue caused by the base treatment for Fmoc-cleavage. The disulfide bond of hCNP22 was constructed using the silyl chloride-sulfoxide method to avoid oxidation at the Met residue. Using amino acid- and dipeptide-resin derivatives, the effects of bases, protecting groups and resin supports on the racemization at the C-terminal Cys residue were examined in detail.
CHEMICAL & PHARMACEUTICAL BULLETIN 08/1996; 44(7):1326-31. · 1.59 Impact Factor
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K Akaji
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ABSTRACT: An efficient method for the disulfide bond formation in peptides by the silylchloride-sulfoxide system is described. Methyltrichlorosilane in trifluoroacetic acid, in the presence of diphenylsulfoxide, is found to cleave various S-protecting groups of cysteine to form cystine directly within 10 to 30 min. No side reactions were observed with nucleophilic amino acids such as Met, His, or Tyr, except for Trp, under the reaction conditions of the silylchloride-sulfoxide treatment. A chlorination of the indole moiety of unprotected Trp, rather than the sulfur-sulfur bond formation, is a dominant reaction when the peptide containing unprotected Trp is treated with the chlorosilane-sulfoxide. However, the disulfide bond can be formed efficiently with no modification at the indole ring by the treatment of the peptide having formyl-protected Trp residue with the silylchloride-sulfoxide system. The formyl group is removed by a brief treatment at basic pH without affecting the disulfide bond formed by the silylchloride-sulfoxide treatment. Total synthesis of human insulin, a two chain peptide containing three disulfide bonds, was achieved unambiguously by sequential and selective formation of disulfide bonds in the protein for the first time. The key reaction in the synthesis is regioselective formation of three disulfide bonds separately using the silyl chloride method described above. Prior to the insulin synthesis, it was confirmed by the syntheses of double-disulfide peptides: b-hANP, unnatural parallel dimer of a-hANP, and human endothelin-1 that no disulfide exchange occurred during the silyl chloride treatment. Using three orthogonal thiol protecting groups, Trt, Acm, and But, three disulfide bonds of human insulin were efficiently constructed by the successive reactions using thiolysis, iodine oxidation, and the sily1 chloride method. Each reaction for the stepwise disulfide formation proceeded within 15 to 60 min with no polymeric product and no solubility problem. The synthetic human insulin had the correct structure and was indistinguishable from natural human insulin.
Yakugaku zasshi journal of the Pharmaceutical Society of Japan 07/1996; 116(6):441-56. · 0.39 Impact Factor
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ABSTRACT: We investigated the effects of bases, resins, and S-protecting groups on the extent of racemization at the C-terminal cysteine during Fmoc-based(Fmoc=fluoren-9-yl-methoxy-carbonyl) solid phase peptide synthesis. The use of 2-chlorotrityl resin was most effective in suppressing the racemization caused by the base treatment for Fmoc-cleavage. Somatostatin was successfully synthesized with practically no racemization using 2-chlorotrityl resin by Fmoc-chemistry.
CHEMICAL & PHARMACEUTICAL BULLETIN 04/1994; 42(3):724-6. · 1.59 Impact Factor
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ABSTRACT: A newly isolated rat brain natriuretic peptide 45 (rBNP45) was synthesized using the 9-fluorenylmethyloxycarbonyl (Fmoc)-based solid-phase method. Tetrafluoroboric acid (HBF4) deprotection was successfully applied for this synthesis, while the conventional trifluoroacetic acid (TFA)-thioanisole method gave unsatisfactory results. The disulfide bond of rBNP45 was constructed by using the silyl chloride method within 10 min, which was extremely advantageous to avoid the formation of Met(O)-rBNP45. The chick rectum relaxant activity of the synthetic rBNP45 was three times as potent as that of alpha-rat atrial natriuretic peptide (alpha-rANP).
CHEMICAL & PHARMACEUTICAL BULLETIN 08/1993; 41(7):1244-8. · 1.59 Impact Factor
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ABSTRACT: Selective and potent HIV protease inhibitors containing allophenylnorstatine [Apns; (2S, 3S)-3-amino-2-hydroxy-4-phenylbutyric acid] as a transition-state mimic were designed and synthesized. Among them, conformationally constrained tripeptide derivatives, kynostatin (KNI)-227 and -272 (Fig. 1), exhibited highly potent antiviral activities against a wide spectrum of HIV isolates. Ready availability due to the simple synthetic procedure and the excellent antiviral properties indicate that KNI-227 and KNI-272 are promising candidates as selective anti-AIDS drugs.
CHEMICAL & PHARMACEUTICAL BULLETIN 09/1992; 40(8):2251-3. · 1.59 Impact Factor
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ABSTRACT: The 13N-labeled opioid tetrapeptide, Tyr-D-Met(O)-Phe-Gly-[13N]NH2 (SD-62), was synthesized by amidation of its activated p-nitrophenol ester with [13N]ammonia (total synthesis time: 25 min, radiochemical yield: 48%). When injected intravenously into mice, [13N]SD-62 was taken up by the brain and this uptake was blocked by naloxone. In addition, the time course of changes in brain radioactivity paralleled that of the analgesic activity of this compound, suggesting that SD-62 underwent binding to brain opioid receptors. Thus, [13N]SD-62 appears to hold some promise for use as a radiopharmaceutical for in vivo studies of opioid peptide behavior, using positron emission tomography.
International Journal of Radiation Applications and Instrumentation Part B Nuclear Medicine and Biology 06/1992; 19(4):455-60.
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ABSTRACT: HIV-1 protease inhibitors containing allophenylnorstatine [Apns; (2S,3S)-3-amino-2-hydroxy-4-phenylbutyric acid]-Pro (syn diastereomer) as a transition-state mimic were established to be potent and highly selective. Z-Asn-Apns-Pro-NHBut (KNI-102) is the only tripeptide exhibiting substantial anti-HIV activity and may be of minimum size for potent, selective inhibition of HIV protease. Ready availability due to its simple chemical structure and stability should make it valuable for studies of the development of metabolically stable anti-AIDS drugs.
CHEMICAL & PHARMACEUTICAL BULLETIN 12/1991; 39(11):3088-90. · 1.59 Impact Factor
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ABSTRACT: New hydroxyl protecting groups of a safety-catch type, i.e., 4-methylsulfinylbenzyl-oxycarbonyl (Msz) group for Tyr and 4-methylsulfinylbenzyl (Msob) ether for Thr, have been developed. O-Msz and O-Msob groups are stable under both acidic and basic conditions and can be removed by a one-pot reaction involving reductive acidolysis using tetrachlorosilane-trifluoroacetic acid (TFA)-scavengers. Using these new protecting groups, a 17 residue-peptide, gamma-endorphin, was successfully synthesized by the efficient solid phase method.
CHEMICAL & PHARMACEUTICAL BULLETIN 12/1991; 39(11):3097-9. · 1.59 Impact Factor
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ABSTRACT: A synthetic method suitable for the preparation of 13N-labeled dermorphin analogue, H-Tyr-D-Met(O)-Phe-Gly-NH2 (SD-62), was established; i.e., SD-62 was synthesized by a 5 min treatment of the active ester precursor with ammonia. When the 13N-labeled SD-62, prepared by this method with [13N]ammonia, was administered into mice, the time profile of the radioactivity accumulation in the brain paralleled well that of the analgesic activity.
CHEMICAL & PHARMACEUTICAL BULLETIN 11/1991; 39(10):2734-6. · 1.59 Impact Factor
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ABSTRACT: Silver tetrafluoroborate (AgBF4) in trifluoroacetic acid (TFA) has been found to cleave the S-trimethyl-acetamidomethyl (Tacm) group or the S-acetamidomethyl (Acm) group without affecting other functional groups in a peptide chain. A newly isolated porcine brain natriuretic peptide-32 (pBNP-32) was synthesized by the combined use of the S-Tacm group and AgBF4 deprotection. The synthetic pBNP-32 was obtained in better yield by the AgBF4 procedure than by the standard I2 procedure. The synthetic pBNP-32 has the highest chick rectum relaxant activity among the known members of the atrial natriuretic peptide-brain natriuretic peptide (ANP-BNP) families. Somatostatin was also synthesized by the Fmoc-based solid-phase method using S-Tacm and AgBF4. In this synthesis, the recently developed reagent tetrafluoroboric acid (HBF4) was applied to cleave the peptide from the resin.
CHEMICAL & PHARMACEUTICAL BULLETIN 07/1990; 38(6):1551-7. · 1.59 Impact Factor
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ABSTRACT: The effect of recombinant human interleukin 1-beta (IL-1 beta) on long-term potentiation (LTP) in the mossy fiber-CA3 pathway of mouse hippocampal slice preparations was investigated. IL-1 beta significantly inhibited LTP in concentrations as low as 2.9 pM (50 pg/ml). This effect of IL-1 beta was blocked by concurrent application of 100 nM Lys-D-Pro-Thr, a tripeptide analogue of IL-1 beta. This is the first evidence that IL-1 beta can regulate LTP of synaptic transmission in the hippocampus.
European Journal of Pharmacology 07/1990; 181(3):323-6. · 2.52 Impact Factor
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ABSTRACT: The hexadodecapeptide corresponding to the entire amino acid sequence of porcine brain natriuretic peptide (pBNP) was synthesized by assembling four segments in solution, followed by HF deprotection and subsequent oxidation to establish an intramolecular disulfide bridge. The synthesis using the newly developed S-trimethylacetamidomethylcysteine [Cys(Tacm)] derivative gave a better yield than that using the S-2,4,6-trimethylbenzylcysteine [Cys(Tmb)] derivative. The chick rectum relaxant activity of the synthetic pBNP was 2.9 times more potent than that of alpha-rat atrial natriuretic peptide (alpha-rANP).
CHEMICAL & PHARMACEUTICAL BULLETIN 06/1990; 38(5):1192-9. · 1.59 Impact Factor
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ABSTRACT: alpha-Rat atrial natriuretic peptide (alpha-rANP) was synthesized by assembling five peptide fragments in solution, followed by HF-dimethylselenide-m-cresol deprotection and subsequent air-oxidation. Synthetic alpha-rANP exhibited more potent diuretic and natriuretic activity in rats than synthetic alpha-hANP.
CHEMICAL & PHARMACEUTICAL BULLETIN 05/1990; 38(4):1072-4. · 1.59 Impact Factor
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ABSTRACT: Alpha-human atrial natriuretic peptide (alpha-hANP) was synthesized by assembling six peptide fragments in solution followed by deprotection with HF and subsequent air-oxidation. The trimethylbenzyl group was employed as an S-protecting group of cysteine. The HF-dimethylselenide-m-cresol system was employed as a final deprotecting reagent and, at the same time, as a reducing reagent of Met(O). Synthetic alpha-hANP elicited potent diuretic and natriuretic activity in rats.
CHEMICAL & PHARMACEUTICAL BULLETIN 03/1990; 38(2):382-8. · 1.59 Impact Factor
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ABSTRACT: Silver tetrafluoroborate (AgBF4) in trifluoroacetic acid (TFA) has been found to cleave the S-trimethylacetamidomethyl (Tacm) group or the S-acetamidomethyl (Acm) group without affecting other functional groups in the peptide chain. Newly isolated porcine brain natriuretic peptide-32 (pBNP-32) was synthesized using AgBF4 and Cys(Tacm) derivatives. The synthetic pBNP-32 had the highest chick rectum relaxant activity among the ANP-BNP families.
CHEMICAL & PHARMACEUTICAL BULLETIN 02/1990; 38(1):273-5. · 1.59 Impact Factor
