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S Kiyoto

Publications and source records attributed to S Kiyoto.

At least 19 recordsLinked to original sources
PubMed1995

WS75624 A and B, new endothelin converting enzyme inhibitors isolated from Saccharothrix sp. No. 75624. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

Novel endothelin converting enzyme (ECE) inhibitors, WS75624 A and B, have been isolated from the fermentation broth of Saccharothrix sp. No. 75624. These inhibitors were purified from an acetone extract of whole culture broth followed by HP-20 column chromatography, silica gel column chromatography and HPLC. WS75624 A and B showed highly potent ECE inhibitory activity, and both had IC50 values of 0.03 microgram/ml. WS75624 A and B also showed other metalloprotease (collagenase and neutral endopeptidase) inhibitory activity with IC50 values of 1 microgram/ml. Since large amount of WS75624 B was isolated, we tried in vivo evaluation using WS75624 B. WS75624 B inhibited big endothelin-induced pressor effect when administered to SD rat intravenously with big ET-1.

Animals↗
PubMed1995

Biological and pharmacological properties of highly selective new endothelin converting enzyme inhibitor WS79089B isolated from Streptosporangium roseum No. 79089.

WS79089B a highly specific endothelin converting enzyme (ECE) inhibitor has been isolated from the fermentation broth of Streptosporangium roseum No. 79089. WS79089B showed highly selective ECE inhibition activity with IC50 value of 0.14 microM and behaved as a competitive inhibitor of ECE, with Ki values of 8.9 x 10(-8) M. The sodium salt of WS79089B (FR901533) inhibited big endothelin-1 (big ET-1) induced pressor effect in a dose dependent manner when administered to male Sprague-Dawley rats intravenously dosed 2 minutes prior to big ET-1 challenge.

Actinomycetales↗
PubMed1994

WS79089A, B and C, new endothelin converting enzyme inhibitors isolated from Streptosporangium roseum. No. 79089. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

WS79089A, B and C, which are novel endothelin converting enzyme (ECE) inhibitors have been isolated from the fermentation broth of Streptosporangium roseum No. 79089. These inhibitors were purified from an acetone extract of whole culture broth followed by Silicar CC-4 column chromatography and HPLC. WS79089A, B and C showed highly selective ECE inhibition activity with IC50 values of 0.73 microM 0.14 microM and 3.42 microM, respectively. On the basis of spectroscopic and chemical evidence, the tentative structures of WS79089A, B and C have been proposed, they have benzo[a]naphtacen chromophores.

Actinomycetales↗
PubMed1992

Mode of relaxing action of FK336, a new antianginal agent, in rabbit aorta.

1. FK336 (10(-6)-10(-4) M) inhibited contractile responses to norepinephrine (NE), KCl and Ca2+ in isolated rabbit aortas. 2. Relaxing effect of FK336 on KCl-response was inhibited by nitroglycerin (NG), but not by nifedipine or verapamil. 3. FK336 inhibited residual NE response and a subsequent Ca2+ response in Ca(2+)-free medium. FK336 did not affect the inositol monophosphate level. 4. Relaxing effect of FK336 on NE response was inhibited by methylene blue, NG, K(+)-channel inhibitors and acetylcholine (ACh), and potentiated by M&B 22,948 and theophylline. 8-Br cGMP and dibutyl cAMP had no effect. 5. FK336 increased cGMP level in rat aorta. 6. Potentiation of isoproterenol-relaxation by FK336 was inhibited by methylene blue. 7. The inhibitory effect of ACh on FK336-relaxation was eliminated by endothelium removal, nordihydroquaiaretic acid and guinacrine, but not by indomethacin. These treatments themselves did not affect FK336-relaxation. 8. The mode of vasorelaxing action of FK336 is discussed.

Acetylcholine↗
PubMed1992

Possible mechanisms of inhibition with atropine against noradrenaline-induced contraction in the rabbit aorta.

1. In the rabbit isolated aorta, atropine (3 x 10(-6) M-10(-4) M) inhibited contractile response to noradrenaline without affecting contraction to KCl. 2. In the presence of contraction to noradrenaline, atropine (3 x 10(-7) M-10(-4) M) caused concentration-dependent relaxation. Pretreatment with theophylline (10(-3) M) potentiated the relaxant action of atropine. Relaxation to atropine was not affected by the specific guanosine 3':5'-cyclic monophosphate phosphodiesterase inhibitor, M & B 22,948 (10(-4) M), tetraethylammonium (10 mM), indomethacin (10(-5) M), propranolol (10(-7) M), nifedipine (10(-6) M) or removal of the endothelium. 3. Relaxation to either atropine or prazosin was not affected by preincubation with prazosin and atropine, respectively. 4. In Ca(2+)-free medium containing EGTA and nifedipine, atropine (10(-7) M-10(-4) M) inhibited the residual noradrenaline response more than the subsequent Ca(2+)-induced contraction. Pretreatment with either theophylline (10(-3) M), forskolin (3 x 10(-7) M) or a low concentration of prazosin (3 x 10(-9) M) also inhibited the residual contraction to noradrenaline and Ca2+. The effect of combined treatment of atropine and any of these agents was much greater than with each individual agent. 5. Atropine (10(-6) M-10(-4) M) also inhibited increases in the level of inositol monophosphates (IP) in response to noradrenaline. Theophylline (10(-3) M) and a low concentration of prazosin (3 x 10(-9) M) also inhibited IP formation. Combined with atropine, the effect was much greater than with each of these agents individually. 6. Atropine did not affect adenosine 3':5'-cyclic monophosphate (cyclic AMP) levels in the aorta and also failed to displace specific [3H]-prazosin binding.7. These results suggest the possibility that smooth muscle relaxation to atropine may be due to the inhibition of phosphoinositide metabolism. The relaxation is not apparently due to an action of atropine on ax-adrenoceptors, or a change in the level of cyclic AMP.

Animals↗
PubMed1992

WS009 A and B, new endothelin receptor antagonists isolated from Streptomyces sp. no. 89009. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

WS009 A and B novel endothelin receptor antagonists, have been isolated from the fermentation broth of Streptomyces sp. No. 89009. These antagonists were purified from the culture filtrate followed by Diaion SP-207, DEAE Toyopearl column chromatography and HPLC. WS009 A and B showed selective activity in an endothelin receptor binding assay with IC50 of 5.8 x 10(-6) M and 6.7 x 10(-7) M, respectively. On the basis of spectroscopic and chemical evidence, the structures of WS009 A and B have been established as 1 and 3, and are highly hydroxylated benz[a]anthraquinone chromophores.

Anthraquinones↗
PubMed1992

WS009 A and B, new endothelin receptor antagonists isolated from Streptomyces sp. no. 89009. II. Biological characterization and pharmacological characterization of WS009 A and B.

WS009 A and B, produced by Streptomyces sp. No. 89009, were found to be competitive and specific antagonists against endothelin (ET)-1 receptors in in vitro studies and also active in in vivo studies. Furthermore, WS009 A and B were specific antagonists for vascular ET-1 receptors (ETA receptors) and significantly prevented the accumulation of intracellular inositol 1,4,5-triphosphate (IP3) in endothelin treated rat aorta tissues.

Animals↗
PubMed1992

WS9326A, a novel tachykinin antagonist isolated from Streptomyces violaceusniger no. 9326. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

Data from several studies suggest that tachykinins may play an important role in the pathophysiology of airway diseases, especially asthma. Our aim is to discover tachykinin antagonists which exhibit therapeutically useful anti-asthmatic activity. In our search for activities inhibiting the binding of [3H]substance P to guinea-pig lung membrane preparations, we have found that the fermentation product, WS9326A, isolated from Streptomyces violaceusniger, is a potent tachykinin receptor antagonist.

Animals↗
PubMed1992

WS9326A, a novel tachykinin antagonist isolated from Streptomyces violaceusniger no. 9326. II. Biological and pharmacological properties of WS9326A and tetrahydro-WS9326A (FK224)

WS9326A binds competitively to [3H]substance P (NK-1 receptor) binding sites on guinea-pig lung membranes (IC50 = 3.6 x 10(-6) M), and acts as a tachykinin antagonist in various functional assays. WS9326A inhibited tracheal constrictions produced by exogenously added substance P and neurokinin A, with IC50 values of 9.7 x 10(-6) M and 3.5 x 10(-6) M, respectively. WS9326A inhibited neurokinin A-induced bronchoconstriction in a dose dependent manner when administered to guinea-pigs intravenously together with neurokinin A, and was also effective in preventing capsaicin-induced bronchoconstriction, which is known to be caused by release of endogenous tachykinins (substance P and neurokinin A). FK224 (tetrahydro-WS9326A; catalytic hydrogenation of WS9326A gave FK224) was more potent than WS9326A in the [3H]substance P receptor binding assay using guinea-pig lung membrane (IC50 = 1.0 x 10(-7) M).

Animals↗
PubMed1992

WS-7338, new endothelin receptor antagonists isolated from Streptomyces sp. No. 7338. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

WS-7338 A, B, C and D, novel endothelin receptor antagonists, have been isolated from fermentation broth of Streptomyces sp. No. 7338. These antagonists were purified from the culture mycelium by extraction with acetone, followed by carbon column chromatography and HPLC. Among them, WS-7338 B showed good activity in an endothelin receptor binding assay with an IC50 of 2.7 x 10(-7) M.

Amino Acid Sequence↗
PubMed1992

WS-7338, new endothelin receptor antagonists isolated from Streptomyces sp. No. 7338. II. Biological characterization and pharmacological characterization of WS-7338 B.

WS-7338, produced by Streptomyces sp. No. 7338, was found to be a competitive and specific antagonist against ET-1 receptors in in vitro studies and WS-7338 B is also active in vivo. Furthermore, WS-7338 B was a specific antagonist for vascular ET-1 receptors (ETA receptors) and significantly prevented the accumulation of intracellular inositol 1,4,5-triphosphate (IP3) in endothelin treated rat aorta tissues.

Animals↗
PubMed1990

WS-7528, a new isoflavanone with estrogen activity isolated from Streptomyces sp. No. 7528. Taxonomy, fermentation, isolation, physico-chemical properties and biological activities.

WS-7528, produced by Streptomyces sp. No. 7528, was extracted from cultured broth, purified by solvent extraction followed by chromatography on silica gel and then isolated as pale yellow powder (C16H14O5, mp 95-98 degrees C). WS-7528 inhibited estrogen binding to its receptor protein in rat uterine cytosol. The IC50 value of WS-7528 for partially purified rat uterine cytosol receptor was 5.7 x 10(-8) M. This compound was found to induce the growth of the estrogen dependent cell line MCF-7. WS-7528 was tested orally and subcutaneously in immature rats to confirm its effect on the growth of the uterus. WS-7528 has also weak anti-inflammatory activity on the carrageenin paw edema of the rat model.

Animals↗
PubMed1989

WS-9659 A and B, novel testosterone 5 alpha-reductase inhibitors isolated from a Streptomyces. I. Taxonomy, fermentation, isolation, physico-chemical characteristics.

WS-9659 A and B, produced by Streptomyces sp. No. 9659, were extracted from cultured broth, purified by solvent extraction followed by chromatography on silica gel and then isolated as prisms (C22H24N2O, mp 161 approximately 162 degrees C, C22H23N2OCl, mp 152 approximately 153 degrees C). WS-9659 A and B have testosterone 5 alpha-reductase inhibitory activity. The IC50 values of WS-9659 A and B for partially purified rat prostate testosterone 5 alpha-reductase were 5.0 x 10(-7) M and 1.0 x 10(-5) M, respectively.

5-alpha Reductase Inhibitors↗
PubMed1989

WS-9659 A and B, novel testosterone 5 alpha-reductase inhibitors isolated from a Streptomyces. II. Structural elucidation of WS-9659 A and B.

On the basis of spectroscopic and chemical evidence, the structures of WS-9659 A and B isolated as inhibitors of testosterone 5 alpha-reductase from a Streptomyces have been established as 1 and 2, respectively. The reductase inhibitory activities of the derivatives 5 and 6, and degradation products 3 and 8 were considerably less active and substantially inactive, respectively.

5-alpha Reductase Inhibitors↗