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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.

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.

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.

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 (ET A receptors) and significantly prevented the accumulation of intracellular inositol 1,4,5-triphosphate (IP 3 ) in endothelin treated rat aorta tissues

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).

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.

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.

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.

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.

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.