Three compounds, NP25301 (1), NP25302 (2) and bohemamine (3), inhibitors of cell adhesion based on LFA-1/ICAM-1, were isolated from the cultured broth of the strain Streptomyces sp. UMA-044. New compounds 1 and 2 were identified as 2-(3'-carbamoylphenoxy) acrylic acid methyl ester and deoxybohemamine, respectively, based on spectroscopic analyses. Compounds 1-3 inhibited adhesion of HL-60 cells to CHO-ICAM-1 cells at IC50 values of 29.5μg/ml for 1, 24.3μg/ml for 2, and 27.2μg/ml for 3.
FR225659 and four related compounds are novel gluconeogenesis inhibitors that consist of a novel acyl-group and three abnormal amino acids. They were isolated from the culture broth of Helicomyces sp. No. 19353 and can be purified by absorptive resin and reverse-phase column chromatography. They are potent inhibitors of gluconeogenesis in primary cultured rat hepatocytes and thus may be useful as anti-diabetic agents.
The novel gluconeogenesis inhibitor FR225659 and four related compounds were isolated from the cultured broth of a fungal strain No. 19353. These compounds inhibited the glucagon-stimulated gluconeogenesis of rat primary hepatocytes and had hypoglycemic effects in two different in vivo models.
During the course of screening for novel gluconeogenesis inhibitors, FR225659 and its related compounds were isolated from a fermentation broth of Helicomyces sp. No. 19353. Spectroscopic analysis concluded that FR225659 is an N-acyl tripeptide consisting of a novel acyl, a 3-chloro-4-hydroxyarginine, a 3-hydroxy-3-methylproline and a dehydrovaline. Degradation study allowed assignment of the absolute configuration of the 3-hydroxy-3-methylproline to be (2S, 3R). FR225656 was shown to possess a dehydroisoleucine instead of the dehydrovaline of FR225659.
The cytoskeletal proteins, actin and myosin, play a central role in pollen tube growth. The pollen tube growth is inhibited by cytochalasin, which interferes with actin polymerization. In the screening of pollen tube growth inhibitors, clethramycin was found from the fermentation broth of an actinomycete strain TP-A0623. The producing strain was isolated from a root of Clethra barbinervis collected in Toyama, Japan and identified as Streptomyces hygroscopicus based on the taxonomic study. Clethramycin showed in vitro antifungal activity against yeast such as Candida albicans and C. glabrata with the MIC of 0.5-8μg/ml, but weak activity against Gram-positive and negative bacteria (MIC≥64μg/ml). Cytotoxicity of clethramycin was moderate and the IC50 was 57μg/ml against HeLa cells and 120μg/ml against WI-38 cells.
Clethramycin is a novel linear polyene polyketide produced by a plant-associated actinomycete Streptomyces hygroscopicus TP-A0623. It possesses a guanidino and carboxyl residue at each end and an O-sulfate group and a hexaene moiety in the molecule, and its molecular formula is C63H99N3O18S. The structure was determined by analyzing 2D-NMR and FAB-MS data, using 13C-enriched compounds. Clethramycin is structurally similar to linearmycin, an inhibitor of spheroplast regeneration in Candida albicans. Clethramycin shows potent antifungal and pollen tube growth inhibitory activity.
Borrelidin, an antibiotic with anti-angiogenic activity, not only suppresses new capillary tube formation, but also collapses formed capillary tubes in a rat aorta culture model. Since it selectively inhibits threonyl-tRNA synthetase, we examined the effect of threonine on its anti-angiogenic activity. We found that a high concentration of threonine (1mM) attenuated the ability of borrelidin to inhibit both capillary tube formation in the rat aorta culture model and human umbilical vein endothelial cells (HUVEC) proliferation, yet did not affect the ability of borrelidin to collapse formed capillary tubes or to induce apoptosis in HUVEC. Borrelidin activated caspase-3 and -8, and inhibitors of both caspase-3 and -8 suppressed borrelidin-induced apoptosis in HUVEC. Taken together, these data suggest that the anti-angiogenic effects of borrelidin are mediated through at least two mechanisms, i.e. one threonine-dependent and the other threonine-independent, and borrelidin induces apoptosis in endothelial cells via the caspase-8/-3 pathway.
SNA-60-367 components, new peptide enzyme inhibitors of aromatase, were isolated from the culture broth of soil bacterium, Bacillus sp. SNA-60-367. These inhibitors are a family of acylated decapeptides that differ from each other in terms of amino acid composition and the nature of the fatty acid side chain. The structures of the fatty acid moieties were shown to be (3-hydroxy)heptadecanoic acid and (3-hydroxy)hexadecanoic acid that possess normal-, iso- or anteiso-type alkyl groups. The amino acid sequence of the open form of the lactone ring of the acylpeptides is RCO-L-Glu-D-Orn-L(or D)-Tyr3-D-allo-Thr-L-Glu-D-X1 (Ala, Aba or Val)-L-Pro-L-Gln-D(or L)-Tyr-L-X102(Ile or Val)-OH. The lactone ring of SNA-60-367 components is formed between Tyr3 and X102.