Synthesis of tetrocarcin derivatives with specific inhibitory activity towards Bcl-2 functions.

Tetrocarcin A was recently identified as an inhibitor of the anti-apoptotic function of Bcl-2. We synthesized novel tetrocarcin derivatives in order to increase their selective inhibitory activity against Bcl-2. It was found that 21-acetoxy-9-glycosyloxy derivatives had potent Bcl-2 inhibitory activity without significant antimicrobial activity.

Inhibition of P-selectin specific cell adhesion by a low molecular weight, non-carbohydrate compound, KF38789.

OBJECTIVE AND DESIGN: P-selectin is a cell adhesion molecule of the selectin family. This study evaluated the effects of novel, low molecular weight P-selectin inhibitors in a cell adhesion assay and a murine model of peritonitis. MATERIALS: U937 or HL60 was used for cell adhesion assay. Human polymorphonuclear cells were studied for the production of superoxide. BALB/c mice were used for the in vivo study. TREATMENT: The thioglycollate (TG)-induced accumulation of leukocytes in mice was measured 6 h after the treatment. KF38789 or antibody (1 mg/kg) was injected intravenously prior to TG injection and at 3 h following initial injection. RESULTS: Low molecular weight, non-carbohydrate inhibitors against P-selectin- mediated cell adhesion were tested. One of the most potent inhibitors, KF38789, inhibited the binding of U937 cells to immobilized P-selectin immunoglobulin G chimeric protein (P-selectin-Ig) with an IC50 value of 1.97 microM. Cell adhesion to both E-selectin-Ig and L-selectin-Ig were not affected even by 100 microM of KF38789. Moreover, KF38789 inhibited P-selectin-induced superoxide production from human polymorphonuclear cells. Intravenously injected KF38789 significantly inhibited the TG-induced accumulation of leukocytes in the mouse peritoneal cavity (p<0.01). CONCLUSION: A novel low molecular weight compound, KF38789, specifically inhibited P-selectin-dependent cell adhesion and the leukocyte recruitment in mouse peritonitis.

Enzymatic synthesis of novel disaccharides using disaccharide phosphorylases.

A method for the synthesis of novel disaccharides was developed. It involved the following two steps. The first step consisted of two continuous reactions: the conversion of maltose to beta-D-glucose-1-phosphate and D-glucose by the phosphorolytic activity of maltose phosphorylase and the specific consumption of only D-glucose by incubation with glucose-consuming yeast cells. The second step involved the addition of an appropriate carbohydrate and its condensation with the remaining beta-D-glucose-1-phosphate by the synthetic activity of maltose phosphorylase or trehalose phosphorylase. Several factors affecting the yields of disaccharides were optimized. Using this method, five maltose-like derivatives and two trehalose-like derivatives were synthesized from maltose and the corresponding carbohydrates. Among these, 4-O-alpha-D-glucopyranosyl-L-fucopyranose (Glc(alpha1-4)Fuc) and alpha-d-glucopyranosyl alpha-D-fucopyranoside (Glc(alpha1-1alpha)Fuc) were purified, and identified by 1H NMR and 13C NMR.

RP-1551s, a family of azaphilones produced by Penicillium sp., inhibit the binding of PDGF to the extracellular domain of its receptor.

Nine azaphilones designated RP-1551-1, -2, -3, -4, -5, -6, -7, -M1, and -M2 were isolated from the culture broth of Penicillium sp. SPC-21609 as inhibitors of PDGF binding to its receptor. RP-1551s inhibit the binding of PDGF AA to the extracellular domain of PDGF alpha-receptor with IC50 values ranging from 0.1 to 2 microM without affecting PDGF BB binding to the extracellular domain of PDGF beta-receptor. PDGF binding was not restored after the PDGF alpha-receptor extracellular domain was washed in an attempt to remove the RP-1551-1 bound to the receptor. This result suggests that RP-1551-1 may irreversibly interact with the PDGF alpha-receptor. Since many azaphilone compounds possess high reactivity with an amino group, RP-1551-1 may prevent PDGF AA binding by reacting with amino groups on the alpha-receptor extracellular domain.

UCH9, a new antitumor antibiotic produced by Streptomyces. II. Structure elucidation of UCH9 by mass and NMR spectroscopy.

The structure of UCH9, which is a novel antitumor agent, was determined by spectroscopic methods. UCH9 consists of an aglycone and five 2,6-dideoxy sugars (three D-olivoses, one 4-O-methyl-D-olivose and one D-oliose). Four of the five sugars are sequentially connected through a beta 1-->3 linkage (olivose-1-->3-4-O-methyl-olivose-1-->3-oliose-1-->3-+ ++olivose). On the basis of the results of spectroscopic analysis, it was found that UCH9 belongs to the aureolic acid family of antibiotics. The structure of UCH9 is unique in that mono- and tetrasaccharide moieties, and a long hydrophobic side chain (sec-butyl group) are attached to the aglycone, while di- and trisaccharide moieties and a methyl or a hydrogen are attached in the case of the known aureolic acid analogs. It is known that aureolic acid analogs from a dimer in the presence of Mg2+. NMR, FAB-MS and atomic absorption analysis revealed that UCH9 isolated from Streptomyces also forms a dimer, containing one equivalent molar Mg2+.

Panosialins, inhibitors of an alpha1,3-fucosyltransferase Fuc-TVII, suppress the expression of selectin ligands on U937 cells.

Panosialins A and B were isolated as inhibitors of an alpha1,3-fucosyltransferase, Fuc-TVII, which is a key enzyme in the biosynthesis of selectin ligands, from culture broth of Streptomyces sp. Panosialins A and B inhibited the Fuc-TVII activity with IC50 values of 4.8 and 5.3 microg/ml, respectively. Panosialin A suppressed expression of selectin ligands on U937 cells, and inhibited the cell adhesion to immobilized E-selectin-immunoglobulin. Panosialins are the first reported Fuc-TVII inhibitors which can suppress the biosynthesis of selectin ligands and then inhibit selectin-mediated cell adhesion.

EI-1511-3, -5 and EI-1625-2, novel interleukin-1 beta converting enzyme inhibitors produced by Streptomyces sp. E-1511 and E-1625. III. Biochemical properties of EI-1511-3, -5 and EI-1625-2.

EI-1511-3, -5 and EI-1625-2, novel interleukin-1 beta converting enzyme (ICE) inhibitors from the culture broths of Streptomyces sp. selectively inhibited the recombinant human ICE activity with IC50 values of 0.09, 0.38 and 0.2 microM, respectively, without inhibiting elastase and cathepsin B. Manumycin G, ent-alisamycin, U-56,407, and manumycin A and B isolated simultaneously from the same strains also inhibited ICE. EI-1511-3, -5 and EI-1625-2 also inhibited mature interleukin-1 beta secretion from THP-1 cells with IC50 values of 5.4, 3.6 and 2.2 microM, respectively. In this article, biological properties of EI-1511-3, -5 and EI-1625-2 and, in addition, properties of manumycin-related compound are described.

EI-1511-3, -5 and EI-1625-2, novel interleukin-1 beta converting enzyme inhibitors produced by Streptomyces sp. E-1511 and E-1625. II. Structure determination.

The structures of three novel interleukin-1 beta converting enzyme inhibitors, EI-1511-3, -5 and EI-1625-2 were determined by spectroscopic methods. Their absolute configurations were also determined by analyses of the CD spectra of the inhibitors and their oxidation products with chromium trioxide.

RES-1149-1 and -2, novel non-peptidic endothelin type B receptor antagonists produced by Aspergillus sp. III. Biochemical properties of RES-1149-1, -2 and structure-activity relationships.

RES-1149-1 and -2, produced by Aspergillus sp. RE-1149, were found to be non-peptidic antagonists for endothelin type B receptor (ET(B) receptor). RES-1149-1 and -2 selectively inhibited the endothelin-1 (ET-1) binding to ET(B) receptor in a competitive manner with IC50 values of 1.5 microM and 20 microM, respectively. RES-1149-1 inhibited the increase in intracellular Ca2+ concentration elicited by 1 nM ET-1 in COS-7 cells expressing human ET(B) receptor, but not in the case of cells expressing ET(A) receptor. In addition, some structure-activity relationships are described.

RES-1149-1 and -2, novel non-peptidic endothelin type B receptor antagonists produced by Aspergillus sp. I. Taxonomy of producing strain, fermentation, isolation, and physico-chemical and biological properties.

RES-1149-1 and -2, novel and non-peptidic endothelin antagonists, were isolated from the cultured broth of a fungus, Aspergillus sp. RE-1149. RES-1149-1 and -2 selectively inhibited the ET-1 binding to endothelin type B receptor (ETB receptor) with IC50 values of 1.5 microM and 20 microM, respectively. Taxonomy of producing strains, fermentation, isolation, and physico-chemical properties of RES-1149-1 and -2 are described.

RES-1149-1 and -2, novel non-peptidic endothelin type B receptor antagonists produced by Aspergillus sp. II. Structure determination and derivatization.

The structures of two novel non-peptidic endothelin type B receptor antagonists, RES-1149-1 and -2 were determined by spectroscopic methods. Several derivatives were synthesized from RES-1149-1 for biological assay.

MS-282a and MS-282b, new inhibitors of calmodulin-activated myosin light chain kinase from Streptomyces tauricus ATCC 27470.

MS-282a and MS-282b were isolated from the culture broth of Streptomyces tauricus ATCC 27470 as inhibitors of smooth muscle myosin light chain kinase (MLCK). MS-282a and MS-282b inhibited the activity of chicken gizzard MLCK with IC50 values of 3.8 microM and 5.2 microM, respectively. Cyclic AMP-dependent protein kinase, cyclic GMP-dependent protein kinase and protein kinase C were not inhibited by 150 microM MS-282a at all. It is likely that MS-282a blocks MLCK activity by antagonizing calmodulin since 1) the compound inhibited calmodulin-dependent but not calmodulin-independent activity of MLCK; 2) the inhibition of MLCK was antagonized by increasing concentrations of calmodulin, and 3) the compound inhibited calmodulin-dependent cyclic nucleotide phosphodiesterase.

AS-183, a novel inhibitor of acyl-CoA: cholesterol acyltransferase produced by Scedosporium sp. SPC-15549.

A novel compound, AS-183, which inhibits acyl-CoA: cholesterol acyltransferase (ACAT), was isolated from the culture broth of a fungus, Scedosporium sp. SPC-15549. AS-183 inhibited ACAT activity in an enzyme assay system using rabbit liver microsomes with an IC50 value of 0.94 microM. AS-183 also inhibited cholesterol ester formation in HepG2, CaCo2, and THP-1 cells with IC50 values of 18.1, 25.5, and 34.5 microM, respectively.

Sapurimycin, new antitumor antibiotic produced by Streptomyces. Structure determination.

The structure of a new anthra-gamma-pyrone antitumor antibiotic sapurimycin was determined by the spectral studies of its methyl ester. Sapurimycin has the same anthra-gamma-pyrone skeleton as pluramycin, but is distinctly different because of the absence of sugars on the D ring and possessing a carboxylmethyl group on C-5.

Synthesis and biological evaluation of quinocarcin derivatives.

Cyanation of quinocarcin readily opened the oxazolidine ring to provide DX-52-1 (2), which was a key compound in the synthesis of quinocarcin derivatives. Various electrophilic reactions toward aromatic ring of DX-52-1 were examined, and 10-substituted (e.g., halogen, nitro, formyl, cyano, hydroxy, etc.) analogs were prepared. Dehydrocyanation of the derivatives could be achieved to reproduce the oxazolidine ring upon treatment with HCl or AgNO3. 10-Chloride 10 and 10-bromide 11 were the most promising among the derivatives prepared. Antitumor activity of 10 was extended to B-16 melanoma.

Reproduction of acute bracken poisoning in a calf with ptaquiloside, a bracken constituent.

Acute bracken fern toxicity in a calf was reproduced with ptaquiloside, a norsesquiterpene glucoside, isolated from the boiling water extract of bracken fern. Ptaquiloside was dissolved in 500 ml of saline and administered by drench at increasing dosages for six days out of every seven for the following periods: 400 mg/day for 24 days, 800 mg/day for 14 days and 1600 mg/day for four days. Neutrophilic granulocytes began to decrease markedly around 50 days after the start of the experiment, and granulocytopenia continued for a further 35 days until the autopsy, despite the discontinuance of ptaquiloside administration. Thrombocytes showed a relatively slow depression and reached 1 X 10(5)/mm3 at the lowest level. The calf was autopsied 86 days after the start of administration of ptaquiloside. Sternal bone marrow was found to be mostly replaced with fat marrow and only small foci of erythropoietic cells and a small number of megakaryocytes remained.