Semi-synthesis and biological evaluation of analogues of UK-2A, a novel antifungal antibiotic from Streptomyces sp. 517-02

Several analogues of UK-2A, a novel antifungal antibiotic isolated from Streptomyces sp. 517-02, were semi-synthesized for structure-activity studies. In vitro antifungal activities of these compounds against Saccharomyces cerevisiae IFO 0203 were evaluated by the conventional paper disk method. Several derivatives exhibited growth inhibitory activity similar to UK-2A.     

Structure-activity relationship studies on niphimycin, a guanidylpolyol macrolide antibiotic. Part 1: The role of the N-methyl-N'-alkylguanidinium moiety

Several N-methyl-N'-alkylguanidinium derivatives were synthesized and used as simplified analogues of niphimycin (NM), a guanidylpolyol macrolide, in structure-activity relationship studies. The C16-alkylated derivative exerted fungicidal activity by directly damaging the fungal plasma membrane and inducing oxidative stress in a manner similar to niphimycin. These results indicate that the N-methyl-N'-alkylguanidinium moiety is required for antifungal activity by NM.     

JU-2, a novel phosphorous-containing antifungal antibiotic from Streptomyces kanamyceticus M8

A novel phosphorous-containing antifungal antibiotic JU-2 was isolated from Streptomyces kanamyceticus M8. Quantitative chemical analysis shows the presence of two phenylalanines, two glucose, one linoleic acid, one crucic acid and one phosphonamide moiety per molcule of the antibiotic. JU-2 shows strong inhibitory activity against various pathogenic and non-pathogenic fungi but no activity against bacteria and yeast.     

5-Heteroatom-substituted pyrazoles as canine COX-2 inhibitors: Part 2. Structure-activity relationship studies of 5-alkylethers and 5-thioethers

Structure-activity relationship (SAR) studies of novel 2-[3-trifluoromethyl-5-alkyl(thio)ether pyrazo-1-yl]-5-methanesulfonyl pyridine derivatives for canine COX enzymes are described. The 4-cyano-5-alkyl ethers were found to have excellent potency and selectivity, whereas the 5-thioethers were potent but less selective than the ether analogs in a canine whole blood (CWB) COX-2 assay.     

Structure-activity relationship studies on a novel class of antiproliferative agents derived from Lavendustin A. Part I: Ring A modifications

The potent antiproliferative agent SDZ LAP 977, which has shown efficacy in a clinical proof of concept study in actinic keratosis patients, has been previously demonstrated to block the cell cycle in mitosis. In the present study, we further explored the mode of action: SDZ LAP 977 binds to the "colchicine binding site" on tubulin and, thus, inhibits tubulin polymerization in vitro. Moreover, we established structure-activity relationships for the effect of modifications in the 2,5-dimethoxyphenyl moiety ("ring A") of the molecule on in vitro antiproliferative activity.     

Isolation of a new antibiotic, alaremycin, structurally related to 5-aminolevulinic acid from Streptomyces sp. A012304

A new antibiotic, which is structurally related to 5-aminolevulinic acid, a precursor of heme biosynthesis, and named alaremycin, was isolated from the culture broth of an actinomycete strain through a random screening with the blue assay to detect the formation of anucleate cells in Escherichia coli. The producing strain was identified as Streptomyces sp. by morphological, physiological, chemical and genetic criteria. Alaremycin was purified from the culture supernatant by HP-20 hydrophobic-interaction chromatography, sequential solvent/water extraction in the acidic or alkaline pH range, and QMA cation-exchange chromatography. The chemical structure of alaremycin was determined as 5-acetamido-4-oxo-5-hexenoic acid by analyses of mass and NMR spectra. The antibacterial activity of alaremycin was enhanced in the presence of 5-aminolevulinic acid.     

Micromonosporin A, a novel 24-membered polyene lactam macrolide from Micromonospora sp. isolated from peat swamp forest

A novel 24-membered polyene lactam macrolide, micromonosporin A (=(3E,5E,7Z,15E,17E,19E,21E)-9,11,13-trihydroxy-14,19,24-trimethyl-1-azacyclotetracosa-3,5,7,15,17,19,21-heptaen-2-one; 1) was isolated from the actinomycete, Micromonospora sp. strain TT1-11, which was isolated from a very acidic peat swamp forest.     

Mollisianitrile, a new antibiotic from Mollisia sp. A59-96

Mollisianitrile (1), a new antibiotic was isolated from the fermentation broth of Mollisa sp. A59-96 together with the two known isocoumarins 2 and 3. 1 exhibited antimicrobial, cytotoxic, and phytotoxic activities. 1 contains a reactive propiolonitrile moiety which is believed to be responsible for its antibiotic activities. Upon incubation with L-cysteine the biological activity was lost.     

A novel xylanase from Streptomyces sp. FA1: Purification,characterization, identification,and heterologous expression

A xylanase (XynA) was purified from the culture medium of Streptomyces sp. FA1, which was previously isolated from a bamboo retting system. XynA had a molecular mass of 43 kDa, displayed maximal activity at pH 5.5, retained 41% of its maximal activity at pH 11.0, and was stable over a wide pH range (3.0 ～ 11.0). Purified XynA was subjected to peptide mass fingerprinting, which led to the cloning of the xynA gene. The xynA gene, which encodes a mature protein of 436 amino acids, was heterologously expressed in E. coli BL21(DE3). The activity in the culture medium could reach 213.5 U/mL, which was 11.2-fold higher than that produced by Streptomyces sp. FA1. BLAST searching revealed that full-length XynA shares less than 90% identity with most of its homologues, whereas amino acids 48-436 of the enzyme share 97% identity with an open reading frame encoding a putative full-length mature xylanase from Streptomyces tendae. The truncated xynA gene, xynA ^48-436 , was cloned and expressed in E. coli, however, no xylanase activity could be detected in the culture medium. Based on these results, it is suggested that XynA is a new member of glycoside hydrolases family10 with exceptional catalytic efficiency at alkaline pH.     

Purification, Characterization, and Substrate Specificities of Multiple Xylanases from Streptomyces sp. Strain B-12-2

The endoxylanase complex from Streptomyces sp. strain B-12-2 was purified and characterized. The organism forms five distinct xylanases in the absence of significant cellulase activity when grown on oat spelt xylan. This is the largest number of endoxylanases yet reported for a streptomycete. On the basis of their physiochemical characteristics, they can be divided into two groups: the first group (xyl 1a and xyl 1b) consists of low-molecular-mass (26.4 and 23.8 kDa, respectively) neutral- to high-pI (6.5 and 8.3, respectively) endoxylanases. Group 1 endoxylanases are unable to hydrolyze aryl-beta-d-cellobioside, have low levels of activity against xylotetraose (X(4)) and limited activity against xylopentaose, produce little or no xylose, and form products having a higher degree of polymerization with complex substrates. These enzymes apparently carry out transglycosylation. The second group (xyl 2, xyl 3, and xyl 4) consists of high-molecular-mass (36.2, 36.2, and 40.5 kDa, respectively), low-pI (5.4, 5.0, and 4.8, respectively) xylanases. Group 2 endoxylanases are able to hydrolyze aryl-beta-d-cellobioside, show higher levels of activity against X(4), and hydrolyze xylopentaose completely with the formation of xylobiose and xylotriose plus limited amounts of X(4) and xylose. The enzymes display intergroup synergism when acting on kraft pulp. Despite intragroup similarities, each enzyme exhibited a unique action pattern and physiochemical characteristic. xyl 2 was highly glycosylated, and xyl 1b (but no other enzyme) was completely inhibited by p-hydroxymercuribenzoate.     

Structure-activity relationships of novel anti-malarial agents. Part 4: N-(3-benzoyl-4-tolylacetylaminophenyl)-3-(5-aryl-2-furyl)acrylic acid amides

In a previous report, we have described novel anti-malarial compounds based on a 2,5-diaminobenzophenone scaffold. Here, we have invesigated acryloyl derivatives carrying a biaryl structure consisting of a terminal aryl residue and a central 2-furyl ring. Several compounds were obtained in the series of para-substituted phenylfurylacryloyl derivatives that displayed improved anti-malarial activity in comparison to earlier described derivatives. From the structure-activity relationships it can be deduced that there has to be a lipophilic moiety in the para-position of the terminal phenyl residue. Furthermore, there are indications that, alternatively, activity may benefit from the presence of a polar moiety with hydrogen bond acceptor properties.     

Structure-activity relationships of novel anti-malarial agents. Part 6: N-(4-arylpropionylamino-3-benzoylphenyl)-[5-(4-nitrophenyl)-2-furyl]acrylic acid amides

We have demonstrated that the p-trifluoromethylphenylpropionylamino residue at the 2-position of the core structure leads to an active benzophenone-type anti-malarial agent. The attempt to improve water solubility by introduction of an amino group into the alpha-position of the arylpropionyl residue resulted in decreased activity.     

5-heteroatom substituted pyrazoles as canine COX-2 inhibitors. Part 1: Structure-activity relationship studies of 5-alkylamino pyrazoles and discovery of a potent, selective, and orally active analog

Structure-activity relationship (SAR) studies of the novel 2-[3-di and trifluoromethyl-5-alkylamino pyrazo-1-yl]-5-methanesulfonyl (SO(2)Me)/sulfamoyl (SO(2)NH(2))-pyridine derivatives for canine COX enzymes are described. The studies led to the identification of 2e as lead with potent in vitro activity, selectivity, and in vivo activity in dogs and cats.     

Structure-activity relationships of novel anti-malarial agents. Part 7: N-(3-benzoyl-4-tolylacetylaminophenyl)-3-(5-aryl-2-furyl)acrylic acid amides with polar moieties

In a previous report, we have provided evidence that novel anti-malarial compounds based on 2,5-diaminobenzophenone farnesyltransferase inhibitors might benefit from the presence of a polar moiety at the para position of the terminal phenyl of the arylfurylacryloyl partial structure. Here, we demonstrate that different moieties with hydrogen bond acceptor properties lead to equipotent or even improved anti-malarial activity in comparison to the nitro group described before.     

Purification and characterization of serine proteinase from a halophilic bacterium, Filobacillus sp. RF2-5

In order to find a unique proteinase, proteinase-producing bacteria were screened from fish sauce in Thailand. An isolated moderately halophilic bacterium was classified and named Filobacillus sp. RF2-5. The molecular weight of the purified enzyme was estimated to be 49 kDa. The enzyme showed the highest activity at 60 degrees C and pH 10-11 under 10% NaCl, and was highly stable in the presence of about 25% NaCl. The activity was strongly inhibited by phenylmethane sulfonyl fluoride (PMSF), chymostatin, and alpha-microbial alkaline proteinase inhibitor (MAPI). Proteinase activity was activated about 2-fold and 2.5-fold by the addition of 5% and 15-25% NaCl respectively using Suc-Ala-Ala-Phe-pNA as a substrate. The N-terminal 15 amino acid sequence of the purified enzyme showed about 67% identity to that of serine proteinase from Bacillus subtilis 168 and Bacillus subtilis (natto). The proteinase was found to prefer Phe, Met, and Thr at the P1 position, and Ile at the P2 position of peptide substrates, respectively. This is the first serine proteinase with a moderately thermophilic, NaCl-stable, and NaCl-activatable, and that has a unique substrate specificity at the P2 position of substrates from moderately halophilic bacteria, Filobacillus sp.     

<Emphasis Type="Italic">Streptomyces gamaensis</Emphasis> sp. nov., a novel actinomycete with antifungal activity isolated from soil in Gama,Chad

During an investigation exploring potential sources of novel species and natural products, a novel actinomycete with antifungal activity, designated strain NEAU-Gz11^T, was isolated from a soil sample, which was collected from Gama, Chad. The isolate was found to have morphological and chemotaxonomic characteristics typical of members of the genus Streptomyces. 16S rRNA gene sequence similarity studies showed that strain NEAU-Gz11^T belongs to the genus Streptomyces with high sequence similarity to Streptomyces hiroshimensis JCM 4098^T (98.0 %). Similarities to other type strains of the genus Streptomyces were lower than 98.0 %. However, the physiological and biochemical characteristics and low levels of DNA–DNA relatedness could differentiate the isolate genotypically and phenotypically from S. hiroshimensis JCM 4098^T. Therefore, the strain is concluded to represent a novel species of the genus Streptomyces, for which the name Streptomyces gamaensis sp. nov. is proposed. The type strain is NEAU-Gz11^T (=CGMCC 4.7304^T=DSM 101531^T).     

A novel cold-adapted esterase from Salinisphaera sp. P7-4: gene cloning, overproduction, and characterization

Salinisphaera sp. P7-4 was isolated from the intestine of silver whiting, Sillago japonicas caught in the Pacific Ocean, and the esterase gene was cloned using the shotgun method. The amino acid sequence deduced from the nucleotide sequence (951 bp) corresponded to a protein of 316 amino acid residues with a molecular weight of 34,443. The esterase had 46 and 44% identities with the esterase enzymes of Ralstonia eutropha JMP134 and Rhodopseudomonas palustris HaA2, respectively. The primary structure of P7-4 esterase showed the conserved catalytic triad (Ser, Asp, His), consensus pentapeptide GXSXG, and oxyanion hole sequence (HG). The protein P7-4 was successfully expressed in Escherichia coli in a biologically active form. The enzyme showed high catalytic activity at low temperatures (5-25° C) with an activation energy of 2.18 kcal/mol. This result indicated that the esterase from Salinisphaera sp. P7-4 is a new cold-adapted enzyme. The enzyme preferentially hydrolyzed acyl-group chains with short chain lengths of ≤10 carbon. Metal ions such as Cd2(+), Co2(+), Cu2(+), Hg2(+), Ni2(+) and Zn2(+) inhibited enzymatic activity. Additionally, EDTA has no effect on its activity, whereas inhibition was observed with PMSF, a serine hydrolase inhibitor.     

Antitumor agents 279. Structure-activity relationship and in vivo studies of novel 2-(furan-2-yl)naphthalen-1-ol (FNO) analogs as potent and selective anti-breast cancer agents

In our ongoing modification study of neo-tanshinlactone (1), we discovered 2-(furan-2-yl)naphthalen-1-ol (FNO) derivatives 3 and 4 as a new class of anti-tumor agents. To explore structure-activity relationships (SAR) of this scaffold, 18 new analogs, 6-12 and 14-24, were designed and synthesized. The C11-esters 7 and 12 displayed broad anti-tumor activity (ED₅₀ 1.1-4.3 μg/mL against seven cancer cell lines), while C11-hydroxymethyl 14 showed unique selectivity against the SKBR-3 breast cancer cell line (ED₅₀ 0.73 μg/mL). Compounds 15 and 22 displayed potent and selective anti-breast tumor activity (ED₅₀ 1.7 and 0.85 μg/mL, respectively, against MDA-MB-231). The SAR results demonstrated that the substitutions from the ring-opened lactone ring C of 1 are critical to the anti-tumor potency as well as the apparent tumor-tissue type selectivity. Treatment with 3 in Brca1^f11/f11p53^f5&6/f5&6Cre^c mice models significantly inhibited the proliferation of mammary epithelial cells and branching of mammary glands.     

TspGWI, a thermophilic class-IIS restriction endonuclease from Thermus sp., recognizes novel asymmetric sequence 5'-ACGGA(N11/9)-3'

A novel prototype class-IIS restriction endonuclease, TspGWI, was isolated from the thermophilic bacterium Thermus sp. GW. The recognition sequence and cleavage positions have been established: TspGWI recognizes the non-palindromic 5-bp sequence 5'-ACGGA-3' and cleaves the DNA 11 and 9 nt downstream in the top and bottom strand, respectively. In addition, an accompanying endonuclease, TspGWII, an isoschizomer of Pst I, was found in Thermus sp. GW cells.     

Characterization and stability studies on surfactant,detergent and oxidant stable α-amylase from marine haloalkaliphilic Saccharopolyspora sp. A9

A halopalkaliphilic marine Saccharopolyspora sp. stain A9 with an ability to produce surfactants, oxidant and detergent stable α-amylase was isolated from marine sediments collected from west coast of India. The α-amylase from strain A9 was purified to homogeneity with the aid of ammonium sulfate precipitation and gel filtration chromatography by using Sephadex G-75, insoluble corn starch and sephacryl S-100 column, with a 39.01-fold increase in specific activity. SDS-PAGE and zymogram activity staining showed a single band equal to molecular mass of 66 kDa. Enzyme was found to be stable in presence of wide range of NaCl concentration with maximum activity found at 11% (w/v) of NaCl. Enzyme showed remarkable stability towards laboratory surfactants, detergents and oxidants. Glucose, maltose and maltotriose were the main end product of starch hydrolysis, indicating it is α-amylase.