α-Galactosidase Activity of Lactobacilli

alpha-Galactosidase (EC 3.2.1.22) activity was observed in cell-free extracts of Lactobacillus fermenti, L. brevis, L. buchneri, L. cellobiosis, and L. salivarius subsp. salivarius. The cultural conditions under which the enzyme activity was detected suggest that the enzyme is constitutive and present in the soluble fraction in the cell. The enzyme preparations readily hydrolyzed melibiose and other oligosaccharides containing alpha(1 --> 6) linked galactose. Although the cell-free extracts of L. fermenti and L. brevis are negative for beta-fructofuranosidase (EC 3.2.1.26), they hydrolyzed melibiose, stachyose, and raffinose in decreasing order of activity. The beta-fructofuranosidase-positive L. buchneri, L. cellobiosis, and L. salivarius preparations hydrolyzed melibiose, raffinose, and stachyose in decreasing rates of activity. The alpha-galactosidases from different lactobacilli showed optimum activity in pH range 5.2 to 5.9. L. fermenti and L. salivarius preparations exhibited maximum activity between 40 to 44 C and 48 to 51 C, respectively, whereas a 38 to 42 C range was observed for other lactobacilli. Cell-free extract of L. cellobiosis was studied for transgalactosylase activity. When incubated with melibiose, a new compound was detected and tentatively identified as manninotriose.     

Antipseudomonal Activity of α-Sulfoaminopenicillins

A series of penicillins characterized by the presence of a sulfoamino or a modified sulfoamino group in the side chain was subjected to in vitro antimicrobial screening tests. Although the most potent members of the series were less active than benzylpenicillin against gram-positive bacteria and comparably active against most gram-negative bacteria, they were, on the average, 8 to 16 times more effective against strains of Pseudomonas aeruginosa. In other comparative laboratory tests against P. aeruginosa, these compounds were about as active as carbenicillin and four to eight times more active than ampicillin. An examination of structure-activity relationships indicated that maximal potency was obtained with penicillins having an alpha-(aromatic or heteroaromatic)-alpha-sulfoaminoacetamido side chain. The compound with an alpha-phenyl group was comparable in activity to those having an alpha-(2- or 3-thienyl) group, whereas any modification in position or structure of the alpha-sulfoamino group reduced activity. Results of studies with a cell-free P. aeruginosa beta-lactamase suggest that the marked inhibitory effects of alpha-sulfoamino penicillins for P. aeruginosa can be attributed, at least in part, to their high degree of resistance to this enzyme. Some derivatives, however, had weak antipseudomonal activity, despite possessing a high degree of beta-lactamase resistance.     

Synthesis,Antioxidant Activity,and Structure–Activity Relationship of SCAP1 Analogues

Nine analogues of antioxidant peptide SCAP1 were successfully synthesised using a solid-phase method on a 2-chlorotrytil resin. The compounds were obtained in a range of yields of 7.0–57.8%. The occurrence of aggregation during the synthesis is suspected to be responsible for the poor yields. All peptides were characterized by high-resolution time-of-flight mass spectrometry (HR-TOFMS) and nuclear magnetic resonance (NMR). The antioxidant activities of the SCAP1 analogues as well as SCAP1 were analysed utilising the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) assay. The results revealed that all of the analysed peptides exhibited moderate antioxidant properties. Moreover, the evaluation of the structure–activity relationship showed that the Asn residue is an important requirement for the antioxidant activity of SCAP1. The replacement of Asn with other amino acid residues (Thr, Pro, Tyr, Trp and Phe) resulted in a decrease in the IC₅₀ values of the peptides. Notably, however, the replacement of the Lys residue with Val marginally increased the activity.

     

α-l-Rhamnosidase Activity in Culture Filtrate of Corticium rolfsii Enzymic Activity at Low pH

A phosphorylation system for formation of ATP from AMP by Zymolyase-treated cells of Candida boidinii (Kloeckera sp.) No. 2201 was developed as an ATP production process. This system was shown to be an energy conversion system, from a reduced C₁ -compound to ATP through reduction of NAD⁺ and oxidative phosphorylation but not substrate level phosphorylation, together with phosphorylation of AMP to ADP.

Reaction conditions for the ATP production were optimized in respect of substrate and coenzyme concentrations, pH and temperature, osmotic pressure, and oxygen supply. Under the optimal conditions, 26 mM (13 g/liter) and 8.5 dim (4g/liter) of ATP were produced with methanol and formate as C₁ -substrate, respectively.     

Chromone-Fused Cytosine Analogues: Synthesis,Biological Activity,and Structure–Activity Relationship

The preparation of a series of novel chromone-fused cytosine analogues, i.e., chromeno[2,3-d]pyrimidines has been carried out from substituted 2-amino-4-oxo-4H-chromene-3-carbonitriles with urea, thiourea, and guanidine under different reaction conditions. These chromone-fused cytosine analogues were evaluated for their in vitro activity against Mycobacterium tuberculosis H₃₇Rv strain and different microbial pathogenic strains in cell culture for their structure–activity relationships, respectively. Among the synthesized compounds, 2d, 3a, and 4e showed better results against Mycobacterium tuberculosis H₃₇Rv. The compounds 2a, 2b, and 3a showed potential antibacterial activity against E. coli and P. aeruginosa, while the majority of compounds were found to be active against S. aureus as compared to ampicillin. The synthesized cytosine analogues having an imine (–C&dbnd;NH) have been less sensitive to the bacterial and fungal strains but have a more beneficial effect on Mycobacterium tuberculosis H₃₇Rv.     

Endopeptidase Activity of Phage λ-Endolysin

JACOB and Fuerst^1,2 demonstrated the presence of a bacteriolytic enzyme (λ-endolysin) in the induced cultures of lysogenic Escherichia coli K12 (λ). The enzyme was later identified as the product of gene R; of phage λ³ which is involved in bacterial lysis at the end of a latent period. The enzyme is apt to form spheroplast-like structures in E. coli² and one would therefore expect its substrate to be murein.     

β-Glucosidase Activity in Phytopathogenic Bacteria

Most of 58 isolates of phytopathogenic and related bacteria comprising 24 species in the genera Agrobacterium, Erwinia, Corynebacterium, Pseudomonas, and Xanthomonas exhibited beta-glucosidase activity, especially the gall-nonforming pathogenic pseudomonads and soft rot organisms. The gall-forming pseudomonads and P. fluorescens exhibited no beta-glucosidase activity, with the exception of one isolate of P. savastanoi which showed slight activity on an inorganic nitrogen-arbutin medium. The best medium for demonstrating beta-glucosidase activity contained peptone as the nitrogen source and arbutin. beta-Glucosidase activity in this medium was indicated by either acid production or browning. P. syringae, in contrast to other bacteria tested, produced most beta-glucosidase in a medium containing large amounts of glucose. Chromatographic analyses confirmed that splitting of the glucoside occurred at the glucosidic linkage. Reaction of sonically treated bacterial cells with indican or p-nitrophenyl-beta-D-glucoside proved a rapid method for assaying relative amounts of beta-glucosidase among bacterial species. Harda's paper-strip method of detecting beta-glucosidase also was useful in revealing the distribution and relative amounts of beta-glucosidase in most bacteria, but did not indicate the relatively greater amount of beta-glucosidase in P. syringae.     

Synthesis of Novel Quinoline–Benzoxazolinone Ester Hybrids: In Vitro Anti-Inflammatory Activity and Antibacterial Activity

Russian Journal of Bioorganic Chemistry - A series of novel quinoline-benzoxazolinone ester hybrids were synthesized characterized and assessed for their in vitro anti-inflammatory and...     

Structure-Herbicidal Activity Relationship of α-Phenylsulfonyl Propanamide

α-Phenylsulfonyl alkanamides were synthesized, and their herbicidal activities were tested under paddy conditions. Some of the α-phenylsulfonyl propanamides showed a high herbicidal activity against paddy weeds with no significant effect on rice plants. The activity of the sulfonyl compound was superior to those of the sulfinyl and thio compounds.     

Platensimycin Activity against Mycobacterial β-Ketoacyl-ACP Synthases

Background

There is an urgent need for the discovery and development of new drugs against Mycobacterium tuberculosis, the causative agent of tuberculosis, especially due to the recent emergence of multi-drug and extensively-drug resistant strains. Herein, we have examined the susceptibility of mycobacteria to the natural product platensimycin.

Methods and Findings

We have demonstrated that platensimycin has bacteriostatic activity against the fast growing Mycobacterium smegmatis (MIC = 14 µg/ml) and against Mycobacterium tuberculosis (MIC = 12 µg/ml). Growth in the presence of paltensimycin specifically inhibited the biosynthesis of mycolic acids suggesting that the antibiotic targeted the components of the mycolate biosynthesis complex. Given the inhibitory activity of platensimycin against β-ketoacyl-ACP synthases from Staphylococcus aureus, M. tuberculosis KasA, KasB or FabH were overexpressed in M. smegmatis to establish whether these mycobacterial KAS enzymes were targets of platensimycin. In M. smegmatis overexpression of kasA or kasB increased the MIC of the strains from 14 µg/ml, to 30 and 124 µg/ml respectively. However, overexpression of fabH on did not affect the MIC. Additionally, consistent with the overexpression data, in vitro assays using purified proteins demonstrated that platensimycin inhibited Mt-KasA and Mt-KasB, but not Mt-FabH.

Significance

Our results have shown that platensimycin is active against mycobacterial KasA and KasB and is thus an exciting lead compound against M. tuberculosis and the development of new synthetic analogues.     

Isocostic Acid,a Promising Bioactive Agent from the Essential Oil of Inula viscosa (L.): Insights from Drug Likeness Properties,Molecular Docking and SAR Analysis

The chemical composition of the essential oil (LEO) and its volatile fractions (V₁–V₁₀) collected during the hydrodistillation process every 15 min from the fresh leaves of I. viscosa (L.), growing in Tunisia, were analyzed by GC‐FID and GC/MS. Eighty‐two compounds, representing 90.9–99.4 % of the total samples, were identified. The crude essential oil (LEO) and its fractions (V₁–V₁₀) were characterized by the presence of a high amount of oxygenated sesquiterpenes (82.7–95.8 %). Isocostic acid ( 1 ) was found to be the most abundant component (37.4–83.9 %) and was isolated from the same essential oil over silica gel column chromatography and identified by spectroscopic methods (¹H, ¹³C, DEPT 135 NMR and EI‐MS) and by comparison with literature data. Furthermore, the fresh leaves essential oil (LEO), its volatile fractions (V₁–V₁₀) as well as compound 1 were screened for their antibacterial, antityrosinase, anticholinesterase and anti‐5‐lipoxygenase activities. It was found that the isolated compound 1 exhibited an interesting antibacterial activity against Staphylococcus aureus ATCC 25923 (MIC=32 μg/mL) and Enterococcus faecalis ATCC 29212 (MIC=32 μg/mL) and the highest antityrosinase activity (IC₅₀=13.82±0.87 μg/mL). Compound 1 was also found to be able to strongly inhibit 5‐lipoxygenase with an IC₅₀ value of 59.21±0.85 μg/mL. The bioactivity and drug likeness scores of compound 1 were calculated using Molinspiration software and interpreted, and the structure‐activity relationship (SAR) was discussed with the help of molecular docking analysis.     

Dryoptkirbioside,A New Fructofuranoside Glycerol,and Other Constituents from Dryopteris kirbi Hook et Grav Rhizomes

A new fructofuranoside glycerol, dryoptkirbioside ( 1 ), along with thirteen known compounds ( 2 - 14 ), was isolated from the MeOH extract of Dryopteris kirbi rhizomes by silica gel column chromatography, Sephadex LH-20 column chromatography, and semipreparative HPLC. The structure of the new compound was determined by analyses of its spectroscopic data including nuclear magnetic resonance (NMR), and high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and chemical conversions. The hexane-soluble portion and the EAF_A fraction showed strong activities against lung (A549), breast (MCF-7), and cervical (HeLa) human cancer cell lines (IC₅₀ values ranging from 4.0 to 8.8 μg/mL). Aspidinol P ( 5 ) and aspidinol B ( 6 ) exhibited moderate to low cytotoxicity on the three cell lines (IC₅₀ values ranging from 20.4 to 58.7 μM). The MeOH extract and hexane-soluble portion had excellent activities against Staphylococcus aureus and Bacillus subtilis (MICs 11.7 and 23.4 μg/mL), whereas the AcOEt- and BuOH-soluble portions were significantly active on S. aureus (MICs 46.9 and 93.8 μg/mL). The main fractions EAF_B, EAF_C and nBF_B displayed excellent activity against S. aureus (MICs 11.7 and 23.4 μg/mL). Aspidinol B ( 6 ) had significant activity, while aspidinol P ( 5 ) was moderately active against S. aureus and B. subtilis (MICs 42.0 and 89.5 μM).     

Synthesis,Biological Activity and Action Mechanism Study of Novel Chalcone Derivatives Containing Malonate

A series of novel chalcone malonate derivatives were synthesized and their antibacterial and antiviral activities were evaluated. All target compounds were characterized by spectral data. The results of antimicrobial bioassay showed that one compound (diethyl [3‐(naphthalen‐2‐yl)‐1‐(3‐nitrophenyl)‐3‐oxopropyl]propanedioate) showed excellent antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo), with an EC₅₀ value of 10.2 μg/mL, which is significantly superior to bismerthiazol (71.7 μg/mL) and thiodiazole copper (97.8 μg/mL). At the same time, the mechanism of two compounds was confirmed by scanning electron microscopy. In addition, another compound (diethyl [3‐(naphthalen‐2‐yl)‐1‐(4‐nitrophenyl)‐3‐oxopropyl]propanedioate) showed significant curative activity to tobacco mosaic virus, with a value of 74.3 %, which was superior to 53.3 % of ningnanmycin. The results of microscale thermophoresis also showed that the Kd value of the combination of two compounds with the coat protein of tobacco mosaic virus was 0.211 and 0.166 μmol/L, which was better than 0.596 μmol/L of ningnanmycin. At the same time, the molecular docking of two compounds with tobacco mosaic virus‐coat protein shows that the compound is well embedded in the pocket between the two subunits of tobacco mosaic virus‐coat protein. These results show that chalcone derivatives containing malonate group can be considered as activators in the design of antibacterial and antiviral agents.     

Antimicrobial Pyridazines: Synthesis,Characterization, Cytotoxicity,Substrate Promiscuity,and Molecular Docking

A facile and convenient synthesis of new pyridazines suitable for use as antimicrobial agents was reported. The hydrazide intermediate was coupled with various benzaldehydes and/or acetophenones and cyclized instantaneously to afford target pyridazine derivatives. The structures of new pyridazines were confirmed by IR, ¹H‐ and ¹³C‐NMR, elemental analysis in addition to representative LC/MS. Antimicrobial activity was screened against 10 bacterial and fungal strains. The new pyridazines showed strong to very strong antibacterial activity against Gram‐negative (GNB) bacteria, while none of them showed significant antifungal activity at the same concentration range. Chloro derivatives exhibited the highest antibacterial activity with MICs (0.892–3.744 μg/mL) lower than that of chloramphenicol (2.019–8.078 μg/mL) against E. coli, P. aeruginosa, and S. marcescens. Prediction of ADME parameters, pharmacokinetics, and substrate promiscuity revealed that these new pyridazines could be promising drug candidates. Cytotoxic studies on rat hepatocytes showed how much safe these new pyridazines on living organisms (IC₅₀>64 μg/mL). MOE docking studies showed a good overlay of these new pyridazines with co‐crystallized ligand within an E. coli DNA gyrase subunit B active sites (4KFG).     

Antibacterial,antifungal, insecticidal,cytotoxicity and phytotoxicity studies on Indigofera gerardiana

The antibacterial, antifungal, acute cytotoxicity, phytotoxicity and insecticidal profile of the crude extract and various fractions of Indigofera gerardiana have been studied. Six bacterial and fungal strains were used, of which Samonella typhi and Microsporum canis were the most susceptible strains with MICs 0.37 mg/mL and 0.09 mg/mL, respectively. The crude extract and the fractions showed low insecticidal activity against Sitophilus oryzae, Rhyzopertha dominica and Callosbruchus analis but no activity against Tribolium castaneum. The brine shrimp lethality assay showed absence of any measurable cytotoxicity of the crude extract and fractions, showing a good safety profile at a preliminary level. All the fractions except crude extract revealed profound and highly significant herbicidal activity against Lemna minor at the concentration of 1000 μg/mL. Indigofera gerardiana was shown by in-vitro assays to be a potential source for natural antifungal, antibacterial and herbicidal agents.     

Chemical Composition,Antibacterial Screening and Cytotoxic Activity of Chiliadenus antiatlanticus (Asteraceae) Essential Oil

The chemical composition and in vitro antibacterial and cytotoxic activities of the essential oil (EO) of Chiliadenus antiatlanticus (Emb. & Maire) Gómiz, an asteraceous species endemic to the southwest of Morocco, were investigated. The EO yield was 1.07±0.28 %, twenty-seven metabolites were identified representing more than 96.4 % of the total composition. Camphor (35.7 %) and derivatives, borneol (4.9 %) and camphene (4.2 %) together with intermedeol (19.9 %), α-pinene (15.5 %) and (E)-pinocarveol (4.1 %) were the major constituents. An antibacterial activity was noticed against 24 strains (all Gram-positive) out of 71 at MICs values=100 μg/mL. The EO also showed significant toxicity towards liver HepG2 (55.8 % of cell viability) and melanoma B16 4A5 (41.6 % of cell viability) tumor cell lines at 100 μg/mL.     

Antibacterial Diphenyl Ether,Benzophenone and Xanthone Derivatives from Aspergillus flavipes

The extract of the strain Aspergillus flavipes DL‐11 exerted antibacterial activities against six Gram‐positive bacteria. During the following bioassay‐guided separation, ten diphenyl ethers ( 1 – 10 ), two benzophenones ( 11 – 12 ), together with two xanthones ( 13 – 14 ) were isolated. Among them, 4′‐chloroasterric acid ( 1 ) was a new chlorinated diphenyl ether. Their structures were elucidated by extensive spectroscopic data analysis, including IR, HR‐ESI‐MS, NMR experiments, and by comparison with the literature data. All compounds showed moderate to strong antibacterial effects on different Gram‐positive bacteria with MIC values that ranged from 3.13 to 50 μg/mL, but none of the compounds exhibited activity against Gram‐negative bacteria Vibrio parahaemolyticus ATCC17802 (MIC>100 μg/mL). In particular, the MICs of some compounds are at the level of positive control.     

Experimental and molecular docking investigation on DNA interaction of N‐substituted phthalimides: antibacterial,antioxidant and hemolytic activities

A series of Schiff base molecules derived from a phthalimide scaffold was investigated as efficient antibacterial, antioxidant and DNA‐interacting agents. The spectroscopic characterization of these derivatives was studied in detail using elemental analysis and spectroscopic techniques. The DNA‐binding profile of title molecules against Ct‐DNA (calf thymus) was investigated by absorbance, fluorescence, hydrodynamics and thermal denaturation investigations. The bacterial inhibition potential of these molecules was investigated against Escherichia coli and Staphylococcus aureus. Molecule 3c emerged as the most active against S. aureus (IC₅₀: 14.8 μg/mL), whereas compounds 3a and 3b displayed potential antibacterial activities against E. coli (IC₅₀: 49.7 and 67.6 μg/mL). Molecular docking studies of these compounds against GlcN‐6‐P synthase were carried out to rationalize antibacterial efficiency of these molecules. These newly synthesized molecules were screened for their scavenging capacity against 2,2‐diphenyl‐1‐picryl‐hydrazyl (DPPH) and H₂O₂ free radicals and the results were compared with ascorbic acid as synthetic antioxidant. The title molecules 3a, 3b and 3e showed less than 20% hemolysis, which indicated their significant non‐toxic behavior.     

Purification,Characterization and Antibacterial Activity of l‐amino Acid Oxidase from Cerastes cerastes

Antibiotic resistance presents a real problem in which new antibacterial molecules from natural secretions could be beneficial in the development of new drugs. In this study, Cerastes cerastes venom was investigated for its antibacterial activity against Gram‐positive and Gram‐negative bacteria. The antibacterial activity was evaluated by measuring the halo inhibition and minimum inhibitory concentration (MIC). An l ‐amino acid oxidase (CcLAAO) was purified from this venom using three chromatographic steps; its homogeneity (60 kDa) was confirmed by SDS‐PAGE. LC–MS/MS analysis of CcLAAO showed similarities with other LAAO enzymes from Echis ocellatus and Viridovipera stejnegeri venoms. CcLAAO presents an antibacterial activity against three bacterial strains (Staphylococcus aureus, Methicillin‐resistant S. aureus, and Pseudomonas aeruginosa) with MIC values of 10, 10, and 20 μg/mL, respectively. However, no effect was observed against Escherichia coli and yeast strains. Kinetic parameters of CcLAAO evaluated on l ‐leucine at pH 8.0 and 20°C were K_m = 0.06 mmol and V_max = 164 mmol/min.     

Reconfirmation of antimicrobial activity in the coelomic fluid of the earthwormEisenia fetida andrei by colorimetric assay

A novel tetrazolium salt, 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenyl)-2H-tetrazolium (MTS) was used in the assessment of antimicrobial activity in earthworm in the presence of phenazine methosulphate (PMS) as an electron coupling reagent. This activity was purified from the coelomic fluid of the earthworm (ECF),Eisenia fetida andrei (Oligochaeta, Lumbricidae, annelids) using a series of column chromatography techniques and was tested against three Gram-negative strains ofEscherichia coli, Pseudomonas aeruginosa, Aeromonas hydrophila and three Gram-positive strains ofStaphylococcus aureus, Bacillus megaterium, Arthrobacter sp., respectively. Only the pigment-free eluate of coelomic fluid of the earthworm (ECFPE) showed activity againstB. megaterium amongst three isolated active fractions. The anion (DEAE-52) exchange effluent of the ECFPE was reported to have the strongest activity againstP. aeruginosa amongst the three active fractions. The 20% acetonitrile eluate (AE) by Sep-Pak C₁₈ cartridge was also tested and showed fair resistance againstE. coli, P. aeruginosa andArthrobacter sp., respectively.