Antibacterial Activity Of Compounds Research Articles

Antimicrobial activities of saponins from Melanthera elliptica and their synergistic effects with antibiotics against pathogenic phenotypes

BackgroundResistance of bacteria and fungi to antibiotics is one of the biggest problems that faces public health. The present work was designated to evaluate the antimicrobial activities of saponins from Melanthera elliptica and their synergistic effects with standard antibiotics against pathogenic phenotypes. The plant extract was prepared by maceration in methanol. The methanol extract was partitioned into ethyl acetate and n-butanol extracts. Column chromatography of the n-butanol extract followed by purification of different fractions led to the isolation of four saponins. Their structures were elucidated on the basis of spectra analysis, and by comparison with those from the literature. The antimicrobial activities of the extracts/compounds alone and their combinations with tetracycline and fluconazole were evaluated using the broth microdilution method through the determination of minimum inhibitory concentration (MIC) and minimum microbicidal concentration.ResultsFour compounds: 3-O-β-d-glucuronopyranosyl-oleanolic acid (1), 3-O-β-d-glucuronopyranosyloleanolic acid 28-O-β-d-glucopyranosyl ester (2), 3-O-β-d-glucopyranosyl(1 → 2)-β-d-glucuronopyranosyl oleanolic acid (3) and 3-O-β-d-glucopyranosyl(1 → 2)-β-d-glucuronopyranosyl oleanolic acid 28-O-β-d-glucopyranosyl ester (4) were isolated. Compounds 1, 2 and 3 showed the largest antibacterial activities (MIC = 8–128 μg/mL) whereas compound 4 displayed the highest antifungal activities (MIC = 8–16 μg/mL). The antibacterial activities of compounds 1 and 2 (MIC = 16–32 μg/mL) against multi-drug-resistant Escherichia coli S2 (1) and Shigella flexneri SDINT are equal to those of vancomycin (MIC = 16–32 μg/mL) used as reference antibiotic.ConclusionsThe present study showed significant antimicrobial activity of compounds 1, 2, 3 and 4 against the tested microorganisms. The saponins act in synergy with the tested standard antibiotics. This synergy could lead to new options for the treatment of infectious diseases and emerging drug resistance.

Skrining Aktivitas Antibakteri Ekstrak Etanol 70% Sepuluh Daun Tanaman Terhadap Klebsiella Pneumoniae

Klebsiella pneumoniae causes several diseases such as chronic obstructive lung disease and community pneumonia. The antibiotics used for treating the infectious diseases cause several side effects. Therefore, alternative medicines which have minimal side effects are needed. This research aimed to investigate antibacterial activity of ten ethanolic extract of leaves against K. pneumoniae, identify compounds and active compounds in extract which has the highest antibacterial activity. Compounds in leaves were extracted using 70% ethanol with maceration method. The disk diffusion method was used for screening antibacterial activity against K. pneumoniae. The identification of group of compounds in extract with the largest inhibitory zone diameter was done using Thin Layer Chromatography (TLC) and bioautographic test was performed to determine the active compounds. The results of antibacterial activity screening tests showed that all extracts have antibacterial activity except bamboo leaf extract. Breadfruit extract (Artocarpus altilis) has the highest antibacterial activity with diameter of inhibition zone of 18,33 ± 5,57 mm. Breadfruit extract contains tannin, polyphenol, alkaloid, terpenoid, saponin, and the active antibacterial compounds were terpenoid and saponin.

(\xb1)-Zanthonitidine A, a Pair of Enantiomeric Furoquinoline Alkaloids from Zanthoxylum nitidum with Antibacterial Activity

A pair of new enantiomeric furoquinoline alkaloids, (±)-zanthonitidine A (1), together with nine known ones (2–10) were isolated from the radix of Zanthoxylum nitidum. Their chemical structures were elucidated based on the extensive spectroscopic analysis. The racemic mixture of 1 was separated by chiral column chromatography, and the absolute configurations of (+)-1 and (−)-1 were determined by the comparison of experimental and calculated electronic circular dichroism spectra. Antibacterial activities of compounds 1–9 were evaluated, and compounds (+)-1, (−)-1, 3, 7 and 8 showed antibacterial activities against Bacillus subtilis, Enterococcus faecalis or Staphylococcus aureus.Graphical

Anthocidins A–D, New 5-Hydroxyanthranilic Acid Related Metabolites from the Sea Urchin-Associated Actinobacterium, Streptomyces sp. HDa1

Four new 5-hydroxyanthranilic acid related compounds, named anthocidins A–D (1–4), two known analogues n-lauryl 5-hydroxyanthranilate (5) and isolauryl 5-hydroxyanthranilate (6), together with benzamide (7), 3-hydroxy-4-methoxycinnamamide (8), and (3S-cis)-hexahydro-3-[(3,4-dihydroxyphenyl)methyl]pyrrolo[1,2-a]pyrazine-1,4-dione (9), were isolated from the fermentation broth of the marine-derived actinomycete, Streptomyces sp. HDa1, which was isolated from the gut of a sea urchin, Anthocidaris crassispina, collected from Hainan Island, China. The structures of these secondary metabolites were elucidated on the basis of their 1D and 2D-NMR and mass spectroscopic data, and anthocidin A was confirmed by single-crystal X-ray diffraction with Cu Kα radiation. Anthocidins A–D (1–4) feature an acetyl group substitution at the amino group and varying alkyl side chains at the carboxyl group of 5-hydroxyanthranilic acid, and compound 5 was isolated as a natural product for the first time. The cytotoxic and antibacterial activity of compounds 1–9 were evaluated.

Synthesis and Antibacterial Activity of New Thiazolidine-2,4-dione-Based Chlorophenylthiosemicarbazone Hybrids.

Series of new thiazolidine-2,4-dione-based chlorophenylthiosemicarbazone hybrids (17–40) were synthesized by the reaction of condensation chlorophenylthiosemicarbazides with formylphenyl 2-(2,4-dioxothiazolidin-5-yl/ylidene)acetates. New compounds were tested on reference strains of Gram-positive and Gram-negative bacteria. The antibacterial activity of target compounds was determined by broth dilution method. Most active compounds possess minimum inhibitory concentration (MIC) = 3.91 mg/L. These compounds were non-toxic at concentrations close to their antibacterial effect. The antibacterial activity of some compounds was similar to or higher than the activity of used reference drugs such as oxacillin and cefuroxime. The structure–activity relationships (SARs) analysis collectively suggests that at least two different molecular mechanisms of their antibacterial activity should be expected.

Synthesis and biological evaluation of an indole core-based derivative with potent antimicrobial activity

Dibenzenesulphonyl diethyl amine has been prepared and used as a starting material to be introduced as an alkylating agent. Reaction of dibenzenesulphonyl diethyl amine with indole in the presence of sodium and absolute ethanol gave seven unexpected products, five of which were separated by flash chromatography. The structure of product 5 was established on the basis of elemental analysis and spectral data [IR, 1H-NMR, 13C-NMR, distortionless enhancement by polarization transfer (DEPT), 1H-1H correlation spectroscopy (COSY) NMR, 1H/13C heteronuclear multiple quantum coherence (HMQC) NMR and mass spectra (CI/Ms and EI/Ms)]. The antibacterial activity of compound 5 is very compatible with ampicillin.

Antibacterial triterpenoids from the leaves of Ilex hainanensis Merr.

One new triterpenoid (1) and seven known analogues (2–8) were isolated from the leaves of Ilex hainanensis Merr.. Their structures were established by analysis of their MS, 1D and 2D NMR spectroscopic data and comparison with those in the literature. The antibacterial activity of compounds 1–8 were evaluated by determination of minimum inhibitory concentration using twofold microdilution broth method against Streptococcus mutans ATCC 25175 (Gram-positive) and Fusobacterium nucleatum ATCC 10953 (Gram-negative). Compounds 3 and 5 showed significant antibacterial activity against S. mutans in concentration of 9.7 μg/mL, while showed little antibacterial activity against F. nucleatum. On the contrary, the inhibitory activity of compounds 1, 2 and 6 against F. nucleatum were higher than them against S. mutans.

Isolation Purification and Structure Elucidation of Antibacterial Active Compounds from Freshwater Cyanobacterium Lyngbya sp.

Cyanobacteria are considered as a rich source of bioactive compounds as they are able to produce a great variety of secondary metabolites characterized by a broad spectrum of biological activities including antiviral, antibacterial, antifungal, and anticancer properties. In the present study, freshwater cyanobacterium Lyngbya sp. was isolated from the Sennayaka samudraya and methanol crude extract was selected based on the previous antibacterial study (Agar disc diffusion method and Broth Microdialution method (Minimum Inhibition Concentration) to isolate and purify antibacterial active compounds. The antimicrobial activity of the methanol crude extract of Lynbya sp. was tested against two human pathogenic Gram-positive bacteria (Bacillus sp., Staphylococcus aureus-ATCC 2593), two human pathogenic Gram-negative bacteria (Escherichia coli-ATCC 25922, 2785 and Salmonella typhi) using bioautochromatography. Ciprofloxacin (5 μg/disc) was used as a positive control whereas DMSO (100%) used as negative control. The antioxidant property in the crude extract was evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging test (Inhibitory Concentration, IC50 = 120.042 ppm). Thin Layer Chromatography (TLC), Column chromatography (CC), Preparative Thin Layer Chromatography (PTLC), Solid Phase Extraction (SPE) and finally High Performance Liquid Chromatography (HPLC) was carried out to purify the antibacterial active ingredient in methanol crude extract. Secondary phytochemical screening was done using TLC spray reagents to identify the antibacterial active chemical compound class. Structure elucidation of isolated compound was carried out using Gas Chromatography Mass Spectrometry (GCMS) and Fourier-Transform InfraRed spectroscopy (FTIR). Two solvent systems, Ethyl acetate: methanol: deionized water (100:13.5:10) and Toluene, ethyl acetate (93:7) were optimised to separate and purify the active compounds in the crude extract by thin layer chromatography plates. One clear band with antibacterial active compounds was detected on the TLC plates, which were developed using Toluene, ethyl acetate (93:7) solvent system by bioautochromatography test and that band was named as A1 (Rf =0.108). A1 showed antibacterial activity against Bacillus sp, E. coli and S.aureus. Three clear bands with antibacterial active compounds were detected on the TLC plates, which were developed using Ethyl acetate: Methanol: Water (100:13.5:10) solvent system by bioautochromatography test and that bands were named as B1 (Rf=0.361), B2 (Rf=0.326), B3 (Rf=0.035). B1 showed antibacterial activity against Bacillus sp, E. coli and S. aureus. B2 showed antibacterial activity against E. coli and Bacillus sp. B3 showed antibacterial activity against Bacillus sp, E. coli and S.aureus. The three main fractions namely fraction 1, 2, 3 were obtained by PTLC and antibacterial activity of each fraction was verified using bioautochromatography and fraction 1 showed potential antibacterial activity whereas fraction 2 and 3 were not shown any activity against test organisms. Secondary chemical screening was given positive result for Arbutin Anthraquinone glycoside and Alkaloid. According to the GC-MS analysis was revealed that fraction 1 contain 3,5-bis (1-1-dimethylethyl)-4-hydroxy-octadecyl ester, 1- Hexadecene and 1-Heptadecanol. These results of the present study revealed that the cyanobacterium Lyngbya sp. had antibacterial activity against the tested human pathogenic bacteria and the Lyngbya sp. is a potential candidate to utilize as a natural source to produce antibiotics. Keywords: Antibacterial activity, PTLC, TLC, HPLC

Synthesis and antibacterial activity of new (2,4-dioxothiazolidin-5-yl/ylidene)acetic acid derivatives with thiazolidine-2,4-dione, rhodanine and 2-thiohydantoin moieties

A series of new (2,4-dioxothiazolidin-5-yl/ylidene)acetic acid derivatives with thiazolidine-2,4-dione, rhodanine and 2-thiohydantoin moiety (28–65) were synthesized by the reaction of (2,4-dioxothiazolidin-5-yl/ylidene)acetic acid chlorides with 5-(hydroxybenzylidene) thiazolidine-2,4-dione, rhodanine and 2-thiohydantoin derivatives. Obtained compounds (28–65) were tested on reference strains of Gram-positive bacteria and ones of the Gram-negative bacteria. The antibacterial activity of target compounds was determined by broth microdilution method. These derivatives showed antibacterial activity generally against Gram-positive bacterial strains. Most active compounds possess MIC = 3.91 mg/L. Our results suggest that presence of electron-withdrawing substituent at phenyl ring is favorable while geometry of molecule does not play important role in antibacterial response. It was confirmed the lack of direct influence of substitution pattern at phenyl ring on antibacterial activity of closely related compounds of series 1–3. The antibacterial activity of some compounds was similar or higher than the activity of commonly used reference drugs such as oxacillin and cefuroxime.

Antimicrobial activity of some medicinal plant extracts against Gram positive and Gram negative bacteria in Bangladesh

Antibacterial active compounds isolated from higher plants appear to be one of the most important alternative approaches to contain antibiotic resistance and the management of disease. The present study was aimed at to investigate the antibacterial activity of some medicinal plant species including seeds namely Centella asiatica, Oxalis corniculata, Phoenix dactylifera, Clitoria ternatea and Nigella sativa. The methanolic and ethanolic extract of Centella asiatica, Oxalis corniculata, Phoenix dactylifera and Clitoria ternatea was investigated for antimicrobial activity at different concentrations by using disc diffusion method against some bacterial strains with standard antibiotic cephachlore (10 μg). The result demonstrated that all the extracts showed antibacterial activities against the isolates, which were dose dependent. The ethanolic extract of Oxalis corniculata at a concentration of 50 μl/disc had the highest effect on the test organism B. subtilis, Salmonella typhi and E. coli with 9.3, 9.7 and 10.8 mm diameter of zone of inhibition respectively while at the same concentration the extract of Clitoria ternatea had a higher antimicrobial activity on Bacillus cereus with 11.3 mm diameter of zone of inhibition. The activities of the plant extracts on the tested pathogens were not as effective as the standard commercial antibacterial disc but was significant. In case of Nigella sativa, Pseudomonas aeruginosa was sensitive to both the ethanolic extract and oils at different concentration. Salmonella typhi shows the same degree of inhibition for ethanolic extract as Bacillus cereus, but greater inhibition for oils. Of all the bacteria, Pseudomonas aeruginosa was the most sensitive bacteria against ethanolic extract and oils, while Bacillus cereus was the most resistant bacteria. Generally, the oils of Nigella sativa sample had higher antibacterial activity against bacteria than ethanolic extract. All the extracts are inhibitory to most common human pathogen S. typhi. The results suggest that the different plant extracts has a significant scope to develop a novel broad spectrum of antibacterial herbal formulations.Asian J. Med. Biol. Res. December 2017, 3(4): 405-411

Structural, Optical and Antimicrobial Analysis of Nickel Doped HAp Synthesized by Solgel Method for Biomedical Applications

Hydroxyapatite (HAp) having chemical formula Ca10 (PO4)6(OH)2 is the main chemical component of human bone tissue (70%), to cope up with the bone response as a bio active material. In this study Ni doped HAp powder with triclinic phase was synthesized by sol-gel method, by doping Ni of different concentrations (0.02, 0.04, 0.06, and 0.08). The various properties due to different concentration of Ni in HAp were characterized by X-ray diffraction analysis (XRD), Energy dispersive x-ray spectroscopy (EDX) and Fourier transform spectroscopy (FT-IR). The thermal gravimetric analysis (TGA-DTA) was also carried out to evaluate the stability of the synthesized HAP powder. Antibacterial activity of compounds against microbial pathogens was done using well diffusion method. High antibacterial activity was observed for Ca0.98 Ni0.02 (PO4)(OH)2. The transmission electron microscopic analysis confirms the presence of the spherical shape morphology of the prepared hydroxyapatite nanoparticle with the particle size of around 20 to 100 nm.

In-Vitro Antibacterial Activity of Plantago Lanceolata Against Some Selected Standard Pathogenic Bacterial

The leaves of Plantago lanceolata have been used for centuries to treat diseases. Currently there is an increasing incidence of multiple antibiotic resistances in microorganisms which is a major threat. Widespread overuse of antibiotics is one led to increasing clinical resistance of previously sensitive microorganisms and the emergence of previously uncommon infections. Thus all these calls for an urgent need to search new, effective and safe anti-bacterial agents. The objective of this study was to determine antibacterial potentials of extracts of P. lanceolata against standard pathogens bacteria. Active antibacterial compounds were extracted using three solvents. The antibacterial sensitivity activities of crude extracts were determined using agar well diffusion assay. MIC and MBC of each crude extracts were also determined using broth dilution method. The test showed various degrees of antibacterial activity towards each standard pathogenic microorganism with mean zone of inhibition ranges up to 18±2mm against S. typhi. The plant extract was showed as low 3±1mm to high 18±2mm diameter inhibition zone. Chloroform extract have the least inhibition zone while the ethanol have highest inhibition zone. The extract value of MIC was showed at the ranges of 12.5mg to 50mg while the MBC were showed at the range of 25mg to 50mg. The result of this study showed that leaves of P. lanceolata have considerable antibacterial potential. The claimed efficacy could be attributable to antibacterial activity of its components but its mode of action is unclear.

Non-enzymatic nitric oxide release from biodegradable S-nitrosothiol bound polymer: synthesis, characterization, and antibacterial effect

Nitric oxide (NO) delivery is an effective method for the development of NO-mediated therapy under the physiological conditions for biological applications. S-nitrosothiol is the most widely used NO donor for therapeutics which is capable of spontaneously releasing NO under physiological conditions and acts as a potential stable source of NO and as an S-nitrosating agent. In this present work, the preparation of a biodegradable and biocompatible polymer poly(acrylic acid) (PAA–CANO) cross linked with the S-nitrosothiol,cysteamine (CANO) is reported. Thus, prepared polymer showed a controlled maximum release of NO up to 6 days and it provided a potential defense against pathogenic bacteria. The prepared PAA–CANO was characterized by various techniques such as Fourier transform infrared spectroscopy, ultraviolet–visible spectrophotometry, nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. In addition, loading of PAA–CANO into spongy scaffolds consisting of chitosan and alginate in 1:2 ratio resulting in a new antibacterial active compound suitable for providing infection-free environment on surgical covers, devices, and apparel is also reported. This polymeric scaffold showed a controlled NO release of 2.43 × 10−10 M/s/cm2. The morphology of the scaffolds is a micro-fibrous structure with a porosity of 57% and it was characterized by scanning electron microscopy. Covalent tethering of nitric-oxide-releasing compound S-nitrosocysteamine to poly(acrylic acid) improves its stability and leads to controlled release of nitric oxide useful for the antibacterial activity.

Phytochemical Profiling, Antioxidant and Antibacterial Activities of Leaf Extracts From Rhus leptodictya

An integral part of nature is herbal plants which contain natural substance essential to promote health. The focal point of this research resides on the phytochemical, antioxidant and antibacterial investigations of Rhus leptoditya leaves. Hexane, dichloromethane, ethyl acetate, acetone, and methanol solvent extracts were tested for their antioxidant and antimicrobial properties. Phytochemical analysis of R. leptodictya extracts revealed the presence of phenols, tannins, saponins, and flavonoids. Acetone extract with total flavonoid contents of 18.22 ± 2.1 mg/g while methanol extract with phenol contents (0.38 ± 0.002 mg/g) exhibited the highest amount amongst the studied extracts in the preliminary phytochemicals screening. The antioxidant activity of the plant extracts was evaluated using TLC based standard qualitative 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The methanol and acetone extracts showed maximum antioxidant bands compared to other selected solvents and promising radical scavenging activity at par with the standard antioxidant ascorbic acid (IC50 = 0.125 ± 0.013 mg/ml). The bioautography assay also demonstrated the bacterial growth inhibition of active compounds present in leave extracts. Acetone and ethyl acetate fractions showed the highest number of antibacterial active compounds against S. aureus. Minimum inhibitory concentration of the extracts examined using microplates of 96 wells containing Muller-Hinton methods against some bacterial strains, revealed methanol and acetone fractions with the lowest MIC value of 0.04 mg/ml against S. pneumoniae, while methanol extract possesses 0.008 mg/ml against S. aureus and B. subtilis. Results from this study project the R. leptodictya leave extracts constituents as health supplements that could be useful in food industries and in the treatment of various infectious diseases.

Structural elucidation and bioassays of newly synthesized pentavalent antimony complexes

Antimony (V) organometallics (1–5) have been synthesized with general formula [SbR′3(O2CR)2], where R' = phenyl, p-tolyl and O2CR are substituted cinnamates. These complexes have been characterized by FT-IR analysis, multinuclear (1H, 13C) NMR spectroscopy and single crystal X-ray diffraction analysis. The crystal structures of [Sb(phenyl)3(4-ClC6H4C2H2O2C)2] (1) and [Sb(p-tol)3(4-OCH3C6H4C2H2O2C)2].CHCl3 (5) displayed distorted geometry between trigonal bipyramidal and square pyramidal with monomeric structure at a five coordinated Sb center. Starting reagents and complexes were evaluated for anticancer, antileishmanial, antibacterial and alpha amylase inhibition potentials. It was observed that complexes 3, 4 and 5 showed significant (p < 0.05) antileishmanial and anticancer activities against Leishmania tropica KWH23 promastigotes and HepG2 cell lines respectively. Antibacterial activity of compound 3 was also significant against E. coli (MIC: 5.55 μg/mL), K. pneumoniae (MIC: 16.66 μg/mL), S. aureus (MIC: 5.55 μg/mL) and P. aeruginosa (MIC: 50 μg/mL). Hence, these new antimony complexes can act as good drug candidates.

Synthesis and Biological Evaluation of Thiosemicarbazide Derivatives Endowed with High Activity toward Mycobacterium Bovis.

Thiosemicarbazides are potent intermediates for the synthesis of pharmaceutical and bioactive materials and thus, they are used extensively in the field of medicinal chemistry. The imine bond (-N=CH-) in this compounds are useful in organic synthesis, in particular for the preparation of heterocycles and non-natural β-aminoacids. In this paper the synthesis of some new thiosemicarbazide derivatives by condensation reaction of various aldehydes or ketones with 4-phenylthiosemicarbazide or thiosemicarbazide is reported. This synthesis method has the advantages of high yields and good bioactivity. The structures of these compounds were confirmed by IR, mass, 1H NMR, 13C NMR, and single-crystal X-ray diffraction studies. All of these compounds were tested for their in-vitro anti-mycobacterial activity. The influence of the functional group and position of substituent on anti-bacterial activity of compounds is investigated too. The preliminary results indicated that all of the tested compounds showed good activity against the test organism. The compounds 11 and 30 showed the highest anti-tubercular activity (0.39 μg/mL). This synthesis method has the advantages of high yields and good bioactivity.

UJI VARIASI DOSIS PERASAN LENGKUAS (Alpinia galanga) TERHADAP PERTUMBUHAN KUMAN Staphylococcus aureus

Infections caused by Staphylococcus aureus if not handled effectively will be able to cause death human. Hasn’t been found effective antibacterial against Staphylococcus aureus. Antibacterial active compounds in the essential oil of ginger have the ability as an antimicrobial, so it can be used as an antibacterial. This study aims to determine effectiveness of the juice of galangal (Alpina galanga) to the growth of Staphylococcus aureus. This study was an experimental study using disc diffusion method. The juice galangal (Alpina galanga) used has dosage of 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%. At dosage of 50% to 100% has the potential to inhibit the growth Staphylococcus aureus. Nonetheless, based on the statistical test dosage of 50%, 60%, 70%, and 80% was significantly different from dosage 90%, 100%, and positive control and negative control. Dosage 90% and 100% was not significantly different, making more used dosage 90% to accelerate the process of growth inhibition Staphylococcus aureus.

Crystal structure, DNA interaction and thermal analysis data of two new antimicrobial active binuclear cadmium and mercury complexes

Two new binuclear Schiff base complexes with the general formula [CdLBr(μ-Br)]2 (1) and [Hg2L(μ-I)2I2] (2) were prepared by the reaction of 2,2-dimethyl-N,N'- bis-(3-phenyl-allylidene)-propane-1,3-diamine (L), CdBr2 and HgI2. The crystal structure of two complexes was determined by X-ray crystallography. The common structures for four-coordinated compounds are square planar or the tetrahedral geometries, which is evaluated by the Houser angular index (τ4). In [CdLBr(μ-Br)]2 (1), each cadmium center is five-coordinated by two iminic nitrogen atoms from Schiff base ligand, two μ2-bridging bromide anions and one terminal coordinating bromide anion. The metal center in this centrosymmetric dimer has a distorted square-pyramidal geometry. [Hg2L(μ-I)2I2] (2) consists of two four-coordinated mercury centers with different coordination spheres (HgN2I2 for Hg1 and HgI4 for Hg2). The TG/DTG diagrams showed that both complexes were completely decomposed under a nitrogen atmosphere. Furthermore, antibacterial activities of compounds have been screened against various bacteria and fungi by Disk diffusion method. Mercury complex inhibited the growth of the microorganisms more efficient than cadmium complex. DNA cleavage potential of compounds was evaluated by agarose gel electrophoresis method. Finally, nano-structure cadmium complex was sono-chemically synthesized and applied as precursor for preparation of cadmium oxide nanoparticles.

Synthesis of 2-phenylamino-thiazole derivatives as antimicrobial agents

A series of 10 new N-phenyl-4-(4-(thiazol-2-yl)-phenyl)-thiazol-2-amine derivatives (3a–j) and 4 new 5-(2-(phenylamino)-thiazol-4-yl)-benzamide ethers (3′a–d) were synthesized from 4-(2-phenylamino)-thiazol-4-yl)-benzothioamide and 2-hydroxy-5-(2-(phenylamino)-thiazol-4-yl)-benzamide with several α-halo-ketones, by the Hantzsch reaction. All compounds were characterized by elemental analysis and spectral data (MS, FT-IR and NMR). The final 14 substances were screened for antimicrobial activity, against two Gram-positive, one Gram-negative bacterial strains, and two fungal strains. Some of the synthesized molecules were more potent than the reference drugs, against the pathogenic strains used. The antibacterial activity of compounds was more pronounced against the Gram-positive strains. Compound 3e manifested the highest growth inhibitory effect against all pathogens tested (MIC of 31.25μg/mL against the Gram-positive bacterial strains and 7.81μg/mL against the Candida strains).

Antibacterial activity of a triterpenoid saponin from the stems of Caesalpinia pulcherrima Linn.

A new compound 1 was isolated from the methanolic extract of the stems of the Caesalpinia pulcherrima Linn. along with a reported compound (2) 3-O-β-D-glucopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl hederagenin 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester. The new compound 1 has m.p. 272–274°C, m.f. C46H74O17, [M]+ m/z 898. It was characterised as 3-O-β-D-glucopyranosyl-(1→4)-α-L-arabinopyranosyl hederagenin 28-O-β-D- xylopyranosyl ester by various colour reactions, chemical degradations and spectral analyses. Antibacterial activity of compound 1 was screened against various Gram-positive and Gram-negative bacteria and showed significant results.