Chemical Constituents and Antimicrobial Activity of Indian Green Leafy Vegetable Cardiospermum halicacabum

The present study was carried out to analyze chemical constituents and antibacterial activity of ethanolic leaf extract of Cardiospermum halicacabum (ECH). The FT-IR spectrum confirmed the presence of alcohols, phenols, alkanes, alkynes, aliphatic ester and flavonoids in ECH. The GC–MS analysis revealed that ECH contained about twenty four compounds. The major chemical compounds identified were cyclohexane-1, 4, 5-triol-3-one-1-carboxylic acid, benzene acetic acid, caryophyllene, phytol and neophytadiene. The ECH was screened for its antibacterial activity against different bacterial strains and anti fungal activity against Candida albicans by agar well diffusion and minimum inhibitory concentration (MIC) assay. ECH exhibited antibacterial and antifungal activity. All the tested bacterial strains showed MIC values ranging from 80 to 125 μg of extract/ml and C. albicans showed 190 μg of extract/ml as a MIC. The maximum activity ECH was observed against human pathogen Staphylococcus aureus followed by Escherichia coli and the fish pathogen Aeromonas hydrophila. ECH exhibited moderate activity against some of the tested multidrug resistant strains.     

Potential of Candida utilis to ferment Ecklonia cava by-product for enhanced anti-methicillin-resistant Staphylococcus aureus (MRSA) activity

In order to utilize the by-product of Ecklonia cava (the remaining biomass of E. cava), microbial fermentation which may result in the production of bioactive compounds using the by-product was applied in this study. The fermentation broth of E. cava by-product fermented with Candida utilis showed enhanced antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA) and food-borne pathogenic bacteria compared to that of control. To perform a more detailed investigation on the antibacterial activity, the broth was extracted with methanol and further fractionated with organic solvents. After 1 day of fermentation, the ethyl acetate (EtOAc) fraction exhibited the highest anti-MRSA activity with minimum inhibitory concentration ranging from 64 to 256 μg mL^?1, suggesting that the fermentation of E. cava by-product with C. utilis could enhance antibacterial activity against MRSA. In addition, high-performance liquid chromatography analysis revealed that dieckol, eckol, eckstolonol, and triphlorethol-A contents in the EtOAc-soluble extract increased significantly. The anti-MRSA activity of E. cava by-product most probably originated from phlorotannins, and the fermentation of C. utilis may have stimulated the breakdown of phlorotannins or have increased the efficiency in extracting phlorotannins.     

Design,synthesis and biological activity evaluation of novel 2,6-difluorobenzamide derivatives through FtsZ inhibition

Novel series of 3-substituted 2,6-difluorobenzamide derivatives as FtsZ inhibitors were designed, synthesized and evaluated for their in vitro antibacterial activity against various phenotype of Gram-positive and Gram-negative bacteria, and their cell division inhibitory activity against three representative strains. As a result, 3-chloroalkoxy derivative 7, 3-bromoalkoxy derivative 12 and 3-alkyloxy derivative 17 were found to exhibit the best antibacterial activity against Bacillus subtilis with MICs of 0.25–1 μg/mL, and good activity (MIC < 10 μg/mL) against both susceptible and resistant Staphylococcus aureus. Additionally, all the three compounds displayed potent cell division inhibitory activity with MIC values of below 1 μg/mL against Bacillus subtilis and Staphylococcus aureus.     

Antibacterial activity of<Emphasis Type="Italic">Ulva lactuca</Emphasis> against methicillin-resistant<Emphasis Type="Italic">Staphylococcus aureus</Emphasis> (MRSA)

Thein vitro antimicrobial activity of the marine green algaeUlva lactuca was examined against gram-positive bacteria, gram-negative bacteria, and a fungus. The ethyl-ether extract of algae exhibited a broad-spectrum of antibacterial activity. but not antifungal activity againstCandida albicans. In particular, theU. lactuca extract showed strong activity aganst the bacterium methicillin-resistantStaphylococcus aureus (MRSA). This result confirms the potential use of seaweed extracts as a source of antibacterial compounds or as a health-promoting food for aquaculture.     

Hepatosplenomegaly and phytotoxicity of a planktonic cyanobacterium Nostoc sp. BHU001 isolated from agricultural pond

Nostoc sp. BHU001, a planktonic cyanobacterium isolated from an agricultural pond in India, was examined for its toxicity. Mice, administered intraperitoneally with Nostoc sp. BHU001 crude extract (50 mg kg^?1 body weight) died at 4.5 h. Examination of liver and spleen showed microcystin (MC)-like symptoms. Serum enzyme aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities increased by 1.6–1.8 and 2.6–3.0-folds, respectively at 50 and 100 mg crude extract kg^?1 body weight. Thin layer chromatography of the crude extract produced five bands (N-1 to N-5). UV absorption maxima of band N-4 corresponded to that of standard microcystin-LR. Further analysis of the band N-4 by high-performance liquid chromatography gave a retention time (R _t ) of 4.61 min similar to that of standard microcystin–LR (LR stands for lysine and arginine). Total MC content was quantified by enzyme-linked immunosorbent assay, and was 189.9 μg g^?1 of crude extract, 9.8 μg l^?1 of spent medium and 5.5 μg l^?1 of pond water. Exposure of rice (Oryza sativa var. Sonam) seeds to the crude extract did not affect their germination, but inhibited the root and shoot growth of seedlings by 27.3 and 42.89 folds at 3 mg ml^?1 crude extract, respectively.     

Synthesis and antibacterial activity of some new derivatives of pyrazole

In this study, we report the synthesis and antibacterial activity of a new series of 5-amido-1-(2,4-dinitrophenyl)-1H-4-pyrazolecarbonitriles. Our results show that all compounds exhibit antimicrobial activities against methicillin susceptible Staphylococcus aureus and methicillin resistant S. aureus with MIC values of 25.1 and 91.0 μM.     

Identification of a Napin-Like Peptide from Eugenia malaccensis L. Seeds with Inhibitory Activity Toward Staphylococcus aureus and Salmonella Enteritidis

This study aimed to purify and characterize peptides from the seeds of Eugenia malaccensis, L. (jambo) with inhibitory activity against the foodborne pathogens Staphylococcus aureus and Salmonella Enteritidis. Crude extract (CE), precipitate fraction 30–60 % and molecules between 3.5 and 10 kDa obtained from precipitate fraction 30–60 % (Em2) showed inhibitory activity against the tested bacterial strains. The highest antibacterial activity was observed for Em2 against S. aureus. The major peak eluted at approximately 30 % in an acetonitrile gradient in reverse-phase chromatography of Em2 (Em2-F1 to Em2-F19), and it showed the highest antibacterial activity, which was twofold higher against S. aureus than against S. Enteritidis. MALDI-ToF spectra of Em2-F18 revealed a molecular mass of 1,231.1 Da and the amino acid sequence showed high identity to the napin family. These findings report for the first time a napin-like peptide from E. malaccensis L. seeds with potential to be applied as a new anti-Staphylococcus molecule.     

Non-toxic plant metabolites regulate Staphylococcus viability and biofilm formation: a natural therapeutic strategy useful in the treatment and prevention of skin infections

In the present study, the efficacy of generally recognised as safe (GRAS) antimicrobial plant metabolites in regulating the growth of Staphylococcus aureus and S. epidermidis was investigated. Thymol, carvacrol and eugenol showed the strongest antibacterial action against these microorganisms, at a subinhibitory concentration (SIC) of ≤ 50 μg ml^?1. Genistein, hydroquinone and resveratrol showed antimicrobial effects but with a wide concentration range (SIC = 50–1,000 μg ml^?1), while catechin, gallic acid, protocatechuic acid, p-hydroxybenzoic acid and cranberry extract were the most biologically compatible molecules (SIC ≥ 1000 μg ml^?1). Genistein, protocatechuic acid, cranberry extract, p-hydroxybenzoic acid and resveratrol also showed anti-biofilm activity against S. aureus, but not against S. epidermidis in which, surprisingly, these metabolites stimulated biofilm formation (between 35% and 1,200%). Binary combinations of cranberry extract and resveratrol with genistein, protocatechuic or p-hydroxibenzoic acid enhanced the stimulatory effect on S. epidermidis biofilm formation and maintained or even increased S. aureus anti-biofilm activity.     

Three new sterigmatocystin analogues from marine-derived fungus Aspergillus versicolor MF359

During the systematic screening of active compounds from marine-derived fungi, the extract of a strain of Aspergillus versicolor MF359 isolated from a marine sponge of Hymeniacidon perleve was identified for detailed chemical investigation. Three new secondary metabolites, named hemiacetal sterigmatocystin (1), acyl-hemiacetal sterigmatocystin (2), and 5-methoxydihydrosterigmatocystin (3), together with a known compound, aversin (4), were characterized. 1 represents a first structure of sterigmatocystin hemiacetal from nature. The antibacterial activities of these identified compounds were evaluated against Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa. Compound 3 showed activity against S. aureus and B. subtilis with MIC values of 12.5 and 3.125 μg/mL, respectively.     

Isolation and biological activities of an endophytic Mortierella alpina strain from the Antarctic moss Schistidium antarctici

The Antarctic endophytic fungus (strain ITA1-CCMA 952) was isolated from the moss Schistidium antarctici found in Admiralty Bay, King George Island, Antarctica. Strain ITA1-CCMA 952 was assigned to the specie Mortierella alpina by phylogenetic analysis based on 18S rRNA gene sequences. This strain produces high levels of polyunsaturated fatty acids (PUFAs), including y-(gamma) linolenic acid and arachidonic acid, which when combined represents 48.3 % of the total fatty acid content. Fungal extracts demonstrated strong antioxidant activity with the EC₅₀ value of 48.7 μg mL^?1 and also a strong antibacterial activity, mainly against the following bacteria: Escherichia coli, with a MIC of 26.9 μg mL^?1 and Pseudomonas aeruginosa and Enterococcus faecalis, both with a MIC of 107 μg mL^?1. A GC–MS analysis of the chloroform fraction obtained from the crude extract revealed the presence of potential antimicrobials (Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) and Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(phenylmethyl)) as the major compounds. Therefore, the M. alpina strain ITA1-CCMA 952 is a promising fungus for the biotechnological production of antibiotics, antioxidant substances and PUFAs. This study highlights the need for more research in extreme environments, such as Antarctica.     

Antifungal and high-performance liquid chromatography analysis of the crude extracts of Acorus calamus,Tinospora cordifolia and Celestrus paniculatus

The antifungal activity of methanolic crude extracts of Acorus calamus, Tinospora cordifolia and Celestrus paniculatus was investigated against Alternaria solani, Curvularia lunata, Fusarium sp., Bipolaris sp. and Helminthosporium sp. at different concentrations (1000, 2000, 3000, 4000 and 5000 μg/ml). At 5000 μg/ml, crude extract of T. cordifolia is found to be highly effective against Helminthosporium sp. followed by A. calamus against A. solani. On the other hand, at 5000 μg/ml, C. paniculatus showed better activity against A. solani and Helminthosporium followed by A. calamus against A. solani at 4000 μg/ml. At 5000 μg/ml, all the three crude extracts showed least activity against fungus C. lunata and Fusarium sp. except A. calamus that showed better activity against C. lunata. The increase in the production of phenolic acid in the extract can be correlated with the induction of resistance in treated plants against phytopathogenic fungi. High-performance liquid chromatography analysis of the crude extract of medicinal plants showed six different phenolic acids (benzoic acid, cinnamic acid, caffeic acid, ferulic acid, gallic acid and tannic acid) present in varying amounts. The results of the study provide scientific basis for the use of the plant extract in the future development as antioxidant, antibacterial, antifungal and anti-inflammatory agent.     

Inhibitory activity of bio-active compounds isolated from <Emphasis Type="Italic">Anadara granosa</Emphasis> in shrimp health management

The crude extract isolated from the visceral mass of Anadara granosa, an intertidal bivalve mollusc was tested for inhibitory activity against pathogenic bacteria of the shrimp and fish viz. Vibrio harveyi and Staphylococcus aureus respectively by agar well diffusion and contact bioautography methods. Maximum inhibitory activity was shown against V. harveyi by methanol and chloroform (9:1) extract. Twelve fractions (1–12) could be separated from the crude extract through column chromatography. Five out of twelve fractions (7, 8, 9, 10, and 11) showed antibacterial activity and they were further run on column chromatography for purity. The fraction no. 9 showed highest antibacterial activity among the five and was subjected to NMR for the proton, C₁₃ and H₁–H₁ correlation, IR and mass spectral analysis for structural elucidation. Structure of the compound isolated from fraction no: 9 was determined as 1-(((2Z, 4Z)-dodeca-2,4-dienoyl)oxy)-3-hydroxypropan-2-yl tetradecanoate.     

Molecular cloning and expression of ranalexin, a bioactive antimicrobial peptide from Rana catesbeiana in Escherichia coli and assessments of its biological activities

The coding sequence, which corresponds to the mature antimicrobial peptide ranalexin from the frog Rana catesbeiana, was chemically synthesized with preferred codons for expression in Escherichia coli. It was cloned into the vector pET32c (+) to express a thioredoxin-ranalexin fusion protein which was produced in soluble form in E. coli BL21 (DE3) induced under optimized conditions. After two purification steps through affinity chromatography, about 1 mg of the recombinant ranalexin was obtained from 1 L of culture. Mass spectrometrical analysis of the purified recombinant ranalexin demonstrated its identity with ranalexin. The purified recombinant ranalexin is biologically active. It showed antibacterial activities similar to those of the native peptide against Staphylococcus aureus, Streptococcus pyogenes, E. coli, and multidrug-resistant strains of S. aureus with minimum inhibitory concentration values between 8 and 128 μg/ml. The recombinant ranalexin is also cytotoxic in HeLa and COS7 human cancer cells (IC₅₀?=?13–15 μg/ml).     

Novel 3-fluoro-6-methoxyquinoline derivatives as inhibitors of bacterial DNA gyrase and topoisomerase IV

Novel (non-fluoroquinolone) inhibitors of bacterial type II topoisomerases (NBTIs) are an emerging class of antibacterial agents. We report an optimized series of cyclobutylaryl-substituted NBTIs. Compound 14 demonstrated excellent activity both in vitro (S. aureus MIC₉₀ = 0.125 μg/mL) and in vivo (systemic and tissue infections). Enhanced inhibition of Topoisomerase IV correlated with improved activity in S. aureus strains with mutations conferring resistance to NBTIs. Compound 14 also displayed an improved hERG IC₅₀ of 85.9 μM and a favorable profile in the anesthetized guinea pig model.     

Antifouling potential of the marine microalga Dunaliella salina

Marine organisms have usually been viewed as sources of environmentally friendly compounds with antifouling activity. We performed a series of operations to investigate the antifouling potential of the marine microalga Dunaliella salina. For the ethyl acetate crude extract, the antialgal activity was significant, and the EC₅₀ value against Skeletonema costatum was 58.9 μg ml^?1. The isolated purified extract was tested for antifouling activity, the EC ₅₀ value against S. costatum was 21.2 μg ml^?1, and the LC₅₀ against Balanus amphitrite larvae was 18.8 μg ml^?1. Subsequently, both UHR–TOF–MS and GC–MS were used for the structural elucidation of the compounds, and a series of unsaturated and saturated 16- and 18-carbon fatty acids were detected. The data suggested that the fatty acid extracts from D. salina possess high antifouling activity, and could be used as substitutes for potent, toxic antifouling compounds.     

The Phenolic Contents and Antimicrobial Activities of Some Marine Algae from the Mediterranean Sea (Algeria)

In this study, three marine algae collected from western coast of algerian mediteranean sea (Ulva lactuca, Dictyota dichotoma, and Corallina elongata) were tested using the agar-well diffusion method for their production of antibacterial and antifungal agents on various organisms that cause diseases of humans and plants (Eschirichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Salmonella sp, Candida albicans, and Penicillium sp.). The total phenol content and antimicrobial activity were determined using different crude seaweeds extracts (methanol, diethylether, and chloroform). The results show that the chloroform extracts of (Ulva lactuca and Corallina elongata) had the highest activity against E. coli and Salmonella sp. The methanol extract obtained from (Ulva lactuca, Dictyota dichotoma, and Corallina elongata) showed antifungal activity for Candida albicans. The results of the study revealed that the seaweeds from Algeria appear to have immense potential as a source of antibacterial and antifungal compounds; they can be used in treating diseases caused by these organisms.     

In-vitro examination and isolation of antidiarrheal compounds using five bacterial strains from invasive species Bidens bipinnata L.

Bidens bipinnata is widely utilized medicinal plant for treatment of diseases like malaria, sore throat, acute nephritis and dysentery. However, despite its traditional uses Bidens bipinnata is not widely explored for its antimicrobial effect. Thus, the current study is aimed to form antimicrobial activity report of Bidens bipinnata extracts, along with isolation and evaluation of antibacterial activity of the isolated compounds through bioassay-guided purification. Hexane extract of its leaves has appeared to be most active thus it is exposed to automated column chromatography. Further purification using High-performance liquid chromatography has led to isolation of active peaks, identified by Gas Chromatography-mass spectrometry, as 16-Pregnenolone and 9-Octadecenoic acid (Z)-, methyl ester. Their antimicrobial activity was confirmed via broth dilution procedure on Staphylococcus aureus, 16-Pregnenolone revealed a strong antimicrobial activity with MIC₅₀ of 72 μg/mL whereas 9-Octadecenoic acid (Z)-, methyl ester display an MIC₅₀ of >250 μg/mL. Present study is the first report on isolation of these compounds from Bidens bipinnata.     

24-Branched Δ5 sterols from Laurencia papillosa red seaweed with antibacterial activity against human pathogenic bacteria

Methanol extract of thirty-eight seaweeds samples were first screened against Gram-positive (Staphylococcus aureus ATCC 25923 and Bacillus subtilis ATCC 6051) and -negative (Escherichia coli ATCC 8739 and Pseudomonas aerugenosa ATCC 9027) bacteria. Laurencia papillosa (Ceramiales, Rhodomelaceae, Rhodophyta) gave maximum antimicrobial activity against these bacteria. It was finally tested against four clinical Gram-negative isolates (E. coli, P. aerugenosa, Klebsiella pneumoniae and Shigella flexineri) and exhibited antibacterial activity. The extract was fractionated by column chromatography and the active fraction was identified as a cholesterol derivative, 24-propylidene cholest-5-en-3β-ol using gas chromatography mass spectrometry (GC–MS). The electrospray ionization mass spectrometry (ESI-MS) and FT-IR spectroscopic analysis also supported the structure of the compound. The minimum inhibitory concentration ranged from 1.2 to 1.7 μg/mL (IC₅₀) against clinical isolates. This is the first report of antibacterial activity of this cholesterol derivative. This compound could be exploited as potential lead molecule against broad spectrum drug development. The results also affirm the potential of seaweeds as an important natural source of antimicrobial compounds for pharmaceutical industries.     

Syntheses of benzophenone-xanthone hybrid polyketides and their antibacterial activities

Muchimangins are benzophenone-xanthone hybrid polyketides produced by Securidaca longepedunculata. However, their biological activities have not been fully investigated, since they are minor constituents in this plant. To evaluate the possibility of muchimangins as antibacterial agent candidates, five muchimangin analogs were synthesized from 2,4,5-trimethoxydiphenyl methanol and the corresponding xanthones, by utilizing p-toluenesulfonic acid monohydrate for the Brønsted acid-catalysis. The antibacterial assays against Gram-positive bacteria, Staphylococcus aureus and Bacillus subtilis, and Gram-negative bacteria, Klebsiella pneumoniae and Escherichia coli, revealed that the muchimangin analogs (±)-1,3,6,8-tetrahydroxy-4-(phenyl-(2′,4′,5′-trimethoxyphenyl)methyl)-xanthone (1), (±)-1,3,6-trihydroxy-4-(phenyl-(2′,4′,5′-trimethoxyphenyl)methyl)-xanthone (2), and (±)-1,3-dihydroxy-4-(phenyl-(2′,4′,5′-trimethoxyphenyl)methyl)-xanthone (3) showed significant activities against S. aureus, with MIC values of 10.0, 10.0, and 25.0 μM, respectively. Analogs (±)-1 and (±)-2 also exhibited antibacterial activities against B. subtilis, with MIC values of 50.0 and 12.5 μM, respectively. Furthermore, (+)-3 enhanced the antibacterial activity against S. aureus, with a MIC value of 10 μM.     

High expression of a plectasin-derived peptide NZ2114 in Pichia pastoris and its pharmacodynamics, postantibiotic and synergy against Staphylococcus aureus

NZ2114, a new variant of plectasin, was overexpressed in Pichia pastoris X-33 via pPICZαA for the first time. The total secreted protein of fermentation supernatant reached 2,390 mg/l (29 °C) and 2,310 mg/l (25 °C), and the recombinant NZ2114 (rNZ2114) reached 860 mg/l (29 °C) and 1,309 mg/l (25 °C) at 96 h induction in a 5-l fermentor, respectively.The rNZ2114 was purified by cation exchange chromatography, and its yield was 583 mg/l with 94.8 % purity. The minimal inhibitory concentration (MIC) of rNZ2114 to four ATCC strains of Staphyloccocus aureus was evaluated from 0.028 to 0.90 μM. Meanwhile, it showed potent activity (0.11–0.90 μM) to 20 clinical isolates of MRSA. The rNZ2114 killed over 99.9 % of tested S. aureus (ATCC 25923 and ATCC 43300) in Mueller-Hinton medium within 6 h when treated with 4?×?MIC. The postantibiotic effect of rNZ2114 to S. aureus ATCC 25923 and ATCC 43300 was 18.6–45.6 and 1.7–3.5 h under 1×, 2×, and 4× MIC, respectively. The fractional inhibitory concentration index (FICI) indicated a synergistic effect between rNZ2114 and kanamycin, streptomycin, and vancomycin against S. aureus ATCC 25923 (FICI?=?0.125), and additivity between rNZ2114 and ampicillin, spectinomycin (FICI?=?0.625), respectively. To S. aureus ATCC 43300 [methicillin-resistant S. aureus (MRSA)], rNZ2114 showed a synergistic effect (FICI?=?0.125–0.3125) with kanamycin, ampicillin, streptomycin, and vancomycin, and antagonism with spectinomycin (FICI?=?8.0625). The rNZ2114 caused only less than 0.1 % hemolytic activity in the concentration of 128 μg/ml, and showed a good thermostability from 20 to 80 °C. In addition, it exhibited the highest activity at pH 8.0. These results suggested that large-scale production of NZ2114 is feasible using the P. pastoris expression system, and it could be a new potential antimicrobial agent for the prevention and treatment of S. aureus especially for MRSA infections.