Source Of Antimicrobial Compounds Research Articles

Fungi from Brazilian Savannah and Atlantic rainforest show high antibacterial and antifungal activity

Brazilian biodiversity is among the biggest ones in the world, providing one of the major sources for bioprospection of new bioactive molecules. This study reports the isolation of new fungal strains from Brazilian biomes, aiming the biotechnological production of antimicrobial compounds against important microorganisms in the field of foodborne diseases, and difficult healing infections. First, 169 filamentous fungi were isolated from soil samples of Savannah and Atlantic Rainforest biomes in São Paulo State. The isolates were investigated about their inhibitory effect on the growth of five microorganisms (Bacillus cereus, Staphylococcus aureus subsp. aureus, Escherichia coli, Salmonella enterica subsp. enterica and Candida albicans), by microdillution assay. Around 93.5% of the isolates showed antimicrobial activity. Among them, 13% presented high activity and were evaluated about their minimal inhibitory concentration (MIC). Results revealed extracts with low MIC (0.31 mg mL−1) and with bactericidal and bacteriolytic activity. These fungi were identified as Trichoderma spp, Fusarium spp., Acremonium spp., Penicillium spp., and Paecilomyces spp. The Brazilian biomes presented themselves as interesting bioprospection spots of new sources of antimicrobial compounds, and this is the first report of antimicrobial potential of fungi from entire Atlantic rainforest or from this geographical area of Brazilian Savannah.

Enhancement of Calibrachoa growth, secondary metabolites and bioactivity using seaweed extracts.

BackgroundCalibrachoa x hybrida (Solanaceae) cultivars are widely used in North and South America as ornamental plants. Their potential as a source of antimicrobial compounds might be enhanced by seaweed extract (SWE) applications.MethodsSWE of Ascophyllum nodosum were applied at 5 and 7 ml/L as a soil drench or foliar spray on Calibrachoa cultivars of Superbells® ‘Dreamsicle’ (CHSD) and Superbells® ‘Frost Fireʼ (CHSF). The total phenolics, tannins and antioxidants composition as well as specific flavonols in leaf extracts were determined. Further, the chemical composition of SWE was assessed.ResultsThe drench and foliar SWE treatments significantly enhanced Calibrachoa cultivars leaf number and area, dry weight, plant height, antioxidant capacity as well as phenolic, flavonols and tannin content. The increased growth and composition of phenols, flavonols and tannins was attributed to the stimulatory effects of SWE mineral composition. The antifungal activity of Calibrachoa cultivars was significantly enhanced following SWE treatments and the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were in the range of 0.07–0.31 mg/ml and from 0.16 to 0.56 mg/ml, respectively. Moreover, antibacterial activity was significantly increased and the MIC and minimum bactericidal concentration (MBC) measurements were in the range of 0.06–0.23 mg/ml and from 0.10 to 0.44 mg/ml, respectively. The most sensitive fungus to SWE treatments was C. albicans and the most sensitive bacterium was E. cloacae.ConclusionThe results suggest that enhanced antifungal and antibacterial activities might be attributed to significant increases of phenolic, flavonols and tannin contents, which ultimately enhance the potential of Calibrachoa as a natural source of alternative antibiotics.

Secondary metabolites, letalithy and antimicrobial activity of six marine sponges from Mochima Bay, Sucre state, Venezuela.

he specimens of the sponges Aplysina lacunosa, Aplysina fulva, Cliona varians, Cinachyrella kuekenthali, Amphimedon viridis and Aaptos pernucleata, were collected in Mochima Bay, Venezuela, in October 2009 with the purpose of identifying families of secondary metabolites and evaluating the antibacterial properties, antifungal and brine shrimp lethal study of the ethyl acetate soluble fractions of these sponges. The chemical evaluation showed the presence of alkaloids, sterols, triterpenes, methylene ketone and tannins. The ethyl acetate soluble fractions of A. pernucleata, A. fulva and A. lacunosa sponges were the only ones that showed antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli; the soluble fraction of A. lacunosa showed the highest inhibition zones. The antifungal activity was not significant, except for A. pernucleata sponge wich showed mild activity against Candida albicans. The most prominent lethal activity in Artemia salina, were observed for C. kuekenthali, A. viridis and A. pernucleata sponges, with LC50 values of 4,10, 1,13 and < 0,01µg/mL respectively. These results allow profiling the sponges A. lacunosa, A. pernucleata and A. fulva as promising sources of antimicrobial compounds and the sponges C. kuekenthali, A. viridis and A. pernucleata as sources of antitumor compounds.

CHEMICAL CHARACTERIZATION AND EVALUATION OF ANTIBACTERIAL, ANTIFUNGAL, ANTIMYCOBACTERIAL, AND CYTOTOXIC ACTIVITIES OF Talinum paniculatum.

SUMMARYIn this study, the bioactivity of Talinum paniculatum was evaluated, a plant widely used in folk medicine. The extract from the T. paniculatum leaves (LE) was obtained by percolation with ethanol-water and then subjecting it to liquid-liquid partitions, yielding hexane (HX), ethyl acetate (EtOAc), butanol (BuOH), and aqueous (Aq) fractions. Screening for antimicrobial activity of the LE and its fractions was evaluated in vitro through broth microdilution method, against thirteen pathogenic and non-pathogenic microorganisms, and the antimycobacterial activity was performed through agar diffusion assay. The cytotoxic concentrations (CC90) for LE, HX, and EtOAc were obtained on BHK-21 cells by using MTT reduction assay. The LE showed activity against Serratia marcescens and Staphylococcus aureus, with Minimum Inhibitory Concentration (MIC) values of 250 and 500 µg/mL, respectively. Furthermore, HX demonstrated outstanding activity against Micrococcus luteusand Candida albicans with a MIC of 31.2 µg/mL in both cases. The MIC for EtOAc also was 31.2 µg/mL against Escherichia coli. Conversely, BuOH and Aq were inactive against all tested microorganisms and LE proved inactive against Mycobacterium tuberculosis and Mycobacterium bovis as well. Campesterol, stigmasterol, and sitosterol were the proposed structures as main compounds present in the EF and HX/EtOAc fractions, evidenced by mass spectrometry. Therefore, LE, HX, and EtOAc from T. paniculatum showed potential as possible sources of antimicrobial compounds, mainly HX, for presenting low toxicity on BHK-21 cells with excellent Selectivity Index (SI = CC90/MIC) of 17.72 against C. albicans.

Chemical composition and antimicrobial activity of hexane leaf extract of Anisopus mannii (Asclepiadaceae).

Objective:The aim was to determine the chemical constituents and antimicrobial activity of the hexane leaf extract of Anisopus mannii against a wide range of human pathogenic microorganisms.Methods:The chemical constituents of the hexane leaf extract was determined using gas chromatography-mass spectrometry (GC-MS) analysis; and the antimicrobial activity was evaluated on “standard strains”, clinical susceptible and resistant bacterial and fungal isolates using the disc diffusion and broth microdilution methods.Results:GC-MS analysis of the hexane leaf extract revealed 32 compounds, representing 73.8% of the identified components. The major compounds were hexadecanoic acid, ethyl ester (34%), oxirane, hexadecyl- (11%) and 9, 12, 15-octadecatrienoic acid, ethyl ester, (Z, Z, Z) (9.6%). Results from the antimicrobial activity demonstrated higher inhibition zones against Bacillus cereus (29 mm), followed by Streptococcus pyogenes (28 mm). Other notable inhibitions were observed with Enterococcus faecalis (27 mm), Proteus vulgaris (26 mm) and MRSA (25 mm). The MIC values ranged from 0.625 mg/mL to 1.25 mg/mL while the MBC/MFC values ranged from 2.5 mg/mL to 5.0 mg/mL.Conclusion:These results support the traditional use of the plant and demonstrate the huge potential of A. mannii as a source of antimicrobial compounds.

Antimicrobial compounds from Magnolia liliflora Desr.

Introduction: Natural products from plants and other biological sources remain an important source of new pharmaceuticals. Magnolia liliflora Desr. is distributed in many parts of East Asia and North America, and is often used as a traditional Chinese medicine to treat allergic rhinitis, sinusitis and headache. Some biological activities against foodborne pathogenic bacteria and chemical composition of M. liliflora from South Korea have been investigated previously. Objectives: To determine the antimicrobial activity and chemical composition of the essential oil from M. liliflora from China. Materials and methods: Pulverized dried flowering buds (10g) of M. liliflora purchased from a registered herbs pharmacy in China were extracted by hydrodistillation with deionized water. The aqueous distillates were extracted with hexane five times. The hexane fractions were combined, dried over anhydrous sodium sulphate and evaporated using vacuum rotary evaporator below 40°C to yield the essential oil. Gas chromatography– mass spectrometry (GC– MS) was used to identify the composition of essential oil. The GC– MS system consisted of an Agilent 7890A gas chromatograph system coupled to a Agilent MS model 5975C MSD (Agilent Technologies, Santa Clara, CA, USA) with a triple-axis detector. The analysis was carried out in triplicate. Minimum inhibitory concentration (MIC) of M. liliflora oil against Staphylococcus epidermidis and Escherichia coli was determined using microplate Alamar blue assay. Ampicillin was used as positive control. Results: Fifteen compounds from M. liliflora oil were identified by GC– MS. The main compounds are eucalyptol (11.98±0.17%), caryophyllene (2.62±0.04%), gamma-terpinene (3.30±0.08%) and (E)-beta-farnesene (23.9±0.36%). MICs of the M. liliflora oil against S. epidermidis and E. coli were determined as 1.024mg/ml and 2.048mg/ml (n =4), respectively. Ampicillin as positive control showed MIC ≤ 0.0005mg/ml on both bacterial isolates. Conclusions: M. liliflora oil could be an important source of antimicrobial compounds. Acknowledgements: We would like to thank Dr Paul Horrocks for assistance with Alamar blue assay.

Antimicrobial activities of Alstonia boonei stem bark, a Nigerian traditional medicinal plant

ObjectiveTo determine the in vitro antimicrobial activities of various solvent extracts of stem bark of Alstonia boonei, a Nigerian traditional medicinal plant against some microorganisms of food and clinical importance. MethodsThe antimicrobial activities of crude solvent extracts of stem bark were determined using well in agar diffusion method against Escherichia coli (E. coli), Staphylococcus aureus, Salmonella typhi, Pseudomonas aeruginosa, Saccharomyces cerevisiae and Kluyveromyces sp. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration were determined to establish the antimicrobial potential of extracts. ResultsThe antimicrobial results revealed that ethanol extract produced maximum zone of inhibition (23.73 mm) against E. coli. All the extracts had no inhibitory activity on Salmonella typhi and Pseudomonas aeruginosa at the lowest concentration tested (3.2 mg/mL). MIC was determined at various concentrations and the least MIC (5.8 mg/mL) was produced by the crude ethanol extract on E. coli, while the least minimum bactericidal concentration (20 mg/mL) was also produced by the ethanol extract on E. coli. Ethanol and chloroform extracts had the highest and least inhibitory effects on the isolates, respectively. ConclusionsThe present study has revealed that the solvent extracts of Alstonia boonei stem bark possess potent antimicrobial activity that can be harnessed. It may also be a new source of antimicrobial compounds that could be used to combat drug resistance which has become a global challenge.

Decontamination of Tomato, Red Cabbage, Carrot, Fresh Parsley and Fresh Green Onion Inoculated with Shigella sonnei and Shigella flexneri by Some Essential Oils (in vitro Conditions)

Background: Essential oils and their major constituents are useful sources of antimicrobial compounds. There are a few reports on the decontamination and antimicrobial activity of essential oils towards Shigella spp. M aterials and Methods: In this study, the antimicrobial and decontamination potentials of essential oils at different concentrations, belonging to plants such as Thymus vulgaris, Saturiea hortensis, Mentha polegium, Cuminum cyminum, Lavandula officinalis and Mentha viridis L. (spearmint), towards Shigella sonnei and Shigella flexneri were investigated. The disk diffusion method demonstrated the antimicrobial potential of the essential oils. R es ults: The ability of essential oils to decontaminate vegetables such as, tomato, red cabbage, carrot, fresh parsley and fresh green onion that were previously inoculated with Shigella spp. was determined. Inhibitory effects of essential oils towards Shigella spp. were noted in the disk diffusion method. There was a reduction in Shigella population following inoculation of cultures with 0.5% and 0.1% (v/v) essential oils. Conclusion: This study confirmed that essential oils have the potential to be used for decontamination of vegetables.

Novel antimicrobial activity of a dichloromethane extract obtained from red seaweed Ceramium rubrum (Hudson) (Rhodophyta: Florideophyceae) against Yersinia ruckeri and Saprolegnia parasitica, agents that cause diseases in salmonids

article i nfo Background: Enteric red mouth disease and Saprolegniasis, which are caused by the bacteria Yersinia ruckeri and the oomycete Saprolegnia parasitica, respectively, are important illnesses that affect salmonid farming. Sanitary problems in farms are addressed by the prevention of disease outbreaks or by the treatment of diseases with chemicals. Environmental and governmental restrictions, toxicity and high treatment costs limit the use of drugs. Marine organisms, such as algae, sponges and corals, have developed an antimicrobial defense strategy based on the production of bioactive metabolites. Among these organisms, seaweeds offer a particularly rich source of potential new drugs. Hence, many pharmacologically active substances have been isolated from seaweeds. In the Ceramium genus, Ceramium rubrum has been emphasized by several authors for its antimicrobial properties. Based on this background, the present study focused on the antimicrobial activity of a lipophilic extract of C. rubrum on Y. ruckeri and S. parasitica. Results: The alga, collected from the Pacific coast of Chile, underwent an ethanol extraction, and the concentrated extract was partitioned between water and dichloromethane. From the dichloromethane extract, fatty acids, fatty acid esters, one hydrocarbon and phytol were identified by Gas Chromatography-Mass Spectrometry (GC/MS) analysis. The antimicrobial study showed that the whole extract was more active than the individual components, which suggests a strong synergistic effect among the components. Conclusions: These results may constitute a basis for promising future applied research that could investigate the use of C. rubrum seaweed as a source of antimicrobial compounds against fish pathogens.

Cell-Free Supernatants Obtained from Fermentation of Cheese Whey Hydrolyzates and Phenylpyruvic Acid by Lactobacillus plantarum as a Source of Antimicrobial Compounds, Bacteriocins, and Natural Aromas

Cheese whey hydrolyzates supplemented with phenylpyruvic acid (PPA) and commercial nutrients can be efficiently metabolized by Lactobacillus plantarum CECT-221 to biosynthesize some compounds with attractive applications in the food market. The main metabolites of cell-free extracts were antimicrobial compounds such as phenyllactic acid (PLA) and lactic acid (LA). The production of PLA by L. plantarum CECT-221 was evaluated in the Man-Rogosa-Sharpe broth supplemented with two biosynthetic precursors: phenylalanine or PPA. Using 30.5 mM PPA, the microorganism increased sevenfold the concentration of PLA producing 16.4 mM PLA in 46 h. A concentration of 40 mM PPA was a threshold to avoid substrate inhibition. The biosynthesis of whey hydrolyzates as a carbon source was enhanced by fed-batch fermentation of PPA; the average productivity of PLA increased up to 45.4 ± 3.02 mM after 120 h with a product yield of 0.244 mM mM(-1); meanwhile, LA reached 26.1 ± 1.3 g L(-1) with a product yield of 0.72 g g(-1). Cell-free fed-batch extracts charged in wells showed bacteriocin activity with halos of 7.49 ± 1.44 mm in plates inoculated with Carnobacterium piscicola and antimicrobial activity against Staphylococcus aureus (11.54 ± 1.14 mm), Pseudomonas aeruginosa (10.17 ± 2.46 mm), Listeria monocytogenes (7.75 ± 1.31 mm), and Salmonella enterica (3.60 ± 1.52 mm). Additionally, the analysis of the volatile composition of the headspace of this cell-free extract revealed that L. plantarum is a potential producer for natural aromas, such as acetophenone, with high price in the market. This is the first report of PLA production from cheese whey and PPA. The extracts showed bacteriocin activity and potential to be applied as an antimicrobial in the elaboration of safer foods.

English

  The seaweed (Halimeda tuna) was examined for antibacterial and antifungal activity in vitro using the well diffusion method, minimum inhibitory concentration, minimum bactericidal concentration and minimum fungicidal concentration. The activity was against 10 bacterial strains (Staphylococcus aureus, Salmonella typhimurium, Salmonella paratyphi, Klebsiella oxytoca, Escherichia coli, Proteus mirabillis, Lactobacillus vulgaris, Pseudomonas sp., Klebsiella pneumonia and Vibrio cholerae)and nine fungal strains (Aspergillus niger, Aspergillus flavus, Alternaria alternaria, Candida albicans, Epidermophyton floccossum, Trichophyton mentagrophytes, Trichophyton rubrum, Pencillium sp. and Rhizopus sp.). The methanolic extracts in the present study exhibited a broad spectrum of antimicrobial activity compared to the ethanolic and chloroform extracts. Results of the present study confirm the potential use of seaweed extracts as a source of antimicrobial compound.   Key words: Halimeda tuna, minimum inhibitory concentration, minimum bactericidal concentration, minimum fungicidal concentration, antimicrobial activity.

Cranberry leaves (Vaccinium macrocarpon) as a source of antimicrobial metabolites

Secondary metabolites from the leaves of North American cranberry (Vaccinium macrocarpon) are under investigation for structure and inhibitory activity against bacterial biofilm formation and cancer cell growth. Compounds were separated by column chromatography using various stationary phases, and characterized by MS and NMR. In addition to several quercetin glycosides, proanthocyanidin subfractions ranging in oligomer size from dimer to octamers, were isolated from the aqueous extracts and characterized by MALDI-TOF MS. Cranberry leaf PACs inhibited biofilm formation by Staphylococcus aureus (MBIC=1.5–3.1µg/mL) as well as the growth of several Candida species and HeLa cells. The quercetin glycosides also inhibited S. aureus biofilms (MBIC=25µg/mL). Constituents of the nonpolar extracts include β-sitosterol and ursolic acid derivatives to be identified. Cranberry leaves may be a useful source of antimicrobial compounds.

Antimicrobial and hemolytic activity of seaweed extracts Ulva fasciata (Delile 1813) from Mandapam, Southeast coast of India

Objective To evaluate the In vitro antimicrobial and hemolytic activity of marine macroalgae Ulva fasciata (U. fasciata) collected from Mandapam coastal waters, and to identify certain seaweed extracts that can act as an alternative of commonly used antibiotics. Methods Seaweeds U. fasciata was collected from Gulf of Mannar, Southeast Coastal Region, Mandapam, Tamil Nadu and was screened for antimicrobial and hemolytic activity. Methanol, butanol and aqueous extracts were tested against selected fish pathogens, Aeromonas hydrophila, Pseudomonas fluorescens, Proteus sp. Vibrio alginolyticus (V. alginolyticus) and Enterobacter sp. and fungal pathogens Rhizopus sp., Aspergillus flavus, Aspergillus sp., Aspergillus niger and Candida sp. The extract was subjected to TLC to determine the presences of peptides and amide groups. And the hemolytic activity was assayed. Results Maximum of 16 mm inhibition zone was observed against V. alginolyticus and the minimum 12 mm against Enterobacter sp., respectively. U. fasciata showed poor activity against the fungal pathogens. The present results showed the use of seaweeds as an antimicrobial agents for pharmacology or as a health-promoting food for aquaculture. Conclusions The screening result confirms that these seaweeds can be further studied and used as possible source of antimicrobial compounds.

The characterisation of bioactive compounds from an Egyptian Leptolyngbya sp. strain

An investigation into the bioactive metabolites from a benthic, mat-forming strain dominating a polluted wastewater canal in Egypt was conducted. Phytochemical screening revealed the presence of saponins, flavonoids and alkaloids; vitamin C was also found at high concentrations. The isolate was investigated as a source of antimicrobial compounds. The lipophilic fraction was extracted using chloroform/methanol and bioassays for antimicrobial compounds were performed using strains of pathogenic bacteria. The fraction that showed the highest bioactivity was purified and its structure elucidated using UV, FTIR, proton-NMR and GC-MS. The compound’s molecular weight was 220 and it was identified as butylated hydroxytoluene which has both antimicrobial and antioxidant activities. On the ecological front, this compound, and the other metabolites detected, seem to enable the isolate to dominate its niche and protect it from adverse conditions. On the commercial front, this compound is used as a food additive and was recently discovered in different cyanobacteria, and can be used as a lead compound for both drug and food industries to substitute for the expensive and hazardous synthetic analogs. Therefore, this strain can be considered as a potential source of bioactive compounds that should be further explored.

The Sponge-associated Bacterium Bacillus licheniformis SAB1: A Source of Antimicrobial Compounds

Several bacterial cultures were isolated from sponge Halichondria sp., collected from the Gujarat coast of the Indo Pacific region. These bacterial cultures were fermented in the laboratory (100 mL) and the culture filtrate was assayed for antibiotic activity against 16 strains of clinical pathogens. Bacillus sp. (SAB1), the most potent of them and antagonistic to several clinically pathogenic Gram-positive, Gram-negative bacteria and the fungus Aspergillus fumigatus was chosen for further investigation. Analysis of the nucleotide sequence of the 16S rDNA gene of Bacillus sp. SAB1 showed a strong similarity (100%) with the 16S rDNA gene of Bacillus licheniformis HNL09. The bioactive compounds produced by Bacillus licheniformis SAB1 (GenBank accession number: DQ071568) were identified as indole (1), 3-phenylpropionic acid (2) and a dimer 4,4′-oxybis[3-phenylpropionic acid] (3) on the basis of their Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance (NMR) and Electrospray Ionization Mass Spectrometer (ESI-MS) data. There is a single reference on the natural occurrence of compound 3 from the leaves of a terrestrial herb Aptenia cordifolia in the literature, so to the best of our knowledge, this is a first report of its natural occurrence from a marine source. The recovery of bacterial strains with antimicrobial activity suggests that marine-invertebrates remain a rich source for the isolation of culturable isolates capable of producing novel bioactive secondary metabolites.

Screening of cultivated seaweeds for antibacterial activity against fish pathogenic bacteria

Because of the evolving resistance of microorganisms to existing antibiotics, there is an increasing need for new antibiotics not only in human but also in veterinary medicine. Competition for space and nutrients led to the evolution of antimicrobial defence strategies in the aquatic environment. Therefore, aquatic organisms, e.g., seaweeds, offer a particularly rich source of potential new drugs. The aim of our studies was to identify seaweeds, which possess activities against fish pathogenic bacteria and could be an alternative to the commonly used antibiotics in aquaculture. Dichloromethane, methanole and water extracts of 26 species of cultivated seaweeds were screened for their antibacterial activities against five fish pathogenic bacteria strains ( Aeromonas salmonicida ssp. salmonicida, Aeromonas hydrophila ssp. hydrophila, Pseudomonas anguilliseptica, Vibrio anguillarum, Yersinia ruckeri). The dichloromethane extracts of Asparagopsis armata, Ceramium rubrum, Drachiella minuta, Falkenbergia rufolanosa, Gracilaria cornea and Halopitys incurvus showed strong antibacterial activities. V. anguillarum and P. anguilliseptica were the two most susceptible bacteria strains. The screening results confirm the possible use of seaweeds as a source of antimicrobial compounds or as a health-promoting food for aquaculture.