Efficacy of nisin A and nisin V semi-purified preparations alone and in combination with plant essential oils to control Listeria monocytogenes

peer-reviewedThe foodborne pathogenic bacterium Listeria is known for relatively low morbidity and high mortality rates reaching up to 25-30%. Listeria is a hardy organism and its control in foods represents a significant challenge. Many naturally occurring compounds, including the bacteriocin nisin and a number of plant essential oils, have been widely studied and are reported to be effective as antimicrobial agents against spoilage and pathogenic microorganisms. The aim of this study was to investigate the ability of semi-purified preparations (spp) containing either nisin A or an enhanced bioengineered derivative nisin V, alone and in combination with low concentrations of the essential oils thymol, carvacrol and trans-cinnamaldehyde, to control L. monocytogenes in both laboratory media and model food systems. Combinations of nisin V-containing spp (25 μg/ml) with thymol (0.02%), carvacrol (0.02%) or cinnamaldehyde (0.02%) produced a significantly longer lag phase than any of the essential oil/nisin A combinations. In addition, the log reduction in cell counts achieved by the nisin V + carvacrol or nisin V + cinnamaldehyde combinations was twice that of the equivalent nisin A + essential oil treatment. Significantly, this enhanced activity was validated in model food systems against L. monocytogenes strains of food origin. We conclude that the fermentate form of nisin V in combination with carvacrol and cinnamaldehyde offers significant advantages as a novel, natural and effective means to enhance food safety by inhibiting foodborne pathogens such as L. monocytogenes.This work was supported by the Irish Government under the National Development Plan, through Science Foundation Ireland Investigator awards to C.H. and R.P.R. (10/IN.1/B3027), and C.H., R.P.R. and P.D.C. (06/IN.1/B98)

Repellent, irritant and toxic effects of plant EO compounds on the malaria vector Anopheles gambiae ss Giles

yrethroids resistance has become widespread among malaria vector Anopheles gambiae populations in Africa. Alternative insecticides must be considered to prevent diseases transmission by An. gambiae bites. The long lasted treated bed nets are particularly efficient to prevent blood meals on humans and thus to reduce the risks of transmissions. Previous studies have identified plant essential oils (EO) as a potential alternative to pyrethroids. Four of them showed significant repellent, irritant and/or toxic effects against An. gambiae. The objective of this study was to evaluate the repellent, irritant and toxic actions of the major compounds of these four EO from citronella (Cymbopogon winterianus), cinnamon (Cinnamomum zeylanicum), cumin (Cuminum cyminum) and thyme (Thymus vulgaris), against females An. gambiae. We tested the spatial repellency, the contact irritancy and the toxicity effects of each product with laboratory tests over 180 females, for each action tested. The complete EO, the mixture of the major compounds (>3%) and the two currently used repellent (DEET) and insecticide (Permethrin) were also tested. The most promising compounds were similarly tested with two strains of An. gambiae: resistant to pyrethroids (KdrKis) and resistant to carbamates (AcerKis). At last assays in tunnels to simulate field conditions were made to determine their efficacy when a blood meal was offered. Carvacrol, geraniol, cuminaldehyde and cinnamaldehyde showed the best repellent and irritant effects among all products tested. Cuminaldehyde and cinnamaldehyde revealed to be more efficient against the resistant strains than the susceptible strain of An. gambiae, and with carvacrol, they were particularly efficient to inhibit blood meals in simulated field conditions. The study also showed interested characteristics of plant EO which led to new research directions to use plant EO for biological control. At last this study was the first to test the efficiency of DEET on resistant An. gambiae strains. (Résumé d'auteur

High concentrations of flavor chemicals are present in electronic cigarette refill fluids.

We characterized the flavor chemicals in a broad sample of commercially available electronic cigarette (EC) refill fluids that were purchased in four different countries. Flavor chemicals in 277 refill fluids were identified and quantified by gas chromatography-mass spectrometry, and two commonly used flavor chemicals were tested for cytotoxicity with the MTT assay using human lung fibroblasts and epithelial cells. About 85% of the refill fluids had total flavor concentrations >1 mg/ml, and 37% were >10 mg/ml (1% by weight). Of the 155 flavor chemicals identified in the 277 refill fluids, 50 were present at ≥1 mg/ml in at least one sample and 11 were ≥10 mg/ml in 54 of the refill fluids. Sixty-one% (170 out of 277) of the samples contained nicotine, and of these, 56% had a total flavor chemical/nicotine ratio >2. Four chemicals were present in 50% (menthol, triacetin, and cinnamaldehyde) to 80% (ethyl maltol) of the samples. Some products had concentrations of menthol ("Menthol Arctic") and ethyl maltol ("No. 64") that were 30 times (menthol) and 100 times (ethyl maltol) their cytotoxic concentration. One refill fluid contained cinnamaldehyde at ~34% (343 mg/ml), more than 100,000 times its cytotoxic level. High concentrations of some flavor chemicals in EC refill fluids are potentially harmful to users, and continued absence of any regulations regarding flavor chemicals in EC fluids will likely be detrimental to human health

Effect of carrot puree edible films on quality preservation of fresh-cut carrots

peer-reviewedFinancial support from the high level talent fund of Henan University of Technology Science and Technology (No. 2012BS024) is gratefully acknowledged.The effect of edible films based on carrot puree, chitosan, corn starch, gelatin, glycerol and cinnamaldehyde on fresh-cut carrots was studied during storage. Several parameters, such as firmness, colour, weight loss, total carotenoids, total phenols, polyphenol oxidase (PPO) activity and peroxidase (POD) activity in coated carrots were determined at regular intervals and then compared with the uncoated carrots throughout the storage period. Significant and expected changes were observed in all carrot samples that were compared. The coating treatment significantly (P < 0.05) delayed the senescence, reduced the deterioration of exterior quality and retained total carotenoids well compared with control (P < 0.05). In addition, significant inhibition of PPO activity (P < 0.05) and POD activity (P < 0.05) as well as reduced accumulation of polyphenols (P < 0.05) were observed for all coated samples. All of these favourable responses induced by coating treatment on minimally processed fresh-cut carrots showed beneficial physiological effects, which would give some useful references to the fresh-cut fruit and vegetable processing industry and satisfy people’s requirements allowing for extending product shelf life without negatively affecting the sensory quality or acceptability.Henan University of Technology Science and Technolog

Self-assembly of Tween 80 micelles as nanocargos for oregano and trans-cinnamaldehyde plant-derived compounds

The self-assembly of Tween 80 (T80) micelles loaded with plant-based oregano essential oil (OR) and trans-cinnamaldehyde (TCA) was studied. The effect of different factors, including the surfactant to oil ratio, the presence of sodium chloride, thermal treatment, and dilution on their formation and physicochemical stability was evaluated. The creation of nano-cargos was confirmed by TEM. The self-associated structures had z-average droplet diameters of 92 to 337 nm without any energy input. Whereas addition of 10% (w/v) NaCl prevented the formation of oregano essential oil nano-assemblies of T80, swollen micelles containing TCA were successfully produced. Moreover, the OR or TCA loaded-micelles had only a slight droplet size variation upon thermal treatment. Ultimately, their antibacterial activity analysis against some food pathogens revealed that the encapsulation of OR and TCA within micelles crucially improved their antibacterial activity. These straightforward and cost-effective designed systems can be applicable in different products, including foods and agrochemicals

α-Hexylcinnamaldehyde synergistically increases doxorubicin cytotoxicity towards human cancer cell lines

α-Hexylcinnamaldehyde (HCA), a compound derived from cinnamaldehyde, was evaluated for its potential chemosensitizing properties

Repellent, irritant and toxic effects of essential oil constituents on Bemisia tabaci (Gennadius)

Whiteflies, Bemisia tabaci, are a widespread pest in agriculture, causing crop loss up to 100% by direct and indirect damage. Controlling this pest has proven difficult due to the fact that they stay underside the leaves and their ability to become resistant to conventional pesticides rapidly. Also, environmental and health concerns associated with the use of synthetic pesticides are rising. Therefore, new methods should be investigated to protect crops from B. tabaci. Insect proof nets (IPNs) create a physical barrier between the crop and a pest insect, but this alone is not suitable against small insects like B. tabaci. A possible solution is combining insect proof nets (IPN) with a naturally occurring repellent. Essential oils, mixtures of volatile secondary metabolites of plants, have been shown to have repellent and toxic abilities against many pest insects, including whiteflies. This study investigates the role of the different compounds in four essential oils; Cumin (Cuminum cyminum), Cinnamon (Cinnalonum zeylanicum), Lemongrass (Cymbopogon citratus) and Citronella grass (Cymbopogon winterianus), to see if the constituents are toxic, repellent or irritant. This is also used as a screening for compounds that seem promising to be used in combination with IPNs in the field. This should be a highly repellent, but not very toxic compound, to repel B. tabaci but with a reduced risk of the fast development of resistance. In this study I found that most constituents of essential oils have one dominant role (i.e. they are for example toxic or repellent but not both) and the effects of these different compounds combined add up in the mixture of the essential oil. As for the essential oil of citronella grass, this oil is less toxic than some of its individual compounds, suggesting interactions between the compounds when mixed. The most promising compounds to be used against B. tabaci in the field, based on their high repellency and low toxicity, are cinnamaldehyde (repellent at &lt;0.084 mg/L and toxic at 8.4 mg/L) and linalool (repellent at 0.006 mg/L but with unknown toxicity). (Résumé d'auteur

Anti Quorum Sensing Activity of Kayu Manis Leaves Extracts (Cinnamomun Burmannii Ness. Ex Bl.) Against Pseudomonas Aeruginosa

Quorum sensing is a communication system among bacterial cells which correlates with biofilm formation. Biofilm can protect bacteria from environment including antibiotic of which can cause higher antibiotic concentration of 100 up to 1000 times. Inhibition of quorum sensing is expected to inhibit the biofilm formation. The cinnamon bark (Cinnamomum burmanii Ness. Ex Bl.) has been known to have antibacterial and antibiofilm activities. Leaves are available abundantly which urges a research to find out the activity as anti quorum sensing against Pseudomonas aeruginosa. The succesive maceration of dried pulverized leaves produced hexane, ethyl acetate, and methanol extracts. Antibacterial activity was observed by microdillution method with MTT assay. Afterwards, the active extract was examined for anti quorum sensing activity by diffusion method in cetrimide Agar. Quorum sensing activity was shown by dark zone (opaque) growth around sample application, observed under UV light of 366 nm. TLC bioautography method was done to observe the active spots by using silica gel F254 as the stationary phase, chloroform-methanol (6:1 v/v) as the mobile phase, loading sample used was 1.25 mg and 30 min of plate contact duration. The ethyl acetate extract inhibited growth of P. aeruginosa with shown by MIC at 8 µg/µL Quorum sensing as well as growth inhibition activities were observed at loading samples 12,5 and 25 mg/wells, while at 6,25 mg the extract only exhibited quorum sensing inhibition. Presences of substances having phenolic, flavonoid, alkaloid and aldehyde/keton as functional groups were detected by TLC method of the extract but no active spot identified on bioautography

Phytochemicals as antibiotic alternatives to promote growth and enhance host health

There are heightened concerns globally on emerging drug-resistant superbugs and the lack of new antibiotics for treating human and animal diseases. For the agricultural industry, there is an urgent need to develop strategies to replace antibiotics for food-producing animals, especially poultry and livestock. The 2nd International Symposium on Alternatives to Antibiotics was held at the World Organization for Animal Health in Paris, France, December 12-15, 2016 to discuss recent scientific developments on strategic antibiotic-free management plans, to evaluate regional differences in policies regarding the reduction of antibiotics in animal agriculture and to develop antibiotic alternatives to combat the global increase in antibiotic resistance. More than 270 participants from academia, government research institutions, regulatory agencies, and private animal industries from >25 different countries came together to discuss recent research and promising novel technologies that could provide alternatives to antibiotics for use in animal health and production; assess challenges associated with their commercialization; and devise actionable strategies to facilitate the development of alternatives to antibiotic growth promoters (AGPs) without hampering animal production. The 3-day meeting consisted of four scientific sessions including vaccines, microbial products, phytochemicals, immune-related products, and innovative drugs, chemicals and enzymes, followed by the last session on regulation and funding. Each session was followed by an expert panel discussion that included industry representatives and session speakers. The session on phytochemicals included talks describing recent research achievements, with examples of successful agricultural use of various phytochemicals as antibiotic alternatives and their mode of action in major agricultural animals (poultry, swine and ruminants). Scientists from industry and academia and government research institutes shared their experience in developing and applying potential antibiotic-alternative phytochemicals commercially to reduce AGPs and to develop a sustainable animal production system in the absence of antibiotics.Fil: Lillehoj, Hyun. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Liu, Yanhong. University of California; Estados UnidosFil: Calsamiglia, Sergio. Universitat Autònoma de Barcelona; EspañaFil: Fernandez Miyakawa, Mariano Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; ArgentinaFil: Chi, Fang. Amlan International; Estados UnidosFil: Cravens, Ron L.. Amlan International; Estados UnidosFil: Oh, Sungtaek. United States Department of Agriculture. Agricultural Research Service; ArgentinaFil: Gay, Cyril G.. United States Department of Agriculture. Agricultural Research Service; Argentin

Sheep liver cytosolic aldehyde dehydrogenase : a fresh perspective : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University, New Zealand

The pre-steady-state mechanism of aldehyde dehydrogenase has been further investigated using synthesised deuterated 4-trans-(N,N-dimethylamino) cinnamaldehyde as a substrate. Reporter groups of the active site of ALDH have indicated the presence of a divalent or trivalent metal electrophile, shown in chapter 3 as being either Fe (II) or Fe (III) . Studies of the spectral properties of NADH bound to aldehyde dehydrogenase have revealed the presence of at least two spectrally different enzyme-NADH species. The consequences of this information are important in interpretation of the kinetic data and understanding apparently contradictory experimental results from different research workers. The steady-state kinetics of ALDH have been further investigated. A sensitive substrate for use in enzyme immunoassays has been designed and synthesised. The preliminary kinetic behaviour observed using this substrate has been studied with three enzymes. Aldehyde dehydrogenase has been used as a model system for studying the effects of electromagnetic radiation on biological systems