Effectiveness of fatty acids and their monoglycerides against gram-negative pathogens

Lipophilic Compounds and Antibacterial Activity of Opuntia ficus-indica Root Extracts from Algeria

The chemical composition, investigated by gas chromatography-mass spectrometry, and antibacterial activity of lipophilic extractives of three varieties of Opuntia ficus-indica roots from Algeria are reported in this paper for the first time. The results obtained revealed a total of 55 compounds, including fatty acids, sterols, monoglycerides and long chain aliphatic alcohols that were identified and quantified. β-Sitosterol was found as the major compound of the roots of the three varieties. Furthermore, considerable amounts of essential fatty acids (ω3, ω6, and ω9) such as oleic, linoleic, and linolenic acids were also identified. The green variety was the richest among the three studied varieties. The antibacterial activity, evaluated with disc diffusion method, revealed that lipophilic extracts were effective mainly against Gram-positive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) (19~23 mm). Gram-negative strains mainly Pseudomonas aeruginosa gave an inhibition zone of 18 mm, which is considered high antibacterial activity. The minimal inhibitory concentrations of the tested bacteria revealed interesting values against the majority of bacteria tested: 75–100 µg mL⁻¹ for Bacillus sp., 250–350 µg/mL for the two Staphylococcus strains, 550–600 µg mL⁻¹ for E. coli, and 750–950 µg mL⁻¹ obtained with Pseudomonas sp. This study allows us to conclude that the lipophilic fractions of cactus roots possess interesting phytochemicals such as steroids, some fatty acids and long chain alcohols that acted as antibiotic-like compounds countering pathogenic strains.

Fatty acid composition profiling in the dorsal skin of Sunda porcupine (Hystrix javanica)

The fatty acid composition in the skin of Sunda porcupine (Hystrix javanica) is an interesting topic due to the special features of quills, especially in the dorsal region. Therefore, this study aims to analyze the composition of fatty acids in the dorsal region of Sunda porcupine skin. It was conducted using skin samples of the thoracodorsal and lumbosacral regions taken by biopsies and from frozen specimens. The skin lipid was extracted and then derivatized into fatty acid methyl ester before analyzing with gas chromatography mass spectrometry. The results showed that the skin is composed of up to 25 fatty acids ranging from C12 to C25 with various types but only 16 were found in both regions and sexes. Fatty acids with an antibacterial effect were found abundantly, such as oleic, palmitic, stearic, and linoleic acids. The total abundance in the thoracodorsal region was higher than lumbosacral, while the composition in male was higher than in female. Based on the results, the fatty acid composition in the dorsal skin region of Sunda porcupine consists of at least 16 types ranging from C12-C25. Additionally, the region and sex were observed to contribute significantly to the variation in skin fatty acid composition.

Synergistic inactivation of Listeria and E. coli using a combination of erythorbyl laurate and mild heating and its application in decontamination of peas as a model fresh produce

We investigated the synergistic antimicrobial activity of erythorbyl laurate (EL) and mild heating co-treatment on the Gram-positive Listeria innocua and Gram-negative Escherichia coli O157:H7 bacteria. EL (2 mM) and mild heating (55 °C for 3 min) resulted in 3.1 and 0.5 log colony forming units (CFU)/mL reductions in the number of L. innocua, respectively, compared to a 6.4 log CFU/mL reduction induced by the combined treatment of EL and mild heating in saline. EL (10 mM) and mild heating (55 °C for 3 min) resulted in 1.3 and 0.7 log CFU/mL reductions in the number of E. coli O157:H7, respectively, compared to a 6.2 log CFU/mL reduction with the combined treatment in saline. EL, a membrane-active compound, showed a strong synergistic effect with mild heating, possibly due to enhanced disruption of the bacterial cell membrane. The synergistic antibacterial effect was evaluated using inoculated English peas (Pisum sativum) and this combined treatment (2 mM EL and mild heating against L. innocua and 10 mM EL and mild heating against E. coli O157:H7) resulted in more than 7 log reductions in the numbers of L. innocua and E. coli O157:H7, inoculated on the surface of fresh peas. The treatments did not show significant difference in the color or texture of treated peas compared to the non-treated controls. This is the first report illustrating synergistic activity of EL and mild heating for both the gram positive (L. innocua) and the gram negative (E. coli O157:H7) bacteria on food. Overall, this research will illustrate the development of more effective and rapid antibacterial surface disinfection method for application in the processing of minimally processed foods.

Antibacterial Filtration Membranes Based on PVDF-co-HFP Nanofibers with the Addition of Medium-Chain 1-Monoacylglycerols

The efficiency of filtration membranes is substantially lowered by bacterial attachments and potential fouling processes, which reduce their durability and lifecycle. The antibacterial and antifouling properties exhibited by the added materials play a substantial role in their application. We tested a material poly(vinylidene fluoride)-co-hexafluoropropylene (PDVF-co-HFP) based on an electrospun copolymer, where an agent was incorporated with a small amount of ester of glycerol consecutively with caprylic, capric, and lauric acids. Each of these three materials differing in the esters (1-monoacylglycerol, 1-MAG) used was prepared with three weighted concentrations of 1-MAG (1, 2, and 3 wt %). The presence of 1-MAG with an amphiphilic structure resulted in the hydrophilic character of the prepared materials that contributed to the filtration performance. The tested materials (membranes) were characterized with rheological, optical (scanning electron microscopy, SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and other methods to evaluate antibacterial and antifouling activities. The pure water flux was 6 times higher than that of the neat PVDF-co-HFP membrane when the added 1-MAG attained only 1 wt %. It was experimentally shown that the PVDF-co-HFP/1-MAG membrane with high wettability improved antibacterial activity and antifouling ability. This membrane is highly promising for water treatment due to the safety of antibacterial 1-MAG additives.

Synergistic Inactivation of Bacteria Using a Combination of Erythorbyl Laurate and UV Type-A Light Treatment

This study evaluated the synergistic antimicrobial activity of erythorbyl laurate (EL) and UV type-A (UVA). To investigate the mode of synergism, changes in gene expression and bacterial inactivation activity were examined. Individual treatments with EL (10 mM) or UVA caused a 1.9- or 0.5-log CFU/ml reduction respectively, whereas EL/UVA co-treatment resulted in a 5.5-log CFU/ml reduction in Escherichia coli viable cell numbers. Similarly, treatment with either EL (2 mM) or UVA for 30 min resulted in a 2.8- or 0.1-log CFU/ml reduction in Listeria innocua, respectively, whereas combined treatment with both EL and UVA resulted in a 5.4-log CFU/ml reduction. Measurements of gene expression levels showed that EL and UVA treatment synergistically altered the gene expression of genes related to bacterial membrane synthesis/stress response. However, addition of 10–50-fold excess concentration of exogenous antioxidant compared to EL reduced the synergistic effect of EL and UVA by approximately 1 log. In summary, the results illustrate that synergistic combination of EL and UVA enhanced membrane damage independent of the oxidative stress damage induced by UVA and thus illustrate a novel photo-activated synergistic antimicrobial approach for the inactivation of both the Gram-positive and Gram-negative bacteria. Overall, this study illustrates mechanistic evaluation of a novel photochemical approach for food and environmental applications.

Use of Medium Chain Fatty Acids To Mitigate Salmonella Typhimurium (ATCC 14028) on Dry Pet Food Kibbles

ABSTRACT

This study evaluated the antimicrobial effects of medium chain fatty acids (MCFAs) against Salmonella Typhimurium (ATCC 14028) when used on dry dog food kibbles. The MIC of three MCFAs, caproic (C6), caprylic (C8), and capric (C10), was determined using the broth micro- and macrodilution assay technique. Using canola oil as a fat coating, the efficacy of each MCFA was then tested on dry dog food kibbles at 37°C for up to 5 h. The MIC was found to be 0.3125, 0.3125, and 0.625% for C6, C8, and C10, respectively. When the MCFAs were tested on fat-coated dry kibbles, all three MCFAs reduced (P ≤ 0.05) Salmonella levels by >4.5 log after 5 h when the Salmonella recovery from a no-treatment control was ∼6.4 log. At each evaluation time point, the three treatments were effective in reducing (P ≤ 0.05) Salmonella loads. No countable colonies of Salmonella were detected at 4 h when the combination of C6+C8 was used on the kibbles (P ≤ 0.05), whereas with the C6+C10 combination, the Salmonella colonies were not detectable between 2 and 4 h after treatments (P ≤ 0.05). Different combinations of C8 and C10 caused Salmonella to drop to a nondetectable limit (1 CFU/g) between 1 and 5 h after treatment (P ≤ 0.05). This study suggests that the use of MCFAs during kibble coating may mitigate postprocessing Salmonella recontamination on dry dog food kibbles.

HIGHLIGHTS

Novel Polyvinyl Butyral/Monoacylglycerol Nanofibrous Membrane with Antifouling Activity

Monoacylglycerols (MAGs) have proven of great interest to the foodstuffs industry due to the promising antibacterial activity they show for controlling microbial contamination. Prior to this paper, this antibacterial agent had not been incorporated in a nanofibrous membrane. This study details convenient fabrication of nanofibrous membranes based on polyvinyl butyral (PVB) containing various concentrations of monocaprin (MAG 10) by an electrospinning process. Increasing the concentration of MAG 10 caused differences to appear in the shape of the nanofibers, in addition to which the level of wettability was heightened. Besides exhibiting antibacterial properties, the functional membranes demonstrated especially good antifouling activity. The novel and efficient nanofibrous membranes described have the potential to find eventual application in medical or environmental fields.

Effectiveness of Dunaliella salina Extracts against Bacillus subtilis and Bacterial Plant Pathogens

Several bacteria pathogens are responsible for plant diseases causing significant economic losses. The antibacterial activity of Dunaliella salina microalgae extracts were investigated in vitro and in vivo. First, biomass composition was chemically characterized and subjected to extraction using polar/non-polar solvents. The highest extraction yield was obtained using chloroform:methanol (1:1 v/v) equal to 170 mg g⁻¹ followed by ethanol (88 mg g⁻¹) and hexane (61 mg g⁻¹). In vitro examination of hexane extracts of Dunaliella salina demonstrated antibacterial activity against all tested bacteria. The hexane extract showed the highest amount of β-carotene with respect to the others, so it was selected for subsequent analyses. In vivo studies were also carried out using hexane extracts of D. salina against Pseudomonas syringae pv. tomato and Pectobacterium carotovorum subsp. carotovorum on young tomato plants and fruits of tomato and zucchini, respectively. The treated young tomato plants exhibited a reduction of 65.7% incidence and 77.0% severity of bacterial speck spot disease. Similarly, a reduction of soft rot symptoms was observed in treated tomato and zucchini fruits with a disease incidence of 5.3% and 12.6% with respect to 90.6% and 100%, respectively, for the positive control.

The genus Tragopogon (Asteraceae): A review of its traditional uses, phytochemistry, and pharmacological properties

ETHNOPHARMACOLOGICAL RELEVANCE

Species of Tragopogon are used in traditional medicine, and consumed as vegetables across the world. In terms of the medicinal uses of Tragopogon, different species have found use in traditional medicine, including uses for wound-healing, treatment of gastrointestinal and hepatic complaints, cancer, kidney and liver dysfunction, inflamed skin and certain cutaneous diseases, as well as constipation, fatigue and anoxia.

AIM OF THE STUDY

The aim of this review is to highlight and critically summarize those species of the genus that have been studied as a source of interesting lead compounds, and their traditional uses and bioactivities.

MATERIALS AND METHODS

A comprehensive and systematic review of literature on traditional uses, phytochemicals and pharmacological properties of the genus Tragopogon was carried out. Information was retrieved from secondary databases such as Scopus, Chemical Abstracts Services (Scifinder), Pubmed, Google Scholar and ScienceDirect, in addition to primary sources including books, PhD and MSc dissertations, and official websites. Species names were validated using "The Plant List" (www.theplantlist.org).

RESULTS

The taxa of the genus Tragopogon are known for their local and traditional uses as medicine for treatment of various diseases, and have been consumed as vegetables and snacks for generations in Eurasia, the Mediterranean, Caucasus, Europe and North America. From the approximately 110 species of Tragopogon, only twelve species have been scientifically evaluated for their bioactivity and/or phytochemical composition. Tragopogon species are a rich source of phytochemical constituents and among those that have been identified are 19 flavonoids, 35 terpenoids, seven bibenzyl derivatives, five benzylphtalides, six stilbenes, nine dihydroisocoumarin derivatives, nine phenylmethane derivatives, three hydroxyphenylacetic acid derivatives, four phenylpropane derivatives, four esters of phenylpropanoic acids, a coumarin derivative, and a spermine derivative. Various extracts of the taxa, in addition to the isolated compounds, demonstrated pharmacological properties such as antitumor, antimicrobial, anti-inflammatory and enzyme inhibitory activities, in addition to hepatoprotective, antihyperlipidaemic and wound-healing properties.

CONCLUSION

This review highlights the traditional uses, phytochemistry and pharmacological properties of the few studied taxa of the genus Tragopogon. Some of the reviewed papers were not of an appropriate methodological standard. For instance, phytochemical profiles were not determined, and the fundamental requirements of the pharmacological properties were not defined such as including appropriate positive and negative controls, and calculating the MIC values. Furthermore, these studies did not provide an in depth evaluation of bioactivity of the extracts and the isolated compounds or in vivo experiments which could indicate therapeutic relevance. From a phytopharmacological point of view, this review recommends more high quality evidence-based research on Tragopogon species for further development of plant-derived remedies and compounds.

Synthesis, characterization and evaluation of 1-monoacylglycerols of unsaturated fatty acids as potential bioactive lipids

The synthesis of 1-monoacylglycerols of selected unsaturated fatty acids and their antimicrobial and cytotoxicity activity is reported in the present study. The monoacylglycerols of fatty acids like undecenoic, oleic, linoleic and erucic acids were prepared by chemical esterification with solketal followed by deprotection. Fatty acids like alpha linolenic, gamma linolenic and ricinoleic acids were initially isolated from natural sources and further enriched in their respective methyl ester forms. The monoacylglycerols of ricinoleic and linolenic acid methyl esters were prepared by enzymatic transesterification with solketal using lipase from Candida antarctica followed by deprotection. The synthesized 1-monoacylglycerols were purified and characterized by spectral studies. The antimicrobial activity revealed that the monoacylglycerol of gamma linolenic acid was the most effective antibacterial followed by the monoacylglycerols of undecenoic and alpha linolenic acids. In the cytotoxicity assay against five cell lines, all the monoacylglycerols exhibited moderate activity but the activity was best against MCF7 Human Breast Adenocarcinoma cell lines.

Analysis of gut microbiota and the effect of lauric acid against necrotic enteritis in Clostridium perfringens and Eimeria side-by-side challenge model

Gut microbiota has been demonstrated to be involved in intestinal nutrition, defense, and immunity, as well as participating in disease progression. This study was to investigate gut microbiota changes in chickens challenged with netB-positive Clostridium perfringens strain (CP1) and/or the predisposing Eimeria species (Eimeria) and fed diets with fishmeal supplementation. In addition, the effects of lauric acid, a medium-chain fatty acid (MCFA), on necrotic enteritis (NE) reduction and modulation of microbiota were evaluated. The results demonstrated that microbial communities in the jejunum were distinct from those in the cecum, and the microbial community change was more significant in jejunum. Challenge of CP1 in conjunction with Eimeria significantly reduced species diversity in jejunal microbiota, but cecal microbiota remained stable. In the jejunum, CP1 challenge increased the abundance of the genera of Clostridium sensu stricto 1, Escherichia Shigella, and Weissella, but significantly decreased the population of Lactobacillus. Eimeria infection on its own was unable to promote NE, demonstrating decrements of Clostridium sensu stricto 1 and Lactobacillus. Co-infection with CP1 and Eimeria reproduced the majority of NE lesions with significant increment of Clostridium sensu stricto 1 and reduction in Lactobacillus. The advance of changes on these two taxa increased the severity of NE lesions. Further analyses of metagenomeSeq, STAMP, and LEfSe consistently showed significant overgrowth of Clostridium sensu stricto 1 was associated with NE. The supplementation of lauric acid did not reduce NE incidence and severity but decreased the relative abundance of Escherichia Shigella. In conclusion, significant overgrowth of C. perfringens as well as other Clostridium species in Clostridium sensu stricto 1 with the decrement of Lactobacillus in the jejunum is the featured microbiota correlated with NE. Controlling proliferation of Clostridium sensu stricto 1 and manipulation of Lactobacillus in the jejunum should be the strategy to prevent NE.

Potential dietary feed additives with antibacterial effects and their impact on performance of weaned piglets: A meta-analysis

This meta-analysis evaluated the use of potential dietary feed additives (pDFA) with antibacterial effects and their impact on the perfomance of weaned piglets. Twenty-three peer-reviewed in vivo studies, comprising 50 trials, were identified between January 2010 and January 2017. The pDFA in these studies could be grouped in 5 classes: antimicrobial peptides, chitosan, lysozyme, medium chain fatty acids/ triglycerides and plant extracts. Mixed-effect meta-analyses with type of pDFA as fixed effect were performed for the growth parameters 'average daily gain' (ADG) and 'feed conversion ratio' (FCR), which are the two most important and used economic performance parameters for farmers. For each class of pDFA, results of the meta-analysis showed significantly higher average daily gain in the group with pDFA compared to the negative control group, while no significant difference with the positive control group was observed. Furthermore, a positive effect on FCR was found, i.e. significantly less feed was needed to gain 1 kg of body weight in the group with pDFA compared to the negative control group. No significant differences with positive control groups were observed for each class of pDFA, except for plant extracts, where the FCR was also significantly reduced in the treatment group. These results suggest that pDFA could reduce the use of antimicrobials without significant negative effects on performance indicators.

Hydrophilic and lipophilic characteristics of non-fatty acid moieties: significant factors affecting antibacterial activity of lauric acid esters

It has been proposed that the hydrophilic and/or lipophilic characteristics of fatty acid derivatives affect their antibacterial activities according to their ability to incorporate into the bacterial cell membrane. To verify this hypothesis, six kinds of lauric acid derivatives esterified with different non-fatty acid moieties were selected to confirm whether antibacterial activity from their precursor (i.e., lauric acid) is retained or lost. Three compounds, monolaurin, sucrose laurate, and erythorbyl laurate, exerted bacteriostatic and bactericidal effects against Gram-positive bacteria, while the others showed no inhibitory activity. Interestingly, the calculated log P (octanol-water partition coefficient) values of monolaurin, sucrose laurate, and erythorbyl laurate were - 4.122, - 0.686, and 3.670, respectively, relatively lower than those of the other compounds without antibacterial activity. Moreover, the hydrophilic-lipophilic balance values of the three compounds with antibacterial activity were higher than those of the other compounds, corresponding to the log P result.

Microflora of processed cheese and the factors affecting it

The basic raw materials for the production of processed cheese are natural cheese which is treated by heat with the addition of emulsifying salts. From a point of view of the melting temperatures used (and the pH-value of the product), the course of processed cheese production can be considered "pasteurisation of cheese." During the melting process, the majority of vegetative forms of microorganisms, including bacteria of the family Enterobacteriaceae, are inactivated. The melting temperatures are not sufficient to kill the endospores, which survive the process but are often weakened. From a microbiological point of view, the biggest contamination problem of processed cheese is caused by gram-positive spore-forming rod-shaped bacteria of the genera Bacillus, Geobacillus, and Clostridium. Other factors affecting the shelf-life and quality of processed cheese are mainly the microbiological quality of the raw materials used, strict hygienic conditions during the manufacturing process as well as the type of packaging materials and storage conditions. The quality of processed cheese is not only dependent on the ingredients used but also on other parameters such as the value of water activity of the processed cheese, its pH-value, the presence of salts and emulsifying salts and the amount of fat in the product.

Formulation, Characterization and Properties of Hemp Seed Oil and Its Emulsions

The formulation, characterization, and anticipated antibacterial properties of hemp seed oil and its emulsions were investigated. The oil obtained from the seeds of Cannabis sativa L. in refined and unrefined form was characterized using iodine, saponification, acid values, and gas chromatography, and was employed for the preparation of stable oil-in-water emulsions. The emulsions were prepared using pairs of non-ionic surfactants (Tween, Span). The effects of the emulsification method (spontaneous emulsification vs. high-intensity stirring), hydrophilic lipophilic balance (HLB), type and concentration of surfactant, and oil type on the size and distribution of the emulsion particles were investigated. It was found that the ability to form stable emulsions with small, initial particle sizes is primarily dependent on the given method of preparation and the HLB value. The most efficient method of emulsification that afforded the best emulsions with the smallest particles (151 ± 1 nm) comprised the high-energy method, and emulsions stable over the long-term were observed at HBL 9 with 10 wt % concentration of surfactants. Under high-intensity emulsification, refined and unrefined oils performed similarly. The oils as well as their emulsions were tested against the growth of selected bacteria using the disk diffusion and broth microdilution methods. The antibacterial effect of hemp seed oil was documented against Micrococcus luteus and Staphylococcus aureus subsp. aureus. The formulated emulsions did not exhibit the antibacterial activity that had been anticipated.

Isolation and Analysis of Phospholipids in Dairy Foods

The lipid fraction of milk is one of the most complex matrixes in foodstuffs due to the presence of a high number of moieties with different physical and chemical properties. Glycerolipids include glycerol and two fatty acids esterified in positions sn-1 and sn-2 with higher concentration of unsaturated fatty acids than in the triglyceride fraction of milk. Sphingolipids consist of a sphingoid base linked to a fatty acid across an amide bond. Their amphiphilic nature makes them suitable to be added into a variety of foods and recent investigations show that phospholipids, mainly phosphatidylserine and sphingomyelin, can exert antimicrobial, antiviral, and anticancer activities as well as positive effects in Alzheimer's disease, stress, and memory decline. Polar lipids can be found as natural constituents in the membranes of all living organisms with soybean and eggs as the principal industrial sources, yet they have low contents in phosphatidylserine and sphingomyelin. Animal products are rich sources of these compounds but since there are legal restrictions to avoid transmission of prions, milk and dairy products are gaining interest as alternative sources. This review summarizes the analysis of polar lipids in dairy products including sample preparation (extraction and fractionation/isolation) and analysis by GC or HPLC and the latest research works using ELSD, CAD, and MS detectors.

The influence of fat and monoacylglycerols on growth of spore-forming bacteria in processed cheese

Highly undesirable microbial contaminants of processed cheese are endospore-forming bacteria of the genera Bacillus and Clostridium. Survival of Bacillus subtilis, B. cereus, Clostridium butyricum and C. sporogenes was examined in model processed cheese samples supplemented with monoacylglycerols. In processed cheese samples, monoacylglycerols of undecanoic, undecenoic, lauric and adamantane-1-carboxylic acid at concentration of 0.15% w/w prevented the growth and multiplication of both Bacillus species throughout the storage period. The two species of Clostridium were less affected by monoacylglycerols in processed cheese samples and only partial inhibition was observed. The effect of milk fat content on microbial survival in processed cheese was also evaluated. The growth of Bacillus sp. was affected by the fat level of processed cheese while population levels of Clostridium sp. did not differ in processed cheese samples with 30, 40 and 50% fat in dry matter.

Chromatographic Analysis and Antioxidant Capacity of Tabernaemontana catharinensis

In this study we evaluated the composition of the crude extract and fractions of Tabernaemontana catharinensis (Apocynaceae) by HPLC/DAD and GC/MS. We also tested the antioxidant capacity and investigated the contents of polyphenols, flavonoids, tannins and alkaloids of T. catharinensis stem bark. The extract and fractions showed inhibition against thiobarbituric acid reactive species (TBARS), in the following order: ethyl acetate (IC50 = 4.7 ± 0.2 μg/mL) > dichloromethane (23.9 ± 1.1 μg/mL) > n-butanolic (25.2 ± 0.4 μg/mL) > crude extract (38.0 ± 0.07 μg/mL). Moreover, the DPPH assay, presented IC50 values ranged from 5.6 ± 0.6 to 30.3 ± 1.3 μg/mL. Contents of total phenols, flavonoids, tannins and alkaloids of T. catharinensis followed the order: ethyl acetate > n-butanolic > dichloromethane fractions > crude extract. HPLC/DAD analyses indicated that gallic, chlorogenic and caffeic acids, and rutin, quercetin and kaempferol are components of the species. Taken together, the results suggest that T. catharinensis could be considered an effective agent in the prevention of diseases associated with oxidative stress.

Chemical Composition, Antioxidant and Antimicrobial Activity of Essential Oil and Extracts of Tragopogon graminifolius, a Medicinal Herb from Iran

Tragopogon graminifolius DC., family Compositae, is widely consumed as a green vegetable in the west of Iran and for the treatment of gastrointestinal and hepatic ailments. In this study, the chemical composition of the essential oil from T. graminifolius aerial parts was evaluated by gas chromatography and gas chromatography mass spectrometry. Moreover, antioxidant and antimicrobial activity of the essential oil and various extracts of T. graminifolius were determined. Fifty-eight compounds representing 87.2% of the essential oil were identified. The main components were n-hexadecanoic acid (22.0%), β-caryophyllene (7.5%), heneicosane (6.6%), and nonanal (5.2%). The essential oil demonstrated the highest DPPH radical scavenging activity (56.6 ± 8.8ug/mL) and the 80% ethanolic extract the highest ferric reducing antioxidant activity (908.2±79.5 mmol Fe2+ ion/g extract). The total phenolic content of the 80% ethanolic extract from the aerial parts was the highest (560.7±18.8 mg/g gallic acid equivalent). In the antimicrobial test, Shigella dysenteriae was the most vulnerable microorganism, followed by Proteus vulgaris, and the essential oil exhibited the highest antibacterial activity among the samples. The results indicated that the essential oil and extracts of T. graminifolius could be consumed as a natural herbal preservative or complementary supplement in the food and pharmaceutical industries.

Marked synergistic bactericidal effects and mode of action of medium-chain fatty acids in combination with organic acids against Escherichia coli O157:H7

The aim of this study was to examine the synergistic bactericidal effects of medium-chain fatty acids (MCFAs; caprylic, capric, and lauric acid) and organic acids (OAs; acetic, lactic, malic, and citric acid) against Escherichia coli O157:H7 and to identify their underlying mechanism(s) of action. E. coli O157:H7 was treated with MCFAs, OAs, or different combinations of MCFAs and OAs. Membrane damage and cell morphology were examined by flow cytometry and transmission electron microscopy, respectively. Combined treatment resulted in an additional log-unit reduction compared with the sum of the reductions obtained after individual treatment. For example, caprylic acid (1.0 mM, or 0.016%) and citric acid (1.0 mM, or 0.012%) alone showed negligible bactericidal effects (0.30- and 0.06-log-unit reductions, respectively); however, a marked synergistic effect (>7.15-log-unit reduction) was observed when the two were combined. Although flow cytometry and microscopic analyses of bacteria treated with individual MCFAs and OAs showed evidence of membrane disruption, the bacteria were still able to form colonies; thus, the cell damage was recoverable. In contrast, cells exposed to combined treatments showed clear membrane disintegration and/or cell death (irreversible damage). The mechanism underlying the antimicrobial effects of combined treatment with MCFAs or OAs may involve disruption of the bacterial membrane, which then facilitates the entry of other antimicrobial compounds into the cytoplasm. The main advantage of combined treatment with very low concentrations of natural antimicrobial compounds is that it is very cost-effective. Thus, this approach may be an alternative to more conventional antimicrobial treatments, such as those currently used in public health, medical centers, and the food industry.

Preliminary nutritional and biological potential of Artocarpus heterophyllus L. shell powder

Artocarpus heterophyllus shell powder was investigated in terms of its nutritional and biological potential. A thorough examination of shell powder demonstrated its potential as a source of minerals, β carotene and dietary fiber, which were assessed gravimetrically & spectrophotometrically. This showed 3.05 ± 0.19 g 100 g(-1) DW of alkaloids followed by saponins and tannins. Three different extracts; acetone, methanol, & mix solvent were used to evaluate phenolic & flavonoid content, antioxidant & antimicrobial activity, GC/MS screening and quantitative analysis of polyphenols. Among all, the methanol extract showed highest antioxidant activity evaluated by DPPH, FRAP & ABTS assays and was significantly correlated with phenolic and flavonoid contents. Phenolic & flavonoid content was found to be 158 ± 0.34 mg (GAE) and 10.0 ± 0.64 mg (CE) respectively. The results of antimicrobial activity showed that L. monocytogenes was more susceptible to all extracts followed by other microorganisms. Catechin, ascorbic & chlorogenic acids were identified as major polyphenols analyzed by LC-MS/MS. GC/MS analysis showed that it contains a variety of compounds with different therapeutic activities. The study revealed that A. heterophyllus shell is a good source of natural antioxidants & other bioactive compounds and can be used in cosmetics, medicines and functional food application.

Nutrient signaling: evolutionary origins of the immune-modulating effects of dietary fat

Many dietary fatty acids (FA) have potent effects on inflammation, which is not only energetically costly, but also contributes to a range of chronic diseases. This presents an evolutionary paradox: Why should the host initiate a costly and damaging response to commonly encountered nutrients? We propose that the immune system has evolved a capacity to modify expenditure on inflammation to compensate for the effects of dietary FA on gut microorganisms. In a comprehensive literature review, we show that the body preferentially upregulates inflammation in response to saturated FA that promote harmful microbes. In contrast, the host opften reduces inflammation in response to the many unsaturated FA with antimicrobial properties. Our model is supported by contrasts involving shorter-chain FA and omega-3 FA, but with less consistent evidence for trans fats, which are a recent addition to the human diet. Our findings support the idea that the vertebrate immune system has evolved a capacity to detect diet-driven shipfts in the composition of gut microbiota from the profile of FA consumed and to calibrate the costs of inflammation in response to these cues. We conclude by extending the nutrient signaling model to other nutrients, and consider implications for drug discovery and public health.

Effects of monolaurin on ruminal methanogens and selected bacterial species from cattle, as determined with the rumen simulation technique

Before being able to implement effective ruminal methane mitigation strategies via feed supplementation, the assessment of side effects on ruminal fermentation and rumen microbial populations is indispensable. In this respect we investigated the effects of monolaurin, a methane-mitigating lipid, on methanogens and important carbohydrate-degrading bacteria present in ruminal fluid of dairy cattle in continuous culture employing the rumen simulation technique. In six experimental runs, each lasting for 10 days, four diets with different carbohydrate composition, based on hay, maize, wheat and a maize-wheat mixture, either remained non-supplemented or were supplemented with monolaurin and incubated in a ruminal-fluid buffer mixture. Incubation liquid samples from days 6 to 10 of incubation were analyzed with relative quantitative polymerase chain reaction (qPCR) of 16S rRNA genes to assess monolaurin-induced shifts in specific rumen microbial populations in relation to the corresponding non-supplemented diets. Monolaurin completely inhibited Fibrobacter succinogenes in all diets while the response of the other cellulolytic bacteria varied in dependence of the diet. Megasphaera elsdenii remained unaffected by monolaurin in the two diets containing maize, but was slightly stimulated by monolaurin with the wheat and largely with the hay diet. The supply of monolaurin suppressed Methanomicrobiales below the detection limit with all diets, whereas relative 16S rRNA gene copy numbers of Methanobacteriales increased by 7-fold with monolaurin in case of the hay diet. Total Archaea were decreased by up to over 90%, but this was significant only for the wheat containing diets. Thus, monolaurin exerted variable effects mediated by unknown mechanisms on important ruminal microbes involved in carbohydrate degradation, along with its suppression of methane formation. The applicability of monolaurin for methane mitigation in ruminants thus depends on the extent to which adverse effects on carbohydrate-degrading bacteria actually impair the supply of digested carbohydrates to the animal.