Potential roles of essential oil and organic extracts of Zizyphus jujuba in inhibiting food-borne pathogens

This study was undertaken to examine the chemical compositions of essential oil and tested the efficacy of oil and organic extracts from seeds of Zizyphus jujuba against food-borne pathogens. The chemical compositions of the oil was analysed by Null. Twenty three compounds representing 91.59% of the total oil were identified. The oil (5 μl of 1:5 (v/v) dilution of oil with methanol) and extracts of hexane, chloroform, ethyl acetate and methanol (300 μg/disc) of Z. jujuba displayed a remarkable antibacterial activity against Staphylococcus aureus (ATCC 6538 and KCTC 1916), Listeria monocytogenes ATCC 19166, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa KCTC 2004, Salmonella typhimurium KCTC 2515 and Escherichia coli ATCC 8739. The scanning electron microscopic studies also demonstrated the effect of essential oil on the morphology of Staph. aureus ATCC 6538 at the MIC value, along with the potential effect on cell viabilities of the tested bacteria.     

Inhibitory parameters of the essential oil and various extracts of Metasequoia glyptostroboides Miki ex Hu to reduce food spoilage and food-borne pathogens

The aim of this work was to examine the chemical composition of the essential oil and various solvent extracts isolated from the floral cone of Metasequoia glyptostroboides Miki ex Hu and to test their efficacy against a diverse range of organisms comprising food spoilage and food-borne pathogenic bacteria. The chemical composition of essential oil isolated by hydrodistillation was analysed by GC-MS. It was determined that 59 compounds, which represented 97.06% of total oil, were present in the oil. The oil contains mainly α-pinene (29.54%), totarol (9.37%), α-thujene (8.63%), bornylene (8.63%), β-caryophyllene (4.40%), totarol acetate (3.98%), δ-3-carene (3.19%) and 2-β-pinene (2.25%). The oil was found containing mainly the oxygenated mono- and sesquiterpenes and their respective hydrocarbons. Antibacterial activity of essential oil, methanol extract and various organic sub-fractions of methanol extract of M. glyptostroboides was determined in vitro using agar diffusion method and MIC determination test against eleven (four Gram-positive, seven Gram-negative) bacterial strains including food spoilage and food-borne pathogens. The essential oil (5 μl/ml, corresponding to 1000 ppm/disc), methanol extract and various organic sub-fractions (7.5 μl/ml, corresponding to 1500 ppm/disc) of M. glyptostroboides exhibited great potential of antibacterial activity against four Gram-positive bacteria such as Bacillus subtilis (ATCC 6633), Listeria monocytogenes (ATCC 19166), Staphylococcus aureus (KCTC 1916), S. aureus (ATCC 6538) and one Gram-negative bacterium, Pseudomonas aeruginosa (KCTC 2004). The zones of inhibition of different concentrations of essential oil, methanol extract and its derived various organic sub-fractions against the tested bacteria were found in the range of 10 ∼ 20 mm and the MIC values were recorded between 125 and 1000 μg/ml. This study shows that M. glyptostroboides mediated essential oil and extracts can be applied in food industries as a natural preservatives or flavoring additives to control food spoilage and food-borne pathogenic bacteria causing severe destruction in food.     

Antibacterial,anti-inflammatory and anti-allergic activities of standardised pomegranate rind extract

Antibacterial, anti-inflammatory and anti-allergic activities of standardised pomegranate rind extract (SPRE) containing 13% w/w ellagic acid were studied in vitro. The antibacterial activity of SPRE was determined using the disc diffusion and broth microdilution methods. SPRE exhibited a potent bacteriostatic effect against Propionibacterium acnes, a Gram-positive anaerobe, with a MIC of 15.6 μg/ml, and Gram-positive facultative anaerobic bacteria, Staphylococcus aureus and Staphylococcus epidermidis, with MICs of 7.8–15.6 μg/ml. Anti-inflammatory activity of SPRE was evaluated by measuring the inhibition of nitric oxide (NO) production by murine macrophage-like RAW264.7 cells. SPRE exhibited a potent NO inhibitory effect, with an IC₅₀ of 10.7 μg/ml. Evaluation of the anti-allergic activity showed that SPRE inhibited the release of β-hexosaminidase from antigen-stimulated rat basophilic leukemia (RBL-2H3) cells with an IC₅₀ of 20.9 μg/ml. In addition, SPRE exhibited only moderate cytotoxicity on human keratinocyte cells, with CC₅₀ of 33.6 μg/ml. These findings support the potential use of SPRE as a nutraceutical for antibacterial, anti-inflammatory and anti-allergic proposes.     

Antibacterial activity of Thai edible plants against gastrointestinal pathogenic bacteria and isolation of a new broad spectrum antibacterial polyisoprenylated benzophenone,chamuangone

Twenty-two edible plant extracts were subjected to evaluation of their antibacterial activity against some gastrointestinal pathogenic bacteria, including Escherichiacoli, Salmonella typhimurium, Salmonella typhi, Shigella sonnei and Helicobacter pylori using the disc diffusion and broth microdilution methods. Sixteen of the plant extracts exhibited antibacterial activity against one or more tested bacteria. Only Garcinia cowa leaf extracts exhibited antibacterial activity against all tested bacteria. Purification of the ethyl acetate extract of G. cowa leaves using an antimicrobial assay-guided isolation afforded a new polyprenylated benzophenone, chamuangone, that exhibited satisfactory antibacterial activity against Streptococcus pyogenes (minimum inhibitory concentration (MIC) 7.8 μg/ml), Streptococcus viridans and H. pylori (MICs 15.6 μg/ml), and Staphylococcus aureus, Bacillus subtilis and Enterococcus sp. (MICs 31.2 μg/ml).     

Resistances to benzalkonium chloride of bacteria dried with food elements on stainless steel surface

To confirm the importance of washing food sediments from the surface of food-related environments, we examined resistances against benzalkonium chloride of pathogenic bacterial (Escherichia coli O26, Pseudomonas aeruginosa and Staphylococcus aureus) cells dried and adhered on stainless steel dishes with milk, beef gravy or tuna gravy. Suspensions (0.1 ml) of these bacteria (8-9 log cfu/ml) were put on a 5 cm ? stainless steel dish and dried at room temperature (20-24 °C) for 90 min in a bio-clean bench with ventilation. Though these bacteria suspended with distilled water decreased 30-40 fold during the drying period, milk and the gravies protected the bacteria. Without the food elements, the adhered E. coli and Stap. aureus were decreased from 6 to<2 log cfu/dish by 0.5 mg/ml benzalkonium chloride (BKC) for 10 min treatment. Although Ps. aeruginosa showed resistance to BKC, the adhered cells were inactivated by 2.0 mg/ml BKC. However, the bactericidal effect disappeared by the food elements, particularly with milk, even at 1.0 and/or 2.0 mg/ml BKC levels. The protective efficiency of milk on bacteria disappeared if washed with water.     

Composition,antimicrobial, antiradical and spasmolytic activity of Ferula heuffelii Griseb. ex Heuffel (Apiaceae) essential oil

The essential oil from underground parts of Ferula heuffelii from N.E. Serbia, was analysed using GC and GC–MS. The main compounds of the essential oil were elemicin (35.4%) and myristicin (20.6%). The essential oil exhibited the best antimicrobial activity against two strains of Candida albicans (MIC = 7.0 and 13.7 μg/ml), as well as against Micrococcus luteus (MIC = 13.7 μg/ml), Staphylococcus epidermidis (MIC = 17.6 μg/ml), Bacillus subtilis (MIC = 21.1 μg/ml) and Micrococcus flavus (MIC = 28.2 μg/ml). In the DPPH radical scavenging assay, essential oil showed substantial activity with SC₅₀ = 22.43 μl/ml. The essential oil was also tested for antispasmodic activity. It inhibited spontaneous contraction of isolated rat ileum dose-dependently, and at the concentration of 86.64 μg/ml exhibited 50% of the maximum effect of atropine. After incubation with 75.00 μg/ml of essential oil, acetylcholine did not induce contractions of ileum, and at 250.00 μg/ml, the essential oil almost completely abolished the spasmodic effect of potassium chloride (80 mM).     

Analysis and the potential applications of essential oil and leaf extracts of <Emphasis Type="Italic">Silene armeria</Emphasis> L. to control food spoilage and food-borne pathogens

The aim of this study was to analyze the chemical composition of essential oil isolated from the floral parts of Silene armeria L. by hydrodistillation and to test the efficacy of essential oil and the various leaf extracts against a diverse range of microorganisms comprising food spoilage and food-borne pathogenic bacteria. The chemical composition of essential oil was analyzed by the GC–MS. It was determined that 28 compounds, which represented 89.03% of total oil, were present in the oil. The oil contained mainly methylamine (21.48%), β-butene (17.97%), α-butene (46.40%), coumaran (0.22%), eugenol (0.21%), α-humulene (0.07%), farnesol (0.05%) and linalool (0.12%). The essential oil (5 μl/ml, corresponding to 1,000 ppm/disc) and various leaf extracts of methanol, ethyl acetate, chloroform and hexane (7.5 μl/ml, corresponding to 1,500 ppm/disc) exhibited promising antibacterial effect against Bacillus subtilis ATCC6633, Listeria monocytogenes ATCC19166, Staphylococcus aureus KCTC1916, S. aureus ATCC6538, Pseudomonas aeruginosa KCTC2004, Salmonella typhimurium KCTC2515, Salmonella enteritidis KCTC2021, Escherichia coli O157-Human, E. coli ATCC8739, E. coli O57:H7 ATCC43888 and Enterobacter aerogenes KCTC2190. The zones of inhibition of different concentrations of essential oil and the various leaf extracts against the tested bacterial pathogens were found in the range of 10–19 and 7–13 mm, respectively, along with their respective MIC values ranging from 125 to 1,000 and 250–2,000 μg/ml. Also, the essential oil had a potential effect on the viable count of the tested bacteria. The results of this study suggest that the essential oil and leaf extracts derived from S. armeria could be used for the development of novel types of antibacterial agents to control food spoilage and food-borne pathogens.     

Effect of lactoferrin and its derivatives against gram-positive bacteria in vitro and, combined with high pressure, in chicken breast fillets

The bactericidal activity of lactoferrin (LF), amidated lactoferrin (AMILF), pepsin digested lactoferrin (PDLF), and its activated (ALF) commercial form, against six strains of three gram-positive bacterial species was investigated. Listeria monocytogenes was most sensitive in vitro, Staphylococcus aureus showed a moderate resistance, and Enterococus faecalis was highly resistant to antimicrobials. When chicken breast fillets were inoculated with L. monocytogenes CECT5725 and treated with antimicrobials, reductions were below 0.5 log CFU/ml in all cases. In combination with high pressure (HHP) treatment at 400 MPa for 10 min, antimicrobials showed a slight additional bactericidal effect, always below 1 log CFU/g. Incorporation of antimicrobials 18 h before or 1 h after HHP treatment generally yielded better results than incorporation 1 h before HHP treatment, although reductions remained below 1.5 log CFU/g in all cases. LF and its derivatives showed a limited potential for pathogen control in meat.     

Isolation and identification of pentagalloylglucose with broad-spectrum antibacterial activity from Rhus trichocarpa Miquel

Rhus trichocarpa Miquel has been utilised both as a food and for medicinal purposes. In this study, we determined that the methanol extracts of the stem and leaf portions of R. trichocarpa inhibited the growth of both Gram-negative and Gram-positive bacteria. The active constituent was isolated, and identified via mass spectrometry and NMR as 1,2,3,4,6-penta-O-galloyl-β-d-glucose. The compound also evidenced a broad spectrum of antibacterial activity against both Gram-negative and Gram-positive bacteria including Staphylococcus aureus (both methicillin-resistant S. aureus and quinolone-resistant S. aureus), Bacillus subtilis, Streptococcus mutans, Escherichia coli, Salmonella typhimurium, and Pseudomonas aeruginosa with MRC values of 16–32 μg/ml, whereas gallate failed to inhibit the growth of Gram-negative bacteria, even at a concentration of 128 μg/ml. The antibacterial activity of penta-O-galloylglucose was restored by the addition of Fe²⁺, whereas gallate was not, thereby indicating that its antibacterial activity could be attributable to the chelation of iron. The results of the time-kill study against S. aureus and E. coli revealed that penta-O-galloylglucose exhibited bacteriostatic activity. These findings indicate that the extracts of R. trichocarpa as well as its active component, penta-O-galloylglucose, may have profound potential for the control of both Gram-positive and negative pathogens.     

High hydrostatic pressure processing reduces Salmonella enterica serovars in diced and whole tomatoes

Fresh and fresh-cut tomatoes have been associated with numerous outbreaks of salmonellosis in recent years. One effective post harvest treatment to reduce Salmonella enterica in tomatoes may be high pressure processing (HPP). The objectives of the study were to determine the potential for HPP to reduce S. enterica serovars Newport, Javiana, Braenderup and Anatum in tryptic soy broth (TSB) and to determine the effect of HPP to reduce the most pressure resistant of the four serovars from fresh diced and whole tomatoes. To evaluate pressure resistance, TSB containing 8 log CFU/ml of one of the four serovars was packaged in sterile stomacher bags and subjected to one of three different pressures (350, 450 or 550 MPa) for 120 s. The most pressure resistant S. enterica serovar evaluated was Braenderup. Subjecting the broth culture to 350, 450 and 550 MPa resulted in a 4.53, 5.74 and 7.09 log reduction in S. Braenderup, respectively. Diced tomatoes (150 g) and whole red round tomatoes (approximately 150 g) were inoculated with 0.1 ml of 9.1 log CFU/ml S. Braenderup, and subjected to the same pressure treatments (350, 450 or 550 MPa). Significant reductions of S. Braenderup concentrations in diced tomatoes (P < 0.05) were seen after processing at 350 (0.46 CFU/g), 450 (1.44 log CFU/g), and 550 MPa (3.67 log CFU/g). In whole tomatoes, significant reductions (P < 0.05) were also seen at 350 (1.41 log CFU/g), 450 (2.25 log CFU/g) and 550 MPa (3.35 log CFU/g). HPP may be an effective post harvest strategy to reduce low levels of S. enterica contamination in whole and diced tomatoes.     

Inactivation of Escherichia coli O157:H7 and Salmonella spp. on alfalfa seeds by caprylic acid and monocaprylin

Alfalfa and other seed sprouts have been implicated in several Escherichia coli O157:H7 and Salmonella spp. human illness outbreaks in the U.S. Continuing food safety issues with alfalfa seeds necessitate the need for discovery and use of novel and effective antimicrobials. The potential use of caprylic acid (CA) and monocaprylin (MC) for reducing E. coli O157:H7 and Salmonella spp. populations on alfalfa seeds was evaluated. The effectiveness of three concentrations of CA and MC (25, 50, and 75 mM) to reduce E. coli O157:H7 and Salmonella spp. populations in 0.1% peptone water and on alfalfa seeds was evaluated. Surviving populations of E. coli O157:H7 and Salmonella spp. were enumerated by direct plating on tryptic soy agar (TSA). Non-inoculated alfalfa seeds were soaked for up to 120 min to evaluate the effect of CA and MC solutions on seed germination rate. For planktonic cells, the efficacy of the treatments was: 75 MC > 50 MC > 25 MC > 75 CA > 50 CA > 25 CA. Both E. coli O157:H7 and Salmonella spp. were reduced to below the detection limit (0.6 log CFU/ml) within 10 min of exposure to 75 MC from initial populations of 7.65 ± 0.10 log CFU/ml and 7.71 ± 0.11 log CFU/ml, respectively. Maximum reductions of 1.56 ± 0.25 and 2.56 ± 0.17 log CFU/g for E. coli O157:H7 and Salmonella spp., respectively, were achieved on inoculated alfalfa seeds (from initial populations of 4.74 ± 0.62 log CFU/g and 5.27 ± 0.20 log CFU/g, respectively) when treated with 75 MC for 90 min. Germination rates of CA or MC treated seeds ranged from 84% to 99%. The germination rates of CA or MC soaked seeds and water soaked seeds (control) were similar (P > 0.05) for soaking times of ≤ 90 min. Monocaprylin (75 mM) can be used to reduce E. coli O157:H7 and Salmonella spp. on alfalfa seeds without compromising seed viability.     

Antimicrobial and human cancer cell cytotoxic effect of synthetic angiotensin-converting enzyme (ACE) inhibitory peptides

Four peptides with high angiotensin-converting enzyme (ACE) inhibitory effect were separated from beef sarcoplasmic protein hydrolysates using commercial enzymes. They were identified as GFHI, DFHING, FHG, and GLSDGEWQ and their 50% inhibition concentration (IC₅₀) values against ACE were 117, 64.3, 52.9, and 50.5 μg/ml, respectively. These peptides were synthesised and further biological activities of these four peptides were measured, including antimicrobial, cytotoxic effect against cancer cells, and macrophage-stimulating effect. Peptide GLSDGEWQ showed growth inhibition on Salmonella Typhimurium, Bacillus cereus, Escherichia coli, and Listeria monocytogenes at a 100 ppm level but not on Staphylococcus aureus and Pseudomonas aeruginosa. Peptide GFHI showed higher inhibition activity on the growth of E. coli and P. aeruginosa at concentrations of 200 and 400 μg/ml. However, peptide FHG inhibited only P. aeruginosa at 200 and 400 μg/ml. The effect of separated peptides on breast cancer (MCF-7), lung cancer (A549), and stomach cancer (AGS) cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Peptide GFHI showed a slight decrease of MCF-7 cell viability in a dose dependent manner. When 400 μg/ml of peptide GFHI was applied to the AGS cell, its viability was decreased by 75%. However, peptide DFHINQ seemed to act as a nutrient to AGS cell because it increased its viability. None of the four peptides had a cytotoxic effect on A549 cells. Nitric oxide (NO) production of peptide GFHI by stimulation of macrophage was investigated at 100, 300, and 1000 μg/ml concentration. NO was not produced in all treatments. From these results it is expected that the ACE inhibitory peptides identified from beef sarcoplasmic protein hydrolysates have both antimicrobial and cancer cell cytotoxic effects.     

Chemical composition,antimicrobial, cytotoxic and antioxidant activities of the essential oil of Artemisia indica Willd

Essential oil from the aerial parts of Artemisia indica was analysed by GC-FID and GC–MS. A total of 43 compounds representing 96.8% of the oil were identified and the major components were found to be artemisia ketone (42.1%), germacrene B (8.6%), borneol (6.1%) and cis-chrysanthenyl acetate (4.8%). Antimicrobial activity of the oil was evaluated against seven clinically significant bacterial and two fungal strains. The essential oil and its major constituents exhibited moderate to potent, broad-spectrum antibacterial and antifungal activities targeting both Gram-positive and Gram-negative bacteria. In vitro cytotoxicity evaluation against four human cancer cell lines THP-1 (leukemia), A-549 (lung), HEP-2 (liver) and Caco-2 (colon) showed that the essential oil exhibited concentration dependant growth inhibition in the 10–100 μg/ml dilution range, with IC₅₀ values of 10 μg/ml (THP-1), 25 μg/ml (A-549), 15.5 μg/ml (HEP-2) and 19.5 μg/ml (Caco-2). It was interesting to note that the essential oil also exhibited potent antioxidant activity.     

Antimicrobial properties and analytical profile of traditional Eruca sativa seed oil: Comparison with various aerial and root plant extracts

The present study investigates the antimicrobial activity of various solvent extracts of Eruca sativa (aerial and root) and seed oil against-antibiotic resistant Gram-negative (Escherichia coli, Pseudomoms aeruginosa and Shigella flexneri) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Among the various preparations, seed oil was the most active, exhibiting a maximum zone inhibition of 97% for Gram-positive bacteria and of 74–97% for Gram-negative bacteria. The MIC of the seed oil was found to be 65–75 and 60–70 μg/ml for Gram-negative and Gram-positive bacteria, respectively. Analytical investigation on main volatile and non-volatile components was performed on seed oil. Among the formers allyl isothiocyanate (40 μg/g), 3-butenyl isothiocyanate (260 μg/g), 4-methylsulfinybutyl isothiocyanate (sulforaphane 743 μg/g), 2-phenylethyl isothiocyanate (159 μg/g) and bis(isothiocyanatobutyl)disulphide (∼5000 μg/g) were determined by head space/SPME/GC–MS analysis. Free fatty acids were 1.6% w/w of the oil and overall 25 fatty acids were identified. Erucic and oleic acids were the main fatty acids both in the free (7.8 and 2.1 mg/ml) and esterified forms (50.6% w/w and 14.9% w/w of total fatty acids). Unsaponifiable fraction was 1.8% w/w.     

Determination of some characteristics coccoid forms of lactic acid bacteria isolated from Turkish kefirs with natural probiotic

In this study, a total of 21 coccoid forms of lactic acid bacteria (lactococci) were isolated from Turkish kefir samples. As a result of the identification tests, 21 lactococci isolates were identified as Lactococcus cremoris (11 strains), Lactococcus lactis (4 strains), Streptococcus thermophilus (3 strains) and Streptococcus durans (3 strains). The amount of produced lactic acid, hydrogen peroxide, proteolytic activity, diacetyl and acetaldehyde productions of the lactococci were determined. Different amounts of lactic acid were produced by strains studies; however, lactic acid levels were 2.3-9.9 mg/ml. While Lac. lactis Z13S, Str. durans Z7S, Z8S, Z15S, Lac. cremoris Z9S, Z16S, Z17S, Z19S, Z20S and Z21S strains were not shown hydrogen peroxide, Lac. lactis Z1S and Z2S strains had a maximum hydrogen peroxide (0.17 μg/ml). Lac. lactis Z2S, Z3S, Str. thermophilus Z5S, Z12S, Str. durans Z7S, Z8S, Lac. cremoris Z14S and Z16S strains were not show proteolytic activity, Lac. cremoris Z20S strain produced the maximum amount (0.09 mg/ml) of proteolytic activity. Acetaldehyde concentration produced in Lactobacillus strains ranged between 0.18 and 3.96 μg/ml. Antimicrobial effects of the lactococci on Escherichia coli NRLL B-704, Staphylococcus aureus 4-63, Pseudomonas aeruginosa ATCC 29212 were also determined by an agar diffusion method. All of the strains were able to inhibit S. aureus, while Lac. lactis Z1S, Z2S and Lac. cremoris Z6S strains were able to inhibit E. coli and P. aeruginosa. Also, Str. thermophilus Z5S strain were able to inhibit P. aeruginosa.     

Bacteriocinogenic Lactobacillus plantarum ST16Pa isolated from papaya (Carica papaya) — From isolation to application: Characterization of a bacteriocin

Strain ST16PA, isolated from papaya was identified as Lactobacillus plantarum based on biochemical tests, PCR with species-specific primers and 16S rDNA sequencing. L. plantarum ST16PA produces a 6.5 kDa bacteriocin, active against different species from genera Enterobacter, Enterococcus, Lactobacillus, Pseudomonas, Streptococcus and Staphylococcus and different serotypes of Listeria spp. The peptide is inactivated by proteolytic enzymes, but not when treated with ??-amylase, catalase, lipase, Triton X-100, SDS, Tween 20, Tween 80, urea, NaCl and EDTA. However, presence of 1% Triton X-114 deactivates the bacteriocin. No change in activity was recorded after 2 h at pH values between 2.0 and 12.0, and after treatment at 100 °C for 120 min or 121 °C for 20 min. The mode of activity against Lactobacillus sakei ATCC 15521, Enterococcus faecalis ATCC 19443 and Listeria innocua 2030C was bactericidal, resulting in cell lysis and enzyme-leakage. No significant differences in cell growth and bacteriocin production were observed when strain ST16Pa was cultured in MRS broth at 26 °C and 30 °C for 24 h (25 600 AU/ml). However, even though strain ST16PA grows well in MRS broth at 15 °C and 37 °C, a reduction of bacteriocin production was observed (400 AU/ml and 1600 AU/ml, respectively). In addition, effect of MRS medium components, different initial pH and additions of glycerol or vitamins to the media on bacteriocin ST16Pa production was studied.Peptide ST16PA adsorbs (400 AU/ml) to producer cells. However, bacteriocin ST16Pa was adsorbed at 50% to cells of L. innocua 2030C and at 75% to L. sakei ATCC 15521 and E. faecalis ATCC 19433 when experiments were conducted at 30 °C and pH 6.5. Adsorption of bacteriocin ST16Pa to target cells at different temperatures, pH and in presence of potassium sorbate, sodium nitrate, sodium chloride, ascorbic acid, Tween 80 and Tween 20 were also studied. To the best of our knowledge, this is the first report on detection of L. plantarum in papaya.     

Bactericidal activities against pathogenic bacteria by selected constituents of plant extracts in carrot broth

HPLC-DAD analysis provided evidence for the certain identification of some constituents of hydroalcoholic extracts from Lithospermum erythrorhizon, Rheum palmatum, Thymus vulgaris, Lippia citriodora, and a mixture of Rosmarinus officinalis, Salvia lavandulifolia and Thymus mastichina. Their inhibitory and bactericidal activities in vitro against Escherichia coli and Staphylococcus aureus were evaluated either in Luria–Bertani (LB) broth or a model food system, Tyndallised carrot broth (TCB). Shikonin exhibited high inhibitory activity against both microorganisms, but to a lesser extent than the basic unit naphthazarin (5,8-dihydroxy-1,4-naphthoquinone). Rhein and carnosic acid showed noticeable inhibitory effects on S. aureus. In inoculated TCB containing 15 mg/L naphthazarin or 47 mg/L shikonin there was about 6 log reductions in E. coli counts, while 20 mg/L naphthazarin, 26.4 mg/L rhein, 45 mg/L shikonin or 68.7 mg/L carnosic acid caused 1.6, 2.4, 3.1 and 3.1 log reductions in S. aureus inocula, respectively. Log reductions obtained for S. aureus in TCB compared unfavourably with those found in LB broth.     

Chemical composition, cytotoxicity effect and antimicrobial activity of Ceratonia siliqua essential oil with preservative effects against Listeria inoculated in minced beef meat

The present study describes the phytochemical profile and the protective effects of Ceratonia siliqua pods essential oil (CsEO), a food and medicinal plant widely distributed in Tunisia. Twenty five different components were identified in the CsEO. Among them, the major detected components were: Nonadecane, Heneicosane , Naphthalene, 1,2-Benzenedicarboxylic acid dibutylester, Heptadecane, Hexadecanoic acid, Octadecanoic acid, 1,2-Benzenedicarboxylic acid, Phenyl ethyl tiglate, Eicosene, Farnesol 3, Camphor, Nerolidol and n-Eicosane. The antimicrobial activity of CsEO was evaluated against a panel of 13 bacteria and 8 fungal strains using agar diffusion and broth microdilution methods. Results have shown that CsEO exhibited moderate to strong antimicrobial activity against the tested species. In addition, the inhibitory effect of this CsEO was evaluated in vivo against a foodborne pathogens Listeria monocytogenes, experimentally inoculated in minced beef meat (2 × 10² CFU/g of meat) amended with different concentrations of the CsEO and stored at 7 °C for 10 days. The antibacterial activity of CsEO in minced beef meat was clearly evident and its presence led to a strong inhibitory effect against the pathogens at 7 °C. On the other hand, the cytotoxic effects of the essential oil against two tumoral human cell lines HeLa and MCF-7 were examined by MTT assay. The CsEO showed an inhibition of both cell lines with significantly stronger activity against HeLa cells. The IC₅₀ values were 210 and 800 μg/ml for HeLa and MCF-7 cells, respectively. Overall, results presented here suggest that the EO of C. siliqua possesses antimicrobial and cytotoxic properties, and is therefore a potential source of active ingredients for food and pharmaceutical industry.     

Immunomodulatory and anticancer activities of phenolics from Garcinia mangostana fruit pericarp

The methanolic extract of Garciniamangostana fruit pericarp was partitioned into butanol and water fractions in this work. Three major phenolics were purified and identified as P₁ [1,3,6,7-tetrahydroxy-2,8-(3-methyl-2-butenyl) xanthone], P₂ [1,3,6-trihydroxy-7-methoxy-2,8-(3-methyl-2-butenyl) xanthone] and P₃ (epicatechin). Strong antioxidant activities were detected for P₁–P₃. In vitro cell proliferation trials indicated that P₁ and P₃ exhibited good immunomodulatory activities when 7.5 μg/ml was used. Furthermore, P₁ and P₃ showed good cytotoxicities against human breast cancer cells (MCF-7) and human colon cancer cells (LOVO). P₁ exhibited the maximal cytotoxicity of 73.06% against MCF-7 cells and of 46.27% against LOVO cells when 62.5 μg/ml was used. The cytotoxicities of P₁, P₂, P₃ and paclitaxel against normal embryonic lung fibroblast cells (HELF) were in a decreasing order: paclitaxel > P₃ > P₁ > P_2. These results suggested that P₁ and P₃ could be used as a potential anticancer agent.