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).     

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.     

Phenolics from hull of Garcinia mangostana fruit and their antioxidant activities

The air-dried fruit hulls of Garcinia mangostana Linn. were extracted with 70% MeOH, and then partitioned into the n-BuOH fractions. Furthermore, three major phenolic components related to their antioxidant activities were purified by silica gel column chromatography and Sephadex LH-20 and then identified as P₁ (1,3,6,7-tetrahydroxy-2,8-(3-methyl-2-butenyl)), P₂ [1,3,6-trihydroxy-7-methoxy-2,8-(3-methyl-2-butenyl) xanthone] and P₃ (epicatechin) using UV–visible spectrophotometry, IR spectrophotometry and NMR spectroscopy, respectively. The antioxidant activities of three major phenolics were evaluated using different tests, including the free radical scavenging capability and total antioxidant activity in a linoleic acid peroxidation. These three phenolic compounds exhibited different antioxidant activities in these antioxidant tests. The hydroxyl radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capabilities and the activity against linoleic acid peroxidation of P₁ were greater than those of P₂ and P₃, while the superoxide anion radical scavenging activity of P₃ was greater than that of P₁, but was close to that of P₂ or α-tocopherol. An activity-guided isolation and purification process was used to identify the components showing the strong DPPH radical scavenging activity from G. mangostana Linn.     

Characterisation of anthocyanins from Garcinia indica Choisy

The present study deals with isolation and characterisation of anthocyanins present in Garcinia indica Choisy (popularly known as kokum), which is a potential source of a natural food colourant. The kokum was found to contain a very high concentration of anthocyanins (2.4 g/100 g of kokum fruit), compared to other natural sources. Acid hydrolysis ascertained that this anthocyanin consisted of a single aglycone, i.e., cyanidin. A comparison of saponified and unsaponified fraction indicated that the pigment was not acylated. HPLC, mass and NMR spectroscopy analyses confirmed that the pigment essentially contains two anthocyanins, which were identified as cyanidin 3-glucoside and cyanidin 3-sambubioside.     

In vitro control of food-borne and food spoilage bacteria by essential oil and ethanol extracts of Lonicera japonica Thunb.

The antibacterial potential of essential oil from flowers and ethanolic leaf extracts of Lonicera japonica Thunb. was evaluated for controlling the growth of a range of food-borne pathogens. Thirty-nine compounds representing 92.34% of the total oil were identified, of which trans-nerolidol (16.31%), caryophyllene oxide (11.15%), linalool (8.61%), p-cymene (7.43%), hexadecanoic acid (6.39%), eugenol (6.13%), geraniol (5.01%), trans-linalool oxide (3.75%), globulol (2.34%), pentadecanoic acid (2.25%), veridiflorol (1.83%), benzyl alcohol (1.63%) and phenylethyl alcohol (1.25%) were the major compounds. The oil and extracts revealed a remarkable antibacterial effect against Listeria monocytogenes ATCC 19116, Bacillus subtilis ATCC 6633, B. cereus SCK 11, Staphylococcus aureus (ATCC 6538 and KCTC 1916), Salmonella enteritidis KCTC 12021, S. typhimurium KCTC 2515, Enterobacter aerogenes KCTC 2190 and Escherichia coli ATCC 8739. However, no effect was observed for Pseudomonas aeruginosa KCTC 2004 and E. coli O157:H7 ATCC 43888. Our findings demonstrate that the oil and extracts derived from L. japonica might be a potential source of preservatives for use in the food or pharmaceutical industries.     

In vitro activity of methanol extracts of plants used as spices against Mycobacterium tuberculosis and other bacteria

This study determined the phenolic composition of two thyme species (Lamiaceae), Origanum minutiflorum O. Schwarz and P.H. Davis and Thymbra spicata L. var. spicata, and assessed their antibacterial and antimycobacterial activities. “Kekik” is a collective term used in Turkey for plants that smell like thyme. O. minutiflorum, (locally “Sutculer kekigi”, endemic) and T. spicata var. spicata (locally “Karakekik”) are widely used in Turkey and are important export commodities.     

Antimicrobial activity of the essential oils of Brazilian species of the genus Cunila against foodborne pathogens and spoiling bacteria

The essential oils from aerial parts of six Brazilian species of the genus Cunila Mill. (Lamiaceae) currently used in beverages and food preparation, and in folk medicine, were obtained by steam distillation and analyzed by GC and GC/MS. The main components of the oils were: Cunila galioides citral (citral −77.9%), C. galioides menthene (mentha-trans-2,8-dienol −20.0%, limonene −13.6%, trans-ocimene −13.0%), C. incisa (1,8-cineole −42.9%, α-terpineol −14.0%), C. spicata (1,8-cineole −47.9%, α-terpineol −37.5%), C. menthoides (menthene −77.8%), C. angustifolia (sabinene −41.4%, γ-terpinene −11.4%), and C. microcephala (menthofuran −94.90%). These oils were screened for antibacterial activity against 15 bacterial species. The oil of C. galioides citral efficiently controlled the growth of Bacillus sp., L. monocytogenes, S. aureus, A. hydrophila, and E. faecalis, showing both contact and gaseous activity. Although less efficient, the other essential oils studied were effective against Bacillus species, S. aureus, and other specific bacteria. MIC and MCC values support their popular use, and indicate that they can be an efficient alternative for the control of foodborne and spoiling bacteria.     

In vitro antibacterial and antioxidant activities of Orthosiphon stamineus Benth. extracts against food-borne bacteria

Extracts of the Orthosiphon stamineus plant were tested for antimicrobial and antioxidant activities against selected food-borne bacteria in vitro. Whole O. stamineus plants (powdered) were extracted using various concentrations (0%, 25%, 50%, 75%, and 100%) of methanol. O. stamineus extracted with 50% methanol, 75% methanol and fraction 5 of a 50% methanolic extract demonstrated inhibitory activity against Vibrio parahaemolyticus. The inhibition observed with these O. stamineus extracts was comparable to the inhibition seen with the natural food preservative 5% lactic acid; this is likely due to the high concentration of rosmarinic acid found in the O. stamineus extracts. This study showed that the highest concentration of rosmarinic acid had the best antibacterial and free radical scavenging activities. This suggests that rosmarinic acid content is closely associated with antibacterial and free radical scavenging activities of O. stamineus extracts.     

Freeze drying technique for microencapsulation of Garcinia fruit extract and its effect on bread quality

Microencapsulation is an enduring technology for protection and controlled release of food ingredients. The Garcinia cowa fruit rinds are rich source of (−)-hydroxycitric acid (HCA), which is reported to have various health benefits. But, HCA is hygroscopic in nature and thermally sensitive. Hence, G. cowa fruit extract was microencapsulated using three different wall materials such as whey protein isolate (WPI), maltodextrin (MD) and combination of whey protein isolate and maltodextrin (WPI + MD in 1:1 ratio) by freeze drying at 30% concentration. The microencapsulated powders were evaluated for their impact on bread quality and free HCA concentration. The microcapsules exhibited wider particle size range of 15–100 μm and HPLC analysis showed that all the three encapsulates yielded higher free (above 85%) and net (above 90%) HCA recovery. Moreover, bread with WPI encapsulates exhibited higher volume, softer crumb texture, desirable colour and sensory attributes and had higher free HCA concentration. This indicated that WPI has excellent encapsulation efficiency than other two wall materials during bread baking.     

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.     

Jasmonoid glucosides,sesquiterpenes and coumarins from the fruit of Clausena lansium

The fruit of Clausena lansium (wampee) is popular in southern China and warm areas of the world. Our chemical study on the fruit yielded three jasmonoid glucosides, 12-β-d-glucopyranosyloxy-6-epi-7-isocucurbic acid-1,6-lactone (1), 12-β-d-glucopyranosyloxyjasmonic acid (2) and 12-hydroxyjasmonic acid (3), two sesquiterpenes, (+)-curcumen-12-oic acid (4) and (+)-(E)-α-santalen-12-oic acid (5), two coumarins, xanthotoxol (6) and indicolactone (7), in addition to 3,4-dihydroxybenzoic acid (8), 5-hydroxymethylfuraldehyde (9), isopropyl β-d-glucopyranoside (10) and stigmasterol (11). Their structures were determined by spectroscopic methods. Compound 1 was a new metabolite and the others excluding 6 were reported from the species for the first time. Compounds 1–7 were evaluated for antioxidant and antibacterial activities. Among them, compound 6 showed antioxidant activity in ferric reducing antioxidant power (FRAP) and DPPH radical scavenging assays as well as antibacterial activity against Staphyloccocus aureus and Shigella dysenteriae, while compound 5 was active against Bacillus cereus.     

Chemical analysis and preliminary toxicological evaluation of Garcinia mangostana seeds and seed oil

The chemical analysis and preliminary toxicological evaluation of Garcinia mangostana seeds and seed oil have been investigated in order to determine the possibility of using them for human and/or animal consumption. Proximate analysis showed that the seeds had high amount of carbohydrate and were rich in oil (21.68 ± 6.18%) but have a low protein content. The physical properties of the oil extracts showed the state to be liquid at room temperature (25 ± 1 °C) and the colour of the oil golden-orange. The specific gravity of the oil was 0.98 ± 0.01. Among the chemical properties of the oil extracts, acid value, saponification number, iodine value, percent free fatty acid and peroxide value compared well with those of conventional edible oils. The seed flour was found to be a good source of minerals. It contained considerable amounts of potassium (7071 mg/kg), magnesium (865 mg/kg) and calcium (454 mg/kg). Fatty acid composition of the seed oil indicated that the oil contained one essential fatty acids small proportions: linoleic acid (1.30%). The most prevalent fatty acids were palmitic acid (49.5%) and oleic acid (34.0%). Weanling albino rats appeared to suffer no toxicological effects when fed with G. mangostana seed oil in their diet for 8 weeks. Weekly monitoring of the rats showed good physical appearance and steady weight increase. Histological examination of sections of the heart, liver, kidney, spleen and lung revealed that the kidney of some of the rats had some degrees of pathology which included diffuse glomerular and tubular degeneration. No lesion was found in the heart and liver of the rats. The seed oil could be useful as an edible oil and for industrial applications.     

Isolation of lactic acid bacteria with inhibitory activity against pathogens and spoilage organisms associated with fresh meat

The use of lactic acid bacteria (LAB) as protective cultures in vacuum-packed chill-stored meat has potential application for assuring and improving food quality, safety and market access. In a study to identify candidate strains suitable for evaluation in a meat model, agar-based methods were employed to screen 181 chilled meat and meat process-related LAB for strains inhibitory to pathogens and spoilage organisms of importance to the meat industry. Six meat-derived strains, including Lactobacillus sakei and Lactococcus lactis, were found to be inhibitory to one or more of the target strains Listeria monocytogenes, Brochothrix thermosphacta, Campylobacter jejuni and Clostridium estertheticum. The inhibitory agents appeared to be either cell-associated or molecules released extracellularly with bacteriocin-like properties. Variations detected in the antimicrobial activity of LAB associated with changes to test parameters such as substrate composition underlined the importance of further in situ evaluation of the inhibitory strains in stored meat trials.     

Modeling inactivation kinetics of food borne pathogens at a constant temperature

Four food borne pathogens (Listeria monocytogenes CA and Ohio₂, Salmonella enteritidis FDA and Salmonella typhimurium E21274, Escherichia coli O157:H7 931 and 933, Staphylococcus aureus 485 and 765) were inactivated under mild temperature (60 °C) and their survival curves determined at selected time intervals. Tailing was observed in all survival curves as a monotonic upward concavity. The resulting survival curves were either described by the Weibull or traditional first-order model and goodness of fit of these models was investigated. Regression coefficients (R²), root mean square error (RMSE) and correlation plots suggested that Weibull model produced a better fit to the data than the traditional model. Hazard plots suggested that the Weibull model was fully appropriate for the data being analysed. Although more studies should be carried out to evaluate the applicability of the nonlinear models, the present study has shown that thermal process calculations should most probably be reconsidered. This could lead to a reduction in under- and over-processing of thermally treated foods     

Phenolic acid profiles of mangosteen fruits (Garcinia mangostana)

The composition of phenolic acids in various parts of mangosteen fruit (Garcinia mangostana) was determined by GC and MS. The total content of phenolic acids, identified by GC-FID ranged from 265.7 ± 12.7 (aril) to 5027.7 ± 188.0 (peel) mg per kg of dry matter of sample. Ten phenolic acids were identified in mangosteen fruit. Of these, protocatechuic acid was the major phenolic acid in the peel and rind, while p-hydroxybenzoic acid was the predominant phenolic acid in the aril. m-Hydroxybenzoic acid was detected only in the peel, while 3,4-dihydroxymandelic was present only in the rind. The phenolic acids liberated from esters and glycosidic bonds were the major fractions of phenolic acids in mangosteen fruit.     

Antibacterial activity of eicosapentaenoic acid (EPA) against foodborne and food spoilage microorganisms

Eicosapentaenoic acid (EPA), a long-chain polyunsaturated fatty acid of ω-3 type was evaluated for its antimicrobial action against the range of foodborne and food spoilage pathogens, using agar disc diffusion assay in Luria broth (LB) media. The EPA exhibited antimicrobial activity against Bacillus subtilis ATCC 6633, Listeria monocytogenes ATCC 19166, Staphylococcus aureus ATCC 6538, S. aureus KCTC 1916 and Pseudomonas aeruginosa KCTC 2004. The minimum inhibitory concentrations (MICs) of the EPA against the tested bacterial strains were found in the range of 500-1350 μg/ml using broth dilution method. EPA reduced the viability of S. aureus at 250, 125 and 62.5 μg/ml after 15 min exposure and a steep decline in colony forming units (CFUs) was observed at 125 μg/ml after 30 min exposure, while similar reduction in CFU rate was exhibited by EPA when treated with 62.5 μg/ml after 180 min. EPA also reduced the CFU numbers of P. aeruginosa at all the concentrations used in this study after 15 min exposure. On the other hand, scanning electron microscopy (SEM) study of bacterial cells clearly exhibited the antibacterial effect of EPA as evidenced by the damages found in the outer membrane of the cells when treated with EPA. The results demonstrated that EPA exerted significant bactericidal and bacteriostatic effects against both P. aeruginosa and S. aureus.     

Antibacterial effects of American cranberry (Vaccinium macrocarpon) concentrate on foodborne pathogens

Antibacterial effects of American cranberry (Vaccinium macrocarpon) concentrate on foodborne pathogens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella Typhimurium, and Staphylococcus aureus in vitro were investigated. Cranberry concentrate at various concentrations was prepared in distilled water (DW) or Brain Heart Infusion (BHI) broth. Pathogens were inoculated in each sample and incubated at 21 and 4 °C for 0, 1, 5, 7, and 24 h (DW samples) and 0, 1, 3, and 5 days (BHI samples). Transmission electron microscopy (TEM) was used to study the effects of cranberry concentrate on cellular structure of pathogens. DW results showed that S. Typhimurium and L. monocytogenes were reduced to non-detectable levels at 5 h in 100 μl/ml treatment at 21 and 4 °C. At 24 h, no target pathogens were detected from the 100 μl/ml treatment. BHI data indicated that the 100 μl/ml treatment reduced the four pathogens by 3-8 log CFU/ml compared with the control on Day 5 at 21 and 4 °C. TEM revealed damage to the bacterial cell walls and membranes. Cranberry concentrate has antibacterial effects on the four foodborne pathogens. Based on potential health benefits and proven antimicrobial effects, American cranberry concentrate may have dual applications as a food preservative.