Antibacterial mode of action of seed essential oil of Eleutherococcus senticosus against foodborne pathogens

This study investigated the antibacterial mechanism of action of the seed essential oil of Eleutherococcus senticosus (ESEO) against foodborne pathogenic bacteria. Preliminarily, the ESEO (1000 μg disc^?1) showed potential antibacterial effect as diameter of inhibition zones (12.0 ± 0.2–37.0 ± 2.0 mm) against the tested foodborne pathogens. The MIC and MBC values of ESEO against the tested bacteria were found in the range of 125–500 and 500–1000 μg mL^?1, respectively. At MIC concentration, the ESEO had potential inhibitory effect on the cell viability of the tested pathogens. In addition, SEM analysis showed the inhibitory effect of ESEO as confirmed by considerable morphological alterations on the cell wall of B. cereus ATCC 13061 and E. coli O157:H7 ATCC 43889. Moreover, the ESEO revealed its mode of action against foodborne pathogens on membrane integrity as confirmed by release of extracellular ATP, 260‐nm absorbing materials and leakage of potassium ions. These findings confirm that the ESEO can be used as a potential antibacterial agent in food industry to inhibit the growth of various foodborne pathogens.     

Isolation of antimicrobial agent from the marine algae Cystoseira hakodatensis

Cystoseira hakodatensis is an unutilised brown algae belonging to family Sargassaceae. A crude methanol extract from the algae showed inhibitory effects on the growths of Bacillus cereus and Bacillus licheniformis. To isolate the major antimicrobial agent, a sequential active‐guided isolation procedure was applied: liquid–liquid extraction, column chromatography and bio‐autography. A marked antimicrobial agent (active α) was isolated in hydrophobic fraction and was determined to phenolics without carbohydrates and proteins by phytochemical test. Regarding the antimicrobial potential, the isolated active α showed better inhibitory effects against B. cereus and B. licheniformis at 2 and 4 times of lower concentrations (62.5 and 31.3 μg mL^?1) in comparison with epigallocatechin gallate. These results showed that C. hakodatensis is a potential source of antimicrobial agent capable of preventing the growth of the two bacteria.     

Growth inhibition of foodborne pathogens by co‐microencapsulation of lactobacilli cell free and propolis extracts

Cell free extracts (CFE) obtained from Lactobacillus plantarum FI 8595 and Lactobacillus reuteri ATCC 55730 alone or in combination with propolis ethanolic or water extracts (1%) were microencapsulated with maltodextrin (25%) before the subsequent spray drying process. They were morphologically characterized by scanning electron microscope. Chemical compositions of pure extracts were identified by gas chromatography–mass spectrometry. Antimicrobial activities of pure and microencapsulated extracts against four foodborne pathogens (Staphylococcus aureus ATCC29213, Listeria monocytogenes ATCC19112, Klebsiella pneumoniae ATCC700603 and Salmonella Paratyphi A NCTC13) were determined using agar well diffusion, broth microdilution and time kill assays. CFE from L. reuteri and L. plantarum consisted of acetic acid, pyrrolo[1,2‐a]pyrazine‐1,4‐dione, hexahydro‐3‐(phenylmethyl)‐, 2,3,4‐trihydroxybenzaldehyde and 9‐octadecenoic acid. The results also indicated the presence of two respective major compounds, namely, 2‐methoxy‐4‐vinylphenol (19.03%) and trans‐cinnamic acid (27.67%) in water and ethanolic propolis extracts. Presence of propolis extracts mainly ethanolic extract in microencapsulation led to higher inhibition zones against all foodborne pathogens (p < .05). The co‐microencapsulation of CFE from L. reuteri in combination with ethanolic or water extract of propolis resulted in 2.34‐ and 2.2‐fold higher inhibition zone towards L. monocytogenes. Pure and microencapsulated CFE from L. reuteri resulted in 2.89 and 2.14 log cfu/ml reduction in growth of S. Paratyphi A at 3 hr, respectively. The co‐microencapsulation of CFE from lactobacilli and propolis extracts mainly ethanolic extract could be suggested as a novel antimicrobial on inhibition of food pathogens, as they contain abundant bioactive substances.     

Bacillus subtilis HJ18‐4 from Traditional Fermented Soybean Food Inhibits Bacillus cereus Growth and Toxin‐Related Genes

Bacillus subtilis HJ18‐4 isolated from buckwheat sokseongjang, a traditional Korean fermented soybean food, exhibits broad‐spectrum antimicrobial activity against foodborne pathogens, including Bacillus cereus. In this study, we investigated the antibacterial efficacy and regulation of toxin gene expression in B. cereus by B. subtilis HJ18‐4. Expression of B. cereus toxin–related genes (groEL, nheA, nheC, and entFM) was downregulated by B. subtilis HJ18‐4, which also exhibited strong antibacterial activity against B. cereus. We also found that water extracts of soy product fermented with B. subtilis HJ18‐4 significantly inhibited the growth of B. cereus and toxin expression. These results indicate that B. subtilis HJ18‐4 could be used as an antimicrobial agent to control B. cereus in the fermented soybean food industry. Our findings also provide an opportunity to develop an efficient biological control agent against B. cereus.     

A Genome‐Scale Modeling Approach to Quantify Biofilm Component Growth of Salmonella Typhimurium

Salmonella typhimurium (S. typhimurium ) is an extremely dangerous foodborne bacterium that infects both animal and human subjects, causing fatal diseases around the world. Salmonella's robust virulence, antibiotic‐resistant nature, and capacity to survive under harsh conditions are largely due to its ability to form resilient biofilms. Multiple genome‐scale metabolic models have been developed to study the complex and diverse nature of this organism's metabolism; however, none of these models fully integrated the reactions and mechanisms required to study the influence of biofilm formation. This work developed a systems‐level approach to study the adjustment of intracellular metabolism of S. typhimurium during biofilm formation. The most advanced metabolic reconstruction currently available, STM_v1.0, was 1st extended to include the formation of the extracellular biofilm matrix. Flux balance analysis was then employed to study the influence of biofilm formation on cellular growth rate and the production rates of biofilm components. With biofilm formation present, biomass growth was examined under nutrient rich and nutrient deficient conditions, resulting in overall growth rates of 0.8675 and 0.6238 h^?1 respectively. Investigation of intracellular flux variation during biofilm formation resulted in the elucidation of 32 crucial reactions, and associated genes, whose fluxes most significantly adapt during the physiological response. Experimental data were found in the literature to validate the importance of these genes for the biofilm formation of S. typhimurium . This preliminary investigation on the adjustment of intracellular metabolism of S. typhimurium during biofilm formation will serve as a platform to generate hypotheses for further experimental study on the biofilm formation of this virulent bacterium.     

Inhibition of Gallic Acid on the Growth and Biofilm Formation of Escherichia coli and Streptococcus mutans

New strategies for biofilm inhibition are becoming highly necessary because of the concerns to synthetic additives. As gallic acid (GA) is a hydrolysated natural product of tannin in Chinese gall, this research studied the effects of GA on the growth and biofilm formation of bacteria (Escherichia coli [Gram‐negative] and Streptococcus mutans [Gram‐positive]) under different conditions, such as nutrient levels, temperatures (25 and 37 °C) and incubation times (24 and 48 h). The minimum antimicrobial concentration of GA against the two pathogenic organisms was determined as 8 mg/mL. GA significantly affected the growth curves of both test strains at 25 and 37 °C. The nutrient level, temperature, and treatment time influenced the inhibition activity of GA on both growth and biofim formation of tested pathogens. The inhibition effect of GA on biofilm could be due to other factors in addition to the antibacterial effect. Overall, GA was most effective against cultures incubated at 37 °C for 24 h and at 25 °C for 48 h in various concentrations of nutrients and in vegetable wash waters, which indicated the potential of GA as emergent sources of biofilm control products.     

外源核苷酸对干酪乳杆菌生长的促进作用及机制

探究2 种外源核苷酸，即5’-单磷酸胞苷（cytidine 5’-monophosphate，5’-CMP）和5’-单磷酸腺苷（adenosine 5’-monophosphate，5’-AMP）对干酪乳杆菌生长的促进作用，探究其对细菌生物被膜、胞外聚合物、粗提物群体感应抑制活性和抗食源致病菌生物被膜活性的影响。结果发现，2 种外源核苷酸对细菌的生长繁殖均有明显促进作用，刺激了细菌生物被膜和胞外聚合物的产生。此外还促进了干酪乳杆菌粗提物群体感应抑制活性和对志贺菌生物被膜的抑制作用。5’-CMP和5’-AMP可以作为细菌生长刺激物使用，在维护肠道健康方面具有广阔应用前景。     

Effects of Nisin and Lysozyme on Growth Inhibition and Biofilm Formation Capacity of Staphylococcus aureus Strains Isolated from Raw Milk and Cheese Samples

Effects of nisin and lysozyme on growth inhibition and biofilm formation capacity of 25 Staphylococcus aureus strains isolated from raw milk (13 strains) and cheese (12 strains) were studied. Nisin was tested at concentrations between 0.5 and 25 μg/ml; the growth of all strains was inhibited at 25 μg/ml, but the resistances of strains showed a great variation at lower nisin concentrations. In contrast, lysozyme tested at concentrations up to 5.0 mg/ml showed no inhibition on the growth of strains. Nisin used at the growth inhibitory concentration prevented the biofilm formation of strains, but strains continued biofilm formation at subinhibitory nisin concentrations. Lysozyme did not affect the biofilm formation of 19 of the strains, but it caused a considerable activation in the biofilm formation capacity of six strains. Twelve of the strains contained both biofilm-related protease genes (sspA, sspB, and aur) and active proteases; eight of these strains were nisin resistant. These results suggest a potential risk of S. aureus growth and biofilm formation when lysozyme is used in the biopreservation of dairy products. Nisin can be used to control growth and biofilm formation of foodborne S. aureus, unless resistance against this biopreservative develops.     

Antimicrobial activities of high molecular weight water‐soluble chitosans against selected gram‐negative and gram‐positive foodborne pathogens

Antimicrobial activities of high molecular weight water‐soluble chitosans (HMWWS) against selected Gram‐negative and Gram‐positive foodborne pathogens (initial inoculation of ca. 6.5 Log CFU mL^?1) were evaluated. Chitosans with 789 kDa and/or 1017 kDa were dissolved in aspartic acid (AS) to obtain 1–4% w/v solutions. Among HMWWS, only 4% 789 kDa AS chitosan reduced E. coli counts by 2 Log CFU mL^?1 from 7.33 at 0 h to 5.16 Log CFU mL^?1 at 96 h, and they were not effective against S. Typhimurium. Depending on the concentrations, HMWWS completely inhibited V. cholerae, V. vulnificus and V. parahaemolyticus as well as B. cereus and L. monocytogenes after 48 h or 96 h of incubation. Compared with the control (no HMWWS), 2% or 3% 1017 kDa AS chitosans showed about 3 Log CFU mL^?1 lower (4.72–4.86 vs. 7.71) for S. aureus at 96 h of incubation.     

Antimicrobial efficacies of essential oils/nanoparticles incorporated polylactide films against L. monocytogenes and S. typhimurium on contaminated cheese

Polylactide based films were formulated by incorporating polyethylene glycol, selected nanopowders (zinc oxide, silver-copper), and essential oils (cinnamon, garlic, and clove) by solvent casting method. Films were tested against three foodborne pathogens (one gram-positive and two gram-negative) for their antibacterial activity. The effectiveness of selected cinnamon oil-based film was ascertained by performing a challenge test with cheese as a food model. In vitro antibacterial efficacies of nanopowders and essential oils were also determined by the decimal reduction concentrations and the minimum bactericidal concentrations for those foodborne pathogens. It was observed that nanopowders exhibited considerably poorer decimal reduction concentrations and minimum bactericidal concentration values in comparison to the essential oils. Silver-copper alloy nanopowders exhibited lower decimal reduction concentrations and minimum bactericidal concentrations values than ZnO against tested pathogens whereas essential oils showed distinct antimicrobial effectiveness against all those pathogens with in vitro decimal reduction concentration values of 87–157 and 77–220 µg/mL for cinnamon and clove oils, respectively. Among the various formulations, it was observed that only essential oils (especially cinnamon and clove) incorporated films exhibited a significant antimicrobial activity against the selected microorganisms. These results indicate that the poor antibacterial activity of the nanopowders and the hydrophobicity of polylactide could be responsible for the ineffectiveness of nanopowders in polylactide based films. Furthermore, the challenge test indicated the polylactide/polyethylene glycol/cinnamon oil film was appropriate to inhibit the growth of L. monocytogenes and S. typhimurium on cheese up to 11 days at refrigerated storage.     

Identification of Bioactive Candidate Compounds Responsible for Oxidative Challenge from Hydro‐Ethanolic Extract of Moringa oleifera Leaves

Free radicals trigger chain reaction and inflict damage to the cells and its components, which in turn ultimately interrupts their biological activities. To prevent free radical damage, together with an endogenous antioxidant system, an exogenous supply of antioxidant components to the body in the form of functional food or nutritional diet helps undeniably. Research conducted by the Natl. Inst. of Health claimed that Moringa oleifera Lam possess the highest antioxidant content among various natural food sources based on an oxygen radical absorbent capacity assay. In this study, a 90% (ethanol:distilled water—90:10) gradient solvent was identified as one of the best gradient solvents for the effectual extraction of bioactive components from M. oleifera leaves. This finding was confirmed by various antioxidant assays, including radical scavenging activity (that is, 1, 1‐diphenyl‐2‐picrylhydrazyl, H₂O₂, and NO radical scavenging assay) and total antioxidant capacity (that is, ferric reducing antioxidant power and molybdenum assay). High‐performance liquid chromatography (HPLC) fingerprints of the 90% gradient extract visually showed few specific peaks, which on further analysis, using HPLC–DAD–ESI–MS, were identified as flavonoids and their derivatives. Despite commonly reported flavonoids, that is, kaempferol and quercetin, we report here for the 1st time the presence of multiflorin‐B and apigenin in M. oleifera leaves. These findings might help researchers to further scrutinize this high activity exhibiting gradient extract and its bio‐active candidates for fruitful clinical/translational investigations.     

Assessment of Oligogalacturonide from Citrus Pectin as a Potential Antibacterial Agent against Foodborne Pathogens

Foodborne diseases are an important public health problem in the world. The bacterial resistance against presently used antibiotics is becoming a public health issue; hence, the discovery of new antimicrobial agents from natural sources attracts a lot of attention. Antibacterial activities of oligogalacturonide from commercial microbial pectic enzyme (CPE) treated citrus pectin, which exhibits antioxidant and antitumor activities, against 4 foodborne pathogens including Salmonella Typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Pseudomonas aeruginosa was assessed. Pectin hydrolysates from CPE hydrolysis exhibited antibacterial activities. However, no antibacterial activity of pectin was observed. Citrus oligogalacturonide from 24‐h hydrolysis exhibited bactericidal effect against all selected foodborne pathogens and displayed minimal inhibitory concentration at 37.5 μg/mL for P. aeruginosa, L. monocytogenes, and S. Typhimurium, and at 150.0 μg/mL for S. aureus.     

Salmonella and Campylobacter biofilm formation: a comparative assessment from farm to fork

It takes several steps to bring food from the farm to the fork (dining table), and contamination with food‐borne pathogens can occur at any point in the process. Campylobacter spp. and Salmonella spp. are the main microorganisms responsible for foodborne disease in the EU. These two pathogens are able to persist throughout the food supply chain thanks to their ability to form biofilms. Owing to the high prevalence of Salmonella and especially of Campylobacter in the food supply chain and the huge efforts of food authorities to reduce these levels, it is of great importance to fully understand their mechanisms of persistence. Diverse studies have evaluated the biofilm‐forming capacity of foodborne pathogens isolated at different steps of food production. Nonetheless, the principal obstacle of these studies is to reproduce the real conditions that microorganisms encounter in the food supply chain. While there are a wide number of Salmonella biofilm studies, information on Campylobacter biofilms is still limited. A comparison between the two microorganisms could help to develop new research in the field of Campylobacter biofilms. Therefore, this review evaluates relevant work in the field of Salmonella and Campylobacter biofilms and the applicability of the data obtained from these studies to real working conditions. © 2018 Society of Chemical Industry     

Effect of nisin‐producing Lactococcus lactis starter cultures on the inhibition of two pathogens in ripened cheeses

The effect of Lactococcus lactis nisin‐producing strains, isolated from Italian fermented foods, on the survival of two foodborne pathogens namely Listeria monocytogenes and Staphylococcus aureus was investigated in experimental cheese production. One of the three Lactobacillus lactis nisin innoculated as starters, Lactobacillus lactis 41FL1 lowered S. aureus count by 1.73 log colony‐forming units (cfu)/g within the first 3 days, reaching the highest reduction, 3.54 log cfu/g, by the end of ripening period of 60 days. There was no effect on L. monocytogenes. The application of L. lactis 41FL1 as bioprotective culture in controlling S. aureus shows considerable promise.     

Bactericidal Activities of Health‐Promoting,Food‐Derived Powders Against the Foodborne Pathogens Escherichia coli,Listeria monocytogenes,Salmonella enterica,and Staphylococcus aureus

We evaluated the relative bactericidal activities (BA₅₀) of 10 presumed health‐promoting food‐based powders (nutraceuticals) and, for comparison, selected known components against the following foodborne pathogens: Escherichia coli O157:H7, Salmonella enterica, Listeria monocytogenes, and Staphylococcus aureus. The relative activities were evaluated using quantitative bactericidal activity [(BA₅₀ value, defined as the percentage of the sample in the assay mixture that resulted in a 50% decrease in colony forming units]. The BA₅₀ values were determined by fitting the data to a sigmoidal curve by regression analysis using concentration–antimicrobial response data. Antimicrobial activity is indicated by a low BA₅₀ value; meaning less material is needed to kill 50% of the bacteria. Olive pomace, olive juice powder, and oregano leaves were active against all 4 pathogens, suggesting that they behave as broad‐spectrum antimicrobials. All powders exhibited strong antimicrobial activity against S. aureus. The following powders showed exceptionally high activity against S. aureus (as indicated by the low BA₅₀ values shown in parentheses): apple skin extract (0.002%); olive pomace (0.008%); and grape seed extract (0.016%). Listeria bacteria were also highly susceptible to apple skin extract (0.007%). The most active substances provide candidates for the evaluation of antimicrobial effectiveness in human food and animal feed. Practical Application : Plant‐derived health‐promoting food supplements, high in bioactive compounds, are candidates for use as antimicrobials in food.     

Anti‐inflammatory and cytotoxic effects of ginseng extract bioconverted by Leuconostoc mesenteroides KCCM 12010P isolated from kimchi

A bioconversion technique using microorganisms has been applied to ginseng to increase content of bioactive ginsenoside and biofunctionality such as anticancer, anti‐obesity and antioxidant activities. The objective of this study was to screen lactic acid bacteria for bioconversion of ginsenosides and to evaluate anti‐inflammatory and cytotoxic effects of bioconverted ginseng extract. Strains isolated from kimchi were screened for their β‐glucosidase activities using esculin agar. Selected strain was identified based on 16S rRNA sequencing and carbohydrate fermentation. During ginseng fermentation, viable cell number and pH were determined. Bioconverted ginsenosides were analysed by HPLC. Anti‐inflammatory effects were evaluated using RAW 264.7 cells, and cytotoxic effects were determined by MTT assay. Among 166 isolates screened, Leuconostoc mesenteroides was selected for ginseng bioconversion, as it showed a higher β‐glucosidase activity and viable cell number than any of the other tested strains. After fermentation for 2 days, viable cell number was 8.8 log CFU mL^?1 and final pH was 4.8. Ginsenoside Rb₂ was bioconverted into ginsenoside Rg₃ (Rb₂ → Rd → Rg₃) by L. mesenteroides. The nitric oxide contents of 2‐day‐fermented extract decreased by as much as 25%, compared to a non‐fermented extract. The cell viabilities of HepG2, HT‐29, HeLa and LoVo treated with fermented ginseng extract also decreased by 49.7%, 20.2%, 21.0% and 8.7%, respectively, compared to those of control cells treated with non‐fermented extract. Ginseng extract bioconverted by L. mesenteroides showed anti‐inflammatory and anticancer effects. Therefore, bioconverted ginseng extract might have applications in the pharmaceutical and/or functional food industry.     

Effect of NaCl on the biofilm formation by foodborne pathogens

This study was designed to evaluate the effect of NaCl on the biofilm formation of Listeria monocytogenes, Staphylococcus aureus, Shigella boydii, and Salmonella Typhimurium. The biofilm cells were cultured in media containing different NaCl concentrations (0% to 10%) for 10 d of incubation at 37 °C using a 24-well polystyrene microtiter plate, collected by swabbing methods, and enumerated using plate count method. The attachment and detachment kinetic patterns were estimated according to the modified Gompertz model. The cell surface hydrophobicity and auto-aggregation were observed at different NaCl concentrations. Most strains showed 2 distinctive phases at lower than 6% NaCl, while the numbers of adhered cells gradually increased throughout the incubation period at 4% to 10% NaCl. At 0% NaCl, the numbers of adhered L. monocytogenes, S. aureus, S. boydii, and S. Typhimurium cells rapidly increased up to 7.04, 6.47, 6.39, and 7.27 log CFU/cm(2), respectively, within 4 d of incubation. The maximum growth rate (k(A)) and specific growth rate (μ(A)) of adherent pathogenic cells were decreased with increasing NaCl concentration. Noticeable decline in the numbers of adherent cells was observed at low concentration levels of NaCl (<2%). The adherence abilities of foodborne pathogens were influenced by the physicochemical surface properties. The hydrophobicity and auto-aggregation enhanced the biofilm formation during the incubation periods. Therefore, this study could provide useful information to better understand the adhesion and detachment capability of foodborne pathogens on food contact surfaces.     

Combating biofilms of foodborne pathogens with bacteriocins by lactic acid bacteria in the food industry

Most foodborne pathogens have biofilm-forming capacity and prefer to grow in the form of biofilms. Presence of biofilms on food contact surfaces can lead to persistence of pathogens and the recurrent cross-contamination of food products, resulting in serious problems associated with food safety and economic losses. Resistance of biofilm cells to conventional sanitizers urges the development of natural alternatives to effectively inhibit biofilm formation and eradicate preformed biofilms. Lactic acid bacteria (LAB) produce bacteriocins which are ribosomally synthesized antimicrobial peptides, providing a great source of nature antimicrobials with the advantages of green and safe properties. Studies on biofilm control by newly identified bacteriocins are increasing, targeting primarily onListeria monocytogenes, Staphylococcus aureus, Salmonella, and Escherichia coli. This review systematically complies and assesses the antibiofilm property of LAB bacteriocins in controlling foodborne bacterial-biofilms on food contact surfaces. The bacteriocin-producing LAB genera/species, test method (inhibition and eradication), activity spectrum and surfaces are discussed, and the antibiofilm mechanisms are also argued. The findings indicate that bacteriocins can effectively inhibit biofilm formation in a dose-dependent manner, but are difficult to disrupt preformed biofilms. Synergistic combination with other antimicrobials, incorporation in nanoconjugates and implementation of bioengineering can help to strengthen their antibiofilm activity. This review provides an overview of the potential and application of LAB bacteriocins in combating bacterial biofilms in food processing environments, assisting in the development and widespread use of bacteriocin as a promising antibiofilm-agent in food industries.     

Modulation of the mutagenicity of food carcinogens by oligomeric and polymeric procyanidins isolated from grape seeds: synergistic genotoxicity with N‐nitrosopyrrolidine

Oligomeric and polymeric procyanidins were isolated from grape seeds, and their antimutagenic potential against food carcinogens was evaluated in the Ames test. Both procyanidins suppressed the mutagenicity of IQ and benzo[a]pyrene but did not modulate the mutagenic activity of MNNG. At the concentrations where antimutagenic activity was expressed, the oligomeric and polymeric procyanidins inhibited the hepatic O‐dealkylation of methoxy‐ and ethoxyresorufin. It is concluded that the antimutagenic activity exhibited by oligomeric and polymeric procyanidins is the consequence of inhibition of CYP1A‐mediated bioactivation. In contrast with these findings, oligomeric and polymeric procyanidins potentiated the mutagenicity of N‐nitrosopyrrolidine; the monomeric tea flavanols (+)‐catechin and (−)‐epicatechin also elicited the same effect. Both the flavanols and procyanidins, at the concentrations studied, failed to elicit a mutagenic response in the Ames test, either in the presence or absence of an activation system. Incorporation of catalase and superoxide dismutase to the activation system failed to prevent the synergistic effect between (+)‐catechin and the nitrosamine. The mutagenic activity of N‐nitrosopyrrolidine was much higher when the bacteria were grown in nutrient broth supplemented with (+)‐catechin compared with bacteria grown in nutrient broth alone. It may be cautiously inferred that the synergistic genotoxicity between polyphenolics and N‐nitrosopyrrolidine involves interaction of (+)‐catechin with bacterial DNA, facilitating the covalent binding of the ultimate carcinogens of the nitrosamine to the DNA. © 2000 Society of Chemical Industry     

Antioxidant activity of prebiotic ginseng polysaccharides combined with potential probiotic Lactobacillus plantarum C88

The potential prebiotic properties of Panax ginseng polysaccharides were studied using ten strains of Lactobacillus plantarum isolated from traditional Chinese fermented foods. These probiotics showed different growth characteristics depending on the extract and strain specificity. L. plantarum C88 showed higher cell densities and growth rate when cultured on P. ginseng polysaccharides. In the in vitro antioxidant assay, P. ginseng polysaccharides combined with L. plantarum C88 were found to possess significant DPPH, ABTS and superoxide anion radicals scavenging activities, and acidic polysaccharides showed better antioxidant activity than neutral polysaccharides. Furthermore, we evaluated the antioxidant effect of acidic P. ginseng polysaccharide combined with L. plantarum C88 strain in natural ageing mice in vivo. Acidic P. ginseng polysaccharide and L. plantarum C88 together inhibited the formation of malondialdehyde (MDA) and increased the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH‐Px), catalase (CAT) and total antioxidant capacities (T‐AOC) in a dose‐dependent manner.