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PubMed1989

Lactobacillus effects on cholesterol: in vitro and in vivo results.

A double blind investigation was conducted on the influence of a commercially available tablet containing Lactobacillus acidophilus and Lactobacillus bulgaricus (Lactinex Becton Dickinson Microbiology Systems, Cockeysville, MD) on human serum lipoprotein concentrations. Tablets containing about 2 X 10(6) viable bacteria of Lactobacillus mixtures or placebo tablets were ingested by 354 nonfasting informed subjects in a dose of one tablet each, taken four times a day. There was a 3-wk washout period between two 6-wk treatment periods. The number of viable lactobacillus in unused returned tablets was the same at the end of the study as in the beginning. Analysis of paired data using Wilcoxon signed ranks test showed no major effects on lipoprotein concentrations for either the placebo-treated group or the lactobacilli-treated group. There were no statistically significant differences for low density lipoprotein concentrations between the lactobacilli-treated group and the placebo-treated group. The high density lipoprotein concentrations increased 1.8 to 3.0 mg/dl in both groups for both study periods. For total cholesterol the placebo-treated group experienced a statistically significant increase in the first period according to the Wilcoxon signed ranks test (from 208.0 to 215.0 mg/dl, P less than .001) but not according to a two-sample Student t test. Total cholesterol did not change significantly for the Lactobacillus-treated group in either period. Cardiac risk factor (ratio of total cholesterol to high density cholesterol) did not vary during the study. Lipoprotein values increased immediately following vigorous exercise compared with following 15 min of resting without either placebo or treatment. Sample controls for assay and reassay gave virtually identical values (coefficient of variation 1.6%), confirming that assay results were quite reliable. Thus, ingestion of commercially available Lactobacillus tablets, which contain about 2 X 10(6) cfu/tablet of L. acidophilus and L. bulgaricus cells in a dose of four tablets daily did not affect serum lipoprotein concentrations.

Buffers↗

PubMed2002

Species-specific identification of commercial probiotic strains.

Products containing probiotic bacteria are gaining popularity, increasing the importance of their accurate speciation. Unfortunately, studies have suggested that improper labeling of probiotic species is common in commercial products. Species identification of a bank of commercial probiotic strains was attempted using partial 16S rDNA sequencing, carbohydrate fermentation analysis, and cellular fatty acid methyl ester analysis. Results from partial 16S rDNA sequencing indicated discrepancies between species designations for 26 out of 58 strains tested, including two ATCC Lactobacillus strains. When considering only the commercial strains obtained directly from the manufacturers, 14 of 29 strains carried species designations different from those obtained by partial 16S rDNA sequencing. Strains from six commercial products were species not listed on the label. The discrepancies mainly occurred in Lactobacillus acidophilus and Lactobacillus casei groups. Carbohydrate fermentation analysis was not sensitive enough to identify species within the L. acidophilus group. Fatty acid methyl ester analysis was found to be variable and inaccurate and is not recommended to identify probiotic lactobacilli.

Carbohydrate Metabolism↗

PubMed1987

Survival of lactic acid bacteria in the human stomach and adhesion to intestinal cells.

The survival of four strains of lactic acid bacteria in human gastric juice, in vivo and in vitro, and in buffered saline, pH 1 to 5, has been investigated. The strains studied include two Lactobacillus acidophilus strains, Lactobacillus bulgaricus, and Streptococcus thermophilus. In addition, the adhesion of these strains to freshly collected human and pig small intestinal cells and to pig large intestinal cells has been studied and the effect of milk on both survival and adhesion tested. As a result of these investigations, an in vitro test system for screening potential cultures for use as human dietary adjuncts can be developed. The ability to survive in gastric juice and to adhere varied significantly for the strains tested; L. acidophilus ADH survived and adhered better than the others while S. thermophilus survived and adhered poorly. For all strains, both survival and adhesion was enhanced by milk. As all strains adhered to some extent to both human and pig intestinal cells, the adhesion mechanism is probably a nonspecific attachment as opposed to other reported specific Lactobacillus adhesion to gastric tissue. From the survival and adhesion data it seems feasible to obtain elevated levels of viable Lactobacillus sp. in human intestine by careful selection of the bacterial strains ingested. Furthermore, the in vitro methods used here should be valuable to screen potential strains. The data presented here can then be correlated with human in vivo studies monitoring the beneficial effect of ingestion of these Lactobacillus.

Animals↗

PubMed2003

Growth and metabolism of selected strains of probiotic bacteria in milk.

Growth and metabolism of five probiotic strains with well-documented health effects were studied in ultra-high temperature (UHT) treated milk, supplemented with 0.5% (w/v) tryptone or 0.75% (w/v) fructose. The probiotic strains were Lactobacillus acidophilus La5, Lb. acidophilus 1748, Lactobacillus rhamnosus GG, Lactobacillus reuteri SD 2112 and Bifidobacterium animalis BB12. Fermentation was followed for 72 h at 37 degrees C and the samples were analysed for pH, log cfu ml(-1), volatile compounds, organic acids and carbon dioxide. The strains reduced pH from 6.7 to between 3.9 and 4.4 after 24 h of incubation. All strains attained viable cell counts above 8.7-9.18 log cfu ml(-1) after 6-16 h of incubation. The two Lb. acidophilus strains showed a stable level of viable cells during 12-72 h of incubation but the three other strains showed a reduction of 0.4-1.1 log cfu ml(-1) from 24 to 72 h of incubation. However, all strains showed cell levels between 7.8 and 8.7 log cfu ml(-1) after 72 h of incubation. After 48 h of incubation, the amount of lactic acid produced varied according to strain from 6949 to 14,000 mg kg(-1) and acetic acid produced varied from 0 to 6901 mg kg(-1). Three of the strains metabolised citrate but only low amounts of diacetyl and acetoin were detected within strains, 0.2-0.8 and 6.5-10 mg kg(-1), respectively. Carbon dioxide produced varied from 221 to 3942 mg kg(-1) and was connected to the citrate-fermenting ability of the strain used and their carbohydrate fermentation pathway. Three of the strains produced detectable levels of acetaldehyde and the concentration varied from 9.4 to 12.6 mg kg(-1) after 24 h of incubation. All five probiotic strains showed very different profiles of metabolites during fermentation; however, the two Lb. acidophilus strains were the most alike. Our findings show the importance of controlling the fermentation time since the probiotic strains produced different amounts of metabolic products according to fermentation time.

Animals↗

PubMed2004

Effects of Lactobacilli and an acidophilic fungus on the production performance and immune responses in broiler chickens.

Accumulated lines of evidence indicate that inactivated probiotics could have beneficial effects similar to those of live probiotics. Two strains of disrupted, cobalt-enriched, lactic acid bacteria (Lactobacillus acidophilus and Lactobacillus casei) and a disrupted fungal mycelium (Scytalidium acidophilum) were spray-mixed onto a mash basal feed, in 2 concentrations, prior to pelleting. The effects of these probiotics on production performance and immune response in broiler chickens were investigated. The production parameters, including BW, feed intake (FI), BW gain (BWG), and feed conversion ratio (FCR), were monitored weekly during a 6-wk trial. The immune response was evaluated by immunizing the birds with the antigen keyhole limpet hemocyanin (KLH) followed by a serological assay to measure blood IgA and IgG titers. Some of the production parameters were significantly improved by low L. casei (LCL; for BW and BWG), high L. acidophilus (LAH; for BW and BWG), and high fungal (FH; for BW, BWG, and FI) in comparison with the nonadditive control (NC-). However, these 3 treatments (LCL, LAH, and FH) did not enhance the measured immune responses. Instead, the titers of serum KLH-specific IgA in high L. casei (LCH) and low L. acidophilus (LAL) were significantly higher than those of NC-, 10 d after immunization. None of the probiotic treatments increased the titer of KLH-specific IgG in blood. Our results indicate that disrupted and cobalt-enriched L. acidophilus or L. casei was able to enhance production performance of broiler chickens. The fungal mycelium, S. acidophilum, when used at a high concentration, also demonstrated its potential for the first time to be used as a probiotic. In addition, the optimal concentration for administering probiotics is strain dependent. A higher dose does not always result in a better performance.

Animal Nutritional Physiological Phenomena↗

PubMed2005

Antibacterial activities of MDPB and fluoride in dentin bonding agents.

The aim of this study was to compare in vitro antibacterial activity of MDPB containing bonding system ABF with activities of three Fluoride containing bonding systems (Fuji Bond LC (FBLC), Prime&Bond NT (PBNT), and FluoroBond (FLB). Two bacterial strains were tested: Streptococcus mutans and Lactobacillus acidophilus. The study was performed on Muller Hinton Agar by Agar Well Technique. The bacterial agar was evenly distributed over the surface of petri dishes. Standard wells were punched into the agar. The test materials were placed in the wells of Muller Hinton agar plates, inoculated with Streptococcus mutans NCTC10449 and Lactobacillus acidophilus. The diameters of inhibition zones produced around the materials were measured after 24 h of incubation at 37 +/- 1 degrees C. For statistical analysis, Duncan's multiple range test was used. The primers of bonding agents were highly effective against to Streptococcus mutans. The MDPB containing primer of ABF Bond produced the greatest inhibition zones against to Lactobacillus acidophilus. It was followed by FLB primer. Lactobacillus acidophilus was resistant to FBLC primer and bonding, ABF, PBNT and FLB bonding agents. The results of this study indicated that, incorporation of MDPB in primer of self-etch system increased its antibacterial activity especially against to Lactobacillus acidophilus. However, all bonding systems except for bonding agent of ABF showed some antibacterial activity against to Streptococcus mutans.

Anti-Bacterial Agents↗

PubMed1997

Antiproliferative effect of fermented milk on the growth of a human breast cancer cell line.

In vivo and in vitro studies have shown an antitumor activity of Lactobacilli in colon cancer, and some epidemiologic studies have indicated a reduced risk of breast cancer in women who consume fermented milk products. We studied the direct effect of milk fermented by five bacteria strains (Bifidobacterium infantis, Bifidobacterium bifidum, Bifidobacterium animalis, Lactobacillus acidophilus, and Lactobacillus paracasei) on the growth of the MCF7 breast cancer cell line. Our results showed a growth inhibition induced by all fermented milks, even though B. infantis and L. acidophilus were the most effective (85% inhibition after 9 days). The antiproliferative effect was not related to the presence of bacteria in fermented milk, and neither whole milk (crude or ultrahigh temperature sterlizied) nor its main fractions (lactalbumin or beta-lactoglobulin fraction) affected cell growth. Our findings suggest the presence of an ex novo soluble compound produced by lactic acid bacteria during milk fermentation or the microbial transformation of some milk components in a biologically active form. Although the mechanism of the antitumor activity is not clear, the present study suggests the potentiality offered by fermented milk as producers of compounds with antiproliferative activity useful in the prevention and therapy of solid tumors like breast cancer.

Animals↗

PubMed2003

Evaluation of the effect of malt, wheat and barley extracts on the viability of potentially probiotic lactic acid bacteria under acidic conditions.

In this work, the effect of cereal extracts, used as delivery vehicles for potentially probiotic lactic acid bacteria (LAB), on the acid tolerance of the cells was evaluated under conditions that simulate the gastric tract. More specifically, the effect of malt, barley and wheat extracts on the viability of Lactobacillus plantarum, Lactobacillus acidophilus and Lactobacillus reuteri during exposure for 4 h in a phosphate buffer acidified at pH 2.5 was investigated. In the absence of cereal extracts all strains demonstrated a significant reduction in their cell population, particularly L. plantarum. The viability of L. plantarum was improved by approximately 4 log(10) cycles in the presence of malt and 3 log(10) cycles in the presence of wheat and barley. The survival of L. acidophilus and L. reuteri was increased by more than 1.5 and 0.7 log(10) cycle, respectively, upon addition of cereal extracts. In order to evaluate the contribution of the cereal constituents on cell survival, the individual effect of glucose, maltose and free amino nitrogen (FAN), which were added at concentrations that correlated to the reducing sugar and FAN content of the cereal extracts, was examined. The viability of L. plantarum was progressively improved as the maltose or glucose concentration increased; an increase by approximately 2 log(10) cycles was observed in the presence of 8.33 g/l sugar. The survival of L. acidophilus increased by more than 1 log(10) cycle, even at very low concentrations of maltose and glucose (e.g., 0.67 g/l), while L. reuteri stability was enhanced in the presence of maltose but no appreciable effect was demonstrated in the presence of glucose. Sugar analysis indicated that glycolysis was inhibited in all cases. Addition of tryptone and yeast extract, used as sources of FAN, enhanced L. acidophilus acid tolerance, but did not affect L. reuteri and L. plantarum. The results presented in this study indicate that malt, wheat and barley extracts exhibit a significant protective effect on the viability of L. plantarum, L. acidophilus and L. reuteri under acidic conditions, which could be mainly attributed to the amount of sugar present in the cereal extracts.

Analysis of Variance↗

PubMed2005

Caseinoglycomacropeptide inhibits adhesion of pathogenic Escherichia coli strains to human cells in culture.

Caseinoglycomacropeptide (CGMP) derived from kappa-casein was investigated for its ability to inhibit the adhesion of 3 strains of verotoxigenic Escherichia coli (VTEC) and 3 strains of enteropathogenic Escherichia coli (EPEC) to human HT29 tissue cell cultures. Effects on adhesion of Desulfovibrio desulfuricans, Lactobacillus pentosus, Lactobacillus casei, Lactobacillus acidophilus, and Lactobacillus gasseri were also investigated. Generally, CGMP exerted effective anti-adhesive properties at a dose of 2.5 mg/mL, albeit with a high degree of strain specificity. The CGMP reduced adhesion of VTEC strains to <50% of the control and reduced adhesion of EPEC strains to between 80 and 10% of the control. The CGMP also reduced the adhesion of L. pentosus and L. casei to 44 and 42%, respectively. A slight but significant reduction of L. acidophilus, to 81%, was observed, but no significant effects were detected with either Dsv. desulfuricans or L. gasseri. Further investigation of the dose response relationships with the E. coli strains gave IC50 values ranging between 0.12 and 1.06 mg/mL.

Adenocarcinoma↗

PubMed1997

Role of bacteria in the pathogenesis of short bowel syndrome-associated D-lactic acidemia.

Previously, we have demonstrated that short bowel syndrome (SBS) patients suffer daily from D-lactic acidemia; in these patients rather high amounts of (bacterial) D-lactate emerge in blood and urine with a circadian rhythm. The aim of this study was to establish the microbial basis of D-lactic acidemia in SBS. Therefore, faecal flora of (young and adult) SBS-patients was analysed qualitatively and quantitatively, and compared to that of controls. The isolated bacterial species were screened for massive D- and/or L-lactate production after in vitro growth. After introduction of oral feeding in SBS-infants shortly after the resection, lactobacilli increased from < or = 1% up to 60 +/- 5% of the faecal flora within 2-3 weeks. In the faeces of patients with oral feeding the lactate producers Lactobacillus acidophilus and Lactobacillus fermentum were the major resident bacteria (each with 10(10)-10(12) cfu/g faeces). During active growth in vitro these lactobacilli produced massive amounts of D- and L-lactic acid from glucose. Use of oral antibiotics in two SBS-children did not reduce the total numbers of lactobacilli, but caused shifts within the intestinal populations of at least lactobacilli. It is concluded that the strongly reduced intestinal capacity for carbohydrate absorption and the oral consumption of easily fermentable carbohydrates form the physiological basis for D-lactic acidemia in SBS, and that the fermentative D-lactate production by intestinal bacteria, especially the abundant, resident lactobacilli, forms its microbial basis. In these patients the antimicrobial and therapeutic effects of antibiotics are unpredictable.

Acidosis, Lactic↗

PubMed2006

Antimicrobial susceptibility of non-enterococcal intrinsic glycopeptide-resistant Gram-positive organisms.

Non-enterococcal Gram-positive bacteria that are intrinsically vancomycin-resistant have been infrequently isolated in association with serious infections. However, well-documented infections have lately been reported with increasing frequency. Because these organisms may be pathogens, we tested the MICs of 19 antimicrobial agents by the agar dilution method for predicting susceptibility. The activity of these antimicrobial agents was assessed against 28 strains (Lactobacillus rhamnosus, 6; Lactobacillus acidophilus, 1; Lactobacillus casei, 1; Lactobacillus fermentum, 2; Lactobacillus brevis, 1; Lactobacillus plantarum, 1; Weissella confusa, 2; Leuconostoc mesenteroides, 7; Leuconostoc lactis, 4; Pediococcus acidilactici, 2; Pediococcus pentosaceus, 1), isolated from clinical specimens in an Argentinian university hospital from 1997 to 2003. The MICs of penicillin for 67% of the Lactobacillus strains and 100% of the Leuconostoc spp. and Pediococcus spp. strains tested were in the 0.25-2 microg/mL range. Erythromycin was the most active antimicrobial overall. Multiresistance was observed in 2 strains (Lactobacillus rhamnosus, 1; Lactobacillus plantarum, 1).

Anti-Bacterial Agents↗

PubMed2005

Marker-free chromosomal integration of the manganese superoxide dismutase gene (sodA) from Streptococcus thermophilus into Lactobacillus gasseri.

A strategy for functional gene replacement in the chromosome of Lactobacillus gasseri is described. The phospho-beta-galactosidase II gene (lacII) was functionally replaced by the manganese superoxide dismutase (MnSOD) gene (sodA) from Streptococcus thermophilus, by adapting the insertional inactivation method described for lactobacilli [Russell, W.M. and Klaenhammer, T.R. 2001 Efficient system for directed integration into the Lactobacillus acidophilus and Lactobacillus gasseri chromosomes via homologous recombination. Appl. Environ. Microbiol. 67, 4361-4364]. L. gasseri carrying the heterologous sodA gene grew on lactose as efficiently as the wild-type parent. An active MnSOD was expressed in the transgenic strain, and the enzyme migrated on PAGE-SOD activity gels to the same position as that of MnSOD from S. thermophilus. The expression of MnSOD from a single copy of sodA integrated in the chromosome of L. gasseri provided enhanced tolerance to hydrogen peroxide, and extended the viability of carbon/energy starved cultures stored at 25 degrees C. This is the first report showing the successful utilization of the pORI plasmids system to generate marker-free gene integration in L. gasseri strains.

Anti-Bacterial Agents↗

PubMed2005

Anticariogenic activity of macelignan isolated from Myristica fragrans (nutmeg) against Streptococcus mutans.

The occurrence of dental caries is mainly associated with oral pathogens, especially cariogenic Streptococcus mutans. Preliminary antibacterial screening revealed that the extract of Myristica fragrans, widely cultivated for the spice and flavor of foods, possessed strong inhibitory activity against S. mutans. The anticariogenic compound was successfully isolated from the methanol extract of M. fragrans by repeated silica gel chromatography, and its structure was identified as macelignan by instrumental analysis using 1D-NMR, 2D-NMR and EI-MS. The minimum inhibitory concentration (MIC) of macelignan against S. mutans was 3.9 microg/ml, which was much lower than those of other natural anticariogenic agents such as 15.6 microg/ml of sanguinarine, 250 microg/ml of eucalyptol, 500 microg/ml of menthol and thymol, and 1000 microg/ml of methyl salicylate. Macelignan also possessed preferential activity against other oral microorganisms such as Streptococcus sobrinus, Streptococcus salivarius, Streptococcus sanguis, Lactobacillus acidophilus and Lactobacillus casei in the MIC range of 2-31.3 microg/ml. In particular, the bactericidal test showed that macelignan, at a concentration of 20 microg/ml, completely inactivated S. mutans in 1 min. The specific activity and fast-effectiveness of macelignan against oral bacteria strongly suggest that it could be employed as a natural antibacterial agent in functional foods or oral care products.

Anti-Bacterial Agents↗

PubMed2006

Influence of intensive and extensive breeding on lactic acid bacteria isolated from Gallus gallus domesticus ceca.

In the present study, lactic acid bacteria (LAB) from the cecum of chickens bred either under intensive (commercial broilers) or extensive (free-range) conditions were isolated, identified and some of their probiotic characteristics determined. The LAB identified by 16S-23S rRNA PCR-ARDRA were mainly of Lactobacillus species and to a lesser extent of Enterococcus spp. for all animals. Free-range chickens showed a higher presence of Lactobacillus acidophilus while Lactobacillus reuteri and Lactobacillus johnsonii were more frequently recovered from commercial broilers. Lactobacillus crispatus was found only in commercial broilers, Lactobacillus vaginalis and Lactobacillus agilis only in free-range chickens and Lactobacillus salivarius in both types. Enterococcus isolates from ceca of commercial broilers showed a higher resistance to antimicrobial drugs. Lactobacillus isolates from free-range chickens presented a higher frequency of in vitro antagonistic activity against selected pathogens than from commercial broilers. All LAB isolates had predominantly non-hydrophobic surfaces, but with variations depending on age of the chickens and breeding conditions. Animal breeding caused variation on composition, antimicrobial susceptibility, antagonistic activity and surface hydrophobicity of LAB from chicken cecum. LAB isolates from ceca of free-range chickens have potential as probiotic agents, which may be used in the future as replacing the use of antimicrobials as growth promoters.

Age Factors↗

PubMed2002

Comparison of two selective media for the detection and enumeration of Lactobacilli in human faeces.

The enumeration of faecal bacteria is an important requirement for many studies of bowel health. One approach is the use of selective culture media for the culture and identification of genera or species from faeces. This study compares the culture of Lactobacilli from dilution series of faecal samples from six healthy human volunteers on two commonly used media, LAMVAB and Rogosa agar. Colonies were counted after a 72-h anaerobic incubation at 37 degrees C, and colony morphology recorded by a single observer. DNA was isolated from a representative number of colonies and genus-specific PCR, single-stranded conformation polymorphism (SSCP) and DNA sequencing performed. Total colony counts ranged from <3.00 to 7.48 log(10) cfu/g of faeces for LAMVAB and 5.09 to 7.66 log(10) cfu/g for Rogosa. For each subject, the total colony count was higher on Rogosa than that obtained with LAMVAB agar. SSCP analysis and DNA sequencing indicated that colony morphology was not an accurate predictor of genus identity. Growth of two species, Lactobacillus acidophilus and Lactobacillus gasseri, was not supported on LAMVAB medium. Rogosa agar was more likely to support growth of non-Lactobacillus species. Therefore, neither medium gave a fully accurate representation of the Lactobacilli species present in human faecal samples.

Adult↗

PubMed2003

The effect of temperature and pH on the growth of lactic acid bacteria: a pH-auxostat study.

The growth of Streptococcus salivarius subsp. thermophilus, Lactococcus lactis subsp. lactis, Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus acidophilus and Lactobacillus paracasei was studied in a pH-auxostat. The computer-controlled smooth change of pH or temperature was used to study the effect of pH and temperature on the culture characteristics (specific growth rate mu growth yield Y(ATP) and specific lactate production rate Q(ATP)). The behaviour of mu and Q(ATP) with an increase of temperature suggested that ATP production capacity was an important factor in determining the maximum growth rate of lactic acid bacteria (LAB). The decrease of Y(ATP) with increase of temperature resulted in the decrease of specific growth rate while Q(ATP) remained constant or even increased. With the decrease of pH, decrease of both Y(ATP) and Q(ATP) was observed. S. thermophilus St20 having the highest maximum specific growth rate of 2.2 h(-1) at 44 degrees C was the most acid sensitive strain. The L. paracasei E1H3 having the lowest mu(max) was the most tolerant strain to pH change. The behaviour of mixed culture of L. bulgaricus and S. thermophilus in milk in a pH-auxostat with pH-decrease was in agreement with the pure culture experiments of the same species. The study showed that pH-auxostat with smooth controlled change of pH and temperature is an effective method for determination of technological characteristics and comparative physiological study of LAB.

Fermentation↗

PubMed1998

Lactic acid bacteria growth promoters from Spirulina platensis.

Spirulina has been used for many years as human food because of its high protein content and nutritional value. Some strains also produce bioactive substances that may inhibit or promote microbial growth. Lactococcus lactis, Streptococcus thermophilus, Lactobacillus casei, Lactobacillus acidophilus, and Lactobacillus bulgaricus were grown in rich media, MRS and RM, as well as in minimal saline medium with and without addition of extracellular products obtained from a late log phase culture of Spirulina platensis in Zarrouk medium. In both MRS and RM media, the extracellular products significantly promote the growth of the lactic acid bacteria assayed. This stimulatory effect was observed in media with pH adjusted to 5.3, 6.3 and 7.0. No effect was observed in minimal saline medium.

Culture Media↗

PubMed2005

Selective growth-inhibiting effects of compounds identified in Tabebuia impetiginosa inner bark on human intestinal bacteria.

The growth-inhibiting activity of anthraquinone-2-carboxylic acid and lapachol identified in the inner bark of taheebo, Tabebuia impetiginosa, toward 10 human intestinal bacteria was evaluated by using a paper disk diffusion bioassay and compared to those of seven lapachol congeners (1,4-naphthoquinone, naphthazarin, menadione, lawsone, plumbagin, juglone, and dichlone) as well as two commercially available antibiotics, chloramphenicol and tetracycline. Anthraquinone-2-carboxylic acid exhibited very strong growth inhibition of Clostridium paraputrificum at 1 microg/disk while 100 microg/disk of lapachol was needed for moderate growth inhibition of the same organism. These two isolates exhibited weak inhibition of Clostridium perfringens and Escherichia coli at 100 microg/disk while no adverse effects were observed on the growth of Bifidobacterium adolescentis, Bifidobacterium bifidum, Bifidobacterium infantis, Lactobacillus acidophilus, and Lactobacillus casei at 1000 microg/disk. Structure-activity relationships indicate that a methyl group in the C-2 position of 1,4-naphthoquinone derivatives might play an important role in antibacterial activity.

Anthraquinones↗