Agar-well Diffusion Assay Research Articles

Antibacterial Activity Against Oral Pathogens and Anti–Oral Cancer Activity of Artemisia Species In Vitro

ABSTRACTThe antimicrobial activities of Artemisia species Plant extracts against oral pathogens were evaluated by agar-well diffusion assay, while its cytotoxicity on human oral carcinoma cell lines was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Streptococcus mutans was the most susceptible to A. selengensis and A. keiskeana with 6.0 and 5.0 mm diameters and was superior to the standard drugs, streptomycin and cetylpridinium chloride (CPC). A. japonica, A. keiskeana, and A. selengensis were susceptible to all tested oral pathogens; A. capillaries and A. sylvatica suppressed the growth of S. mutans, S. sobrinus, and S. epidermidis. A. selengensis had the most control of all oral pathogens, showing the strongest cytotoxicity against oral gingival carcinoma cell. Artemisia sp. showed mild cytotoxicity against oral squamous carcinoma cell. The cytotoxicity against the oral tongue carcinoma cell was observed in all tested Artemisia sp. except for A. sylvatica. Taken together, A. keiskeana and A. selengensis suppressed the growth of the tested bacteria and was cytotoxic to human oral carcinoma cell lines.

Antimicrobial Effects of Ferula persica Gum Extract and Gold Nanoparticles on Pseudomonas aeruginosa

Background: In the treatment of bacterial infections, drug resistance is a global problem; Pseudomonas aeruginosa is no exception. This bacterium is among the important causes of nosocomial infections, especially burn wound infections, and it is resistant to most applicable antibiotics. Objectives: The present study aimed to evaluate the anti-bacterial effects of Ferula persica gum extract and gold nanoparticles on P. aeruginosa strains isolated from burn wound infections in Isfahan in 2012. Materials and Methods: In this experimental study, 150 P. aeruginosa strains carrying the blaSPM-1 gene were isolated from burn wound infections and were confirmed by biochemical tests. The anti-microbial activities of Ferula persica gum extract and gold nanoparticles were evaluated by agar well-diffusion assay and microdilution antimicrobial susceptibility tests. The results were compared to ciprofloxacin. Results: The highest mean zone of inhibition (18 mm) was observed in a concentration of 250 mg/mL of F. persica extract, which was equal to that of ciprofloxacin. In the gold nanoparticles, the highest mean growth inhibition zone (10.18 mm) was observed in the dilution of 50 ppm. The highest zone of inhibition of nanoparticle-extract synergy was observed in the dilution of 125 mg/mL extract + 25 ppm nanoparticle (9.89 mm). The MIC and MBC of the extract were 69.25 ± 42.36 mg/mL and 102.25 ± 16.76 mg/mL, respectively. The MIC and MBC of the nanoparticle-extract mixture were 50.78 ± 19.26 mg/mL and 54.11 ± 19.72 mg/mL, respectively. Conclusions: The results of the present study showed that the extract of F. persica gum and the gold nanoparticles had antiPseudomonas aeruginosa effects, which were more pronounced when they were used separately.

Antibacterial activity of aquatic gliding bacteria.

The study aimed to screen and isolate strains of freshwater aquatic gliding bacteria, and to investigate their antibacterial activity against seven common pathogenic bacteria. Submerged specimens were collected and isolated for aquatic gliding bacteria using four different isolation media (DW, MA, SAP2, and Vy/2). Gliding bacteria identification was performed by 16S rRNA gene sequencing and phylogenetic analysis. Crude extracts were obtained by methanol extraction. Antibacterial activity against seven pathogenic bacteria was examined by agar-well diffusion assay. Five strains of aquatic gliding bacteria including RPD001, RPD008, RPD018, RPD027 and RPD049 were isolated. Each submerged biofilm and plastic specimen provided two isolates of gliding bacteria, whereas plant debris gave only one isolate. Two strains of gliding bacteria were obtained from each DW and Vy/2 isolation medium, while one strain was obtained from the SAP2 medium. Gliding bacteria strains RPD001, RPD008 and RPD018 were identified as Flavobacterium anhuiense with 96, 82 and 96 % similarity, respectively. Strains RPD049 and RPD027 were identified as F. johnsoniae and Lysobacter brunescens, respectively, with similarity equal to 96 %. Only crude extract obtained from RPD001 inhibited growth of Listeria monocytogenes (MIC 150 µg/ml), Staphylococcus aureus (MIC 75 µg/ml) and Vibrio cholerae (MIC 300 µg/ml), but showed weak inhibitory effect on Salmonella typhimurium (MIC > 300 µg/ml). Gliding bacterium strain RPD008 should be considered to a novel genus separate from Flavobacterium due to its low similarity value. Crude extract produced by RPD001 showed potential for development as a broad antibiotic agent.

An in vitro Investigation of the Antagonistic Effects of Multiple Strains of Lactobacillales on Salmonella enterica Serovar Choleraesuis

Objectives: The aim of this study was to investigate the conditions for viable lactic acid bacteria (LAB) cells and their heat-killed LAB, and the formulation as well as an alternative treatment to antibiotics to reduce infection, invasion and the inhibition of IL-8 secretion induced by S. choleraesuis for HT-29 cells. Methods: To examined the efficacy of live LAB and heat-killed products in (1) inhibiting Salmonella choleraesuis growth by the plate agar-well diffusion assay, (2) adhering to swine intestinal cells and human intestinal Caco-2 cell line, (3) inhibiting the invasion of HT-29 cell line by Salmonella choleraesuis, and (4) inhibiting Salmonella choleraesuis induced interleukin (IL)-8 secretion by HT-29 cells Results: The results indicated that viable LAB and heat-killed products significantly reduced S. choleraesuis infection, invasion in the HT-29 cell line, and had the adhesion ability of the LAB to the swine intestinal cells and human intestinal Caco-2 cell line. Both viable and heat-killed LAB powder possess an ability to reduce the S. choleraesuis induced interleukin (IL)-8 secretion by HT-29 cells, and viable bacteria powder products are the most effective. Conclusion: Both viable and heat-killed LAB powder products were potentially useful for the protection of the epithelial cells against Salmonella infection, invasion and the induced inflammation for swine and human.

English

The study aimed to determine the influence of sample preparation and extraction parameters on the antibacterial activity of inflorescences from banana (Musa balbisiaba cv. Saba). Banana inflorescences were extracted using various solvent extractions and tested for antibacterial activity using agar-well diffusion assay against gram-positive bacteria (Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes and Brochothrix thermosphacta) and gram-negative bacteria (Salmonella typhimurium, Salmonella enteritidis, Escherichia coli O157:H7, Enterobacter sakazakii, Yersinia enterocolitica and Vibrio parahaemolyticus) The effects of geographical origin, drying methods and extraction parameters (sample-to-solvent ratio, extraction time and temperature as well as methanol to solvent ratio) on antibacterial activity of the banana by-product were carried out. Among all the extracts evaluated, methanolic extract from the buds showed significant higher inhibitory against all gram positive bacteria ranging from 12.56-13.54 mm. Interestingly, no significant different (p>0.05) was observed on the effect of geographical origin as well as extraction methods on the antibacterial capacity. Meanwhile, the extracts produced from 50°C oven dried sample seem to have comparable antibacterial activity with the freeze dried samples. Extraction parameters (sample-to-solvent ratio, extraction time and temperature as well as methanol to solvent ratio) were found responsible in determining the efficacy of the antibacterial. In conclusion, methanolic extracts from banana inflorescence buds could be a new source of natural antibacterial and further bioassay guided fractionation should be carried out to determine the bioactive compounds and their biological activities.

A novel bacteriocin produced by Lactobacillus plantarum LpU4 as a valuable candidate for biopreservation in artisanal raw milk cheese

Indigenous lactic acid bacteria-producing bacteriocins could enhance the microbiological safety of traditional cheeses. This study aimed to detect bacteriocinogenic strains among 35 Lactobacillus plantarum isolated from artisanal, raw sheep-milk cheeses. The isolates were identified by API 50 CHL and species-specific PCR. As displayed by agar well-diffusion assay, the cell-free supernatant of L. plantarum LpU4 showed the highest antimicrobial activity against Enterococcus faecalis JH2-2. The activity was not detected after treatment with proteinase K, pepsine and pronase. An active peptide band was shown by tricine–sodium dodecyl sulfate (SDS)–polyacrylamide gel electrophoresis and subsequent bioassay. MALDI-TOF analysis revealed a protein of 4,866.7 Da, having no homology with other known bacteriocins. The novel bacteriocin (named plantaricin LpU4) was heat stable (121 °C for 15 min), unaffected by chemicals as Tween 20, SDS, Triton ×100, EDTA, NaCl and exposure to a wide range of pH. The synthetic machinery encoding for the plantaricin was plasmid-located, as deduced by plasmids curing. Activity spectrum included several lactic acid bacteria and Staphylococcus aureus strains having antibiotic resistance phenotype. Plantaricin LpU4 showed a bacteriostatic mode of action and an enhanced activity at acidic pHs. Maximal production (3,200 AU.mL−1) was reached during the late exponential phase of growth of L. plantarum LpU4. Relatively low temperature (15–25 °C) and initial pH between 5.5 and 6.2 increased the production. Since L. plantarum LpU4 produced the bacteriocin under experimental conditions mimicking the cheese environment, it could be considered a promising candidate for use as biopreservative in traditional cheese.

High-throughput screening assays for antibacterial and antifungal activities of Lactobacillus species

We describe high-throughput screening techniques to rapidly detect either antimicrobial activity, using an agar-well diffusion assay in microtiter plates, or antifungal activity using an agar-spot assay in 24-well plates. 504 Lactobacillus isolates were screened with minimal laboratory equipment and screening rates of 2000–5000 individual antimicrobial interactions.

English

Thirty isolates of Bacillus were collected from chickpea rhizosphere and screened for their in vitro inhibition against root rot (Rhizoctonia bataticola) and wilt (Fusarium oxysporum f.sp. ciceri) pathogens and growth promotion of chickpea. Based on the in vitro inhibition and growth promotion tests, the best eight isolates were selected and PCR-based detection of antibiotics genes viz., surfactin, iturin, fengycin and bacillomycin D was carried out. The isolate which produced all these antibiotics and showed maximum in vitro inhibition (CaB 5) was further used for crude antibiotics extraction and inhibition assays. The presence of antibiotics in crude extract was detected through TLC. The inhibitory effect of the crude extract was proved through agar-well diffusion assay and spore germination inhibition test. From this study, it was inferred that the Bacillus subtilis strain CaB5 was promising in inhibiting the root rot and wilt pathogens of chickpea and enhance seedling vigour. Key words: Biological control, plant growth promotion, surfactin, iturin, fengycin.

The activity of different extracts from Panax quinquefolium L. cultures against pathogenic Staphylococcus aureus with respect to ginsenoside content

Ginsenosides can be isolated from various cultures of Panax quinquefolium L., American ginseng. The aim of the study was to determine the antibacterial activity of extracts from leaves, stalks, hairy root cultures and field roots of P. quinquefolium L. containing ginsenosides against Staphylococcus aureus isolates obtained from various clinical materials. The agar well diffusion assay was used to evaluate microbial growth inhibition at various concentrations of extracts. The susceptibility of the clinical isolates to recommended antibiotics was determined with the disk-diffusion method. The results showed that the tested extracts inhibited the growth of all S. aureus clinical isolates, including MRSA (methicillin-resistant S. aureus) with MIC values ranging from 0.5 mg/mL to 1.7 mg/mL. The level of antimicrobial activity of extracts depends on the ginsenoside content. Both field roots and hairy root cultures represent excellent sources of these metabolites. Extracts with ginsenosides were found to inhibit multidrug-resistant staphylococci and can be a valuable complement to antistaphylococcal therapy.

Evaluating the Antibacterial Potential of Streptomyces sp.

Background and Objectives: Marine bacteria are recognized as an untapped resource of bioactive metabolites of diverse structure and functions. The present research is focused on the screening of the antagonistic potential of bacteria isolated from marine sponge against human and shrimp pathogens. Methods and Findings: In this study, a total of 51 strains of bacteria isolated from five species of marine sponges sourced from the Vizhinjam littoral (Indian Ocean) were screened for possible antagonistic activity against human and shrimp pathogens. Of the 51 bacterial isolates, twelve strains isolated from marine sponges, S.officinalis and D. nigra showed different ranges of activity. The results of agar-well diffusion assay showed that, out of the twelve strains, MAPS 15 strain showed the highest activity which subdued the growth of all the tested 20 bacterial pathogens. The molecular characterization based on partial 16S rRNA sequence revealed that the active isolate MAPS 15 was Streptomyces sp. Conclusion: This study serves as a basis for further research on the possibility of utilizing Streptomyces sp. for the development of human and veterinary grade antibiotics.

Antibacterial and cytotoxic properties of boron-containing dental composite

Secondary dental caries are one of the major reasons for restoration replacements. Incorporating antimicrobial properties into dental materials would limit the initiation and progression of dental caries. In the current study, dental composites having 1%, 5%, and 10% (w/w) sodium pentaborate pentahydrate were prepared and analyzed for their mechanical properties, degree of monomer conversion (DC) rate, antibacterial effects against Streptococcus mutans, and biocompatibility with human dental pulp stem cells (hDPSCs). Incorporation of boron into the composites significantly decreased flexural strength and DC in a dose-dependent manner, but the value for 1% boron-containing composite still remained within acceptable levels. Compressive strength and diametral tensile strength were not found to be different from those of controls. Although no inhibition zone was detected in an agar-well diffusion assay for any materials tested, significant bacterial growth inhibition was obtained in a direct contact test for boron-containing composites. Immunocytochemical and lineage-specific gene expression analysis revealed that composites with boron content increased the osteogenic and odontogenic capacity of hDPSCs. Boron-containing dental composites showed promising results for future clinical applications, displaying nontoxic, osteogenic, and odontogenic-inducing characteristics with remarkable antibacterial activity against S. mutans, and are hence potentially able to prevent secondary caries.

English

The bacteriocins produced by lactic acid bacteria (LAB) which acted as antimicrobial substances or preservative component on fermented food product (yoghurt, kunu and fufu) was investigated against selected indicator food spoilage causing bacteria and antibiotics. The agar-well diffusion assay was employed to investigate the antagonistic activity against indicator organisms (Staphylococcus aureus, Shigella spp., Salmonella typhi and Escherichia coli). Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus delbrueckii sub bulgaricus, Lactobacillus amylophilus, Lactococcus lactis and Leuconostoc mesenteroides were isolated from yoghurt, fufu and kunu. L. lactis showed the largest inhibition zone against S. typhi and S. aureus as 19 and 14 mm, respectively, while L. amylophilus showed antimicrobial activity against all the indicator organisms. Isolates from fufu generally showed more inhibition on S. aureus, S. typhi and E. coli, while L. plantarum showed no inhibitory zone against the indicator organisms. All the isolates were susceptible to ciprofloxacin, but resistant to ampiclox, zinnacef and amoxacillin, while variable susceptibility/resistance to pefloxacin, gentamycin rocephin, streptomycin, septrin and erythromycin was observed. LAB showed inhibitory properties against the food spoilage and pathogenic organisms tested, and have been reported to produce various antimicrobial compounds including organic acid, hydrogen peroxide, di-acetyl and bacteriocin. This study is important in risk assessment related to fermented food products, as well as the potential use of these LAB isolates in pharmaceutical industries. Key words: Lactic acid bacteria, fermented foods, yoghurt, ‘kunu’, ‘fufu.

Antimicrobial and Antioxidant Activity of Crude Extracts of Rauvolfia caffra var. caffra (Apocynaceae) From Tanzania

As part of an effort to search for extracts and compounds with new antimicrobial efficacy to fight against bacterial resistance, the antibacterial activity of Rauvolfia caffra var. caffra (Sond.), a plant of family Apocynaceae used in Traditional Medicine in Tanzania, was investigated. Ethanol, methanol and water extracts from leaf, stem and root barks were tested against three species of bacteria namely Escherichia coli (ATCC 25922) (Gram -ve), Staphylococcus aureus (ATCC 25923) (Gram +ve) and Enterococcus faecalis (ATCC 51299) (Gram +ve) using Agar-well diffusion assay method and minimum inhibitory concentration on Mueller-Hinton Agar plates. The extracting solvents were removed by vacuo evaporator to obtain gummy-like extracts. This was then dissolved in dimethylsulfoxide (10% DMSO). The DMSO without plant extracts was used as a negative control whereas Gentamicin® as the standard antibiotic was used as a positive control. The Zone of Inhibition (ZOI) measured in mm and Relative Inhibitory Zone Diameter (RIZD) was calculated. Results showed that R. caffra exhibited antimicrobial inhibitory activity at a range of 1.25 to 5.0 mg/ml with activity most prominent with methanol extract (ZOI of 28.33± 0.33 mm and RIZD of 95% for S. aureus; and ZOI of 26.66 ± 0.33 mm for E.coli and 19.0 ± 0.57 mm for E. faecalis at P< 0.05). To characterize further, the alkaloid from the root bark was extracted according to the standard procedure. The antioxidant activity of the alkaloids and ethanolic extracts was determined using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and reducing capacity assays. The results indicated that alkaloid fraction of the root and 80% ethanolic extracts of stem bark exhibited high antioxidant activity. The phytochemical analysis indicated that R. caffra is rich in alkaloids, anthraquinones, anthocyanoides, flavonoids, saponins, tannis and reducing sugars. This study provides supportive evidence that methanol and ethanol extracts of R. caffra can be used as herbal medicine in control of E.coli, S. aureus and E. faecalis.

Antibacterial activities of extracts from Ugandan medicinal plants used for oral care

Ethnopharmacological relevanceMedicinal plants are widely used for treatment of oral/dental diseases in Uganda. Aim of the studyTo investigate antibacterial activities of 16 commonly used medicinal plants on microorganisms associated with periodontal diseases (PD) and dental caries (DC). Materials and methodsPulp juice and solvent extracts (hexane, methanol and water) from the plants were tested against Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia associated with PD and Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus associated with DC. Tests were done using agar well-diffusion (pulp juice) and agar-dilution (Solvent extracts) assays. ResultsPulp juice from Zanthoxylum chalybeum and Euclea latidens showed activity against all the bacteria, Zanthoxylum chalybeum being most active. Hexane extract from aerial part of Helichrysum odoratissimum was most active (MIC: 0.125–0.5mg/ml). Methanol extract from leaves of Lantana trifolia showed activity against all bacteria (MIC: 0.25–1mg/ml). ConclusionSeveral of the tested plants showed antibacterial activities against bacteria associated with PD and DC, meriting further investigations.

Qualitative detection of class IIa bacteriocinogenic lactic acid bacteria from traditional Chinese fermented food using a YGNGV-motif-based assay

In the present study, a YGNGV-motif-based assay was developed and applied. Given that there is an increasing demand for natural preservatives, we set out to obtain lactic acid bacteria (LAB) that produce bacteriocins against Gram-positive and Gram-negative bacteria. We here isolated 123 LAB strains from 5 types of traditional Chinese fermented food and screened them for the production of bacteriocins using the agar well diffusion assay (AWDA). Then, to acquire LAB producing class IIa bacteriocins, we used a YGNGV-motif-based assay that was based on 14 degenerate primers matching all class IIa bacteriocin-encoding genes currently deposited in NCBI. Eight of the LAB strains identified by AWDA could inhibit Gram-positive and Gram-negative bacteria; 5 of these were YGNGV-amplicon positive. Among these 5 isolates, amplicons from 2 strains (Y31 and Y33) matched class IIa bacteriocin genes. Strain Y31 demonstrated the highest inhibitory activity and the best match to a class IIa bacteriocin gene in NCBI, and was identified as Enterococcus faecium. The bacteriocin from Enterococcus avium Y33 was 100% identical to enterocin P. Both of these strains produced bacteriocins with strong antimicrobial activity against Listeria monocytogenes, Escherichia coli, and Bacillus subtilis, hence these bacteriocins hold promise as potential bio-preservatives in the food industry. These findings also indicated that the YGNGV-motif-based assay used in this study could identify novel class IIa bacteriocinogenic LAB, rapidly and specifically, saving time and labour by by-passing multiple separation and purification steps.

김치의 저장성 향상을 위한 항균활성 우수 유산균 선발

김치는 살균공정 없이 유통되기 때문에 유통과정에서도 발효가 진행되는 특성을 가지고 있어 김치의 산도가 계속 증가하여 김치의 상품성이 저하되는 문제점을 안고 있다. 본 연구에서는 김치발효과정 중 과도한 산생성에 관여하는 균주 선발과 더불어 이들 균주의 성장을 억제할 수 있는 항균활성을 지닌 균주를 김치로부터 선발하고자 하였다. 우선 김치과숙 관련 균주를 선발한 결과 Lb. plantarum 20-10, Lb. plantarum A-1, P. pentosaceus A-2, P. pentosaceus A-5, Lb. plantarum A-6, P. pentosaceus B-11로 동정이 되었다. 이들 균주를 억제할 수 있는 항균활성을 지닌 균주를 적숙기 김치로부터 선발한 결과 Lc. lactis, Lb. brevis 두 균주가 항균활성이 우수한 것으로 나타났다. 이들 균주의 김치 종균으로서의 적용 가능성을 살펴본 결과 모든 균주가 pH 3.5에서의 내산성, 3% NaCl에서의 내염성, 4°C에서의 생육가능성을 나타내었다.

Testing of Bacterial Endophytes from Non-Host Sources as Potential Antagonistic Agents against Tomato Wilt Pathogen &amp;lt;i&amp;gt;Ralstonia solanacearum&amp;lt;/i&amp;gt;

The study was taken up with the objective of testing whether the endophytic organisms isolated from crops that are normally non-hosts to the bacterial wilt pathogen Ralstonia solanacearum possessed pathogen-antagonistic activity and to evaluate the selected isolates for the alleviation of wilt disease in the target tomato crop through horizontal movement of promising organisms. Sixteen endophytic bacteria (EB) isolated from the micropropagated cultures of grape, watermelon and papaya were tested for potential antagonistic effects against R. solanacearum tomato isolate “NH-01” through agar-well diffusion assay. Enterobacter cloacae from papaya (EB-11) displayed the maximum antagonistic effect followed by Bacillus subtilis (EB-06) and B. flexus (EB-07) from watermelon and B. pumilus (EB-02) from grape. Testing the above organisms for crop protection through seed fortification of susceptible tomato cv. Arka Vikas at sowing in R. solanacearum inoculated (Ral+) organic cocopeat showed EB-02 and EB-11 promising (33% and 32% survival, respectively, four weeks after sowing against 15% in Ral+ control). A second trial showed 37%, 28%, 21% and 55% seedling survival 6 weeks after sowing for EB-02, EB-06, EB-07 and EB-11 respectively, compared to 2.5% in non-treated control. Assessing the four endophytes for crop protection in Ral+ sick-soil through seedling fortification at transplanting indicated less disease incidence in treated sets (40%, 40%, 20% and 20% survival, respectively, six weeks after transplanting) over non-fortified control (5%). Endophytic fortification of seedlings through hypocotyl inoculation showed some systemic resistance induction upon seedling transplanting to sick soil but not with petiole fortification. Seedling growth was enhanced by the isolates EB-06 and EB-07. The study thus identifies four endophytic organisms from crops unrelated to tomato possessing potential antagonistic activity against the wilt pathogen and prospects for exploitation as biocontrol agents coupled with seedling growth promotion effects.

Amish Burn Ointment and Burdock Leaf Dressings

Amish burn wound ointment (ABO) contains honey, lanolin, oils, glycerin, bees wax, and other natural additives. Although there are many anecdotal reports that this ointment covered with a burdock leaf (BL) dressing promotes burn wound healing, little scientific testing of this treatment has occurred. The goal of this study was to evaluate in vitro some of the components of this treatment modality for antimicrobial and cytotoxic activities. The ABO was tested for sterility using standard microbiological techniques. Because of the semisolid, lipid-based nature of the salve, the at-use product could not be tested in bioassays. Samples of BL and the dry ingredients (DI) used in the ointment were provided by the Amish vendor. Aqueous extracts of the DI and of the BL were prepared and freeze dried. The freeze-dried extracts were reconstituted, filtered, and tested separately on keratinocyte and fibroblast cell cultures for cytotoxicity (growth inhibition assay) and against a panel of susceptible and resistant microbes for antimicrobial activity (Nathan's agar-well diffusion assay) in a series of concentrations (% wt/vol). Neither DI nor BL extracts demonstrated antimicrobial activity against any of organisms tested. The DI extract inhibited growth of both keratinocytes and fibroblasts at the 0.1% concentration. The 0.1 and 0.03% concentrations of the BL extract were cytotoxic to both keratinocytes and fibroblasts. Although tests for microbial growth from the at-use preparation of the ABO were negative, extracts of the DI and BL did not demonstrate any antimicrobial activity. Additionally, both extracts inhibited the growth of skin cells in vitro at higher concentrations. These results suggest caution in the use of ABO and BL dressings if there is more than a minimal risk of complications from the burn injury.

Total phenolic composition, antibacterial and antioxidant activities of Fagara heitzii Aubr. & Pellegr. medicinal plant of Gabon

Fagara heitzii Aubr. & Pellegr is a shrub indigenous to secondary forest. The plant is widely used for its various pharmacological properties. The powdered plant samples were analyzed for their phytochemical screening using standard laboratory methods. The total phenols were measured using the Folin-Ciocalteu method. Proanthocyanidins content were determined by the method of HCl-butanol hydrolysis. Antioxidant activities were evaluated with 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. The plant is rich in phenolic compounds with tannins being the most abundant compounds in the methanolic and aqueous extracts while flavonoids and proanthocyanidins are abundant in methanol and chloroform extracts. Overall, we found that the extracts tested reduced the concentration of the free radical. The oxidation of linoleic acid was weakly inhibited by methanolic and aqueous extracts of Fagara heitzii (48.8 and 39.4 % ± 0.05 of reduction). In addition, the F. heitzii extracts had a good antimicrobial activity against tested microorganisms. In the agar-well diffusion assay, the extracts are active on both Gram positive and negative bacteria. The broth microdilution assay gave minimal inhibitory concentration values ranging from 16 to 400 μg/mL. Our results suggest that Fagara heitzii has both antioxidant and antibacterial activities.

보골지, 오미자, 계혈등 추출물의 항균활성

This study was performed to identify safe natural food preservatives from medicinal herbs and to evaluate the antimicrobial effects of medicinal plants against microorganisms. Medicinal herbs were extracted 3 times with methanol at 45℃ for 3 h and fractionated with n-hexane. The antimicrobial effects of the fractions were determined by measuring the diameter of the inhibition zone by using an agar-well diffusion assay. The MIC of fractions for the inhibition of microorganisms was determined using a microplate reader. The antimicrobial effects of fractions were greater against gram positive bacteria than against gram negative bacteria, but the difference was not significant. The antimicrobial effects of fractions were concentration dependent. While these results have implications, the underlying mechanisms of microbial inactivation need to be further elucidated. The results showed the possibility of developing safer food preservatives.