Antimicrobial Activity and Mechanism of Flavonoids from Litchi Pericarp
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The concentration of total flavanoids from litchi pericarp(LPF) was determined by spectrofluorimetry,and its antimicrobial and bactericidal activities against microbes,as well as the mechanisms were investigated.The purity and yield of extract was 48.56% and 13.61%,respectively.Meanwhile,the diameter of inhibition zone of Escherichia coli,Staphylococcus aureus and Saccharomgces cerevislac by oxford plate assay were 15.1,14.0 and 13.8 mm,respectively.The maximum inhibitory rate of Aspergillus niger reached 28.75% under the concentration of 10 mg/mL.The minimal inhibitory concentration(MIC) and minimal bactericidal concentration(MBC) of LPF were also measured by plate dilution method.As the results,the MIC of LPF against E.coli and St.aureus were 2.5 mg/mL and MBC were 5 mg/mL,while those of Sa.cerevislac and A.niger were 5 mg/mL and no bactericidal activity observed.Observation under scanning electron microscope revealed that the antimicrobial activity and the bactericidal function of LPF against St.aureus were directly relevant to the structure destruction of cells membrance and wall.Keywords:
Minimum bactericidal concentration
Aspergillus niger
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The leaves of Mangifera indica were subjected to ethanol extraction and the extracts fractioned by suspending the extract in 20% ethanol and partitioned with different organic solvents (n-hexane, chloroform, ethyl acetate) in order of increasing polarity. Standard methods were used for both extraction and phytochemical screening. Modified agar well diffusion method was adopted for screening the antimicrobial activities. The test was carried out in triplicates. The test organisms were S. aureus , S. epidermidis , P. aeruginosa , E. coli , K. pneumoniae , P. mirabilis , P. vulgaris and C. albicans . The leaf extract was phytochemically screened and revealed the presence of Flavonoid, Alkaloid, Tannins, Steroid, Saponins, Cardiac glycosides, Anthraquinone, Triterpenoids. The chloroform leaf extract showed strong antimicrobial activity on both gram positive and gram negative organisms; followed by the aqueous extract. The ethyl acetate leaf extract ranked third. n-hexane leaf extract had the least antimicrobial activity. The 100 mg/ml concentration exerted a broad spectrum antimicrobial activity with the highest diameter zone of inhibition of 18mm against Staphylococcus aureus and Klebsiella pneumoniae . This activity was followed by the 50 mg/ml and 25 mg/ml concentrations in that order. Fifty (50) mg/ml exerted the diameter zones of inhibitions of 10.5 mm while 25 mg/ml concentrations exerted the diameter zones of inhibitions of 7.5 mm. Also the least antimicrobial activity was exerted by the 25 mg/ml concentration, followed by the 50 mg/ml concentration with diameter zones of inhibitions of 4 mm and 7.5mm respectively, against S. epidermidis and C. albicans and some Gram negative organisms. The data obtained showed broad spectrum activities with increasing diameter zone of inhibitions at increasing concentrations, which showed that the inhibitory effects of the extracts were not only solvent dependent but also concentration dependent (Figures 1 – 8). The extracts were subjected to MIC evaluation and the findings showed that E. coli and K. pneumoniae were the most sensitive. The MBC showed no value. This study shows that the leaves of M. indica when purified to the appropriate pharmacological level, contain some active principles with antimicrobial potential that will be useful in preventing and curing diseases. Keywords: M. oleifera , Antimicrobial, Phytochemical, Infectious isolates
Phytochemical
Mangifera
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The antibacterial effect of Azadirachta indica against Pseudomonas aeruginosa, Klebsiella ozanae, Staphylococcus aureus and Escherichia coli was determined using the agar cup plate technique.The phytochemical components of A. indica showed the presence of saponin and phlobatanin and the absence of alkaloids, tannins, phenolics, glycosides, flavonoids and triterpenes.The result showed that the test organisms were susceptible to 500mg/ml, 50mg/ml and 5mg/ml of the plant extract.The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined.The result showed that the MIC and MBC were 5mg and 50mg respectively for Pseudomonas aeruginosa, Kl. ozanae, Staphylococcus aureus and Escherichia coli.The result of the study suggests that extracts of A. indica could be suitable for the treatment of various infections caused by P. aeruginosa, K. ozanae, S. aureus and E. coli.
Azadirachta
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Objective: The aim of this present study is to evaluate the activity of green tea extracted in different solvents on different microorganism such as on Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 8739, Salmonella abony NCTC 6017, Pseudomonas aeruginosa ATCC 9027, Candida albicans ATCC 10231, Esteritia coli mutant NCIM 2567, Bacillus subtilis ATCC 6633 &Lactobacillus lichmani ATCC 7830. Method: Zone of inhibition of aqueous, methanolic and ethanolic extracts were measured and compared by using cup plate method. 5μg, 10μg, 15μg & 20μg concentration of the extract were used. MIC (Minimum inhibitory concentration)& MBC (Minimum bactericidal concentration ) were observed with the concentrations of 100μg, 75μg, 50μg & 25μg .Result: Result of zone of inhibition shows that aquous extract at the concentration of 20μg/ml is most effective to inhibit Escherichia coli growth compare to standard.Also minimum inhibitory concentration (MIC) & minimum bactericidal concentration (MBC) result suggest that aquous extract is more effective than ethanolic and methanolic extract to inhibit the growth of both Escherichia coli &Escherichia coli mutant. Conclusion: Significant antimicrobial activity has been shown by all extracts against Escherichia coli but other microorganism inhibition is not so significant compare to Escherichia coli . Methanolic and ethanolic extract has shown little antimicrobial activity against all microorganisms as compared to the aqueous extract.
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The antibacterial activity of the extract of Ocimum gratissimum was determined against Escherichia coli and Staphylococcus aureus . The phytochemical analysis of the leaf extract revealed the presence of bioactive bases responsible for antibacterial property, such as Saponin, Alkanoid, Flavonoid, Tanin and Steroid. The methanolic extraction of the active ingredient of the leaves was carried out using the method as described by Fatope, et al., (1993). The minimum inhibitory concentration (MIC) was 12.5mg/ml for E. coli and 25mg/ml for S. aureus and also had minimum bactericidal concentration of 6.25mg/ml for E. coli and 12.5mg/ml for S. aureus . The concentration 1.0mg/disc inhibited the isolates with highest diameter zone of inhibition as 15mm for E. coli and 13mm for S. aureus while the lowest diameter zone of inhibition as 8mm for E. coli and 7mm for S. aureus were recorded at concentration of 0.1mg/disc. Statistical analysis of the extract showed no significant difference (P> 0.05) the test isolates were sensitive to leaf extract of Ocimum gratissimum which implies that the leaf extract of Ocimum gratissimum can serve as a source of therapeutic agent and possess antibacterial properties. Keywords- Ocimum gratissimum, Escherichia coli , Staphylococcus aureus Bactericidal, Bacteriostatic, Crude extract
Ocimum gratissimum
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Medicinal plants offer a major and accessible source of health care to people living in developing countries. Increasing drug resistant microbial infections intensified the search for new, safer, and more efficacious agents against microbial infections. Acanthus sennii is one of the medicinal plants used traditionally for the treatment of different infectious diseases in Ethiopia. Therefore, this study was carried out to evaluate antibacterial activity of A. sennii against pathogenic bacteria. Plant materials were extracted by maceration technique with chloroform, ethanol and water solvents. The antibacterial activities of the crude extracts of the plant were carried out by the agar well diffusion method. Broth dilution method was used to determine minimum inhibitory and streak plate bactericidal concentration of extracts. The results revealed that ethanol extracts of leaves revealed high antibacterial activity against standard strains of Staphylococcus aureus with inhibition zone of 14±0.6 mm at 25 mg/ml and 17±0.7 mm at 50 mg/ml. Ethanol extracts of buds showed high antibacterial activity against standard strains of S. aureus with inhibition zone of 25.7±0.7 mm at 100 mg/ml, also against standard strains of E. coli with inhibition zone of 16 mm at 50 mg/ml and 23.7 mm at 100 mg/ml. The mean minimum inhibitory concentration of 5.2±1.8 and 2.6±0.5 mg/ml was recorded for ethanol extract of leaves against standard strains of E. coli and clinical isolates of S. aureus; the mean minimum bactericidal concentration of 4.2±1.0 mg/ml with ethanol extract of leaves against standard strains of S. aureus; and the mean minimum bactericidal concentration of 12.5 mg/ml against standard strains and clinical isolates of E. coli. The result showed that A. sennii could be a candidate in the search for new antibacterial agents against these bacteria and its use in ethnomedicinal treatment of infectious diseases used by local communities may be validated. Isolating bio-active components and determining toxicity are future agenda.
Keywords: Acanthus sennii, Antibacterial activity, E. coli, Minimum inhibition concentration, Minimum bactericidal concentration, S. aureus
Maceration (sewage)
Agar diffusion test
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Agar Dilution Method
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A study has being conducted on the Nephelium lappaceum L. leaves methanolic extract. The study aims to evaluate the antimicrobial activity of methanolic extract of the N. lappaceum L. leaves and to evaluate the acute toxicity properties of methanolic extract of N. lappaceum L. leaves. All different concentration of extract ranging from 50 mg/ml, 100 mg/ml, 200 mg/ml, 300 mg/ml and 400 mg/ml were tested against Gram-positive bacteria, Bacillus subtilis, Staphylococcus aureus and Gram-negative bacteria, Escherichia coli, Pseudomonas aeruginosa. The antimicrobial activities of the extract were determined by the disc diffusion method, mimimum inhibitory concentration method and minimum bactericidal
concentration method. Zone of inhibition of extracts were compared with the standard antibiotic, Streptomycin which acts as positive control, while DMSO (10%) used as negative control. The highest antimicrobial activity
exhibited against P.aeruginosa which was about 17.3 mm ± 1.53 compared to E.coli which did not show any activity. The lowest minimum inhibitory concentrations were 50 mg/ml against P.aeruginosa, B.subtilis, and S.aureus. The lowest minimum bactericidal concentrations taken were
50 mg/ml which showed against P.aeruginosa. The toxicity test also tested on Artemia salina and resulted that the LC50 value which is 3.16 mg/ml as compared to 1.0 mg/ml, thus the extract is not toxic.
Artemia salina
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Agar diffusion test
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Enterobacter aerogenes
Streptococcus Pyogenes
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Agar diffusion test
Phytochemical
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Objective: To evaluate the antimicrobial activity of methanol extract of Syzygium calophyllifolium Walp. leaf against the gram-negative bacteria, namely, Escherichia coli , Klebsiella pneumonia , Salmonella typhi , Proteus miriabilis and Pseudomonas aeruginosa, the gram-positive bacteria Bacillus cereus , Bacillus subtilis , Sarcina lutea , Staphylococcus aureus and Bacillus megaterium, three fungal species strains, commonly causing systemic infections in immune compromised patients such as Candida albicans , Aspergillus niger and Saccharomyces cerevisiae . Methods: The dried leaves were ground finely and extracted in methanol for 48 h at room temperature (26 °C-28 °C). This was then filtered using Whatman No.1 filter paper. The different concentration of (5 µl, 10 µl, 15 µl) methanol extract of leaves of S. calophyllifolium was investigated in vitro by an agar diffusion method and the MIC by macro-broth dilution method in the present study. The antibacterial antibiotics Ampicillin (10µ/ml), Ofloxin (1 mg/ml) and the antifungal antibiotics Nyastatin (20µg/ml), Tobramycin (10µ/ml) were used as positive controls. Results: The largest zone of inhibition was noted against E. coli (25±mm in diameter) and S. cerevisiae (25±mm in diameter) at the highest concentration (15 µl). B. cereus, K. pneumoniae, P. aeruginosa and E. coli showed the highest MIC (10±mg/ml) and MBC (20±mg/ml). Conclusion: The result revealed that the methanol extract of S. calophyllifolium leaf has a broad spectrum of antimicrobial activity. Keywords : Syzygium calophyllifolium , Eugenia calophyllifolia, Myrtaceae, Antimicrobial activity, Minimum inhibitory concentration
Klebsiella pneumonia
Agar diffusion test
Aspergillus niger
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This study was undertaken to investigate the antibacterial properties and the mode of actions of crude extract of Aspergillus fumigatus SSH01. Antibacterial properties was observed against Gram-positive pathogens and showed inhibition against Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, methicillin-resistant S. aureus S547 (MRSA) and Listeria monocytogenes L10 with minimum inhibitory concentration (MIC, 0.097- 12.5 mg/ml) and minimum bactericidal concentration (MBC, 0.195 – 25 mg/ml). No surviving cells were detected after 15 h of treatment with the 2MIC of extracts for time-kill assay. Leakage of cellular contents of the treated test pathogens were identified and increased as the concentrations of the extracts increased. The study of morphological surface has shown the bacterial membrane was disrupted and caused loss of viability. This implies the antibacterial effects of A. fumigatus SSH01 extract may serve as the potential antibiotic.
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Gram
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The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured at concentrations of 0.01–2.56 mg/mL of grape and mulberry leaves ethanolic extracts. The MIC values were ranged from 0.08 to 0.16 mg/mL against Ps. aeruginosa Ps9, and 0.32 mg/mL against each of S. aureus St3, E. coli Ec3, and S. typhi Sa1. Whereas, the MBC values were ranged from 0.32 to 1.28 mg/mL of the tested extracts. The effects of the tested extracts were also studied representing the bactericidal effect of the grape extract with a ratio of 2 against all investigated isolates, except S. typhi Sa1. Whereas, the mulberry extract had a bactericidal effect towards S. aureus St3 and E. coli Ec3 with ratio of 2, and a bacteriostatic effect against Ps. aeruginosa Ps9 and S. typhi Sa1 with a ratio ≥4. The investigated bacteria found to have a strong ability to form biofilms with densities ranged from 0.67 to 0.80. Both tested extracts inhibited these biofilms with percentages ranged from 48 to 66% at sub-inhibitory concentrations (SICs) ranged from 0.04 to 0.16 mg/mL. In addition, the tested extracts have an excellent cytotoxic activity towards colon cancer cell lines (HCT-16). Five phenolic compounds detected in the tested extracts of grape and mulberry using high performance liquid chromatography (HPLC) after 9.53 min of the retention time. The phenolic compounds of both tested extracts were gallic, coumaric, ferulic, chlorogenic and caffeic with concentrations ranged from 1.28 to 6.56 µg/mL.
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Chlorogenic Acid
Grape seed extract
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