Shigella Flexineri Research Articles

A new 30-norfriedelane triterpnoid from Caloncoba lophocarpa (Oliv.) Gilg. (Achariaceae)

The chemical investigation of the methanol extract of the roots of Caloncoba lophocarpa (Oliv.) Gilg. exhibited a new 30-norfriedelane triterpenoid, laphocarpanol (1), together with seven known compounds, caloncobalactone (2), friedelin (3), friedelanol (4), asperphernamate (5), stigmasterol (6), sitosterol (7) and sitosterol-3-O-β-D-glucopyranoside (8). The structures of the compounds were elucidated by extensive spectroscopic and spectrometric analyses (1D and 2D NMR, ESI-MS) and by comparison with previously reported data. All the compounds were tested for their antifungal and antibacterial activities. Compound 1 displayed weak antibacterial effect with MIC value of 62.5 μg/mL against Shigella flexineri. All the isolates were found to be inactive against the tested fungal strains.

Analysis of Biochemical and Antimicrobial Properties of Bioactive Molecules of Argemone mexicana.

This study identified phytochemicals in Argemone mexicana (A. mexicana) extracts that are responsible for its medicinal properties, and the best solvent for their extraction. The extracts of the stem, leaves, flowers, and fruits of A. mexicana were prepared at low (corresponding to room temperature) and high temperatures (corresponding to the boiling points) in various solvents, viz., hexane, ethyl acetate, methanol, and H2O. The UV-visible absorption spectra of various phytoconstituents in the isolated extracts were determined through spectrophotometry. Qualitative tests for the screening of phytoconstituents in the extracts were performed to identify various phytochemicals. We identified the presence of terpenoids, alkaloids, cardiac glycosides, and carbohydrates in the plant extracts. The antioxidant and anti-human immunodeficiency virus type 1 reverse transcriptase (anti-HIV-1RT) potential, as well as the antibacterial activity of various A. mexicana extracts were determined. These extracts showed strong antioxidant activities. The extracts exhibited antimicrobial activities against Salmonella typhi, Staphylococcus epidermis, Citrobacter, Neisseria gonorrhoeae, and Shigella flexineri. These extracts significantly inhibited HIV-1 reverse transcriptase activity. The aqueous leaf extract prepared at a temperature equivalent to the boiling point, i.e., 100 °C, was identified to be the most active against pathogenic bacteria and HIV-1 RT.

Green synthesis, characterization and antibacterial activity of Tin (IV) oxide nanoparticles using root extract of Cassia tora

Synthesis of nanoparticles via green resources is a pollutant free, easy, ecofriendly, and low cost method. Nanoparticles synthesized by using plant materials are generally non-toxic. Aqueous root extract of plant, Cassia tora showed the presence of phytochemical constituents like alkaloids, flavonoids, phenols, tannins, saponins etc. which are directly involved in the reduction of metal salts hence forming metal nanoparticles. Thermal treatment of these metal nanoparticles changes them to their oxides. Tin (IV) oxide nanoparticles prepared via this route were first characterized and then evaluated for their antibacterial potential against three species of Gram negative bacteria viz., Salmonella typhi, Escherichia coli &Shigella flexineri and two speices of Gram positive bacteria viz. Bacillus cereus & Staphylococcus aureus. The current study reports the synthesis and characterization of Tin (IV) oxide nanoparticles using Cassia tora root extract.Synthesized nanoparticles were evaluated for their antibacterial activity. Results of antimicrobial activity showed excellent antibacterial property against Gram negative bacteria than Gram positive bacteria. Research has proved that green methods are more effective for generation of nanoparticles than the traditional methods, used in past as there are less chances of failure and shows enhanced biological activity.

Investigation on green synthesized nanocomposites of magnetite using Salvia hispanica for antibacterial activity

Fe3O4-Chia seeds mucilage nanocomposites (Fe3O4-CSM nanocomposites) were synthesized using an unconventional, eco-friendly co-precipitation method utilizing Salvia hispanica (chia seeds) seeds mucilage extract which serve as stabling and reducing agents. Phytochemical analysis of Salvia hispanica seeds mucilage gave positive results for flavonoids, saponins, amino acids, proteins and carbohydrates. The FTIR & XRD techniques were used for characterization of synthesized Fe3O4-nanoparticles (NPs) and Fe3O4-CSM nanocomposites. FTIR analysis identifies the presence of possible functionalities like Fe-O, N–H, –COO, C = O, C–H and O–H groups. X-ray diffraction confirmed the formation of Fe3O4-CSM nanocomposites (magnetite). The average size of Fe3O4-CSM nanocomposites was found to be 20.7 nm. The antibacterial activity of the synthesized Fe3O4-Nps, Fe3O4-CSM nanocomposites was investigated against different bacterial strains such as Escherichia coli, Shigella flexineri, Salmonella typhi, Staphylococcus aureus and Bacillus cereus. The results showed that the synthesized Fe3O4-CSM nanocomposites exhibited excellent antibacterial activity against different bacterial strains.

Biofabrication of silver nanoparticles using Praecitrullus fistulosus fruit extract exhibits in vitro antibacterial and anticancer activity

The silver nanoparticles were synthesized using green mediated approach aided by the fruit of extract of Praecitrullus fistulosus to evaluate its biological properties. The synthesized silver nanoparticle (hereafter named as Pf@AgNPs) was characterized using UV–visible spectroscopy, FTIR, DLS, Zeta potential followed by TEM. The average size of the synthesized nanoparticles was found to be 24 nm. In this work, spherical morphology of the nanoparticles was identified by TEM with a range between 18 and 30 nm. The zeta potential of AgNPs was found to be −5.2 eV. The antibacterial activity of Pf@AgNPs was evaluated against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Shigella flexineri and Pseudomonas aeruginosa using disc diffusion and minimum inhibitory concentration assay with proven activities. The dye degradation property of Pf@AgNPs was tested and effectively acts on Rhodamine compared to that of methylene blue and trypan blue dyes. Further, in vitro cytotoxic potential of Pf@AgNP's was tested against various human cancer cell lines using an MTT assay. Among tested cell lines, an A549 cells was found to be more sensitive and IC50 was found to be 23.45 ± 1.27 μg/mL. Further evaluation using clonogenic assay, scratch assay, DNA fragmentation, microscopy and western blot analysis supports the cytotoxic potential of Pf@AgNP's. Results showed that fragmented DNA and altered expression of Bax/Bcl2 protein ratio clearly indicated the activation of apoptosis in treated A549 cells. Further, angiosuppressive potential of Pf@AgNP's using CAM assay using in ovo model showed that significant decrease in the microvessel density indicating the angiosuppressive activity of Pf@AgNP's.

Biochemical Characterization of Different Chemical Components of Parthenium hysterophorus and Their Therapeutic Potential against HIV-1 RT and Microbial Growth.

Parthenium hysterophorus possesses certain allelochemicals responsible for their medicinal effects. The presence of oils, polyphenols, alkaloids, terpenes, pseudoguaianolides, and histamines in P. hysterophorus has been shown to exhibit medicinal properties. However, the systematic biomedical properties of this plant are still unexplored. The extracts of leaves, stem, and flower of P. hysterophorus, both at low and high temperatures (equivalent to boiling points of different solvents) were prepared. The extracts prepared in hexane, ethylacetate, methanol, and water were analyzed spectrophotometrically and colorimetrically and resolved on TLC for the presence of phytochemicals. The analyses of the free radical quenching potential of plant extracts were done by DPPH assay. The total antioxidant capacity was determined by phosphomolybdate assay and the ferric reducing antioxidant power (FRAP) assay was used to determine the reduction potential of the extracts. The spectrophotometric and qualitative analysis of plant extracts demonstrated the presence of alkaloids, terpenoids, carbohydrates, and cardiac glycosides. The occurrence of more than one Rf values for extracts determined by TLC indicated the presence of more than one phytochemical compound. The P. hysterophorus extracts contained strong antioxidant activity. These extracts exhibited strong antimicrobial activity against Staphylococcus epidermis, Salmonela typhi, Neisseria gonococci or gonococci, Citrobacter, and Shigella flexineri. The evaluation of the antimicrobial potential of P. hysterophorus extracts was done by the disc diffusion method. These extracts also showed significant inhibition against HIV-1 RT activity. The anti-HIV-1 RT activity was done using Roche Kit. The P. hysterophorus extracts displayed the presence of many phytochemicals with strong antioxidant, antimicrobial, and anti-HIV-1 RT properties.

ANTAGONISTIC EFFECT OF LACTOBACILLUS ACIDOPHILUS AGAINST ENTEROPATHOGENS AND ITS UTILIZATION FOR DEVELOPMENT OF PROBIOTIC FOOD MIXTURES

Probiotics are live microbial supplement, which beneficially affect the host by improving the intestinal microbial balance. Lactobacillus acidophilus is one of the most common probiotic bacteria which have beneficial effects on the microbiota of the gastrointestinal tract. In the present study, L. acidophilus was used as the probiotic culture. The antagonistic effect of L. acidophilus against the enteropathogens strains of E. coli (MTCC 40), Salmonella enteritidis (MTCC 3219), Bacillus cereus (MTCC 430), Staphylococcus aureus (MTCC 430) and Shigella flexineri (MTCC 1457) was studied. The results showed that L.acidophilus was able to inhibit the growth of some of the selected pathogens in varying degrees. It was found to be most effective with a zone of inhibition of 24 mm recorded against Staphylococcus aureus. The antagonistic effect may be due to the production of organic acids, bacteriocins and hydrogen peroxide. Later, an attempt wasmade to develop probiotic food mixtures containing banana flour, soya flour, tomato, mango and papaya involving L acidophilus. The food mixture (25g) was mixed with 150ml water and stirred to obtain uniform slurry. Adjusted the pH to 4.5 and autoclaved at 121°C (1.5 kg cm-2) for 15 minutes. After cooling this was inoculated with 300µl (8.07log cfu ml-1) liquid culture of L. acidophilus (24 hour old culture) and incubated at 37° C for 24 hours. After fermentation it was freeze dried. The viability of the developed food mixtures were assessed for 6 months and it showed good viability which was within the recommended level of probiotic organism to assure health benefits.

Chemical Composition and Synergistic Antimicrobial Effects of a Vegetatively Propagated Cameroonian Lemon, Citrus x limon (L.) Osbeck

This study analyzed the antimicrobial effects of compounds present in the roots and leaves of Citrus x limon (L.) Osbeck to help understand how this plant (1) ecologically modulates microbial defense in the rhizosphere and (2) protects against food-borne bacterial pathogens. Antimicrobial effects of C. limon collected from a farm in Foumban in Cameroon are reported against Salmonella typhi, Salmonella typhimurium, Salmonella enteritidis, Escherichia coli, Shigella flexineri, and Saccharomyces cerevisiae. The study modeled synergistic antifungal effects of an essential oil from the roots of C. limon or E-caryophyllene when combined with the isolated compounds against S. cerevisiae. Twenty-four compounds were identified from the methanol extracts of the roots and leaves: 10 prenylated coumarins (1–10), six methoxylated flavones (11–16), two limonoids (18 and 19), a phenylalanine derivative (20), lupeol, stigmasterol, sitosterol, and sitosterol-3-O-β-d-glucoside. Major compound 16, atalantoflavone, was esterified using lauric acid to yield the undescribed 5,4′-dilaureate atalantoflavone (16a). The essential oil from the roots contained methyl esters of hexadecanoic acid (39%) and 9-octadecenoic acid (9.3%) and sesquiterpenes β-bisabolene (10.1%) and α-santalene (8.0%). The antimicrobial effects of the root extract, leaf extract, compounds 1, 2, 4, 7–9, 11, 12, 14, 16, 16a, and 18 were evaluated against S. typhi, S. typhimurium, S. enteritidis, E. coli, S. flexineri, and S. cerevisiae. Compounds 11, 16, and 18 from the root extract of C. x limon showed significant antimicrobial effects with a minimum inhibitory concentration (MIC) of 62.5 μg/mL against S. flexineri, whereas compounds 5, 7, 11, and 18 showed significant antimicrobial effects with a MIC of 62.5 μg/mL against S. typhi. The essential oil from the roots synergized compounds 11–14 against S. cerevisiae. A synergistic MIC of 7.8 μg/mL was registered by combining 12 and E-caryophyllene.

New Bioactive Flavonoid Derivative from the Leaves of <i>Caloncoba echinata</i>

Background: <i>Caloncoba echinata</i> is used in traditional medicine as vomiting, against lice and mange as well as in the treatment of dermal infection, leprosy, pustular eruption (small-pox) [1, 4]. It has been reported that the non-edible vegetable oil from <i>Caloncoba</i> <i>echinata</i> seeds possess potent antibacterial activity on <i>Escherichia coli</i> and <i>Staphylococcus aureus </i>[5]. Objective: This work addressed the phytochemical investigation of the methanolic extract of leaves of <i>Caloncoba echinate</i>. Both extracts and all the isolates were screened for the antibacterial activities. Method: All the compounds were characterized by spectroscopic and mass spectrometric methods, and by comparison with literature data. The antibacterial activity of both extract and some isolated compounds against bacteria was determined using broth microdilution method in 96-well microtitre sterile plates as previously described [11]. Results: From the methanolic crude extract of the leaves of <i>Caloncoba echinate</i>, a new derivative flavonol named Kaempferol-4',7-dimethoxy-3-<I>O</I>-(6"-<I>O</I>-acetyl)-<i>β</i>-<I>NULL</I>-glucopyranoside (<i>1</i>) together with nine known compounds namely ermanin-3-<I>O</I>-<i>β</i>-<I>D</I> glucopyranoside (<i>2</i>), Kaempferol-4′,7-dimethoxy-3-<I>O</I>-(3",4",6"-<I>O</I>-triacetyl)-<i>β</i>-<I>NULL</I> glucopyranoside (3), friedelan-3-one (4), 29-hydroxyfriedelan-3-one (<i>5</i>), mixture of <i>β</i>-sitosterol and stigmasterol (<i>6-7</i>), mixture of <i>β</i>-sitosterol and stigmasterol glucoside (<i>8-9</i>), Lupeol (10) were isolated. Furthermore, compounds (<i>2</i>) and (<i>5</i>) were reported here for the first time from the <i>Caloncoba</i> genus. Crude extract exhibited a significant activity against the five bacteria with the MIC = 62.5µg/mL for <i>Salmonella typhi</i>,<i> Escherishia coli</i>,<i> Shigella flexineri</i> and the MIC = 32.25µg/mL for <i>Salmonella typhimurium</i>,<i> S. enteritidis</i>. For the isolated compounds, the best activities were recorded by compound (<i>1</i>) showing a moderate activity against <i>Salmonella typhi</i> (MIC = 32.25µg/mL; MBC/MIC = 8), <i>Salmonella typhimurium</i> (62.5µg/mL; MBC/MIC = 4), <i>Salmonella enteritidis</i> (62.25 µg/mL; MBC/MIC = 2). Conclusion: These results showed that the antimicrobial activities could be mainly attributed to the constituents of flavonol glycoside <i>(1)</i>. In addition, the antibacterial bioactivities and determined constituents support the use of this specie by traditional healers to treat a certain number of bacterial diseases.

Antimicrobial and antinematicidal metabolites from Streptomyces cuspidosporus strain SA4 against selected pathogenic bacteria, fungi and nematode.

The exploration of novel therapeutic agents and other bioactive secondary metabolite from Streptomyces species, for possible agricultural farming, pharmaceutical and industrialized applications, has been, and still is, essential. The existing studies were aimed with biologically potential Streptomyces species and its antagonistic activity against dreadful microorganisms. Totally, morphological three different actinomycetes were selected from the fertile agricultural lands. Among the three, the isolate SA4 exhibited significant antimicrobial and anti-nematicidal activity towards selected microbial pathogens such as E Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Salmonella typhi, Bacillus subtilis, Proteus vulgaris, Shigella flexineri, Candida albicans, and Fusarium sp. The prospective strain SA4 was identified as Streptomyces cuspidosporus. The isolate SA4 optimized for secondary metabolites production with International Streptomyces project 4 (ISP 4) medium, pH 7.0 at 37°C for 14days. Gas Chromatography-Mass spectrometry (GCMS) analysis of strain SA4 bioactive extract publicized the existence of 1,2-Benzenedicarboxylic acid, bis(2-Methylpropyl) ester compound and occupied by high peak area and its possessed significant biological properties.

Antibacterial Flavonoids and Other Compounds from the Aerial Parts of Vernonia guineensis Benth. (Asteraceae).

An extensive phytochemical study of the aerial parts of Vernonia guineensis Benth. (Asteraceae) led to the isolation of a new flavone, vernoguinoflavone and a naturally isolated glycerol ester, eicosanoic acid 2-hydroxy-1,3-propanediyl ester, together with eighteen known secondary metabolites including quercetin, luteolin, vernopicrin, vernomelitensin, β-amyrin, oleanolic acid, ursolic acid, lupeol, betulinic acid, β-carotene, a mixture of stigmasterol and β-sitosterol, β-sitosterol-3-O-β-D-glucoside, 2,3-dihydroxypropyl heptacosanoate, pentacosanoic acid, docosan-1-ol, tritriacontan-1-ol, and heptatriacontan-1-ol. Eleven compounds are reported herein for the first time from this species. The structures of these compounds were elucidated on the basis of extensive spectroscopic analyses, particularly 1D and 2D NMR, and HR-ESI-MS and by comparison of their data with those reported in the literature. The crude extract, fractions and some isolated compounds were evaluated for their antibacterial activity against Gram-negative bacteria: Escherichia coli (ATCC 25922), Shigella flexineri (NR 518), Salmonella muenchen, Salmonella typhimurium and Salmonella typhi (ATCC 19430). All the tested compounds demonstrated inhibitory activities against the tested enteric bacteria with MIC values ranging from 3.12 to 100 μg/ml. Three flavonoids isolated from the most active fraction demonstrated the best bioactivities against Escherichia coli, Salmonella muenchen and Salmonella typhimurium with MIC values ranging from 3.12 to 25 μg/mL.

Bacteriological assessment of some borehole water samples in Mile 50, Abakaliki, Ebonyi State, Nigeria

Water as excellent natural resource is meant to be of high quality to reduce the outbreak of water-borne diseases. Bacteriological load of some borehole water samples in Mile 50 Abakaliki were carried out to determine their potability. Fifteen borehole water samples were sampled during rainy and dry season from June to July and November to December 2018 respectively. The total bacterial count was determined by tenfold serial dilution method using peptone water. Eight bacterial species namely Vibrio cholerae, Pseudomonas aeroginosa, Escherichia coli, Staphylococcus aureus, Salmonella typhi, Shigella flexineri, Proteus vulgaris and Klebsiella pneumoniaewere isolated using standard analytical procedures. The bacterium that had the highest frequency of occurrence during both rainy and dry season’s was K. pneumoniae with percentage frequency of 21.81% and 20.79% respectively, and P. vulgaris had the least value of 6.96% during rainy season. E. coli and S. aureus have the least value of 5.94% during dry season. Amoxicillin (30ug) was mostly resisted by the bacterial isolates why being was more susceptible to Ciprofloxacin (10ug) among the antibiotics used for susceptibility test. Two way analysis of variance (ANOVA) was used to determine the level of significance among the bacteriological analyses of both seasons. Therefore, there is need to create awareness about the present situation of the borehole waters and the necessity for further treatment of water by consumers, before it can be used for both drinking and domestic purposes to prevent disease outbreak in the area.

Physicochemical, Bacteriological and Parasitological Examination of Selected Fish Pond Water Samples in Awka and Its Environment Anambra State, Nigeria

A fish pond with recommended water quality will produce healthy fishes. Fish ponds with poor water quality will cause fish mortality and outbreak of diseases to fish consumers. Physicochemical analysis was done using standard analytical methods, the total bacterial count was determined by dilution and membrane filtration techniques. Parasitological analysis was done using the centrifugation method. A total of fifteen well waters were sampled during wet season. Results showed that the temperature ranged from 27°C to 29°C, pH, 6.21 to 8.15; dissolved oxygen, 4.28 mg/l to 5.78 mg/l, electrical conductivity, 166.36 µs/cm to 394.00 µs/cm; total dissolved solids, 41 mg/l to 121 mg/l; total suspended solids, 1.00 mg/l to 19.40 mg/l; total solids, 42.00 mg/l to 140.4 mg/l; turbidity values, 7.01 NTU to 10.36 NTU; nitrate, 3.10 mg/l to 28.00 mg/l; total alkalinity, 36 mg/l to 91 mg/l; phosphate, 1.26 mg/l to 13.11 mg/l; sulphate, 0.39 mg/l to 4.37 mg/l; total chloride, 7.08 mg/l to 14.19 mg/l; carbonates, 1.33 mg/l to 2.35 mg/l; bicarbonates, 34.59 mg/l to 89.38 mg/l; total hardness, 25.31 mg/l to 53.04 mg/l; calcium hardness, 23.94 mg/l to 51.96 mg/l; magnesium hardness, 1.08 mg/l to 4.20 mg/l; total acidity, 2 mg/l to 22 mg/l; potassium, 0.04 mg/l to 2.23 mg/l; cadmium, 0.00 mg/l to 0.04 mg/l; lead, 0.01 mg/l - 0.16 mg/l; chromium, 0.00 mg/l - 0.03 mg/l; mercury was not detected, copper, 0.00 mg/l - 0.04 mg/l; arsenic, 0.00 mg/l - 0.02 mg/l; zinc, 0.00 mg/l to 0.02 mg/l; iron, 0.01 mg/l - 1.19 mg/l. The total bacterial counts ranged from 3.60-4.12 log cfu/ml; total coliforms, 14-46 cfu/100ml, Vibrio cholerae, 0-11 cfu/100ml; Vibrio parahaemolyticus, 0-15 cfu/100ml; faecal coliform, 1-9 cfu/100 ml; Acinetobacter calcoaceticus, 0-8 cfu/100 ml; Bacillus subtilis, 0-9 cfu/ml; Staphylococcus aureus, 0-5 cfu/ml; Pseudomonas aeruginosa, 0-12 cfu/100 ml; Pseudomonas fluorescens, 0-12 cfu/100 ml and Clostridium perfringens were not detected in any of the samples. Twelve bacterial species namely Klebsiella pneumoniae, Acinetobacter calcoaceticus, Escherichia coli, Staphylococcus aureus, Vibrio cholerae, Pseudomonas fluorescens, Pseudomonas aeruginosa, Proteus mirabilis, Vibrio parahaemolyticus, Bacillus subtilis, Shigella flexineri and Salmonella typhi were isolated and identified using standard analytical and molecular procedures. Parasites identified were Ichthyobodo species, Diplostomum species, Myxobolus species, Chilodonella species, Bothriocephalus species, Ambiphrya species and Leech species. Salmonella typhi had the highest frequency of isolation (20.63%) while Acinetobacter calcoaceticus and Staphylococcus aureus had the lowest frequency of isolation (2.83%). Ichthyobodo species had the highest frequency of isolation (21.43%) while Leech species had the lowest frequency of isolation (5.71%). Some of the physicochemical, bacteriological and parasitological parameters had values above World Health Organization admissible limits and therefore proper sanitary practices and water treatments must be employed to prevent epidemic among fish consumers.

Evaluation of Anxiolytic and Antibacterial Activity of Methanol Extract of Leaves of Mimosa pudica

Background: Mimosa pudica belongs to the family of Mimosoideae. Traditional Chinese medicinal practitioners have long revered the bark, leaves and flowers of Mimosa for its potent health benefits. Limited modern scientific research has been conducted on the qualities of this plant. As part of our ongoing research of traditional medicinal plant, this study evaluated the anxiolytic and antibacterial activity of methanol extract of Mimosa pudica (MEMP) leaves. Method: The effect of MEMP on central nervous system (CNS) for anxiolytic activity was determined by mice light-dark box test, Elevated plus maze test and Hole board test. Disc diffusion assay was used to determine the antibacterial activity of MEMP. Result: Preliminary phytochemical screening revealed the presence of reducing sugar, tannin, glycoside, alkaloids and flavonoids. The present study demonstrated that MEMP showed significant anxiolytic (p<0.05) effect at the doses of 200 and 400 mg/kg body weight in Light-dark box test, Elevated plus maze test. The movement of mice after administration of MEMP at doses of 200 and 400 mg/kg body weight decreased significantly in hole-board test, which indicated the high possibility of having anxiolytic activity. The MEMP showed dose-dependent antibacterial activity against the experimental bacterial strains namely Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus agalactiae, Escherichia coli, and Shigella flexineri. Conclusion: The present study indicates that the MEMP extract possesses anxiolytic and antibacterial activity in a dose-dependent manner. Hence, the present work rationalizes the traditional uses of this plant. So, the plant may be further subjected to chemical investigation to isolate and purify the bioactive compound(s) responsible for its pharmacological activity.

Two new flavones glycosides with antimicrobial activities from Clerodendrum formicarum Gürke (Lamiaceae)

Clerodendrum formicarum Gürke from the Lamiaceae family is a Cameroonian medicinal plant. The crude methanol, methanol residual and ethyl acetate extracts of leaves have been phytochemically studied using chromatography column to afford four compounds; two new flavones glycoside: clerodendronone 1a (3) and clerodendronone 1b (4) along with two known compounds: 5,7-dihydroxy-4′-methoxyflavone (1) and 5-hydroxy-7,4′-dimethoxyflavone (2). Compound structures have been elucidated on the basis of their spectroscopy data and with literature information. The anti-microbial activities of extracts and three isolated compounds were performed. The antibacterial activity was evaluated against four gram positive, five gram negative and three fungus. Clerodendronone 1b (4) showed good antibacterial activity against bacterial gram negative Shigella flexineri NR518 (MIC = 62.5 μg/ml) and moderate activity against Staphylococcus aureus NR46374 (MIC = 250 μ/ml). The ethyl acetate extract recorded good antibacterial activity against Staphylococcus aureus NR46003 (MIC = 125 µg/ml) and Staphylococcus aureus NR46374 (MIC = 125 μg/ml).

Synthesis, Characterization and Anti – Bacterial Activities of SnO2 Nanoparticles Using Biological Molecule

Nano – crystalline SnO2 particles have been synthesized by co–precipitation method using DNA, a biomaterial, as capping agent. The nanoparticles obtained were characterized using XRD, SEM and TEM. The XRD confirms the crystalline nature and formation of SnO2 nanoparticle. The optical properties were studied using FTIR spectroscopy. The effect of SnO2 nanoparticles on the growth of some common food and water poisoning pathogens were studied. To understand the mechanism of antibacterial activity and to confirm the role of reactive oxygen species, the samples were annealed at different temperature and the bacterial activity is probed. Antibacterial studies were done against three bacterial strains namely, Staphylococcus aureus (ATCC 9144), Shigella flexineri (ATCC 2908) and Escherichia Coli (ATCC 25922).

Apple, Guava and Pineapple Fruit Extracts as Antimicrobial Agents against Pathogenic Bacteria

This investigation was conducted to compare the antimicrobial properties of alcohol fruit extracts from Apple (Malus pumila), Guava (Psidium guajava), and Pineapple (Ananas comosus) against eight bacteria: Staphylococcus aureus, Enteroaggregative E.coli (EAEC), Enterotoxigenic E.coli (ETEC), Enterobacter cloacae, Shigella flexineri, Enterococcus faecalis, Klebsiella, and Pseudomonas aeruginosa. All the fruits were bought fresh from the market, cut into small cubes, and sun dried to a crisp over 4-5 days. After being blended to a fine powder, 75g of each powder was passed through a Soxhlet apparatus containing 250 ml of 99% ethanol to obtain a crude extract. This process was repeated with 250 ml of methanol to obtain a methanolic crude extract. The antimicrobial properties of the extracts were tested using agar well diffusion, Norfloxacin used as positive control and water as negative control. The inhibition zones from each extract were measured and an activity index was calculated from the mean zone sizes. All fruits showed some degree of antimicrobial properties with the highest activity index (2.6) being from Pineapple ethanolic and methanolic extracts against EAEC. Both Apple ethanolic and methanolic extracts showed activity only against Staph. aureus and EAEC. Guava extracts were effective against all the strains except for ETEC. Pineapple extracts were strongly active against all the bacteria. The methanolic extracts of Apple and Guava showed slightly larger zones compared to their ethanolic extracts. For Pineapple, inhibition zones from the ethanolic extracts were slightly larger. The results of this investigation show great promise for potential antimicrobial drugs.

A COMPARATIVE STUDY ON THE EFFECT OF SOLVENTS ON THE PHYTOCHEMICAL PROFILE AND BIOLOGICAL POTENTIAL OF ORMOCARPUM COCHINCHINENSE AUCT. NON (LOUR.) MERRILL

&lt;p&gt;&lt;strong&gt;Objective: &lt;/strong&gt;Plants contain different classes of phytochemicals which have different levels of solubility in solvents, based on their polarity. Hence, this study aims to compare the effects of various solvents on the phytochemical profile and biological potential of &lt;em&gt;Ormocarpum cochinchinense&lt;/em&gt;. The present study is the first to evaluate the antifungal activity of the plant.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;The sequential extraction was carried out using two sets of solvent systems namely hexane, ethyl acetate, ethanol and chloroform, acetone, methanol. The extracts were subjected to standard phytochemical analysis, antimicrobial activity by disc diffusion method against eight bacteria and six fungi and antioxidant activity by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;Varied range of phytochemicals was found in the extracts. Acetone extract was rich in phenolic compounds, whereas terpenoids were extracted only in methanol. Acetone extracts showed highest antibacterial activity with a maximum zone of 14.5 mm against &lt;em&gt;Shigella flexineri&lt;/em&gt; whereas ethyl acetate extract showed the best antifungal activity with the highest zone of inhibition of 12 mm against &lt;em&gt;Trichophyton menta agrophytes.&lt;/em&gt; Hexane and chloroform extracts did not show any antimicrobial activity. For DPPH assay, the ethanol extracts showed the highest percentage inhibition of 92.87%. &lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;The present investigation on the plant &lt;em&gt;O. cochinchinense&lt;/em&gt; has proved that the selection of solvent for extraction should be based on the target compounds and their bioactivity and concludes that acetone was the best for the extraction of antibacterial compounds and ethyl acetate for antifungal compounds whereas, ethanol was the best for extracting antioxidant compounds in &lt;em&gt;O. cochinchinense.&lt;/em&gt;&lt;/p&gt;

Combination therapy with polymyxin B and netropsin against clinical isolates of multidrug-resistant Acinetobacter baumannii.

Polymyxins are last-resort antibiotics for treating infections of Gram-negative bacteria. The recent emergence of polymyxin-resistant bacteria, however, urgently demands clinical optimisation of polymyxin use to minimise further evolution of resistance. In this study we developed a novel combination therapy using minimal concentrations of polymyxin B. After large-scale screening of Streptomyces secondary metabolites, we identified a reliable polymixin synergist and confirmed as netropsin using high-pressure liquid chromatography, nuclear magnetic resonance, and mass spectrometry followed by in vitro assays using various Gram-negative pathogenic bacteria. To evaluate the effectiveness of combining polymixin B and netropsin in vivo, we performed survival analysis on greater wax moth Galleria mellonella infected with colistin-resistant clinical Acinetobacter baumannii isolates as well as Escherichia coli, Shigella flexineri, Salmonella typhimuruim, and Pseudomonas aeruginosa. The survival of infected G. mellonella was significantly higher when treated with polymyxin B and netropsin in combination than when treated with polymyxin B or netropsin alone. We propose a netropsin combination therapy that minimises the use of polymyxin B when treating infections with multidrug resistant Gram-negative bacteria.

English

Thymus vulgaris, Cinnamomum zeylanicum and Ocimum gratissimum are spices widely used as aroma enhancers and food preservatives. This work assessed the chemical composition, antioxidant and antimicrobial effect of their essential oils on some food pathogenic bacteria, namely, Staphylococcus aureus, Citrobacter freundii, Enterobacter cloacae, Morganella morganii, Escherichia coli, Salmonella typhimurium, Proteus vulgaris and Shigella flexineri. After chemical analyses of the essential oils by gas chromatography and gas chromatography coupled to mass spectroscopy, the antimicrobial effects were subsequently assessed by disk and microdilution methods, while the antioxidant evaluations were performed by free radical scavenging activity. T. vulgaris essential oil composed of p-cymene (45.90%) and thymol (23.72%) which exhibited the highest inhibitory diameters of 20.33±0.58 and 18.00±1 mm, respectively, on the growth of S. aureus and C. freundii. O. gratissimum essential oil with thymol as major compound (47.11%) was more active to inhibit the growth of C. freundii and S. flexineri with respective inhibitory diameters of 18±1.73 and 16±2 mm. Essential oil from dry leaves of C. zeylanicum containing cinnamaldehyde (82.23%) and linalool (12.12%) was found to have the lowest values for minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) (≤3.53 mg/mL) considering the growth of S. flexineri, C. freundii and E. cloacae. Regarding the antioxidant effect, C. zeylanicum and T. vulgaris essential oil showed the most scavenging effect with half-maximal DPPH scavenging concentration (SC50) of 2.5 × 10-5 and 6.5 × 10-5 mg/ml, respectively. Their antioxidant effects were higher than conventionally used antioxidants in food products, butylhydroxyltoluene (BHT) and vitamin C. Key words: Spices, essential oils, chemical composition, antibacterial and antioxidant effects.