Antibacterial properties of traditionally used Indian medicinal plants

In search of broad-spectrum antibacterial activity from traditionally used Indian medicinal plants, 66 ethanolic plant extracts were screened against nine different bacteria. Of these, 39 extracts demonstrated activity against six or more test bacteria. Twelve extracts showing broad-spectrum activity were tested against specific multidrug-resistant (MDR) bacteria, methicillin-resistant Staphylococcus aureus (MRSA) and extended spectrum beta-lactamases (ESbetaL)-producing enteric bacteria. In vitro efficacy was expressed in terms of minimum inhibitory concentration (MIC) values of plant extracts. MIC values ranged from 0.32-7.5 mg/ml against MRSA and 0.31-6.25 mg/ml against ESbetaL-producing enteric bacteria. The overall activity against all groups of bacteria was found in order of Plumbago zeylanica > Hemidesmus indicus > Acorus calamus > Camellia sinensis > Terminalia chebula > Terminalia bellerica > Holarrhena antidysenterica > Lawsonia inermis > Mangifera indica > Punica granatum > Cichorium intybus and Delonix regia. In addition, these extracts showed synergistic interaction with tetracycline, chloramphenicol and ciprofloxacin against S. aureus and/or Escherichia coli. The ethanolic extracts of more than 12 plants were found nontoxic to sheep erythrocytes and nonmutagenic, determined by Ames test using Salmonella typhimurium test strains (TA 97a, TA 100, TA 102 and TA 104). Based on above properties, six plants-Plumbago zeylanica, Hemidesmus indicus, Acorus calamus, Punica granatum, Holarrhena antidysenterica and Delonix regia-were further subjected to fractionation-based study. Ethyl acetate, acetone and methanol fractions of more than six plants indicated that the active phytocompounds were distributed mainly into acetone and ethyl acetate fractions, whereas they were least prevalent in methanol fractions as evident from their antibacterial activity against MDR bacteria. Gram-positive and Gram-negative MDR bacteria are almost equally sensitive to these extracts/fractions, indicating their broad-spectrum nature. However, strain- and plant extract-dependent variations in the antibacterial activity were also evident. Time-kill assay with the most promising plant fraction Plumbago zeylanica (ethyl acetate fraction) demonstrated killing of test bacteria at the level lower than its MIC. Further, identification of active constituents in each fraction and their additive and synergistic interactions are needed to exploit them in evaluating efficacy and safety in vivo against MDR bacteria.     

海娜花抗真菌有效成分的提取工艺优化与抑菌效力研究

目的 研究海娜花抗真菌有效成分的提取工艺优化与抑菌效力。方法 分别采用回流提取法与超声提取法提取海娜花。采用高效液相色谱作定量分析,流动相A为磷酸二氢铵30 mmol/L、B为甲醇（用磷酸调pH=3）,梯度洗脱,温度为30℃,进样量为20μL,色谱柱为Agilent Zorbax SB-C18柱（250 mm×4.6 mm,5μm）。考察溶剂、温度、时间对有效成分提取效果的影响,确定最佳提取工艺。采用美国临床实验室标准化委员会（NCCLS）产孢丝状真菌抗真菌药敏试验方案M38-A,以白色念珠菌为模型菌,对海娜花提取物的抗真菌效力进行初步研究。结果与结论 回流提取法的最佳工艺条件为10倍量70%乙醇溶液,100℃下回流提取1.0 h,共提取3次。超声提取法的最佳工艺条件为10倍量70%乙醇溶液,50℃下超声提取1.5 h,共提取3次。海娜花提取物对白色念珠菌的最低抑菌浓度（MIC）为320～640μg/mL。     

Comparative Study of Hydroalcoholic Extracts of Momordica charantia L. against Foodborne Pathogens

The antimicrobial effect of 24 different hydroalcoholic extracts (100, 75, 50 and 25% methanol and water) obtained from four parts (leaf+stem (aerial), peel, pulp and seed) of Momordica charantia L. were investigated against five Gram-positive, six Gram-negative and four fungal strains. The extraction was done by individual cold percolation method using hexane, different hydroalcoholic solvent (100, 75, 50 and 25% methanol) and water. The antimicrobial activity was done by agar well diffusion assay. The extracts, which showed >15 mm zone of inhibition, were further screened to determine minimum inhibitory concentration and minimum bactericidal concentration using a broth dilution method performed in 96-well microtitre plate. The extractive yield was highest in aqueous extracts of all the four parts closely followed by 25% methanol. Micrococcus flavus was the most susceptible Gram-positive bacteria and Pseudomonas testosteroni was the most susceptible Gram-negative bacteria. The highest antibacterial activity was shown by 100% methanol. The Gram-negative Pseudomonas spp. was more susceptible towards all the extracts than the Gram-positive bacteria or fungal strains investigated. One hundred percent and 50% methanol extracts of seed showed lowest minimum inhibitory concentration and minimum bactericidal concentration values, that is <39 and 625 μg/ml, respectively, against Pseudomonas pictorum. Therefore, these extracts would be of interest in the control of Pseudomonas spp. in food industry as well as used for therapeutic purposes.     

Phytochemical standardization,antioxidant, and antibacterial evaluations of Leea macrophylla: A wild edible plant

In Ayurveda, Leea macrophylla Roxb. ex Hornem. (Leeaceae) is indicated in worm infestation, dermatopathies, wounds, inflammation, and in symptoms of diabetes. The present study aims to determine the antioxidant and antibacterial potential of ethanolic extract and its different fractions of Leea macrophylla root tubers using phytochemical profiling which is still unexplored. Quantitative estimations of different phytoconstituents along with characterization of ethanol extract using high performance liquid chromatography (HPLC) were performed using chlorogenic acid as a marker compound for the first time. The extract and its successive fractions were also evaluated for in vitro antioxidant activity using different models. The extract was further tested against a few Gram-positive and Gram-negative bacteria for its antibacterial activity. Phytochemical screening and quantitative estimations revealed the extract to be rich in alkaloid, flavonoid, phenols, and tannins, whereas chlorogenic acid quantified by HPLC in ethanol extract was 9.01% w/w. The results also indicated potential antioxidant and antibacterial activity, which was more prominent in the extract followed by its butanol fraction.     

Antioxidant and antibacterial activities of the ethyl acetate extracts of endophytic fungi isolated from Ageratum conyzoides L.

Accumulating evidence has demonstrated that endophytic fungi metabolites possess important biological activities. Ageratum conyzoides L. (Asteraceae) is an invasive aromatic herb with immense therapeutic importance. In the present study, we aimed to isolate and identify endophytic fungi in the roots, stems, leaves and flowers of Ageratum conyzoides L. and evaluate its antioxidant activity (DPPH, ABTS⁺ and FRAP assays), the contents of flavonoids and phenolic and antibacterial activity of their ethyl acetate extracts. Accordingly, a total of 25 endophytic fungi were isolated from Ageratum conyzoides L. and classified into 14 genera based on the Internal transcribed spacer sequence, among which Fusarium sp. (20%) were found to be the dominant groups. All fungal extracts exhibited antioxidant activity, and the extracts of fungi WZ07 exhibited antioxidant activities as well as higher flavonoids and phenolic content in all tests. Moreover, the extracts of fungi WL01 had good antibacterial activity against both Gram-positive and Gram-negative bacteria. We, for the first time, reported the antioxidant and antibacterial activity of endophytic fungi from Ageratum conyzoides L., which may help lay the foundation for developing other medicinal components.     

Antioxidant,antibacterial, and anti-inflammatory activities of standardized brazilin-rich Caesalpinia sappan extract

Abstract

Context: Brazilin is a major active principle of Caesalpinia sappan L. (Leguminosae or Fabaceae). For industry aspects, brazilin-rich extract (BRE) has been prepared and standardized to contain 39% w/w brazilin. BRE may have more advantages than brazilin in term of a lower-cost production process.

Objectives: To investigate the antioxidant, antibacterial, and anti-inflammatory activities of BRE.

Material and methods: BRE was prepared by a simple one-step purification of the crude ethanol extract of C. sappan heartwood (CSE) using a Diaion® HP-20 column. The antioxidant activities were determined using three methods, including DPPH radical scavenging, reducing power, and β-carotene bleaching assays, at concentration ranges of 1–10, 10–100, and 10–100?µg/mL, respectively. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of BRE (15.6–1000?µg/mL) against Gram-positive and Gram-negative bacteria were determined by the broth microdilution method. Anti-inflammatory activity of BRE (0.1–5?µg/mL) was evaluated as anti-denaturation activity using bovine serum albumin as a substrate.

Results and discussion: On the basis of β-carotene bleaching assay, BRE showed antioxidant activity with an EC₅₀ value of 60.5?µg/mL, which was almost equal to that of pure brazilin (52.1?µg/mL). Gram-positive bacteria were more sensitive to all tested samples than Gram-negative bacteria. BRE possessed higher antibacterial activities than CSE, but lower than brazilin. MIC/MBC values of 62.5–125/125 and 250–500/250–500?µg/mL were obtained for BRE against Gram-positive and Gram-negative bacteria, respectively. A low concentration (0.1?µg/mL) of brazilin, BRE, and CSE showed anti-inflammatory activity by inhibiting protein denaturation up to 46.8, 54.1, and 61.9%, respectively.     

Chemical composition and antimicrobial activity of extracts from Gliocladium sp. growing wild in Tunisia

The chemical composition of chloroformic, ethyl acetate, butanolic, and methanolic extracts isolated from the fungus Gliocladium sp. using different solvents of increasing polarity was analyzed by GC-FID and GC-MS. Furthermore, the antimicrobial activity of extracts was tested against five Gram-positive and Gram-negative bacteria and four pathogenic fungi. The tested extracts exhibited an interesting antibacterial activity against all bacteria tested, even against Gram-negative bacteria presenting frequently a higher resistance and against all fungi except Candida albicans.     

The antimicrobial activity of garlic and onion extracts

Aqueous extracts of garlic (Allium sativum) and onion (Allium cepa) were tested for activity against Gram-positive organisms, Gram-negative organisms and fungi. A significant growth inhibition was shown by most of the organisms, tested at random. A quantitative assessment of the activity was carried out by determining the minimum bacteriostatic and bactericidal concentrations of the extracts against Gram-positive and Gram-negative organisms. Garlic extract showed greater activity as compared to the extract of onion. The activity of the garlic extract on the mouth flora of volunteers was then investigated. A mouth wash containing 10% garlic in quarter Ringer solution produced a drastic reduction in the number of oral bacteria.     

Effect of Mimosa pudica (Linn.) extract on anxiety behaviour and GABAergic regulation of 5-HT neuronal activity in the mouse

Mimosa pudica (Linn.) (M. pudica L.) is a plant used in some countries to treat anxiety and depression. In the present study we investigated the effects of an aqueous extract of M. pudica L. on mouse anxiety-like behaviour using the elevated T maze, and on regulation of dorsal raphe nucleus (DRN) 5-hydroxytryptamine (5-HT) neuronal activity using an in-vitro mouse brain slice preparation. Acute treatment with M. pudica L. extract had an anxiolytic effect on behaviour in the elevated T maze, specifically on inhibitory avoidance behaviour. Acute application of the extract alone had no effect on the activity of DRN 5-HT neurones. However, when co-applied with the GABA(A) receptor agonist THIP (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol), the extract enhanced the inhibitory effect of the THIP on DRN 5-HT neurones. These observed effects of M. pudica L. on both behaviour and GABA modulation of 5-HT neuronal activity are similar to the effects of diazepam, the established anxiolytic and positive modulator of the GABA(A) receptor. This study suggests that the aqueous extract of M. pudica L. contains a positive modulator of GABA(A) receptor function and provides impetus for further investigation of the neuropharmacologically active constituents of the extract.     

Mechanism of decreased susceptibility for Gram-negative bacteria and synergistic effect with ampicillin of indole-3-carbinol

Indole-3-carbinol (I3C) is a natural compound found in a wide variety of plant food substances including members of the family Cruciferae with antioxidant and potential chemopreventive properties. In a previous study, I3C exhibited broad spectrum antibacterial activities. Particularly, it showed a more potent antibacterial activity against Gram-positive bacteria than Gram-negative bacteria. To elucidate this disparity of antibacterial activity between Gram-positive and Gram-negative bacteria, we investigated the actions of the efflux pumps and the lipopolysaccharide (LPS) barrier of the outer membrane of Gram-negative bacteria. The results showed that the antibacterial activity of I3C was affected by the barrier action of LPS in the outer membrane rather than by the efflux pumps. To assess its potential for combination therapy in treating bacterial infections, we investigated its synergy effects in combination with conventional antibiotics. The results demonstrated that I3C showed considerable synergistic activity in combination with ampicillin against drug-resistant isolates.     

Antibacterial activity and chemical modifications of PS-5 at the C-3 side chain

Using PS-5 as starting material, the effects of chemical modification at the C-3 side chain were studied on the antibacterial activity against Gram-positive and Gram-negative bacteria including beta-lactamase-producers. Among 35 side chains tested, 4-pyridylthio showed the highest antibacterial activity against the Gram-positive bacteria, and D-cysteinyl against the Gram-negative microbes. In general, compared with acetamidoethylthio in PS-5, basic side chains showed improved antibacterial activity against the staphylococci and pseudomonads, whereas the antibiotic activity against the Gram-negative bacteria decreased with bulky side chains. The introduction of 6-aminopenicillanate and 7-aminocephalosporanate to the C-3 side chain of carbapenem significantly reduced the antibacterial activity against the beta-lactamase-producing microbes.     

Growth inhibition of foodborne and nosocomial pathogens by aqueous fraction of bearded Argostemma (Argostemma involucratum Hemsl., Rubiaceae)

The crude methanol extract of Bearded Argostemma (Argostemma involucratum Hemsl., Rubiaceae) showed a good and broad spectrum of antibacterial activity against both Gram-negative and Gram-positive bacteria. The activity was increased on fractionation (hexane, dichloromethane and water), particularly in the aqueous fraction which was more active than the methanol extract and streptomycin (no activity was shown against tested moulds). Both the hexane and dichloromethane fractions were inactive. The objective of this experiment was to investigate the antibacterial activity of hexane, dichloromethane, and aqueous fractions of Argostemma involucratum Hemsl. The aqueous fraction of Bearded Argostemma may be a possible new option for the treatment of bacterial infections.     

Synthesis and antibacterial activity of new tetracyclic quinolone antibacterials.

A series of 8-substituted-9,1-(epoxymethano)-7-fluoro-5-oxo-5H- thiazolo[3,2-a]quinoline-4-carboxylic acids having a novel tetracyclic structure was synthesized and tested for antibacterial activity. The nature of the heteroatom (N, O, or S) substituted at the 8-position had little influence on the antibacterial activity. Among the six pyrrolidinyl derivatives and the five piperazinyl derivatives, the 8-(3-hydroxy-1-pyrrolidinyl) derivative 6h and the hydrochloride of the 8-(4-methyl-1-piperazinyl) derivative 6l showed the most potent activity against both Gram-positive and Gram-negative bacteria. Against nalidixic acid resistant strains, isolated from Escherichia coli KC-14, compound 6h was less potent than 6l. Replacement of the piperazinyl nitrogen atom by a carbon atom, an oxygen atom, or a sulfur atom (corresponding to the piperidino, morpholino, or thiomorpholino group, respectively) enhanced the activity against Gram-positive bacteria, but reduced the activity against Gram-negative bacteria. Compound 6l also showed potent in vivo antibacterial activity against Gram-positive and Gram-negative bacteria, and did not cause convulsions in mice with the concomitant administration of fenbufen. Replacement of the carboxy group by a sulfonic acid group in 6l resulted in a complete loss of antibacterial activity.     

Antimicrobial activity of crude epicarp and seed extracts from mature avocado fruit (Persea americana) of three cultivars

The epicarp and seed of Persea Americana Mill. var. Hass (Lauraceae), Persea Americana Mill. var. Shepard, and Persea americana Mill. var Fuerte cultivars of mature avocados (n?=?3) were ground separately and extracted with both absolute ethanol and distilled water. Extracts were analyzed for antimicrobial activity using the microtiter broth microdilution assay against four Gram-positive bacteria, six Gram-negative bacteria, and one yeast. Antimicrobial activity against two molds was determined by the hole plate method. The ethanol extracts showed antimicrobial activity (104.2–416.7 μg/mL) toward both Gram-positive and Gram-negative bacteria (except Escherichia coli), while inhibition of the water extracts was only observed for Listeria monocytogenes (93.8–375.0 μg/mL) and Staphylococcus epidermidis (354.2 μg/mL). The minimum concentration required to inhibit Zygosaccharomyces bailii was 500 μg/mL for the ethanol extracts, while no inhibition was observed for the water extracts. No inhibition by either ethanol or water extracts was observed against Penicillium spp. and Aspergillus flavus.     

Antibacterial Activity of Silphium perfoliatum. Extracts

Abstract

Methanol and hexane extracts obtained from above-and below-ground organs of the cup plant Silphium perfoliatum. L. (Asteraceae) were analyzed by gas chromatography–mass spectrometry (GC-MS). Eighty-five components were identified in the extracts. Moreover, evaluation of the content of total secondary metabolites (flavonoids, o.-dihydroxyphenols, and glycoside-bonded oleanolic acid) was made in the methanol extract. It was found that leaf, inflorescence, and rhizome extracts of S. perfoliatum. were characterized by antibacterial action toward Gram-positive (Enterococcus faecalis., Staphylococcus aureus.) and Gram-negative (Escherichia coli., Pseudomonas aeruginosa. bacteria). All the extracts showed extremely high activity toward Staphylococcus aureus. FDA 209P strains (MIC values: 1.00 mg/mL for rhizome alcohol and hexane extracts; 2.50 mg/mL for leaf and inflorescence alcohol extracts and for leaf hexane extracts; 5.00 mg/mL for inflorescence hexane extracts). In general, alcohol extracts had slightly stronger antibacterial properties compared with lipophilic ones. Among the alcohol extracts, those made of S. perfoliatum. rhizomes had the highest activity compared with the leaf and inflorescence extracts.     

Antimicrobial, cytotoxic and antioxidant activity of selected basidiomycetes from Yemen

Dichloromethane, methanol and aqueous extracts of 23 selected Basidiomycetes species fruiting bodies collected in Yemen were screened in vitro for their antibacterial activities against three Gram-positive bacteria (Staphyloccocus aureus, Bacillus subtilis, Micrococcus flavus), two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa) and against one yeast fungus (Candida maltosa), as well as for their cytotoxic and antioxidant activity. The highest antibacterial activity was shown by extracts from Agaricus sp. (Type 1), Coriolopsis caperata, Ganoderma colossus, Ganoderma resinaceum, Phellorinia herculea and Tulostoma obesum. Strong antioxidative effects employing the DPPH assay were exhibited by methanol extracts from Ganoderma resinaceum, Inonotus ochroporus, Phellinus rimosus and Phellorinia herculea. The results provide evidence that some of the studied fungi might be potential sources for new biologically active agents.     

Sperabillins, new antibacterial antibiotics with potent in vivo activity. Taxonomy, fermentation, isolation and biological activity.

A Gram-negative bacterium was found to produce new antibacterial antibiotics, sperabillins A, B, C and D, and the producing bacterium was characterized and identified as Pseudomonas fluorescens YK-437. Sperabillins were isolated by column chromatographies using cation-exchange resins, activated carbon and cation-exchange Sephadex, and preparative reverse-phase HPLC. Sperabillins showed antibacterial activity against Gram-negative and Gram-positive bacteria including antibiotic-resistant strains of Pseudomonas aeruginosa and Staphylococcus aureus. Sperabillin A inhibited DNA, RNA, protein, and cell wall biosynthesis in Escherichia coli. Sperabillins showed good protective effects in experimentally infected mice.     

Antimicrobial activity of seven hypericum entities from central Italy

Methanol-acetone extracts from aerial parts of seven entities of the genus Hypericum [H. perforatum L. subsp. perforatum, H. perforatum L. subsp. veronense (Schrank) Ces., H. montanum L., H. hyssopifolium Chaix, H. hirsutum L., H. hircinum L. subsp. majus (Aiton) N. Robson, H. tetrapterum Fr.] growing in the Appennino Umbro-Marchigiano (central Italy) were tested in vitro for their antimicrobial activity against two Gram-positive bacteria (Staphylococcus aureus and Enterococcus faecalis), two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and the yeast Candida albicans, by the Kirby-Bauer agar diffusion method. The two H. perforatum subspecies were particularly active against Gram-positive and Gram-negative bacteria, supporting the use of these plants in the traditional medicine of central Italy to treat wounds, skin and infectious diseases. However significant values of inhibition were given also by H. hirsutum against S. aureus and P. aeruginosa, and by H. hyssopifolium, H. hircinum subsp. majus and H. tetrapterum against C. albicans. These results suggest that hypericin and hyperforin are the main components responsible for antimicrobial activity, but not the only ones, as other extracts, showing a low level of these compounds, possess evident activity. Isolation of pure compounds from the most active extracts is in progress.     

Antibacterial Activity of Jordanian Medicinal Plants

The antibacterial activity of ethanol extracts of 15 plant species used in the traditional medicine in Jordan and other Middle East countries were tested. Extracts of certain parts of these plants were tested in vitro against 14 pathogenic bacterial species and strains using the agar diffusion method. Results evaluated as the diameter of inhibition zone of bacterial growth showed that 25 mg/well of 12 plant extracts have antibacterial activity on one or more of the tested bacteria. Three plants exhibited broad spectrum antibacterial activity: Punica granatum L., Quercus infectoria Olive., and Rhus coriaria L. The most susceptible bacteria were Pseudomonas aeruginosa, Bacillus cereus and Streptococcus pyogenes (ATCC 12351), and the most resistant species were Escherichia coli (ATCC 25922 and clinical isolates), Klebsiella pneumoniae, Shigella dysentriae (ATCC 49345), and Yersinia enterocolitica (ATCC 9610). The minimum inhibitory concentrations (MIC) of active extracts ranged from 4-32 mg/ml while the minimum bactericidal concentrations (MBC) were exerted at higher doses 8-62 mg/ml.     

Phytochemical contents and biological evaluation of Ruta chalepennsis L. growing in Saudi Arabia

Phytochemical screening of Ruta chalepensis L. exhibited the presence of different chemical groups. The dried aerial parts of the plant was total extracted by ethanol and successively using chloroform, ethyl acetate and Butanol, out of the successive extracts four compounds namely, scopletin, kaempferol, quercetin, quercetin 3-O-α-L-rhamno glucopyranosyl (Rutin) were isolated and biological evaluations. Total ethanol and successive extracts; chloroform, ethyl acetate and Butanol were produced excellent antimicrobial activities against gram negative bacteria, gram positive bacteria and fungi. Ethyl acetate extract was the best for inhibition of the microorganism’s growth. All extracts (total ethanol, and successive extracts) showed DPPH radical scavenging activity in a concentration–dependent manner. The best antioxidant activity was obtained by ethyl acetate & n-butanol extract (94.28%, IC₅₀?=?56.6?µg/ml). Also All extracts (total ethanol, and successive extracts) showed anticoagulant activity at higher concentration with prolonged clotting time 6:30 and 4:30?s at 10?mg/ml concentrations, respectively.