Antimicrobial activities of diterpene dialdehydes, constituents from myoga (Zingiber mioga Roscoe), and their quantitative analysis

The antimicrobial activities of the three diterpene dialdehydes, miogadial, galanal A and galanal B, isolated from flower buds of the myoga (Zingiber mioga Roscoe) plant were investigated with some strains of bacteria, yeasts and molds. Among the three compounds, miogadial exhibited relatively greater antimicrobial activity than the others against Gram-positive bacteria and yeasts. Galanals A and B also behaved as antimicrobial agents against Gram-positive bacteria and yeasts. The content of miogadial in the flower buds was much higher than that in the leaves, whereas galanals A and B were contained at high levels in the leaves and rhizomes.     

Screening of plant extracts for antimicrobial activity against bacteria and yeasts with dermatological relevance

There is cumulative resistance against antibiotics of many bacteria. Therefore, the development of new antiseptics and antimicrobial agents for the treatment of skin infections is of increasing interest. We have screened six plant extracts and isolated compounds for antimicrobial effects on bacteria and yeasts with dermatological relevance. The following plant extracts have been tested: Gentiana lutea, Harpagophytum procumbens, Boswellia serrata (dry extracts), Usnea barbata, Rosmarinus officinalis and Salvia officinalis (supercritical carbon dioxide [CO2] extracts). Additionally, the following characteristic plant substances were tested: usnic acid, carnosol, carnosic acid, ursolic acid, oleanolic acid, harpagoside, boswellic acid and gentiopicroside. The extracts and compounds were tested against 29 aerobic and anaerobic bacteria and yeasts in the agar dilution test. U. barbata-extract and usnic acid were the most active compounds, especially in anaerobic bacteria. Usnea CO2-extract effectively inhibited the growth of several Gram-positive bacteria like Staphylococcus aureus (including methicillin-resistant strains - MRSA), Propionibacterium acnes and Corynebacterium species. Growth of the dimorphic yeast Malassezia furfur was also inhibited by Usnea-extract. Besides the Usnea-extract, Rosmarinus-, Salvia-, Boswellia- and Harpagophytum-extracts proved to be effective against a panel of bacteria. It is concluded that due to their antimicrobial effects some of the plant extracts may be used for the topical treatment of skin disorders like acne vulgaris and seborrhoic eczema.     

生姜中6个姜辣素类成分的抗菌活性研究

为了探究生姜化学成分的抗菌活性及初步构效关系,采用色谱法从生姜中分离得到6个姜辣素类化合物,采用波谱法对这6个成分进行鉴定,分别为5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-4-decen-3-one(1)、5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-4-dodecen-3-one(2)、5-hydroxy-1-(4-hydroxy-3-methoxyphenyl)-4-tetradecane-3-one(3)、[6]-姜酚(4)、[8]-姜酚(5)和[10]-姜酚(6)。采用抗菌纸片扩散法测定6个化合物对15株病原菌株的抗菌活性。结果表明化合物1和4抗菌活性最好,而6对所有菌株均无活性。初步构效关系分析表明:烯醇型化合物对革兰氏阳性菌的抗菌活性优于姜酚型化合物;而姜酚型化合物对革兰氏阴性菌的抗菌活性优于烯醇型化合物。此外,姜辣素类成分脂肪链的长度增加,可能导致抗菌活性降低。     

Antimicrobial activity and phytochemical analyses of Polygonum aviculare L. (Polygonaceae), naturally growing in Egypt

Polygonum aviculare (Polygonaceae) is an herb commonly distributed in Mediterranean coastal regions in Egypt and used in folkloric medicine. Organic and aqueous solvent extracts and fractions of P. aviculare were investigated for antimicrobial activities on several microorganisms including bacteria and fungi. Phytochemical constituents of air-dried powered plant parts were extracted using aqueous and organic solvents (acetone, ethanol, chloroform and water). Antimicrobial activity of the concentrated extracts was evaluated by determination of the diameter of inhibition zone against both Gram-negative and Gram-positive bacteria and fungi using paper disc diffusion method.Results of the phytochemical studies revealed the presence of tannins, saponins, flavonoids, alkaloids and sesquiterpenes and the extracts were active against both Gram-negative and Gram-positive bacteria. Chloroform extract gave very good and excellent antimicrobial activity against all tested bacteria and good activity against all tested fungi except Candida albicans. Structural spectroscopic analysis that was carried out on the active substances in the chloroform extract led to the identification of panicudine (6-hydroxy-11-deoxy-13 dehydrohetisane).Evaluation of the antimicrobial activity of panicudine indicated significant activity against all tested Gram-negative and Gram-positive organisms. Panicudine displayed considerable activity against the tested fungi with the exception of C. albicans. Antimicrobial activity of the extracts was unaffected after exposure to different heat treatments, but was reduced at alkaline pH. Studies of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of panicudine on the tested organisms showed that the lowest MIC and the MBC were demonstrated against Salmonella paratyphi, Bacillus subtilis and Salmonella typhi and the highest MIC and MBC were against Staphylococcus aureus.     

Antimicrobial compounds from Eremophila serrulata

We report a search for antimicrobial compounds in the Australian plant Eremophila serrulata. Bioassay directed fractionation of a diethyl ether extract prepared from the leaves of E. serrulata led to the isolation of two compounds, an omicron-naphthoquinone, 9-methyl-3-(4-methyl-3-pentenyl)-2,3-dihydronaphtho[1,8-bc]pyran-7,8-dione (2), and a serrulatane diterpenoid, 20-acetoxy-8-hydroxyserrulat-14-en-19-oic acid (3). Two other known serrulatane-type diterpenoids, 8,20-dihydroxyserrulat-14-en-19-oic acid (4) and 8,20-diacetoxyserrulat-14-en-19-oic acid (5) were also isolated. None of these compounds had previously been tested for antimicrobial activity. Compounds 2-5 showed antimicrobial activity against Staphylococcus aureus (ATCC 29213) with minimum inhibitory concentrations (MICs) ranging from 15.6 to 250mug/mL. Compound 2 was the most active with an MIC of 15.6mug/mL and a minimum bactericidal concentration (MBC) of 125mug/mL. This compound also showed antimicrobial activity against other Gram-positive bacteria including Streptococcus pyogenes, and Streptococcus pneumoniae. No activity was observed for this compound against all Gram-negative bacteria tested.     

Bioactivity of crude extracts and some constituents of Blutaparon portulacoides (Amaranthaceae).

Crude extracts (aerial parts and roots, both dried), methylenedioxyflavonol, and a mixture of acyl steryl glycosides isolated from Blutaparon portulacoides, were assayed for their toxicity against Trypanosoma cruzi trypomastigotes and Leishmania amazonensis amastigotes from axenic cultures. The antimicrobial activity was also investigated, in a screening conducted using fifteen strains of Gram-positive and Gram-negative bacteria, along with the yeasts, Candida albicans and Candida tropicalis. To assess the antibacterial activity of the isolated compounds, the minimum inhibitory concentrations (MICs) were determined. There are no reports of acyl steryl glycosides in the genus Blutaparon and their biological activities are being evaluated for the first time.     

Antimicrobial activity of some Salvia species essential oils from Iran

The aerial parts of Salvia multicaulis, S. sclarea and S. verticillata were collected at full flowering stage. The essential oils were isolated by hydrodistillation and analyzed by combination of capillary GC and GC-MS. The in vitro antimicrobial activity of the essential oils were studied against eight Gram-positive and Gram-negative bacteria (Bacillus subtilis, Bacillus pumulis, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and three fungi (Candida albicans, Saccharomyces cerevisiae and Aspergillus niger). The results of antibacterial activity tests of the essential oils according to the disc diffusion method and MIC values indicated that all the samples have moderate to high inhibitory activity against the tested bacteria except for P. aeruginosa which was totally resistant. In contrast to antibacterial activity, the oils exhibited no or slight antifungal property, in which only the oil of S. multicaulis showed weak activity against two tested yeasts, C. albicans and S. cerevisiae.     

Terpenes with antimicrobial activity from Cretan propolis

Five terpenes, the diterpenes: 14,15-dinor-13-oxo-8(17)-labden-19-oic acid and a mixture of labda-8(17),13E-dien-19-carboxy-15-yl oleate and palmitate as well as the triterpenes, 3,4-seco-cycloart-12-hydroxy-4(28),24-dien-3-oic acid and cycloart-3,7-dihydroxy-24-en-28-oic acid were isolated from Cretan propolis. Moreover, 18 known compounds were also isolated, seven of them for the first time as propolis components. All structures were established on the basis of spectroscopic analysis and chemical evidence. All isolated compounds were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria as well as against some human pathogenic fungi showing a broad spectrum of antimicrobial activity.     

Anti-Helicobacter pylori activity of the methanolic extract of Geum iranicum and its main compounds

Geum iranicum Khatamsaz, belonging to the Rosaceae family, is an endemic plant of Iran. The methanol extract of the roots of this plant showed significant activity against one of the clinical isolates of Helicobacter pylori which was resistant to metronidazole. The aim of this study was the isolation and evaluation of the major compounds of G. iranicum effective against H. pylori. The compounds were isolated using various chromatographic methods and identified by spectroscopic data (1H and 13C NMR, HMQC, HMBC, EI-MS). An antimicrobial susceptibility test was performed employing the disk diffusion method against clinical isolates of H. pylori and a micro dilution method against several Gram-positive and Gram-negative bacteria; additionally the inhibition zone diameters (IZD) and minimum inhibitory concentrations (MIC) values were recorded. Nine compounds were isolated: two triterpenoids, uvaol and niga-ichigoside F1, three sterols, beta-sitosterol, beta-sitosteryl acetate, and beta-sitosteryl linoleate, one phenyl propanoid, eugenol, one phenolic glycoside, gein, one flavanol, (+)-catechin, and sucrose. The aqueous fraction, obtained by partitioning the MeOH extract with water and chloroform, was the most effective fraction of the extract against all clinical isolates of H. pylori. Further investigation of the isolated compounds showed that eugenol was effective against H. pylori but gein, diglycosidic eugenol, did not exhibit any activity against H. pylori. The subfraction D4 was the effective fraction which contained tannins. It appeared that tannins were probably the active compounds responsible for the anti-H. pylori activity of G. iranicum. The aqueous fraction showed a moderate inhibitory activity against both Gram-positive and Gram-negative bacteria. The MIC values indicated that Gram-positive bacteria including Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis are more susceptible than Gram-neagative bacteria including Escherichia coli and Pseudomonas aeruginosa.     

Composition, antimicrobial and antioxidant activity of the extracts of Eryngium palmatum Pančić and Vis. (Apiaceae)

The chemical composition, antimicrobial and antioxidant activity of Eryngium palmatum, an endemic plant species from the Balkan Peninsula, were investigated. The flavonoids apigenin (9.5±0.3 mg g^?1) and apigenin 7-O-glucoside (2.4±0.1 mg g^?1) were determined in a methanol extract of aerial parts using HPLC analysis. The methanol extract of roots contained catechin (5.0±0.1 mg g^?1), epicatechin (2.9±0.1 mg g^?1), chlorogenic acid (1.6±0.0 mg g^?1), gallic acid (0.9±0.0 mg g^?1) and rosmarinic acid (0.9±0.2 mg g^?1). GC-FID and GCMS analysis of a chloroform extract of aerial parts showed that the main volatile constituents were falcarinol, linoleic acid, hexadecanoic acid and methyl linoleate (comprising 32.6%; 24.4%; 19.9; 13.2% of the volatile fraction, respectively), while octanoic acid, tetradecanol and dodecanol dominated in the chloroform extract of the roots (34.9%; 25.8%; 22.2% of the volatile fraction, respectively). Investigation of antimicrobial activity by broth microdilution showed that the methanol and chloroform extracts of aerial parts and roots exerted a significant effect (MIC 3.5–15.6 μg mL^?1) against tested Gram-positive and Gram-negative bacteria. The methanol extracts of aerial parts or roots exerted moderate ferric reducing antioxidant power, DPPH radical scavenging activity and hydroxyl radical scavenging activity.     

Antimicrobial activity and composition of the essential oil of Gontscharovia popovii from Iran

The aerial parts of Gontscharovia popovii (B. Fedtsch. and Gontsch.) Boriss. were collected at full flowering stage. The essential oil was isolated by hydrodistillation and analyzed by a combination of capillary GC and GC-MS. Thirty-one components were identified with the main constituent being carvacrol (71.9%), followed by linalool (5.5%), p-cymene (4.5%) and gamma-terpinene (4.4%). The in vitro antimicrobial activity of the essential oil of G. popovii was studied against seven Gram-positive and Gram-negative bacteria (Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and three fungi (Candida albicans, Saccharomyces cerevisiae and Aspergillus niger). The results of the bioassays showed that the oil exhibited strong antimicrobial activity against all the tested fungi and bacteria except for the resistant bacterium Pseudomonas aeruginosa.     

Trypanocidal and antimicrobial activities of Moquinia kingii.

A chloroform crude extract (aerial part) and two compounds, apigenin (1) and cynaropicrin (2), isolated from Moquinia kingii were evaluated against Trypanosoma cruzi trypomastigotes in vitro. Antimicrobial activity was also screened using twenty-two strains including gram-positive and gram-negative bacteria and the yeasts Candida albicans and C. tropicalis. The chloroform crude extract, fractions and isolated compounds from M. kingii were active for both activities. The IC50 values for trypanocidal activity obtained for cynaropicrin and apigenin were 93.5 microg/ml and 181 microg/ml, respectively, while the minimum inhibitory concentrations (MICs) varied from 100 microg/ml to 2500 microg/ml, against the strains of bacteria and yeasts evaluated.     

Chemical composition and antimicrobial activity of the essential oil of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica)

The chemical composition and the antimicrobial activity of the essential oil isolated from the needles of endemic Dalmatian black pine (Pinus nigra ssp. dalmatica) from Croatia were investigated. The chemical composition of the essential oil was determined by GC and GC/MS analyses, and the main compounds identified were α-pinene, β-pinene, germacrene D, and β-caryophyllene. Disc-diffusion and broth-microdilution assays were used for the in vitro antimicrobial screening. The Dalmatian black pine essential oil exhibited a great potential of antibacterial activity against Gram-positive bacteria (MIC=0.03-0.50% (v/v)) and a less pronounced activity against Gram-negative bacteria (MIC=0.12-3.2% (v/v)). The volatile compounds also inhibited the growth of all fungi tested, including yeast.     

Copper complexes of imidazole-2-, pyrrole-2- and indol-3-carbaldehyde thiosemicarbazones: inhibitory activity against fungi and bacteria

Copper complexes of thiosemicarbazones of imidazole-2-carbaldehyde, pyrrole-2-carbaldehyde and indole-3-carbaldehyde were synthesised and characterised. The antimicrobial properties of the free ligands and their complexes were evaluated against yeasts, moulds and bacteria (Gram-positive and Gram-negative). Some copper chelates exhibited a moderate inhibitory activity, better than that of the corresponding free ligands. In particular, the pyrrole derivative [Cu(HL(2))(2)] proved to be a wide spectrum agent, showing an interesting inhibition of the growth of all Gram-positive bacteria and fungi tested at concentrations of 12-50 microg/mL. In contrast, a selective effect was observed for imidazole and indole chelates against fungi and Gram-positive bacteria, respectively.     

Antimicrobial activity of volatile component and various extracts ofEnteromorpha linza (Linnaeus) J. Agardh from the coast of Izmir, Turkey

The methanol, dichloromethane, hexane, chloroform and volatile components ofEnteromorpha linza were testedin vitro for their antimicrobial activity against five Gram-positive, four Gram-negative bacteria andCandida albicans ATCC 10239. GC-MS analysis of the volatile components ofE. linza resulted in the identification of 35 compounds which constituted 84.76% of the total compounds. The volatile components ofE. linza consisted of n-tetratriacontane (8.45%), 1-heptadecanamine (6.65%) and docosane (6.46%) as major components. The methanol and chloroform extracts showed more potent antimicrobial activity than hexane and dichloromethane extracts. The volatile oils of these algae did not remarkably inhibit the growth of tested microorganisms.     

Antimicrobial evaluation of coumarins and flavonoids from the stems of Daphne gnidium L.

The antimicrobial activity of stems methanol extract from Daphne gnidium L. collected from Sardinia (Italy) was evaluated against 6 strains of standard and clinical isolated gram (+/-) bacteria. The antimicrobial effect on two strains of fungi was also tested. The extract in toto exhibited antibacterial activity against Bacillus lentus and Escherichia coli, but was inactive against fungi. Four coumarins (daphnetin, daphnin, acetylumbelliferone, daphnoretin) and seven flavonoids (luteolin, orientin, isoorientin, apigenin-7-O-glucoside, genkwanin, 5-O-beta-D-primeverosyl genkwanine, 2,5,7,4'-tetrahydroxyisoflavanol) present in the plant extract were also investigated against the same strains of bacteria and fungi assayed for the crude extract. The most active compounds were daphnetin, genkwanin, and 2,5,7,4'-tetrahydroxyisoflavanol.     

New classes of Gram-positive selective antibacterials: inhibitors of MRSA and surrogates of the causative agents of anthrax and tuberculosis

An antimicrobial phenolic stilbene, (E)-3-hydroxy-5-methoxystilbene, 1 was recently isolated from the leaves of Comptonia peregrina (L.) Coulter and shown to possess inhibitory activity against several Gram-positive bacteria, including isolates of methicillin-resistant Staphylococcus aureus (MRSA), Mycobacterium bovis BCG, and avirulent Bacillusanthracis (Sterne strain), among others. These results prompted the design and synthesis of two new classes of compounds, phenoxystyrenes and phenothiostyrenes, as analogs of the natural antimicrobial stilbene. These and additional stilbenoid analogs were synthesized using new, efficient, copper-mediated coupling strategies. Minimum inhibitory concentration (MIC) antimicrobial assays were performed on all compounds prepared. These preliminary structure-activity relationship studies indicated that both new classes of synthetic analogs, as well as the stilbenes, show promising activity against Gram-positive bacteria when at least one phenolic moiety is present, but not when absent. The potencies of the phenolic phenoxystyrenes and phenothiostyrenes were found to be comparable to those of the phenolic stilbenes tested.     

The antimicrobial activity of extracts of the lichen Cladonia foliacea and its (-)-usnic acid, atranorin, and fumarprotocetraric acid constituents

The antimicrobial activity of the chloroform, diethyl ether, acetone, petroleum ether, and ethanol extracts of the lichen Cladonia foliacea and its (-)-usnic acid, atranorin, and fumarprotocetraric acid constituents against 9 bacteria and fungi has been investigated. The extracts and pure compounds alone were found active against the same bacteria and the same yeasts. Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Proteus vulgaris, Listeria monocytogenes, Aeromonas hydrophila, Candida albicans, and Candida glabrata growth were inhibited. In addition, the MICs of the extracts, (-)-usnic acid, atranorin and fumarprotocetraric acid were determined.     

Chemical composition and antimicrobial activity of volatile compounds of Tamarix boveana (Tamaricaceae)

The chemical composition of the Tamarix boveana volatile oils obtained from the whole aerial part, flowers, leaves and stems by steam distillation was analysed using gas chromatograph (GC)-flame ionization detectors (FID) and GC-MS. Sixty-two components were identified. Hexadecanoic acid (18.14%), docosane (13.34%), germacrene D (7.68%), fenchyl acetate (7.34%), Benzyl benzoate (4.11%) were found to be the major components in the whole aerial parts. This composition differed according to the tested part: 2.4 Nonadienal was the main compound in the flowers (12.13%) while germacrene D was the major component in leaves (31.43%) and hexadecanoic acid in the stems (13.94%). To evaluate in vitro antimicrobial activity, all volatile oils were tested against six Gram-positive and Gram-negative bacteria and four fungi. The T. boveana volatile oils exhibited an interesting antibacterial activity against all strains tested except Pseudomonas aeruginosa but no antifungal activity was detected.     

Antimicrobial activities of eucalyptus leaf extracts and flavonoids from Eucalyptus maculata

AIMS: We investigated the antimicrobial activities of eucalyptus leaf extracts to find effective antibacterial agents. METHODS AND RESULTS: The antimicrobial activities of leaf extracts from 26 species of eucalyptus were measured. Extracts of Eucalyptus globulus, E. maculata and E. viminalis significantly inhibited the growth of six Gram-positive bacteria (Staphylococcus aureus, MRSA, Bacillus cereus, Enterococcus faecalis, Alicyclobacillus acidoterrestris, Propionibacterium acnes), and of a fungus (Trichophyton mentagrophytes), but they did not show strong antibacterial activity against Gram-negative bacteria (Escherichia coli, Pseudomonas putida). 2',6'-dihydroxy-3'-methyl-4'-methoxy-dihydrochalcone, eucalyptin and 8-desmethyl-eucalyptin, isolated from E. maculata extracts, exhibited potent antimicrobial activities against seven micro-organisms with minimum inhibitory concentrations (MIC) ranging from 1.0 to 31 mg l(-1). CONCLUSIONS: The eucalyptus extracts and three compounds from E. maculata were found to be effective against micro-organisms that cause food poisoning, acne and athlete's foot. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows potential uses of extracts from E. globulus, E. maculata and E. viminalis, and antimicrobial compounds isolated from E. maculata.