Bioactivity studies of extracts from Tridax procumbens.

An updated review on the biological activity of Tridax procumbens is presented. A detailed biological screening comprised of gram-positive and gram-negative bacteria, yeasts and fungi using crude extracts of this plant was undertaken. The n-hexane extract of the flowers showed activity against Escherichia coli. The same extract of the whole aerial parts was active against Mycobacterium smegmatis, Escherichia coli, Salmonella group C and Salmonella paratyphi. The ethyl-acetate extract of the flowers was active against Bacillus cereus and Klebsiella sp. The aerial parts extract also showed activity only against Mycobacterium smegmatis and Staphylococcus aureus, while the aqueous extract showed no antimicrobial activity. None of the tested extracts was active against the yeasts, Candida albicans, Candida tropicalis and Rhodotorula rubra; or the fungi: Aspergillus flavus, Aspergillus niger, Mucor sp. and Trichophyton rubrum.     

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 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.     

Antimicrobial activity of extracts of the lichen Parmelia sulcata and its salazinic acid constituent

The antimicrobial activity of the acetone, chloroform, diethyl ether, methanol, and petroleum ether extracts of the lichen Parmelia sulcata and its salazinic acid constituent have been screened against twenty eight food-borne bacteria and fungi. All of the extracts with the exception of the petroleum ether extract showed antimicrobial activity against Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Proteus vulgaris, Yersinia enterocolitica, Staphylococcus aureus, Streptococcus faecalis, Candida albicans, Candida glabrata, Aspergillus niger, Aspergillus fumigatus, and Penicillium notatum. Salazinic acid did not show antimicrobial activity against L. monocytogenes, P. vulgaris, Y. enterocolitica, and S. faecalis but showed activity against Pseudomonas aeruginosa and Salmonella typhimurium as well. The MIC values of the extracts and the acid for the bacteria and fungi have also been determined.     

Synthesis, structure and biological activity of cobalt(II) and copper(II) complexes of valine-derived schiff bases

We have synthesized two cobalt(II) 2 and copper(II) 3 complexes of valine-derived Schiff bases. The obtained complexes were characterized by elemental analysis, FT-IR and X-ray diffraction. Biological studies of complexes 2 and 3 had been carried out in vitro for antimicrobial activity against Gram-positive, Gram-negative bacteria and human pathogenic fungi. Compound 3 was proven to be a broad spectrum agent, showed a significant inhibition of the growth of Gram-positive bacteria (Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, Micrococcus luteus), and pathogenic fungi (Candida spp., Cryptococcus neoformans, Rhodothece glutinis, Saccharomyces cerevisia, Aspergillus spp., Rhizopus nigricans) tested and a moderate activity against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Proteus vulgaris and Enterobacter aerogenes) tested. The in vitro cytotoxicity of compound 3 was evaluated using hemolytic assay, in which the compound 3 was found to be non-toxic to human erythrocytes even at a concentration of 500mug/mL.     

Antimicrobial activity of extracts of chemical races of the lichen Pseudevernia furfuracea and their physodic acid, chloroatranorin, atranorin, and olivetoric acid constituents

The antimicrobial activity and the MIC values of the ethanol, chloroform, diethyl ether, and acetone extracts of the chemical races of Pseudevernia furfuracea (var. furfuracea and var. ceratea) and their physodic acid, chloroatranorin, atranorin, and olivetoric acid constituents have been investigated against some microorganisms. Nearly all extracts of both chemical races showed antimicrobial activity against Aeromonas hydrophila, Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, Proteus vulgaris, Staphylococcus aureus, Streptococcus faecalis, Yersinia enterocolitica, Candida albicans, Candida glabrata, Alternaria alternata, Ascochyta rabiei, Aspergillus niger, Fusarium culmorum, Fusarium moniliforme, Fusarium oxysporum, Fusarium solani, and Penicillium notatum. There was no antimicrobial activity of the extracts against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Pseudomonas syringae, Salmonella typhimurium, Alternaria citri, Alternaria tenuissima, and Gaeumannomyces graminis. Chloroatranorin and olivetoric acid were active against the same microorganisms with few exceptions. Physodic acid was active against about the same bacteria and yeasts and inactive against all of the filamentous fungi tested. Also no activity of atranorin against the filamentous fungi was observed.     

Synthesis of pseudopeptides based L-tryptophan as a potential antimicrobial agent

Four compounds named L-BTrpPA, L-Trp-o-PA, L-Trp-m-PA and L-Trp-p-PA, pseudopeptides constructed from pyridine and tryptophan units, were synthesized and tested against the Gram-positive, Gram-negative strains of bacteria and human pathogenic fungi. L-Trp-o-PA proved to be a broad-spectrum antimicrobial agent, showing a significant inhibition of the growth of Gram-positive bacteria (Staphylococcus aureus, methicillin-resistant S. aureus, Bacillus subtilis, Micrococcus luteus), and pathogenic fungi (Candida spp., Cryptococcus neoformans, Rhodotorula glutinis, Saccharomyces cerevisiae, Aspergillus spp., Rhizopus nigricans) tested and activity against Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris, Enterobacter aerogenes) tested. The in vitro cell cytotoxicity of L-Trp-o-PA was evaluated using haemolytic assay, in which the compound was found to have low lytic property, even up to the concentration of 4000 microg/mL, it only lysed 6-7% of erythrocytes, which was 100-fold greater than the MICs (minimum inhibitory concentration).     

Design and synthesis of spiro[indole-thiazolidine]spiro[indole-pyrans] as antimicrobial agents

A series of novel spiro[indole-thiazolidine]spiro[indole-pyran] derivatives were synthesized from N-(bromoalkyl)indol-2,3-diones via monospiro-bisindole intermediates; the two indole nuclei being connected via N-(CH(2))(n)-N linker. Synthesized compounds were evaluated for their antimicrobial activities in vitro against three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, and Staphylococcus epidermis), four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumonia) as well as four fungi (Aspergillus niger, Aspergillus fumigatus, Aspergillus flavus, and Candida albicans) using Cup plate method. Bis spiro-indoles exhibited stronger antibacterial and antifungal efficiency than their corresponding mono spiro-indoles. Compound 10e, the most active derivative was shown to inhibit the growth of all bacterial strains and two fungal strains (A. niger and C. albicans).     

New trifluoromethyl quinolone derivatives: Synthesis and investigation of antimicrobial properties

A series of quinolone derivatives, containing different heterocyclic amines were prepared. Synthesized compounds were evaluated for their in vitro antimicrobial activities against two Gram-positive bacteria, three Gram-negative bacteria as well as four fungi. All the derivatives showed good activity towards Gram-positive bacteria and less activity towards Gram-negative bacteria. They also showed moderate to comparable activity against Aspergillus niger and Candida albicans and low to moderate antifungal activity against Aspergillus fumigatus and Aspergillus flavus.     

In vitro evaluation of Datura innoxia (thorn-apple) for potential antibacterial activity

Various parts of Datura innoxia were examined for potential antibacterial activity by preparing their crude aqueous and organic extracts against Gram-negative bacteria (Escherichia coli and Salmonella typhi) and Gram-positive bacteria (Bacillus cereus, Bacillus subtilis and Staphylococcus aureus). The results of agar well diffusion assay indicated that the pattern of inhibition depends largely upon the plant part, solvent used for extraction and the organism tested. Extracts prepared from leaves were shown to have better efficacy than stem and root extracts. Organic extracts provided potent antibacterial activity as compared to aqueous extracts. Among all the extracts, methanolic extract was found most active against almost all the bacterial species tested. Gram-positive bacteria were found most sensitive as compared to Gram-negative bacteria. Staphylococcus aureus was signifi cantly inhibited by almost all the extracts even at very low MIC followed by other Gram-positives. For Escherichia coli (a Gram-negative bacterium), the end point was not reached for ethyl acetate extract while it was very high for other extracts. The study promises an interesting future for designing a potentially active antibacterial agent from Datura innoxia.     

Antimicrobial activity of isocytisoside and extracts of Aquilegia vulgaris L

AIMS: The aim of this study was to analyse the antimicrobial properties extracts of Aquilegia vulgaris, and their principial flavonoid component and to compare the obtained results with the activity of gentamicin and nystatin. METHODS AND RESULTS: The ethanol, acetone and isopropanol extracts as well as the subextracts isolated from the methanol extract together with the main flavonoid: 4'-methoxy-5,7-dihydroxyflavone 6-C-glucoside (isocytisoside) were obtained from the leaves with stems of Aquilegia vulgaris L. All the extracts were analysed by TLC to confirm flavonoids and phenolic acids occurrence. The antimicrobial activity was tested by the method of series dilutions against different Gram-positive, Gram-negative bacteria and also fungi. The results have shown that the extracts, subextracts and isocytisoside inhibit growth of all studied micro-organisms, revealing the greatest activity against Gram-positive Staphylococcus aureus, Staph. epidermidis and the mould Aspergillus niger. CONCLUSIONS: The antimicrobial activity of the tested materials it is possibly related to the content of isocytisoside. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has determined new activity of A. vulgaris and suggested the necessity of further studies.     

Characterization and analysis of antibiotic activity of some aquatic actinomycetes

Nine different isolates of aquatic actinomycetes identified as Streptomyces spp. were studied for their morphological and cultural characteristics. One of these isolates (C4-S, Streptomyces violaceusniger) was extensively studied for its inhibitory effect against a wide range of Gram-positive, Gram-negative bacteria, Mycobacterium vaccae ATCC 29678, Candida albicans and several food associated filamentous fungi and yeasts. Most of these were characterized by flexous sporophore morphology and their inability to produce cultural pigments. Bioassay results indicated that S. violaceusniger of 10 days culture age was highly active against Gram-positive cocci and bacilli with an inhibition zone of 16-25 mm, and slightly active against M. vaccae ATCC 29678 with an inhibition zone of 5-10 mm. The inhibitory effect was slight against Escherichia coli, Aspergillus niger 1 and C. albicans with an inhibition zone of 8-10 mm for each of them. There was no inhibitory effect of S. violaceusniger against other Gram-negative bacteria, filamentous fungi and yeast. The nature of the active molecule produced by S. violaceusniger showed a maximum absorption in the UV region at 210-260 nm.     

Synthesis of 1,2,4-triazole derivatives containing benzothiazoles as pharmacologically active molecule

In attempt to make significant pharmacologically active molecule, we report here the synthesis and in vitro antimicrobial and antitubercular activity of various series of 3-(3-pyridyl)-5-(4-nitrophenyl)-4-(N-substituted-1,3-benzothiazol-2-amino)-4H-1,2,4-triazole. The antimicrobial activity of title compounds were examined against two Gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes), two Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and three fungi (Candida albicans, Aspergillus niger, Aspergillus clavatus) using the broth microdilution method and antitubercular activity H(37)Rv using Lowenstein-Jensen agar method.     

In vitro antibacterial activity of laboratory grown culture of Spirulina platensis

The hexane, ethyl acetate, dichloromethane, methanol extracts and spent media (extracellular substances) were tested in vitro for their antibacterial activity for which one Gram-positive bacterium (Staphylococcus aureus) and four Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, and Klebsiella pneumoniae) were used as test organisms. The methanol extract showed more potent activity than other organic extracts, spent medium of the culture exhibited little activity against E. coli only. No inhibitory effect was found against Klebsiella pneumoniae.The broth microdilution assay gave minimum inhibitory concentrations (MIC) values ranging from 1 to 512 μg/ml. The MIC of methanol extract against S. aureus and E. coli were 128 μg/ml and 256 μg/ml, respectively.     

Antimicrobial activity of Brazilian copaiba oils obtained from different species of the Copaifera genus

The antimicrobial activity of copaiba oils was tested against Gram-positive and Gram-negative bacteria, yeast, and dermatophytes. Oils obtained from Copaifera martii, Copaifera officinalis, and Copaifera reticulata (collected in the state of Acre) were active against Gram-positive species (Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, Bacillus subtilis, and Enterococcus faecalis) with minimum inhibitory concentrations ranging from 31.3-62.5 microg/ml. The oils showed bactericidal activity, decreasing the viability of these Gram-positive bacteria within 3 h. Moderate activity was observed against dermatophyte fungi (Trichophyton rubrum and Microsporum canis). The oils showed no activity against Gram-negative bacteria and yeast. Scannning electron microscopy of S. aureus treated with resin oil from C. martii revealed lysis of the bacteria, causing cellular agglomerates. Transmission electron microscopy revealed disruption and damage to the cell wall, resulting in the release of cytoplasmic compounds, alterations in morphology, and a decrease in cell volume, indicating that copaiba oil may affect the cell wall.     

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.     

Semisynthesis and antimicrobial activity of novel guttiferone-A derivatives

Six derivatives of guttiferone-A (LFQM-79, 80, 81, 82, 113 and 114) were synthesized and evaluated for their antimicrobial activity against the opportunistic or pathogenic fungi Candida albicans (ATCC 09548), Candida glabrata (ATCC 90030), Candida krusei (ATCC 6258), Candida parapsilosis (ATCC 69548), Candida tropicalis (ATCC 750), Cryptococcus neoformans (ATCC 90012), Trichophyton tonsurans, Microsporum gypseum and also against the opportunistic and pathogenic Gram-positive bacteria Staphylococcus aureus (ATCC 6538), Staphylococcus epidermidis (ATCC 12228), Bacillus cereus (ATCC 11778) and Gram-negative Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 9027), Salmonella typhimurium (ATCC 14028), Proteus mirabilis (ATCC 25933). The antimicrobial activities of derivatives were compared with guttiferone-A and they presented to be more potent than the original molecule and sometimes greater than standard drugs established in therapeutics. The current study showed that derivatives of guttiferone-A possess potent antimicrobial activity and are relatively non-cytotoxic, which reveal these new molecules as promising new drug prototype candidates, with innovative structural pattern.     

Synthesis and antimicrobial properties of imidazolium and pyrrolidinonium salts

For the purpose of developing new disinfectants and antiseptics, we searched for compounds having high bactericidal activity against gram-positive bacteria, gram-negative bacteria, and fungi. Three different series of quaternary imidazolium and pyrrolidinonium salts were synthesized: series A (1-alkyl-3-methylimidazolium chlorides and bromides); series B (1-alkyl-2-methyl-3-hydroxyethylimidazolium chlorides); and series C (N-alkyl-N-hydroxyethylpyrrolidinonium). Series B and C were newly designed. These three series were tested to evaluate their antibacterial and antifungal properties for the first time. Seven microbial strains were used in the study: Escherichia coli KCTC1924, Salmonella typhimurium KCTC1926, Staphylococcus aureus 209 KCTC1916, Staphylococcus aureus R209 KCTC1928, Bacillus subtilis KCTC1914, Candida albicans KCTC1940, and Chlorella regularis. The antimicrobial efficiency was measured by bacterial and fungal growth inhibition expressed as minimal inhibitory concentration (MIC) values. Series A and B imidazolium salts had very good antimicrobial activity against the examined Gram-negative bacteria, Gram-positive bacteria, and fungi. Also the pyrrolidinonium salt was found to have low MIC for some of tested microorganisms. The antibacterial and antifungal active properties of the salts depend upon the structure of functional groups and the alkyl chain length in the imidazolium and pyrrolidinonium ring. Among the synthesized quaternary imidazolium and pyrrolidinonium salts, the imidazolium salts containing a long alkyl chain and the introduction of a hydroxyethyl chain and methyl group into the imidazolium ring structure leads to broad spectrum active antimicrobial agents which not only have bacteriostatic properties but could be powerful bactericides.     

三种百合鳞茎提取物的抑菌作用

采用纸片琼脂扩散法测定了宜昌百合、岷江百合及兰州百合鳞茎甲醇提取物对革兰氏阳性细菌(金黄色葡萄球菌、枯草芽孢杆菌)和革兰氏阴性细菌(大肠杆菌、沙门氏菌)的抑制活性,并对3种百合鳞茎提取物的含量与抑菌活性进行了剂量-效应关系分析。结果表明:3种百合鳞茎提取物对4种细菌均具有抑制活性,对革兰氏阳性细菌的抑菌活性高于对革兰氏阴性细菌的抑菌活性,且宜昌百合和岷江百合两种野生百合鳞茎提取物的抑菌活性均高于普通食用的兰州百合;3种百合鳞茎提取物的含量与抑菌活性之间存在明显的剂量-效应关系,即随着提取物含量的升高,抑菌活性明显升高。     

The antimicrobial effects of propolis collected in different regions in the Basque Country (Northern Spain)

The antimicrobial activity of 19 propolis extracts prepared in different solvents (ethanol and propylene glycol) (EEP/PEP), was evaluated against some bacterial and fungal isolates using the agar-well diffusion method. It was verified that all the samples tested showed antimicrobial activity, although results varied considerably between samples. Results revealed that both types of propolis extracts showed highly sensitive antimicrobial action against Gram-positive bacteria and fungi at a concentration of 20% (Staphylococcus aureus, Streptococcus mutans, Candida albicans and Saccharomyces cerevisae) with a minimal inhibitory concentration (MIC) ranging from 0.5 to 1.5 mg/ml, with a moderate effect against Streptococcus pyogenes (MIC from 17 to 26 mg/ml). To our knowledge, this is the first study showing elevated antimicrobial activity against Gram-negative bacteria [Salmonella enterica (MIC from 0.6 to 1.4 mg/ml)] and lesser activity against Helicobacter pylori (MIC from 6 to 14 mg/ml), while Escherichia coli was resistant. This concluded that the Basque propolis had a strong and dose-dependent activity against most of the microbial strains tested, while database comparison revealed that phenolic substances were responsible for this inhibition, regardless of their geographical origin and the solvent employed for extraction. Statistical analysis showed no significant differences (P ≤ 0.05) between EEP and PEP extracts.