Antimicrobial activity of hydrophobic xanthones from Cudrania cochinchinensis against Bacillus subtilis and methicillin-resistant Staphylococcus aureus

Ten xanthones with one or two isoprenoid groups and a prenylated benzophenone isolated from roots of Cudrania cochinchinensis (Moraceae) were tested for their antimicrobial activities against Bacillus subtilis and methicillin-resistant Staphylococcus aureus (MRSA). Among these compounds, gerontoxanthone H exhibited considerable antibacterial activity against B. subtilis (MIC = 1.56 microg/ml). Four xanthones, gerontoxanthone I, toxyloxanthone C, cudraxanthone S, and 1,3,7-trihydroxy-2-prenylxanthone, showed weak antibacterial activity against the bacterium (MICs = 3.13-6.25 microg/ml). These compounds also exhibited similar MIC values against methicillin-sensitive S. aureus, MRSAs, and Micrococcus luteus.     

An acylated phloroglucinol with antimicrobial properties from Helichrysum caespititium

A new acylated form of a phloroglucinol with significant antimicrobial properties was isolated by bioactivity guided fractionation from Helichrysum caespititium (Asteraceae). The structure elucidation, and conformation of the new phloroglucinol, 2-methyl-4-[2',4',6'-trihydroxy-3'-(2-methylpropanoyl) phenyl]but-2-enyl acetate, was established by high field NMR spectroscopic and MS data. The compound inhibited growth of Bacillus cereus, B. pumilus, B. subtilis and Micrococcus kristinae at the very low concentration of 0.5 microg/ml and Staphylococcus aureus at 5.0 microg/ml. Six fungi tested were similarly inhibited at low MICs, Aspergillus flavus and A. niger (1.0 microg/ml), Cladosporium chladosporioides (5 microg/ml), C. cucumerinum and C. sphaerospermum (0.5 microg/ml) and Phylophthora capsici at 1.0 microg/ml.     

Flavonols and an oxychromonol from Piliostigma reticulatum

The leaf extract from the plant Piliostigma reticulatum was found to exhibit antimicrobial activity against some bacteria and fungi such as Staphylococcus aureus (NCTC 6571), Escherichia coli (NCTC 10418), Bacillus subtilis (NCTC 8236), Proteus vulgaris (NCTC 4175), Aspergillus niger (ATCC 10578) and Candida albicans (ATCC 10231). Upon investigation of the chemical constituents present in the leaf extract, a total of seven compounds were isolated and their structures were unambiguously established by spectroscopic methods including HR-MS and NMR spectrometry. Four of the isolated compounds were novel, namely 6-C-methyl-2-p-hydroxyphenyloxychromonol (piliostigmol), 1, 6,8-di-C-methylquercetin-3,3',7-trimethyl ether, 2, 6,8-di-C-methylquercetin-3,3'-dimethyl ether, 3 and 3',6,8,-tri-C-methylquercetin-3,7-dimethyl ether, 4. The other three were known C-methylated flavonols and they were isolated from P. reticulatum for the first time. These were 6-C-methylquercetin-3-methyl ether, 5, 6,8-di-C-methylkaempferol-3-methyl ether, 6 and 6-C-methylquercetin-3,3',7-trimethyl ether 7. All the isolated compounds were tested for cytotoxicity using the brine shrimp toxicity assay and all of them were active albeit at different levels. With respect to antibacterial activity piliostigmol, 1 showed the highest activity against E. coli (MIC=2.57 microg/ml, 0.006 micromol), which is three times more that of Amoxicillin, where as 4 and 7 showed the least activity.     

Synthesis, structure, and structure-activity relationship analysis of enamines as potential antibacterials

Twenty-four enamines were synthesized and reported for the first time. Their chemical structures were confirmed by means of 1H NMR, ESI mass spectra, and elemental analyses, and four of them were determined by single crystal X-ray diffraction analysis. All of the compounds were assayed for antibacterial (Bacillus subtilis ATCC 6633, Escherichia coli ATCC 35218, Pseudomonas fluorescens ATCC 13525, and Staphylococcus aureus ATCC 6538) and antifungal (Aspergillus niger ATCC 16404, Candida albicans ATCC 10231, and Trichophyton rubrum ATCC 10218) activities by MTT method. Compounds (E)-ethyl 3-(4-hydroxyphenylamino)-2-(4-methoxyphenyl)acrylate (9b), (E)-ethyl 3-(3,5-difluorophenylamino)-2-(4-chlorophenyl)acrylate (11b), (E)-ethyl 3-(3,5-dichlorophenylamino)-2-(4-chlorophenyl)acrylate (12b), and (E)-ethyl 3-(4-methylphenylamino)-2-(4-chlorophenyl)acrylate (15b) showed considerable antibacterial activities against S. aureus ATCC 6538 with MICs of 3.8, 1.9, 1.1, and 0.9 microg/mL, respectively. Structure-activity relationship (SAR) analysis disclosed, generally, an E-isomer exhibited higher antibacterial activity than the corresponding Z-isomer. An electron-withdrawing group on A-ring led to some decrease in activity, while on B-ring, a similar substitution provided higher activity.     

Antiviral and antimicrobial assessment of some selected flavonoids

In the current study, the results of antibacterial, antifungal, and antiviral activity tests of four flavonoid derivatives, scandenone (1), tiliroside (2), quercetin-3,7-O-alpha-L-dirhamnoside (3), and kaempferol-3,7-O-alpha-L-dirhamnoside (4), are presented. Antibacterial and antifungal activities of these compounds were tested against Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, Klebsiella pneumoniae, Acinetobacter baumannii, Staphylococcus aureus, Bacillus subtilis, and Enterococcus faecalis, as well as the fungus Candida albicans by a micro-dilution method. On the other hand, both DNA virus Herpes simplex (HSV) and RNA virus Parainfluenza-3 (PI-3) were employed for antiviral assessment of the compounds using Madin-Darby bovine kidney and Vero cell lines. According to our data, all of the compounds tested were found to be quite active against S. aureus and E. faecalis with MIC values of 0.5 microg/ml, followed by E. coli (2 microg/ml), K. pneumoniae (4 microg/ml), A. baumannii (8 micro/g/ml), and B. subtilis (8 microg/ml), while they inhibited C. albicans at 1 microg/ml as potent as ketoconazole. However, only compound 3 displayed an antiviral effect towards PI-3 in the range of 8-32 microg/ml of inhibitory concentration for cytopathogenic effect (CPE).     

The antimicrobial activity of essential oil from Dracocephalum foetidum against pathogenic microorganisms

A number of essential oils from Mongolian aromatic plants are claimed to have antimicrobial activities. The essential oil of Dracocephalum foetidum, a popular essential oil used in Mongolian traditional medicine, was examined for its antimicrobial activity. Eight human pathogenic microorganisms including B. subtilis, S. aureus, M. lutens, E. hirae, S. mutans, E. coli, C. albicans, and S. cerevisiae were examined. The essential oil of Dracocephalum foetidum exhibited strong antimicrobial activity against most of the pathogenic bacteria and yeast strains that were tested; by both the agar diffusion method and the minimum inhibitory concentration (MIC) assay (MIC range was 26-2592 microg/ml). Interestingly, Dracocephalum foetidum even showed antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) strains. We also analyzed the chemical composition of the oil by GC-MS and identified several major components, including n-Mentha-1,8-dien-10-al, limonene, geranial, and neral.     

Erythrina poeppigiana-derived phytochemical exhibiting antimicrobial activity against Candida albicans and methicillin-resistant Staphylococcus aureus

AIMS: To screen five phytochemicals isolated from Erythrina poeppigiana (Leguminosae) for antimicrobial activity against both Candida albicans and methicillin-resistant Staphylococcus aureus (MRSA). METHODS AND RESULTS: Roots of E. poeppigiana were macerated with acetone and the chloroform-soluble fraction of the residue was subjected to repeated silica gel column chromatography using various eluting solvents. Structures of the isolated compounds were determined by extensive spectroscopic studies. Each compound was dissolved in dimethyl sulphoxide and added to agar plates (final concentration: 1.56-100 microg ml(-1)) and minimum inhibitory concentrations (MICs) against C. albicans and MRSA were determined. Spectral data indicated the presence of three different types of phytochemicals; isoflavonoids (erypoegin A, demethylmedicarpin and sandwicensin), alpha-methyldeoxybenzoin (angolensin) and cinnamylphenol (erypostyrene). While all compounds showed anti-MRSA activity in this concentration range, isoflavonoids and alpha-methyldeoxybenzoin failed to inhibit the growth of C. albicans. Erypostyrene (E-1-[2-hydroxy-4-methoxy-5-(gamma,gamma-dimethylallyl)benzyl]-2-(4-hydroxyphenyl)ethylene) exhibited not only the highest anti-MRSA activity (MIC value of 6.25 microg ml(-1)) but also anti-candidal potency (MIC value of 50 microg ml(-1)). The compound reduced viable cell numbers of C. albicans and MRSA by approximately 1 of 2000 and 1 of 1000 after 1 h incubation at each MIC, respectively. CONCLUSIONS: A new cinnamylphenol, erypostyrene, possessed anti-candidal and anti-MRSA activity. SIGNIFICANCE AND IMPACT OF THE STUDY: Erypostyrene could be a leading candidate for development of antimicrobial agents with anti-candidal and anti-MRSA activity.     

Synthesis and potent antimicrobial activity of some novel 2-phenyl or methyl-4H-1-benzopyran-4-ones carrying amidinobenzimidazoles

Series of flavones and methyl-4H-1-benzopyran-4-ones carrying mono or diamidinobenzimidazoles at different positions were synthesized and evaluated for antibacterial and antifungal activities against E. coli, S. aureus, MRSA (methicillin-resistant S. aureus), MRSE (methicillin-resistant S. epidermidis), S. faecalis and C. albicans, C. krusei. The results showed that while all diamidines are inactive, the compounds having monoamidinobenzimidazoles at the C-6 position of the 2-phenyl-4H-1-benzopyran-4-one have potent antibacterial activities, particularly, against Gram-positive bacteria. Compounds 23 and 22 exhibited the best inhibitory activity with MIC values of 1.56 microg/ml against S. aureus, MRSA, MRSE and 3.12 microg/ml against C. albicans, respectively.     

Steroidal saponins from Asparagus acutifolius

Six new steroidal saponins (1-6) were isolated from the roots of A. acutifolius L., together with a known spirostanol glycoside (7). Their structures were elucidated mainly by extensive spectroscopic analysis (1D and 2D NMR, FABMS and HRESIMS). Compounds 4-7 demonstrated antifungal activity against the human pathogenic yeasts C. albicans, C. glabrata and C. tropicalis with MICs values between 12.5 and 100 microg/ml.     

Antibacterials and modulators of bacterial resistance from the immature cones of Chamaecyparis lawsoniana

As part of an on-going project to characterize compounds from immature conifer cones with antibacterial or modulatory activity against multidrug-resistant (MDR) strains of Staphylococcus aureus, eight compounds were isolated from the cones of Chamaecyparis lawsoniana. The active compounds were mainly diterpenes, with minimum inhibitory concentrations ranging from 4 to 128 microg/ml against MDR effluxing S. aureus strains and two epidemic methicillin-resistant (EMRSA) clinical isolates. The compounds extracted were the diterpenes ferruginol, pisiferol and its epimer 5-epipisiferol, formosanoxide, trans-communic acid and torulosal, the sesquiterpene oplopanonyl acetate and the germacrane 4beta-hydroxygermacra-1(10)-5-diene. Some of these compounds also exhibited modulatory activity in potentiating antibiotic activity against effluxing strains and ferruginol, used at a sub-inhibitory concentration, resulted in an 80-fold potentiation of oxacillin activity against strain EMRSA-15. An efflux inhibition assay using an S. aureus strain possessing the MDR NorA efflux pump resulted in 40% inhibition of ethidium bromide efflux at 10 microM ferruginol (2.86 microg/ml). We report the (1)H and (13)C NMR data for the cis A/B ring junction epimer of pisiferol which we have named 5-epipisiferol. We also unambiguously assign all (1)H and (13)C NMR resonances for trans-communic acid.     

Antimicrobial activity in cultures of endophytic fungi isolated from Garcinia species

The aim of the present study was to screen for antimicrobial activity in endophytic fungi isolated from surface sterilized leaves and branches of five Garcinia plants, G. atroviridis, G. dulcis, G. mangostana, G. nigrolineata and G. scortechinii, found in southern Thailand. Fermentation broths from 377 isolated fungi were tested for antimicrobial activity by the agar diffusion method. Minimum inhibitory concentrations (MICs) were obtained for crude ethyl acetate extracts. Seventy isolates (18.6%) displayed antimicrobial activity against at least one pathogenic microorganism, such as Staphylococcus aureus, a clinical isolate of methicillin-resistant S. aureus, Candida albicans and Cryptococcus neoformans. The results revealed that 6-10%, 1-2% and 18% of the crude ethyl acetate extracts inhibited both strains of S. aureus (MIC 32-512 microg mL(-1)), Ca. albicans and Cr. neoformans (MIC 64-200 microg mL(-1)), and Microsporum gypseum (MIC 2-64 microg mL(-1)), respectively. Isolates D15 and M76 displayed the strongest antibacterial activity against both strains of S. aureus. Isolates M76 and N24 displayed strong antifungal activity against M. gypseum. Fungal molecular identification based on internal transcribed spacer rRNA gene sequence analysis demonstrated that isolates D15 (DQ480353), M76 (DQ480360) and N24 (DQ480361) represented Phomopsis sp., Botryosphaeria sp. and an unidentified fungal endophyte, respectively. These results indicate that some endophytic fungi from Garcinia plants are a potential source of antimicrobial agents.     

Synthesis, structural characterization and antimicrobial activities of 4- and 6-coordinate nickel(II) complexes with three thiosemicarbazones and semicarbazone ligands

To investigate the relationship between antimicrobial activities and the molecular structures of nickel(II) complexes with thiosemicarbazone and semicarbazone ligands, nickel(II) complexes with ligands Hmtsc, Hatsc, Hasc and H2dmtsc, were prepared and characterized by elemental analysis, FT-IR, 1H and 13C NMR spectroscopies, magnetic susceptibility measurements, UV-Vis absorption spectra, TG/DTA and single-crystal X-ray analysis. Their antimicrobial activities were evaluated by the MIC against four bacteria (B. subtilis, S. aureus, E. coli and P. aeruginosa), two yeasts (C. albicans and S. cerevisiae) and two molds (A. niger and P. citrinum). The 4-coordinate, diamagnetic nickel(II) complexes showed antimicrobial activities which were different from those of free ligands or the starting nickel(II) compounds; [Ni(mtsc)(OAc)] 1 showed selective and effective antimicrobial activities against two Gram-positive bacteria (B. subtilis and S. aureus) and modest activities against a yeast (S. cerevisiae), [Ni(mtsc)Cl] 3 exhibited moderate activities against a Gram-positive bacterium (S. aureus), and [Ni(atsc)(OAc)] 5 showed modest activities against two Gram-positive bacteria (B. subtilis and S. aureus). On the other hand, the 6-coordinate, paramagnetic nickel(II) complexes with two protonated or deprotonated ligands ([Ni(mtsc)2] 2, [Ni(atsc)(mtsc)] 4, [Ni(atsc)2] 6, [Ni(Hatsc)2](NO3)(2)7, [Ni(Hatsc)2]Cl(2)8 and [Ni(Hasc)2](OAc)(2)9) and the sterically crowded 4-coordinate, diamagnetic nickel(II) complex ([Ni(dmtsc)] 10) did not inhibit the growth of the test organisms. The structure-activity correlation in this series of nickel(II) complexes was discussed based on their ligand-replacement abilities.     

Studies on heterocyclic compounds: spiro [indole-3,2'-thiazolidine] derivatives. Antimicrobial activity of monohalogenated 3'-phenylspiro 3H-indole-3,2'-thiazolidine-2,4' (1H)-diones

The following halogenated 3'-phenyl [3H-indole-3,2'-thiazolidine]-2,4'(1H)-dione of general formula (A) were synthesized and screened for antimicrobial activity. (formula: see text) where: X = H (I, III, V, VII, IX, XI, XIII, XV), CH3 (II, IV, VI, VIII, X, XII, XIV, XVI); Y = H (I, II), 3-F (III, IV), 2-Cl (V, VI), 3-Cl (VII, VIII), 4-Cl (IX, X), 2-Br (XI, XII), 3-Br (XIII, XIV), 4-Br (XV, XVI). The synthetic approach involves the preparation of variously substituted Schiff-bases of indol-2,3-dione, which then are subjected to cyclocondensation with alpha-mercaptoalkanoic acids, to give spirothiazolidinones of type (A). The prepared compounds were screened against S. aureus, B. cereus, M. paratuberculosis, E. coli, S. typhi, Pr. mirabilis, Ps. aeruginosa, C. albicans, S. cerevisiae, A. niger by a disk-diffusion assay (Kirby-Bauer modified. The results of the antimicrobial screening showed that the prepared compounds exhibited varying degrees of activity against Gram-positive, Gram-negative bacteria, and fungi. 3-Fluoro-derivative (III) showed inhibitory activity especially toward S. aureus and C. albicans. Chloroderivatives (VII) and (VIII) showed broad-spectrum "in vitro" antimicrobial activity, and were especially inhibitory toward S. aureus, E. coli, and S. Typhi. Fluoro-derivative (IV) and bromo-derivatives (XIII) and (XIV) possessed marked antimicrobial activity against M. paratuberculosis.     

Leishmanicidal cycloartane-type triterpene glycosides from Astragalus oleifolius

Two new cycloartane-type glycosides oleifoliosides A (1) and B (2) were isolated from the lower stem parts of Astragalus oleifolius. Their structures were identified as 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-xylopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane and 3-O-[beta-xylopyranosyl-(1 --> 2)-alpha-arabinopyranosyl]-6-O-beta-glucopyranosyl-3beta,6alpha,16beta,24(S),25-pentahydroxycycloartane, respectively, by means of spectroscopic methods (IR, 1D and 2D NMR, ESI-MS). Three known cycloartane glycosides cyclocanthoside E (3), astragaloside II (4) and astragaloside IV (5) were also isolated and characterized. All five compounds were evaluated for in vitro trypanocidal, leishmanicidal and antiplasmodial activities as well as their cytotoxic potential on primary mammalian (L6) cells. Except for the compound 5, all compounds showed notable growth inhibitory activity against Leishmania donovani with IC50 values ranging from 13.2 to 21.3 microg/ml. Only weak activity against Trypanosoma brucei rhodesiense was observed with the known compounds astragaloside II (4, IC50 66.6 microg/ml) and cyclocanthoside E (3, IC50 85.2 microg/ml), while all compounds were inactive against Trypanosoma cruzi and Plasmodium falciparum. None of the compounds were toxic to mammalian cells (IC50's > 90 microg/ml). This is the first report of leishmanicidal and trypanocidal activity of cycloartane-type triterpene glycosides.     

Antimicrobial and antiviral screening of novel indole carboxamide and propanamide derivatives

A few series of indole derivatives were screened for antimicrobial, antifungal and anti-HBV activities. The compounds were tested for their in vitro antibacterial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and for their antifungal activity against Candida albicans using a disc diffusion method, which measures the diameter of the inhibition zone around a paper disc soaked in a solution of the test compounds. The antimicrobial activity results showed that all compounds are as a active as the standard compound ampicillin against Staphylococcus aureus. It was also found that indole carboxamide derivatives, substituted at 3-position with several benzyl groups, showed better inhibition of Bacillus subtilis than their congeners substituted at 2-position. Activity patterns of the compounds against Escherichia coli and Staphylococcus aureus were found slightly different by the same method. In this case, there was no correlation between structure and activity of the compounds. The antifungal activity of carboxamide derivatives was found higher compared to that of the propanamide derivatives. The minimum inhibitory concentration (MIC) values of some indole derivatives were also determined by the tube dilution technique. The MIC values of the compounds were found nearly 20- to 100-fold smaller compared to the standard compounds ciprofloxacin and ampicillin (1.56-3.13 microg/ml and 1.56-12.5 microg/ml, respectively) against Staphylococcus aureus, Bacillus subtilis and Escherichia coli. The MIC values of the tested compounds showed that these are better inhibitors for Candida albicans. Indole derivatives were screened by the anti-HBV susceptibility test. No compound showed good inhibition against the HBV virus.     

Antibacterial activity of extracts and neolignans from Piper regnellii (Miq.) C. DC. var. pallescens (C. DC.) Yunck

The evaluation of the activity of the aqueous and ethyl acetate extracts of the leaves of Piper regnellii was tested against gram-positive and gram-negative bacteria. The aqueous extract displayed a weak activity against Staphylococcus aureus and Bacillus subtilis with minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of 1000 micrograms/ml. The ethyl acetate extract presented a good activity against S. aureus and B. subtilis with MIC and MBC at 15.62 micrograms/ml. In contrast to the relative low MICs for gram-positive bacteria, gram-negative bacteria were not inhibited by the extracts at concentrations < or = 1000 mg/ml. The ethyl acetate extract was fractionated on silica gel into nine fractions. The hexane and chloroform fractions were active against S. aureus (MIC at 3.9 micrograms/ml) and B. subtilis (MIC at 3.9 and 7.8 micrograms/ml, respectively). Using bioactivity-directed fractionation, the hexane fraction was rechromatographed to yield the antimicrobial compounds 1, 2, 5, and 6 identified as eupomatenoid-6, eupomatenoid-5, eupomatenoid-3, and conocarpan, respectively. The pure compounds 1 and 2 showed a good activity against S. aureus with MIC of 1.56 micrograms/ml and 3.12 micrograms/ml, respectively. Both compounds presented MIC of 3.12 micrograms/ml against B. subtilis. The pure compound 6 named as conocarpan was quite active against S. aureus and B. subtilis with MIC of 6.25 micrograms/ml. The antibacterial properties of P. regnellii justify its use in traditional medicine for the treatment of wounds, contaminated through bacteria infections.     

Anti-staphylococcal acylphloroglucinols from Hypericum beanii

As part of an ongoing project to investigate the anti-staphylococcal properties of the Hypericum genus, an acylphloroglucinol, 1,5-dihydroxy-2-(2'-methylpropionyl)-3-methoxy-6-methylbenzene (1), was isolated from the dichloromethane extract of the aerial parts of H. beanii (Guttiferae), together with a minor related acylphloroglucinol 1,5-dihydroxy-2-(2'-methylbutanoyl)-3-methoxy-6-methylbenzene (2) as a mixture in a 5:2 ratio. The known compounds 1,7-dihydroxyxanthone (3), stigmasterol, catechin and shikimic acid were also isolated from this plant. The structures of the compounds were characterized by extensive 1- and 2D NMR spectroscopy and mass spectrometry. The minimum inhibitory concentration (MIC) values the acylphloroglucinol mixture and (3) against a panel of multidrug-resistant strains of Staphylococcus aureus ranged from 16-32 microg/ml to 128-256 microg/ml, respectively.     

Anti-Candida and mode of action of two newly synthesized polymers: a modified poly (methylmethacrylate-co-vinylbenzoylchloride) and a modified linear poly (chloroethylvinylether-co-vinylbenzoylchloride) with special reference to Candida albicans and Candida tropicalis

Polymeric antimicrobial agents represent a new and important direction that is developing in the field of antimicrobial agents. Antimicrobial activity of two newly synthesized polymers: a modified poly (methylmethacrylate-co-vinylbenzoylchloride) and a modified linear poly (chloroethylvinylether-co-vinylbenzoylchloride) have been investigated and found to be active. Both polymers have showed a broad antimicrobial activity against C. albicans and C. tropicalis. Minimal inhibitory concentrations (MIC's) for poly (methylmethacrylate-co-vinylbenzoyl chloride) were 100, 75 and 100 microg/ml in case of C. albicans (ATCC 2091), C. albicans (SC5314) and C. tropicalis, respectively. However, polycholoroethylvinylether-covinylbenzoylchloride inhibited C. albicans (ATCC 2091), C. albicans (SC5314) and C. tropicalis with minimum inhibitory concentration values (MIC's) of 150 microg/ml against the three tested Candida strains. Mode of action studies of both polymers on the medically important yeasts, C. albicans and C. tropicalis revealed that poly (methylmethacrylate-co-vinylbenzoylchloride) induced cytotoxicity, DNA damage, and altered cell permeability and morphology, which was manifested as aggregated and swollen yeast cells (C. albicans ATCC 2091) by fluorescent microscopy examination. Poly (chloroethylvinylether-co-vinylbenzoylchloride) increased cell permeability, and respiration for C. albicans and C. tropicalis. The tested polymers at 50 microg/ml had pronounced effects on C. albicans and C. tropicalis cell wall phosphopeptidomannane, proteins, sugars and phosphorus. Generally, the two polymers proved effective against the tested microorganisms, but growth inhibitory effect varied according to the composition of the polymer active group. Many investigators consider polymeric antimicrobial agents as a potential new approach for enhancing the efficiency of some existing antimicrobial agents, including prolonged activity, reduce their toxicity, as well as reduce the environmental issues associated with product use.     

Antimicrobial evaluation of indole-containing hydrazone derivatives

There has been an increasing importance of drug-resistant pathogens in clinical microbiological and antibacterial research. Indoles and hydrazone-type compounds constitute important classes of compounds in the search for effective agents against multidrug-resistant microbial infections. In this study a series of 1-methylindole-3-carboxaldehyde hydrazone derivatives were evaluated for their in vitro antimicrobial activities using the two-fold serial dilution technique against Staphylococcus aureus, methicillin-resistant S. aureus, methicillin-resistant S. aureus isolate, Escherichia coli, Bacillus subtilis, and Candida albicans. The minimum inhibitory concentration (MIC) of the test compounds and the reference standards sultamicillin, ampicillin, fluconazole, and ciprofloxacin was determined. All compounds possessed a broad spectrum of activity having MIC values of 6.25-100 microg/ml against the tested microorganisms. Aromaticity and disubstitution of the phenyl ring with especially fluorine and chlorine atoms were found to be significant for the antimicrobial activity     

Antibacterial and antifungal activity of cicerfuran and related 2-arylbenzofurans and stilbenes

Cicerfuran, 2-(2-methoxy-4,5-methylenedioxyphenyl)-6-hydroxybenzofuran, is an antifungal phytoalexin previously isolated from the roots of chickpea, Cicer spp. The synthesis of cicerfuran, five 2-arylbenzofuran analogues and nine stilbene intermediates was reported recently. The antimicrobial activities of these compounds were evaluated against two species of bacteria, Bacillus subtilis and Pseudomonas syringae, and four species of filamentous fungi, Aspergillus niger, Botrytis cinerea, Cladosporium herbarum and Monilinia aucupariae. Stilbenes with a free hydroxyl group were active against both bacteria and fungi with MICs in the range 25-100microg/ml. Cicerfuran was the only 2-arylbenzofuran that showed antimicrobial activity with MICs as low as 25microg/ml. Some aspects of the structure-activity relationship are discussed.