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1.
In a continuing search for compounds with antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), a chloroform extract of roots of Aralia continentalis was found to contain continentalic acid (CA, C(20)H(30)O(2)), a diterpenic acid. This compound exhibited potent activity against standard methicillin-susceptible Staphylococcus aureus (MSSA) as well as clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA). It was determined that continentalic acid had minimum inhibitory concentrations (MICs) of approximately 8-16 microg/mL against S. aureus, including the MSSA and MRSA standard strains. Therefore, the results obtained in this study suggest that continentalic acid might have potential as an adjunct in the treatment of antibiotic-resistant bacteria.  相似文献   

2.
HIV-1 integrase inhibitory substances from Coleus parvifolius   总被引:14,自引:0,他引:14  
For the purpose of discovering anti-HIV-1 agents from natural sources, water and EtOH extracts of 50 Thai plants were screened for their inhibitory activity against HIV-1 integrase (IN), an enzyme essential for viral replication. Of these plants, an EtOH extract of Coleus parvifolius Benth. (aerial parts) showed potent activity against HIV-1 IN with an IC50 value of 9.2 microg/mL. From this extract, 11 compounds were isolated and identified as luteolin 5-O-beta-d-glucopyranoside (1), luteolin (2), luteolin 7-methyl ether (3), luteolin 5-O-beta-d-glucuronide (4), 5-O-beta-d-glucopyranosyl-luteolin 7-methyl ether (5), rosmarinic acid (6), rosmarinic acid methyl ester (7), daucosterol (8), a mixture of alpha- and beta-amyrin (9, 10) and phytol (11). Of these compounds, rosmarinic acid methyl ester (7), rosmarinic acid (6), luteolin (2) and luteolin 7-methyl ether (3) exhibited inhibitory activities against HIV-1 IN with IC50 values of 3.1, 5.0, 11.0 and 11.0 microM, respectively. Among rosmarinic acid derivatives, the HIV-1 IN inhibitory activity increased in turn for a dimer (IC50 = 5.0 microM), a trimer (IC50 = 1.4 microM), and a tetramer (IC50 = 1.0 microM).  相似文献   

3.
Machaerium multiflorum yielded two additional new (+)-trans-hexahydrodibenzopyrans (HHDBP's), machaeriol C (1) and machaeriol D (2), and three new 5,6-seco-HHDBP's, machaeridiol A (3), machaeridiol B (4), and machaeridiol C (5). Their structures and stereochemistries were determined by 1D and 2D NMR data, including HMBC, NOESY, and circular dichroism experiments. Machaeriol C (1) demonstrated in vitro antibacterial activity against Staphylococcus aureus (IC(50) 0.65 microg/mL) and methicillin-resistant S. aureus (MRSA) (IC(50) 0.70 microg/mL), while its corresponding 5,6-seco-analogues machaeridiol A (3) and machaeridiol B (4) showed antibacterial activity against S. aureus and MRSA (IC(50) 1.0-2.6 microg/mL) and antifungal activity against Candida albicans (IC(50), 2.0-3.5 microg/mL). In addition, machaeridiol B (4) demonstrated antiparasitic activities against Plasmodium falciparum D6 and W2 clones and Leishmania donavani with IC(50) values of 0.64, 0.22, and 0.9 microg/mL, respectively.  相似文献   

4.
The aim of the present study was to evaluate the potential antimicrobial activity of 14 plants used in northeast México for the treatment of respiratory diseases, against drug-sensitive and drug-resistant strains of Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenzae type b and Mycobacterium tuberculosis. Forty-eight organic and aqueous extracts were tested against these bacterial strains using a broth microdilution test. No aqueous extracts showed antimicrobial activity, whereas most of the organic extracts presented antimicrobial activity against at least one of the drug-resistant microorganisms tested. Methanol-based extracts from the roots and leaves of Leucophyllum frutescens and ethyl ether extract from the roots of Chrysanctinia mexicana showed the greatest antimicrobial activity against the drug-resistant strain of Mycobacterium tuberculosis; the minimal inhibitory concentration (MIC) were 62.5, 125 and 62.5 microg/mL, respectively; methanol-based extract from the leaves of Cordia boissieri showed the best antimicrobial activity against the drug-resistant strain of Staphylococcus aureus (MIC 250 microg/mL); the hexane-based extract from the fruits of Schinus molle showed considerable antimicrobial activity against the drug-resistant strain of Streptococcus pneumoniae (MIC 62.5 microg/mL). This study supports that selecting plants by ethnobotanical criteria enhances the possibility of finding species with activity against resistant microorganisms.  相似文献   

5.
A phytochemical investigation of the CHCl(3) fraction of an ethanol extract of the root of Guatteria multivenia furnished nine compounds, of which four are sesquiterpenes (1-4) and five are alkaloids (5-9). Of the four sesquiterpenes, two are new (1, 3), named guatterin A (1) and dihydromadolin-K (3), and two are known (2, 4), identified as madolin-K (2) and madolin-W (4). The five known alkaloids were identified as liriodenine (5), lysicamine (6), lanuginosine (7), guadiscine (8), and O-methylpallidine (9). All the known compounds were isolated from this species for the first time. Structures of the new compounds were determined by extensive NMR studies, including DEPT, COSY, HMQC, HMBC, and NOESY. Compound 7 showed weak inhibitory effect against Candida albicans secreted aspartic proteases (SAP) with IC(50) of 45 microg/mL. Compound 5 was found to have antimicrobial activity against C. albicans, Cryptococcusneoformans, Staphylococcus aureus, and methicillin-resistant S. aureus (MRS) with IC(50)/MIC values of 3.5/6.25, 2.0/12.5, 2.0/3.13, and 2.0/3.13 microg/mL, respectively.  相似文献   

6.
Bioassay-directed fractionation of extract of Arnebia euchroma led to the isolation of alkannin (1), shikonin (2), and their derivatives (3-8) as the active principles against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). The stereochemistry of alpha-methylbutyryl alkannin (8) is revealed for the first time, and the antimicrobial activity of 8 was compared with its corresponding diastereomer (9). The derivatives 3-9 showed stronger anti-MRSA activity [minimum inhibitory concentrations (MICs) ranged from 1.56 to 3.13 microg/mL] than alkannin or shikonin (MIC = 6.25 microg/mL). Anti-MRSA activity of derivatives was bactericidal with minimum bactericidal concentration (MBC)/MIC < or = 2. In a time-kill assay, the bactericidal activity against MRSA was achieved as rapidly as 2 h. The derivatives 3-9 were also active against vancomycin-resistant Enterococcus faecium (F935) and vancomycin-resistant Enterococcus faecalis (CKU-17) with MICs similar to those with MRSA. Aromatic ester derivatives were also synthesized for antimicrobial activity comparison. None of these compounds were active against Gram-negative bacteria tested. Their cytotoxicity was also evaluated on selected cancer cell lines, and they expressed their activity in the range 0.6-5.4 microg/mL (CD(50)). Our results indicate that the ester derivatives of alkannin are potential candidates of anti-MRSA and anti-VRE agents with antitumor activity.  相似文献   

7.
Daucane sesquiterpenes from Ferula hermonis   总被引:1,自引:0,他引:1  
The roots of Ferula hermonis Boiss yielded two new daucane esters, 14-(4'-hydroxybenzoyloxy)dauc-4,8-diene (1) and 14-(4'-hydroxy-3'-methoxybenzoyloxy)dauc-4,8-diene (2), together with the four known sesquiterpenes jaeschkeanadiol p-hydroxybenzoate (3), jaeschkeanadiol benzoate (4), jaeschkeanadiol (5), and epoxyjaeschkeanadiol (6). The identities of the isolated compounds were ascertained primarily using NMR and MS data. Compounds 1 and 3 exhibited antimicrobial activity against Staphylococcus aureus with IC(50) 1.5 and 3.5 microg/mL, respectively, and against Methicillin-resistant S. aureus with IC(50) 2.0 and 4.0 microg/mL, respectively.  相似文献   

8.
Galangin is one of the active antimicrobial principles of propolis or 'bee glue' and Helichrysum aureonitens, a perennial herb used by South African indigenes to treat infection. The effect of this compound and antibacterial agents with known mechanisms of action upon the cytoplasmic membrane integrity of Staphylococcus aureus was investigated by comparing potassium loss profiles from bacterial cell suspensions. Using an agar dilution assay, the minimum inhibitory concentrations (MICs) of the flavonol galangin, the bacteriostatic antibiotic novobiocin and the bactericidal antibiotic penicillin G against Staphylococcus aureus NCTC 6571 were determined as being 50 microg/mL, 62.5 ng/mL and 31.3 ng/mL, respectively. When 5x10(7)cfu/mL Staphylococcus aureus were suspended in 'potassium-free' media containing 50 microg/mL galangin, a 60-fold decrease in viability was observed after 12 h. Populations of 1x10(9) cfu/mL Staphylococcus aureus incubated for 12 h in 50 microg/mL galangin lost 21% more potassium than untreated control populations. Novobiocin had no effect on potassium loss, but populations incubated in 31.3 ng/mL penicillin G exhibited a 6% increase in potassium loss. This data clearly demonstrates that galangin causes a significant increase in potassium loss from Staphylococcus aureus cells, which may be attributed to either direct damage to the cytoplasmic membrane or indirect damage effected through autolysis/weakening of the cell wall and consequent osmotic lysis.  相似文献   

9.
Two octanordammaranes, mansumbinone (1) and 3,4-seco-mansumbinoic acid (2), and two sesquiterpenes, beta-elemene (3) and T-cadinol (4) have been isolated from the oleo-resin of Commiphora molmol (Engl.). The structures of these compounds were established unambiguously by a series of 1D and 2D-NMR analyses. We have also unambiguously assigned all (1)H and (13)C NMR resonances for 2 and revised its (13)C data. The crude extract of the oleo-resin of C. molmol displayed potentiation of ciprofloxacin and tetracycline against S. aureus, several Salmonella enterica serovar Typhimurium strains and two K. pneumoniae strains. The antibacterial activity of terpenes 1-4 was determined against a number of Staphylococcus aureus strains: SA1199B, ATCC25923, XU212, RN4220 and EMRSA15 and minimum inhibitory concentration (MIC) values were found to be in the range of 4-256 microg/ml. The highest activity was observed by the seco-A-ring octanordammarane 2 with an MIC of 4 microg/ml against SA1199B, a multidrug-resistant strain which over-expresses the NorA efflux transporter, the major characterized antibiotic pump in this species. This activity compared favorably to the antibiotic norfloxacin with an MIC of 32 microg/ml. Compound 2 also displayed weak potentiation of ciprofloxacin and tetracycline activity against strains of Salmonella enterica serovar Typhimurium SL1344 and L10.  相似文献   

10.
The diterpene isopimaric acid was extracted from the immature cones of Pinus nigra (Arnold) using bioassay-guided fractionation of a crude hexane extract. Isopimaric acid was assayed against multidrug-resistant (MDR) and methicillin-resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentrations (MIC) were 32-64 microg/mL and compared with a commercially obtained resin acid, abietic acid, with MICs of 64 microg/mL. Resin acids are known to have antibacterial activity and are valued in traditional medicine for their antiseptic properties. These results show that isopimaric acid is active against MDR and MRSA strains of S. aureus which are becoming increasingly resistant to antibiotics. Both compounds were evaluated for modulation activity in combination with antibiotics, but did not potentiate the activity of the antibiotics tested. However, the compounds were also assayed in combination with the efflux pump inhibitor reserpine, to see if inhibition of the TetK or NorA efflux pump increased their activity. Interestingly, rather than a potentiation of activity by a reduction in MIC, a two to four-fold increase in MIC was seen. It may be that isopimaric acid and abietic acid are not substrates for these efflux pumps, but it is also possible that an antagonistic interaction with reserpine may render the antibiotics inactive. 1H-NMR of abietic acid and reserpine taken individually and in combination, revealed a shift in resonance of some peaks for both compounds when mixed together compared with the spectra of the compounds on their own. It is proposed that this may be due to complex formation between abietic acid and reserpine and that this complex formation is responsible for a reduction in activity and elevation of MIC.  相似文献   

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