Inhibitory effects of Caesalpinia sappan on growth and invasion of methicillin-resistant Staphylococcus aureus

In the present study, we investigated antimicrobial activity of Caesalpinia sappan against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and effect of Caesalpinia sappan extract on the invasion of MRSA to human mucosal fibroblasts (HMFs). Chloroform, n-butanol, methanol, and aqueous extracts of the Caesalpinia sappan showed antimicrobial activity against standard methicillin-sensitive Staphylococcus aureus (MSSA) as well as MRSA. Methanol extract of Caesalpinia sappan demonstrated a higher inhibitory activity than n-butanol, chloroform, and aqueous extracts. In the checkerboard dilution method, methanol extract of Caesalpinia sappan markedly lowered the minimal inhibitory concentrations (MICs) of ampicillin and oxacillin against MRSA. To determine whether methanol extract of Caesalpinia sappan inhibits the MRSA invasion to HMFs, the cells were treated with various sub-MIC concentrations of methanol extract and bacterial invasion was assayed. MRSA invasion was notably decreased in the presence of 20-80 microg/ml of Caesalpinia sappan extract compared to the control group. The effect of Caesalpinia sappan extract on MRSA invasion appeared dose-dependent. These results suggest that methanol extract of Caesalpinia sappan may have antimicrobial activity and the potential to restore the effectiveness of beta-lactam antibiotics against MRSA, and inhibit the MRSA invasion to HMFs.     

Quercus infectoria: a candidate for the control of methicillin-resistant Staphylococcus aureus infections

Acetone, ethyl acetate, 95% ethanol and aqueous extracts of Quercus infectoria (Q. infectoria) demonstrated significant antibacterial activities against all strains of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA). Inhibition zones were in the range 11.75-16.82 mm. Both MRSA and MSSA strains exhibited minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values at 0.13 and 0.13-1.00 mg/mL, respectively. At 2 MIC, the growth of two representative MRSA strains was continually inhibited for at least 20 h. Surviving MRSA cells were not detected within 12-14 h after treatment with the extract at 4 MIC concentration. Staphylococcus aureus ATCC 25923 demonstrated similar results.     

白木香种子挥发油的化学成分及抗菌活性研究

采用石油醚浸提法提取白木香种子的挥发油,用滤纸片琼脂扩散法测定白木香种子挥发油的抗耐甲氧西林金黄色葡萄球菌(MRSA)活性,结果表明样品具有弱抗MRSA活性,并用GC-MS技术鉴定了其中的19个化学成分.     

Phytochemical flavones isolated from Scutellaria barbata and antibacterial activity against methicillin-resistant Staphylococcus aureus

A crude extract prepared from Scutellaria barbata D. Don (Lamiaceae) was analyzed in the effort to discover antibacterial compounds against high-level strains of methicillin-resistant Staphylococcus aureus (MRSA). Apigenin and luteolin were isolated from the plant as active constituents against the bacteria. These flavonoid congeners were selectively toxic to S. aureus, including the MRSA and methicillin-sensitive S. aureus strains.     

Antimicrobial activity of xanthones from Calophyllum species, against methicillin-resistant Staphylococcus aureus (MRSA).

During the past 5 years, a considerable number of known and new xanthones from the Calophyllum species of Sri Lanka have been isolated and characterized. We have investigated the antimicrobial activity of Calophyllum xanthones, with a special reference to methicillin-resistant Staphylococcus aureus (MRSA). These activity studies were carried out using the agar plate method. Calozeloxanthone, a xanthone which has been isolated from C. moonii and C. lankensis, showed the highest activity against methicillin-resistant S. aureus (MRSA) strains at a concentration of 8.3 microg/ml. Hence, calozeyloxanthone appears to hold promise as an antimicrobial agent in the treatment of infections with S. aureus, including methicillin-sensitive S. aureus (MRSA), and should be investigated further.     

Activity of Zanthoxylum clava-herculis extracts against multi-drug resistant methicillin-resistant Staphylococcus aureus (mdr-MRSA)

In a continuing search for compounds with antibiotic activity against methicillin-resistant Staphylococcus aureus (MRSA) possessing multidrug ef flux systems, we have demonstrated activity associated with extracts from Southern prickly ash bark, Zanthoxylum clava-herculis. Bioassay-guided isolation of an alkaloid extract led to the characterization of the benzo[c]phenanthridine alkaloid chelerythrine as the major active principle. This compound exhibited potent activity against strains of MRSA, which were highly resistant to clinically useful antibiotics via multidrug ef flux mechanisms.     

Methylsulfomycin I, a new cyclic peptide antibiotic from a Streptomyces sp. HIL Y-9420704

Methylsulfomycin I (1) is a new cyclic peptide antibiotic isolated from the fermentation broth of a Streptomyces sp. HIL Y-9420704. Its structure was elucidated by NMR and GC-MS. The in vitro activity (MIC) against a wide range of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-, and teicoplanin-resistant strains, is described.     

Phenylnaphthalene compounds from the subterranean part of Vitex rotundifolia and their antibacterial activity against methicillin-resistant Staphylococcus aureus

A careful investigation of the subterranean part of Vitex rotundifolia has shown that this plant contains five novel lignans having a 1-phenylnaphthalene-type skeleton together with four known lignans. These structures were elucidated on the basis of spectroscopic data. Furthermore, some of the isolated compounds showed antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA).     

A novel antibacterial iridoid and triterpene from Caiophora coronata

Bioassay-guided fractionation of the antibacterial CH(2)Cl(2)-MeOH extract obtained from the aerial parts of the Argentinean plant Caiophora coronata led to the isolation of a new triterpene, 1beta,3beta-dihydroxyurs-12-en-27-oic acid, 1, and a new iridoid, 1alpha-methoxy-6alpha,10-dihydroxyisoepiiridomyrmecin (caiophoraenin), 2, along with the known iridoid isoboonein 3. Their structures were established by spectroscopic techniques (1D and 2D NMR, HRFABMS, FTIR). The MIC values of isolated compounds were determined against methicillin-sensitive (MSSA) and -resistant (MRSA) strains of Staphylococcus aureus, Bacillus subtilis (BS), vancomycin-resistant Enterococcus faecium (VREF), Escherichia coli (EC), E. coli imp (ECimp), and Candida albicans (CA). Compound 1 was found active against BS, MSSA, MRSA, VREF, and ECimp with MIC values of 2, 4, 4, 4, and 16 microg/mL, respectively.     

The antibacterial principle of Caesalpina sappan

Using a bioassay-directed purification scheme, the active antibacterial principle from Caesalpina sappan was isolated and identified to be brasilin. This compound showed potent activity against antibiotic-resistant bacteria, notably methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), multi-drug resistant Burkholderia cepacia as well as a number of other bacteria. The minimal inhibitory concentrations ranged from 4 to 32 microg/mL. The results from time-kill studies showed that brasilin is bactericidal against MRSA. The addition of brasilin to growing MRSA cells resulted in a rapid inhibition of incorporation of [(3)H] thymidine or [(3)H] serine into DNA and proteins, respectively. Exposure of MRSA to a sub-MIC level of brasilin for ten consecutive subcultures did not induce resistance to the compound. The Trypan blue dye exclusion test showed that brasilin lacked cytotoxicity against Vero cells. In conclusion, brasilin is an antibacterial principle from C. sappan and it has the potential to be developed into an antibiotic.     

76株耐甲氧西林葡萄球菌药敏结果分析

目的 分析耐甲氧西林葡萄球菌药敏结果,以提高MRSA和MRS的检出率。 方法 分析我院2009年1月-2010年2月分离的76株耐甲氧西林葡萄球菌药敏结果。 结果药敏试验结果显示,耐甲氧西林葡萄球菌对万古霉素敏感率最高,达100.00%。治愈67例,治愈率为88.16%（67/76）; 治愈出院者平均住院时间为15.02±7.3天。 结论 耐甲氧西林葡萄球菌对万古霉素敏感率最高。     

Activity of plant flavonoids against antibiotic-resistant bacteria

Thirty eight plant-derived flavonoids representing seven different structural groups were tested for activities against antibiotic-resistant bacteria using the disc-diffusion assay and broth dilution assay. Among the flavonoids examined, four flavonols (myricetin, datiscetin, kaempferol and quercetin) and two -flavones (flavone and luteolin) exhibited inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA). Myricetin was also found to inhibit the growth of multidrug-resistant Burkholderia -cepacia, vancomycin-resistant enterococci (VRE) and other medically important organisms such as -Klebsiella pneumoniae and Staphylococcus epidermidis. Myricetin was bactericidal to B. cepacia. The results of the radiolabel incorporation assay showed that myricetin inhibited protein synthesis by -B. cepacia. The structure-activity relationship of these flavonoids is discussed.     

Isopimaric acid from Pinus nigra shows activity against multidrug-resistant and EMRSA strains of Staphylococcus aureus

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.     

Bioactive carbazole alkaloids from Clausena wallichii roots

Four new carbazole alkaloids, clausenawallines C-F (1-4), along with 18 known compounds (5-22) were isolated from the roots of Clausena wallichii. Compounds 3, 9, and 22 exhibited significant antibacterial activity against methicillin-resistant Staphylococcus aureus SK1 (MRSA SK1) and Staph. aureus TISTR 1466 with MIC values in the range 4-16 μg/mL, whereas compound 4 showed the highest cytotoxicity against oral cavity cancer (KB) and small-cell lung cancer (NCI-H187) with IC(50) values of 10.2 and 4.5 μM, respectively.     

Antibacterial activity of plants used in traditional medicines of Ghana with particular reference to MRSA

ETHNOPHARMACOLOGICAL RELEVANCE: : In an ethno botanical survey carried out in the Akwapim-North district of the Republic of Ghana, 25 plant species, used in traditional medicine to treat skin disease and/or to treat antimicrobial (viral, bacterial or protozoan) infections were identified. AIM OF STUDY: : To investigate the antimicrobial activity of traditional Ghanaian medicines with special interest in anti-methicillin-resistant Staphylococcus aureus (MRSA) activity. MATERIALS AND METHODS: : Chloroform, ethanol and aqueous extracts (including use of a Stomacher) of these plants were prepared and agar-well diffusion tests, MIC's and MBC's were used to investigate antimicrobial activity. RESULTS: Extracts of 13 plant species inhibited the growth of one or more of the following bacteria: MRSA, methicillin-sensitive Staphylococcus aureus (MSSA), Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris. Extracts from 11 of these 13 plant species also inhibited the growth of three or more of 14 additional clinical isolates of MRSA. Aqueous extracts of Alchornea cordifolia were active against all 21 bacterial strains tested and showed the highest levels of antibacterial activity overall with MIC's against MRSA in the range of 1.6-3.1 mgml(-1) and MBC's in the range of 6.3-12.5 mgml(-1). CONCLUSIONS: : The presence of antibacterial activity in extracts of Elaeophorbia drupifera, Rauwolfia vomitoria and the leaves of Solanum verbascifolium, plants traditionally used to treat skin infections, are reported for the first time. Extracts from Alchornea cordifolia, also used to treat wounds, had the widest spectrum of antibacterial activity.     

In vitro antibacterial effects of Cinnamomum extracts on common bacteria found in wound infections with emphasis on methicillin-resistant Staphylococcus aureus

Ethnopharmacological relevance

Cinnamomum species have been widely used in many traditional systems of medicine around the world. In the Malaysian traditional system of medicine, the leaves, stem bark and stem wood of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum have been used to treat wound infections. To study the antibacterial effects of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum against common bacteria found in wound infections with primary focus on methicillin-resistant Staphylococcus aureus (MRSA).

Materials and methods

The crude extracts from the leaves, stem-bark and stem-wood of Cinnamomum iners, Cinnamomum porrectum, Cinnamomum altissimum and Cinnamomum impressicostatum were obtained using sequential extraction with hexane, ethylacetate, methanol and water. The volatile oils were obtained by hydro-distillation. The antibacterial activities of extracts were investigated using disk diffusion assays and broth microdilution assays.

Results

The volatile oils obtained from the stem-bark of Cinnamomum altissimum, Cinnamomum porrectum and Cinnamomum impressicostatum have shown significant antibacterial activity against a wide range of Gram positive and Gram negative bacteria including MRSA. A few test extracts have shown better activity against MRSA as compared to methicillin sensitive Staphylococcus aureus (MSSA). Amongst all the test extracts, Cinnamomum impressicostatum stem-bark water extract produced the largest inhibition zone of 21.0 mm against MRSA while its inhibition zone against MSSA was only 8.5 mm. The minimum inhibitory concentration (MIC) of this extract against MRSA was 19.5 μg mL⁻¹ and the corresponding minimum bactericidal concentration (MBC) was 39.0 μg mL⁻¹.

Conclusions

This study has scientifically validated the traditional use of Cinnamomum species in treating wound infections. Of high scientific interest was the observation that the antibacterial effect of Cinnamomum impressicostatum stem-bark crude water extract against MRSA was significantly higher than its effect against MSSA, suggesting that the extract contains a compound(s) with higher specific neutralising activity against the drug resistance markers of MRSA.     

Antibacterial activity of leaf essential oils and their constituents from Cinnamomum osmophloeum

The antibacterial activities of the essential oils from leaves of two Cinnamomum osmophloeum clones (A and B) and their chemical constituents were investigated in this study. The nine strains of bacteria, including Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Salmonella sp., and Vibrio parahemolyticus, were used in the antibacterial tests. Results from the antibacterial tests demonstrated that the indigenous cinnamon B leaf essential oils had an excellent inhibitory effect. The MICs (minimum inhibitory concentrations) of the B leaf oil were 500 microg/ml against both K. pneumoniae and Salmonella sp. and 250 microg/ml against the other seven strains of bacteria. Cinnamaldehyde possessed the strongest antibacterial activity compared to the other constituents of the essential oils. The MICs of cinnamaldehyde against the E. coli, P. aeruginosa, E. faecalis, S. aureus, S. epidermidis, MRSA, K. pneumoniae, Salmonella sp., and V. parahemolyticus were 500, 1000, 250, 250, 250, 250, 1000, 500, and 250 microg/ml, respectively. These results suggest that C. osmophloeum leaf essential oil and cinnamaldehyde are beneficial to human health, having the potential to be used for medical purposes and to be utilized as anti-bacterial additives in making paper products.     

Screening of Chinese medicinal plants for inhibition against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA)

ETHNOPHARMACOLOGICAL RELEVANCE: Traditional herbs are a valuable source of novel antibacterials in combating pathogenic isolates of methicillin-resistant Staphylococcus aureus (MRSA), a global nosocomial problem. AIM OF THE STUDY: To assess in vitro anti-MRSA activity of extracts from Chinese herbs. The minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) were determined in the setting of clinical MRSA isolates. MATERIALS AND METHODS: A collection of 19 plant extracts were obtained and bioassay-guided phytochemical analysis performed. Antibacterial susceptibilities were screened for inhibitory zone and MICs/MBCs determined by serial dilution with a standardized microdilution broth methodology. 9 MRSA isolates and a standard control strain (ATCC 25923) were cultured and exposed to the plant extract and isolated compound. Vancomycin was used as a positive control agent. RESULTS: All the presented 19 plants showed anti-MRSA activity with MIC of 1.25-3.07mg/ml. The most active antimicrobial plants were Dendrobenthamia capitata, Elsholtzia rugulosa, Elsholtzia blanda, Geranium strictipes and Polygonum multiflorum (MIC< or =1.43mg/ml), and betulinic acid isolated from the active ethyl acetate fraction of Dendrobenthamia capitata extract was determined with MIC/MBC values as 62.5/125.0mg/ml. CONCLUSIONS: Dendrobenthamia capitata, Elsholtzia rugulosa, Elsholtzia blanda, Geranium strictipesPolygonum multiflorum and betulinic acid demonstrate promising anti-MRSA potential.     

Antimicrobial activities of naphthazarins from Arnebia euchroma

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.     

Antimicrobial and antiparasitic (+)-trans-hexahydrodibenzopyrans and analogues from Machaerium multiflorum

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.