GC/MS Composition and Resistance Modulatory Inhibitory Activities of Three Extracts of Lemongrass: Citral Modulates the Activities of Five Antibiotics at Sub-Inhibitory Concentrations on Methicillin-Resistant Staphylococcus aureus.

We investigated whether three extractable fractions of lemongrass (Cymbopogon citratus): aqueous and ethanol extracts and lemongrass essential oil exhibited any antimicrobial resistance modulatory effects if used in combination with selected antibiotics ampicillin, tetracycline, streptomycin, cefloxacin and amoxicillin on methicillin-resistant Staphylococcus aureus (MRSA). MRSA growth inhibition (zones of inhibition) was greatest for the lemongrass oil at concentrations of 1, 2, 5, 10 and 20 % (wt/vol). The MIC for lemongrass oil was 0.5 mg/mL, while it was 4 mg/mL for both the aqueous and ethanol extracts. Evaluation of extracts for antibacterial resistance modifying activities when used in combination with either of the five antibiotics at sub-inhibitory concentrations, showed that lemongrass oil highly potentiated the activities of three antibiotics; amoxicillin, streptomycin and tetracycline. The ethanol extract enhanced the activity of tetracycline and ampicillin, while the aqueous extract only increased the activity of tetracycline against MRSA. The activity of cefloxacin with the extracts was either indifferent. Analysis of the lemongrass oil by GC/MS showed the prominence of three compounds: the two isomers neral and geranial of citral and, the acetate geranyl acetate, which together made up 94 % of the composition. The compounds were also observed in the ethanol and water extracts but to a lesser extent when analyzed by HPLC-UV (λ 233 nm). Our study confirms the antibacterial properties of the extracts especially, lemongrass oil. It also demonstrates that lemongrass oil potentiates the activities of three antibiotics against the biofilm-forming MRSA. This biocidal, anti-biofilm disruption and antibiotic potentiating abilities are mainly attributable to citral and geranyl acetate, further evidence of lemongrass oil as a very useful source of phytochemicals, especially citral for the fight against antibiotic resistance.

Antibiofilm Activity of Azadirachta indica and Catharanthus roseus and Their Synergistic Effects in Combination with Antimicrobial Agents against Fluconazole-Resistant Candida albicans Strains and MRSA.

The rapid emergence and spread of antimicrobial resistance has become a global public health concern that threatens the effective treatment of infectious diseases. One major approach adopted to overcome antimicrobial resistance is the use of plant extracts individually and/or with combination of antibiotics with plant extracts, which may lead to new ways of treating infectious diseases and essentially representing a potential area for further future investigations. In this study, the antifungal activities of Azadirachta indica leaf and Catharanthus roseus flower extracts against fluconazole-resistant Candida albicans strains (isolated from pregnant women with vulvovaginal candidiasis) and anti-methicillin-resistant Staphylococcus aureus (MRSA) were evaluated by agar well diffusion, microdilution, and biofilm inhibition assays. Subsequently, the determination of the combined antimicrobial activity of the individual plant extracts with (fluconazole and voriconazole) and (ampicillin, tetracycline, and streptomycin) against C. albicans strains and MRSA, respectively, was evaluated by checkerboard microdilution assay. Results from the study showed that the antimicrobial activity of the two plant extracts determined by time-kill kinetics was fungistatic with their MICs ranging from 0.1 to 4 mg/mL. Interestingly, all extracts were proved as good biofilm inhibitors of resistant C. albicans and MRSA from 10.1 to 98.82%. Their combination interaction with fluconazole, voriconazole, ampicillin, tetracycline, and streptomycin ranged from synergy to antagonism as per the parameters used. Overall, these results showed that A. indica leaf and C. roseus flower extracts have significant antifungal property. Furthermore, A. indica leaf and C. roseus flower extracts alone or in combination with fluconazole and voriconazole could provide a promising approach to the management of candidiasis caused by drug-resistant strains as well as their interaction with the antibacterial agents to combat the common infections caused by MRSA.

Current perspectives on supercharging reagents in electrospray ionization mass spectrometry.

In electrospray ionization mass spectrometry (ESI-MS), analytes are introduced into the mass spectrometer in typically aqueous-organic solvent mixtures, including pH modifiers. One mechanism for improving the signal intensity and simultaneously increasing the generation of higher charge-state ions is the inclusion of small amounts (approx. <0.5% v/v mobile phase solution) of charge-inducing or supercharging reagents, such as m-nitrobenzyl alcohol, o-nitrobenzyl alcohol, m-nitrobenzonitrile, m-(trifluoromethyl)-benzyl alcohol and sulfolane. We explore the direct and indirect (colligative properties) that have been proposed as responsible for their modes of action during ESI. Of the many theorized mechanisms of ESI, we re-visit the three most popular and highlight how they are impacted by supercharging observations on small ions to large molecules including proteins. We then provide a comprehensive list of 34 supercharging reagents that have been demonstrated in ESI experiments. We include an additional 19 potential candidate isomers as supercharging reagents and comment on their broad physico-chemical properties. It is becoming increasingly obvious that advances in technology and improved ion source design, analyzers e.g. the use of ion mobility, ion trap, circular dichroism (CD) spectroscopy, together with computer modeling are increasing the knowledge base and, together with the untested isomers and yet-to-be unearthed ones, offer opportunities for further research and application in other areas of polymer research.

Levels of Polychlorinated Biphenyls in Plastic Resin Pellets from Six Beaches on the Accra-Tema Coastline, Ghana.

BACKGROUND: Polychlorinated biphenyls (PCBs) are organic compounds, known to be carcinogenic and banned by the Stockholm Convention. PCBs are hydrophobic substances able to accumulate in organic materials, including plastic pellets. Plastic resin pellets are industrial raw materials that are remolded finished products for industrial and domestic use, commonly used for packaging. Plastic resin pellets were chosen as the medium for monitoring hydrophobic contaminants because they are able to adsorb PCB contaminants. Pellets can be unintentionally washed into the ocean where hydrophobic contaminants such as PCBs are also deposited. OBJECTIVES: We aimed to identify PCB congeners and quantify PCB pollution levels in the marine environment using resin plastic pellets collected from six beaches along the Accra-Tema coastline in Ghana. METHODS: Plastic resin pellets (5 g) were extracted with 200 mL of n-hexane for 16 hours by Soxhlet extraction. Concentrations of PCBs from the extracts were determined using gas chromatography with an electron capture detector. RESULTS: The individual PCB congeners detected were PCB 28, 52, 101, 105, 138, 153, 156 and 180. PCB 28 was detected at all six beaches, with a total concentration of 43.5 ng/g pellet (mean/beach 7.25 +/- 2.47 ng/g pellet; CV = 34%), while PCB 138 was only detected on one beach (Castle Beach) at a total concentration of 0.8 ng/g pellet. The concentration of PCBs ranged from 7.4 ng/g (Sunset Beach) to 47.5 ng/g (Castle Beach) (mean 16.4±15.4 ng/g per beach; CV=94%). DISCUSSION: PCB concentrations at Castle Beach have been studied previously, showing an increase from 39 ng/g to 47.5 ng/g, whereas levels decreased significantly from 28 ng/g to 14.2 ng/g in Sakumono Beach over the span of three years. CONCLUSIONS: The concentrations of four detected PCB congeners (28, 52, 101 and 156) were significantly higher than the World Health Organization (WHO) allowable daily intake of 6 ng/g food per day for PCBs. A more efficient industrial and domestic waste disposal system is advocated for Ghana.