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ACS Applied Materials & Interfaces Jan 2020Using enzymes as bioelectrocatalysts is an important step toward the next level of biotechnology for energy production. In such biocatalysts, a sacrificial cofactor as...
Using enzymes as bioelectrocatalysts is an important step toward the next level of biotechnology for energy production. In such biocatalysts, a sacrificial cofactor as an electron and proton source is needed. This is a great obstacle for upscaling, due to cofactor instability and product separation issues, which increase the costs. Here, we report a cofactor-free electroreduction of CO to a high energy density chemical (methanol) catalyzed by enzyme-graphene hybrids. The biocatalyst consists of dehydrogenases covalently bound on a well-defined carboxyl graphene derivative, serving the role of a conductive nanoplatform. This nanobiocatalyst achieves reduction of CO to methanol at high current densities, which remain unchanged for at least 20 h of operation, without production of other soluble byproducts. It is thus shown that critical improvements on the stability and rate of methanol production at a high Faradaic efficiency of 12% are possible, due to the effective electrochemical process from the electrode to the enzymes via the graphene platform.
Topics: Biocatalysis; Carbon Dioxide; Enzymes, Immobilized; Graphite; Methanol; Oxidation-Reduction
PubMed: 31816230
DOI: 10.1021/acsami.9b17777 -
Mycotoxin Research Aug 2023The antifungal and antiaflatoxigenic effects of four distinct plant species against Aspergillus flavus and Aspergillus parasiticus were investigated. Essential oils and...
The antifungal and antiaflatoxigenic effects of four distinct plant species against Aspergillus flavus and Aspergillus parasiticus were investigated. Essential oils and methanolic extracts were prepared from aerial parts of Lippia javanica, Ocimum gratissimum, Satureja punctata, and stem barks of Toddalia asiatica by hydro-distillation and maceration, respectively. The poisoned food method was used to confirm the antifungal activity of essential oils and methanolic extracts from four different plant species against Aspergillus flavus and Aspergillus parasiticus, and high-performance liquid chromatography was used to quantify the antiaflatoxigenic activity. The essential oils of Satureja punctata and Lippia javanica showed the highest antiaflatoxigenic activity against the fungi strains tested at concentrations of 1.25, 2.5, and 5 µL/mL, followed by Ocimum gratissimum essential oil while Toddalia asiatica essential oil exerted moderate antiaflatoxigenic activity. Meanwhile, the methanolic extracts showed a wide spectrum of low to high antifungal and antiaflatoxigenic activities at concentrations of 125, 250, and 500 µg/mL against A. flavus and A. parasiticus. This study has indicated that the essential oils of Satureja punctate, Lippia javanica, and Ocimum gratissimum had substantial antifungal and antiaflatoxigenic activities compared to their methanolic extracts, while Toddalia asiatica methanolic extract had a moderate antifungal activity compared to its essential oil.
Topics: Aspergillus flavus; Oils, Volatile; Aflatoxins; Antifungal Agents; Methanol; Plant Extracts
PubMed: 37261704
DOI: 10.1007/s12550-023-00490-6 -
Molecules (Basel, Switzerland) Dec 2019Methanol is metabolized in the body to highly toxic formaldehyde and formate when consumed accidentally. Methanol has been typically analyzed with gas...
Methanol is metabolized in the body to highly toxic formaldehyde and formate when consumed accidentally. Methanol has been typically analyzed with gas chromatography-flame ionization detector (GC-FID). However, its retention time may overlap with other volatile compounds and lead to confusion. Alternative analysis of methanol using gas chromatography/mass spectrometry (GC/MS) also has limitations due to its similar molecular weight with oxygen and low boiling point. In this study, methanol and internal standard of deuterium-substituted ethanol were derivatized with 3,4-dihydro-2H-pyran under acid catalysis using concentrated hydrochloric acid. The reaction products including 2-methoxytetrahydropyran were extracted with solid-phase microextraction followed by GC/MS analysis. This method was successfully applied to measure the lethal concentration of methanol in the blood of a victim with a standard addition method to overcome the complex matrix effect of the biospecimen. Identification of the metabolite formate by ion chromatography confirmed the death cause to be methanol poisoning. This new method was a much more convenient and reliable process to measure methanol in complex matrix samples by reducing sample pretreatment effort and cost.
Topics: Benzenesulfonates; Gas Chromatography-Mass Spectrometry; Humans; Methanol; Pyrans
PubMed: 31877660
DOI: 10.3390/molecules25010041 -
Journal of Medical Entomology Sep 2023The massive and inappropriate use of synthetic insecticides is causing significant and increasing environmental disruption. Therefore, developing effective natural...
The massive and inappropriate use of synthetic insecticides is causing significant and increasing environmental disruption. Therefore, developing effective natural mosquitocidal compounds could be an alternative tool for malarial vector control. The present study investigates the larvicidal and adulticidal effect of methanol and acetone extracts of leaves from Lippia chevalieri, Lippia multiflora, Cymbopogon schoenanthus, and Lantana camara against Anopheles arabiensis, to control the most widespread vector transmitting malaria in sub-Saharan. Africa. Extracts were evaluated following WHO modified test procedure against third- to fourth-instar larvae and, non-blood-fed females from 3- to 5-day-old field populations of An. arabiensis under laboratory conditions using WHO larval and CDC bottle bioassays, respectively. Mortality was recorded after 24-h exposure and several compounds were identified in the extracts. The methanolic and acetonic extracts of L. camara were effective against larvae showing lethal concentrations to 50% (LC50) of the population, at 89.48 and 58.72 ppm, respectively. The acetonic extracts of C. schoenanthus and L. chevalieri showed higher toxicities LC50s of 0.16% and 0.22% against female adults, respectively. The methanolic extracts of L. multiflora and L. chevalieri LC50s were effective at 0.17% and 0.27%, respectively, against female adults. These results indicate that the plant extracts tested may represent effective means to control An. arabiensis when used to treat the surface of the marshes.
Topics: Female; Animals; Anopheles; Methanol; Acetone; Kenya; Mosquito Vectors; Larva; Plant Leaves; Plant Extracts; Insecticides; Culex
PubMed: 37478413
DOI: 10.1093/jme/tjad066 -
Scientific Reports Apr 2022Osteoporosis affects millions of people worldwide. As such, this study assessed the macrophage-dependent in vitro anti-osteoporosis, phytochemical profile and...
Osteoporosis affects millions of people worldwide. As such, this study assessed the macrophage-dependent in vitro anti-osteoporosis, phytochemical profile and hepatotoxicity effects in zebrafish larvae of the stem bark extracts of P. africana. Mouse bone marrow macrophages (BMM) cells were plated in 96-well plates and treated with P. africana methanolic bark extracts at concentrations of 0, 6.25, 12.5, 25, and 50 µg/ml for 24 h. The osteoclast tartrate-resistant acid phosphatase (TRAP) activity and cell viability were measured. Lipopolysaccharides (LPS) induced Nitrite (NO) and interleukin-6 (IL-6) production inhibitory effects of P. africana bark extracts (Methanolic, 150 µg/ml) and β-sitosterol (100 µM) were conducted using RAW 264.7 cells. Additionally, inhibition of IL-1β secretion and TRAP activity were determined for chlorogenic acid, catechin, naringenin and β-sitosterol. For toxicity study, zebrafish larvae were exposed to different concentrations of 25, 50, 100, and 200 µg/ml P. africana methanolic, ethanolic and water bark extracts. Dimethyl sulfoxide (0.05%) was used as a negative control and tamoxifen (5 µM) and dexamethasone (40 µM or 80 µM) were positive controls. The methanolic P. africana extracts significantly inhibited (p < 0.001) TRAP activity at all concentrations and at 12.5 and 25 µg/ml, the extract exhibited significant (p < 0.05) BMM cell viability. NO production was significantly inhibited (all p < 0.0001) by the sample. IL-6 secretion was significantly inhibited by P. africana methanolic extract (p < 0.0001) and β-sitosterol (p < 0.0001) and further, chlorogenic acid and naringenin remarkably inhibited IL-1β production. The P. africana methanolic extract significantly inhibited RANKL-induced TRAP activity. The phytochemical study of P. africana stem bark revealed a number of chemical compounds with anti-osteoporosis activity. There was no observed hepatocyte apoptosis in the liver of zebrafish larvae. In conclusion, the stem bark of P. africana is non-toxic to the liver and its inhibition of TRAP activity makes it an important source for future anti-osteoporosis drug development.
Topics: Animals; Chlorogenic Acid; Gas Chromatography-Mass Spectrometry; Humans; Interleukin-6; Methanol; Mice; Osteoporosis; Phytochemicals; Plant Bark; Plant Extracts; Prunus africana; RAW 264.7 Cells; Zebrafish
PubMed: 35487926
DOI: 10.1038/s41598-022-10629-7 -
Journal of Chromatography. A Feb 2022Determining the methanol partition coefficient (K) in octanol/water system is important to assess the risk of its impact to humans and the environment. In this paper, we...
Determining the methanol partition coefficient (K) in octanol/water system is important to assess the risk of its impact to humans and the environment. In this paper, we report a novel method for the determination of the K of methanol with headspace gas chromatography (HS-GC), using a three-phase equilibrium-based phase ratio variation approach. Three headspace vials with different phase ratios [(1) 0.2 mL of water plus 3 mL of octanol, (2) 1 mL of water plus 3 mL of octanol and (3) 1 mL of water plus 10 mL of octanol] were used in the experiment. After pre-standing at 25 °C for > 10 h and equilibrating in the headspace oven at a temperature of interest for additional 25 min, the methanol signals of the vapor phase (i.e., the headspace) in these vials were measured by HS-GC, from which the K of methanol can be calculated based on the established equations. The results showed that the method has good precision (within 0.06 log unit in standard deviation) and acceptable accuracy (with method error within 0.5 log unit). A correlation between the K of methanol and temperature extrapolated the K values in a temperature range of interest. The present method represents a simple and in-situ approach for the determination of the K of methanol and is also suitable to be applied to other volatile compounds.
Topics: Chromatography, Gas; Gases; Humans; Methanol; Octanols; Water
PubMed: 35065461
DOI: 10.1016/j.chroma.2022.462825 -
Molecules (Basel, Switzerland) Nov 2022is a commonly known spice used in traditional medicine to treat several ailments. In this study, comprehensive phytochemical profiling of the essential oils and...
is a commonly known spice used in traditional medicine to treat several ailments. In this study, comprehensive phytochemical profiling of the essential oils and methanol extracts of leaves and stems was performed, alongside assessing their potential inhibitory activity in vitro and in silico. The essential oils were chemically profiled via GC-MS. Moreover, the methanol extracts were profiled using HPLC-PDA-ESI-MS/MS. The antibacterial activity of the essential oils and methanol extracts against was determined by adopting the micro-well dilution method. GC-MS analysis unveiled the presence of 21 constituents, where eugenol represented the major component (57.84%) and (59.76%) in both leaves and stems of essential oils, respectively. A total of 61 compounds were annotated in both leaves and stems of methanolic extracts displaying richness in phenolic compounds identified as ()catechin and ()gallocatechin monomers and proanthocyanidins, hydrolyzable tannin derivatives (gallotannins), flavonoids, and phenolic acids. The stem essential oil showed the most promising inhibitory effects on exhibiting an MIC value of 3.9 µg/mL, comparable to clarithromycin with an MIC value of 1.95 µg/mL. Additionally, in silico molecular modeling studies revealed that decanal, eugenol, terpineol, delta-cadinene, and amyl vinyl showed potential inhibitory activity on urease as demonstrated by high-fitting scores indicating good binding to the active sites. These findings indicate that comprises valuable phytochemical constituents with promising therapeutic effects, particularly the stem, an economic agro-industrial waste.
Topics: Pimenta; Oils, Volatile; Gas Chromatography-Mass Spectrometry; Helicobacter pylori; Chromatography, Liquid; Methanol; Eugenol; Tandem Mass Spectrometry; Phytochemicals; Plant Extracts
PubMed: 36432065
DOI: 10.3390/molecules27227965 -
BMC Complementary Medicine and Therapies Aug 2022Symphonia globulifera and Allophylus abyssinicus are used in the management of skin rashes and sores, cough, malaria, digestive diseases, stomach ache, wounds and...
INTRODUCTION
Symphonia globulifera and Allophylus abyssinicus are used in the management of skin rashes and sores, cough, malaria, digestive diseases, stomach ache, wounds and helminthic infections among others in Uganda, Kenya, Ethiopia, Cameroon. This study aimed at determining the phytochemical profile and antimicrobial activity of these two plants.
METHODS
The stem bark and leaves of both plants were collected from Bwindi Impenetrable National Park and air-dried under shade at room temperature. Cold maceration, decoction and infusion with methanol, water and ethyl acetate as solvents were used in phytochemical extraction. Preliminary qualitative screening and thin layer chromatography were used for phytochemical profiling. Antimicrobial activity was analysed by agar well diffusion assay, broth macro-dilution assay and fractional inhibition concentration index (FICI).
RESULTS
The leaves and stem bark of both plants have a diverse set of phytochemical compounds of variable polarity including, tannins, alkaloids, flavonoids, saponins, quinones and anthraquinones among others. Generally, methanol and water extracts of S. globulifera and A. abyssinicus had in-vitro bactericidal activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa but weak fungistatic activity against Candida albicans. Allophylus abyssinicus leaf water and S. globulifera leaf methanol extract combination had a synergistic activity (ΣFICI = 0.37) against S. aureus. Similarly, A. abyssinicus stem bark water extract and A. abyssinicus leaf water extract combination had an additive effect (ΣFICI = 1) against P. aeruginosa.
CONCLUSION
The leaves and stem bark crude extracts of S. globulifera and A. abyssinicus possess a wide range of bioactive phytochemical compounds but have weak antimicrobial activity against S. aureus, E. coli, P. aeruginosa and C. albicans.
Topics: Anti-Infective Agents; Candida albicans; Escherichia coli; Methanol; Microbial Sensitivity Tests; Phytochemicals; Plant Bark; Plant Extracts; Plant Leaves; Sapindaceae; Staphylococcus aureus; Water
PubMed: 35999537
DOI: 10.1186/s12906-022-03692-0 -
Biosensors Jan 2023The measurement of ethanol and toxic alcohol (methanol and isopropanol) strengths in beverages and spirits is crucial for health reasons but also for the identification...
The measurement of ethanol and toxic alcohol (methanol and isopropanol) strengths in beverages and spirits is crucial for health reasons but also for the identification of adulterated products. Many methodologies have been reported in the literature, based mainly on chromatographic and on spectroscopic techniques. Chromatographic techniques are laborious and time-consuming, while spectroscopic techniques are rapid and need no special sample pretreatment. All techniques were only applied to off-line or at-line manner. In the present work, Raman spectroscopy was used for fast and non-destructive measurements. A "through the container" method was developed for a non-invasive analysis, i.e., analysis without unsealing the bottles. This method, coupled with a miniature portable Raman, can serve for in-line measurements in a production line. The optimum laser focus for maximum spirit signal and minimum glass-wall signal was investigated. Calibration curves for the alcohols of interest were constructed and validated. The limits of detections were calculated and proved to be lower than the legitimate values. The influences of the liquor color and the bottle color, shape, and thickness were checked. Twenty-eight alcoholic products were studied. The concentrations found were compared against the nominal values (from the bottle labels).
Topics: Ethanol; Alcoholic Beverages; Spectrum Analysis, Raman; Beverages; Methanol
PubMed: 36671970
DOI: 10.3390/bios13010135 -
Chemical Society Reviews Nov 2014Hydrogen, a clean energy carrier with high energy capacity, is a very promising candidate as a primary energy source for the future. Photoelectrochemical (PEC) hydrogen... (Review)
Review
Hydrogen, a clean energy carrier with high energy capacity, is a very promising candidate as a primary energy source for the future. Photoelectrochemical (PEC) hydrogen production from renewable biomass derivatives and water is one of the most promising approaches to producing green chemical fuel. Compared to water splitting, hydrogen production from renewable biomass derivatives and water through a PEC process is more efficient from the viewpoint of thermodynamics. Additionally, the carbon dioxide formed can be re-transformed into carbohydrates via photosynthesis in plants. In this review, we focus on the development of photoanodes and systems for PEC hydrogen production from water and renewable biomass derivatives, such as methanol, ethanol, glycerol and sugars. We also discuss the future challenges and opportunities for the design of the state-of-the-art photoanodes and PEC systems for hydrogen production from biomass derivatives and water.
Topics: Biomass; Electrochemical Techniques; Electrodes; Ethanol; Glycerol; Hydrogen; Methanol; Polysaccharides; Solar Energy; Water
PubMed: 24599050
DOI: 10.1039/c3cs60392j