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Molecules (Basel, Switzerland) Jan 2022Saponins are plant and marine animal specific metabolites that are commonly considered as molecular vectors for chemical defenses against unicellular and pluricellular...
Saponins are plant and marine animal specific metabolites that are commonly considered as molecular vectors for chemical defenses against unicellular and pluricellular organisms. Their toxicity is attributed to their membranolytic properties. Modifying the molecular structures of saponins by quantitative and selective chemical reactions is increasingly considered to tune the biological properties of these molecules (i) to prepare congeners with specific activities for biomedical applications and (ii) to afford experimental data related to their structure-activity relationship. In the present study, we focused on the sulfated saponins contained in the viscera of , a sea cucumber present in the Indian Ocean and abundantly consumed on the Asian food market. Using mass spectrometry, we first qualitatively and quantitatively assessed the saponin content within the viscera of . We detected 26 sulfated saponins presenting 5 different elemental compositions. Microwave activation under alkaline conditions in aqueous solutions was developed and optimized to quantitatively and specifically induce the desulfation of the natural saponins, by a specific loss of HSO. By comparing the hemolytic activities of the natural and desulfated extracts, we clearly identified the sulfate function as highly responsible for the saponin toxicity.
Topics: Alkalies; Animals; Cattle; Chromatography, Liquid; Hemolysis; Hemolytic Agents; Holothuria; Hydrolysis; Indian Ocean; Microwaves; Saponins; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Structure-Activity Relationship; Sulfates; Tandem Mass Spectrometry; Viscera
PubMed: 35056852
DOI: 10.3390/molecules27020537 -
Translational Andrology and Urology Sep 2019Uric acid (UA) urolithiasis comprises around 5-10% of all stones and can frequently recur. Due to the fact that UA stones form in acidic urine with a pH <5.5, these... (Review)
Review
Uric acid (UA) urolithiasis comprises around 5-10% of all stones and can frequently recur. Due to the fact that UA stones form in acidic urine with a pH <5.5, these patients require special attention compared to other stone patients. The international guidelines suggest treatment and metaphylaxis by urinary alkalization. The objective of this review is to critically asses the available evidence concerning the method and efficacy of this treatment modality. A systematic review on the methods of metaphylactic therapy using oral alkalization of UA urolithiasis was conducted by two authors. Evidence was sought using a predefined search strategy in seven different databases. The provided evidence was critically evaluated using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Cochrane collaboration tool for assessing the risk of bias. Twelve manuscripts were included of which one was a randomised trial. They focussed on ways to alkalize urine and its effect on stone recurrence. Because of their methodology and heterogeneity, the evidence is presented in a narrative review. There were differences in medication used for alkalizing urine, ways of monitoring urine pH and evaluating its efficacy. The reported outcomes also differed between studies. There is currently a lack of clear evidence for the method of alkalization of urine and the method of pH measurement. Besides this, for an established treatment modality, there is lack of long term results for the alkalization therapy. In conclusion, urine alkalization is an established treatment modality for the metaphylaxis of UA urolithiasis despite the lack of evidence from high quality studies on the methods of alkalization and its treatment efficacy. The studies published on this topic are scarce and contain notable risks of bias which should be kept in mind when interpreting the stated results.
PubMed: 31656751
DOI: 10.21037/tau.2019.05.01 -
Environmental Science & Technology Oct 2023The transformation of 2-line ferrihydrite to goethite from supersaturated solutions at alkaline pH ≥ 13.0 was studied using a combination of benchtop and advanced...
The transformation of 2-line ferrihydrite to goethite from supersaturated solutions at alkaline pH ≥ 13.0 was studied using a combination of benchtop and advanced synchrotron techniques such as X-ray diffraction, thermogravimetric analysis, and X-ray absorption spectroscopy. In comparison to the transformation rates at acidic to mildly alkaline environments, the half-life, , of 2-line ferrihydrite reduces from several months at pH = 2.0, and approximately 15 days at pH = 10.0, to just under 5 h at pH = 14.0. The calculated-first order rate constants of transformation, , increase exponentially with respect to the pH and follow the progression log = log + ·pH. Simultaneous monitoring of the aqueous Fe(III) concentration via inductively coupled plasma optical emission spectroscopy demonstrates that (i) goethite likely precipitates from solution and (ii) its formation is rate-limited by the comparatively slow redissolution of 2-line ferrihydrite. The analysis presented can be used to estimate the transformation rate of naturally occurring 2-line ferrihydrite in aqueous electrolytes characteristic to mine and radioactive waste tailings as well as the formation of corrosion products in cementitious pore solutions.
Topics: Ferric Compounds; Iron Compounds; Minerals; Water; Hydrogen-Ion Concentration; Oxidation-Reduction
PubMed: 37822288
DOI: 10.1021/acs.est.3c05260 -
PloS One 2022This manuscript presents an inventory of the carbonate system from the main water masses comprising the marine current system on Brazil's northeast coast (South Atlantic...
This manuscript presents an inventory of the carbonate system from the main water masses comprising the marine current system on Brazil's northeast coast (South Atlantic Ocean). For this purpose, four transects were conducted with an approximate length of 357 km (each one) through the platform and continental slope of the Sergipe-Alagoas sedimentary basin. Water samples were then collected in vertical profiles measuring from 5 to 1,799 meters depth, totaling 34 stations. Total alkalinity, calcium, and total boron were obtained analytically from these samples and by relationships with salinity. Speciation and concentration of the carbonate system were obtained by means of thermodynamic modeling. The results revealed that the empirical models used to calculate the concentrations of TA, calcium and total boron showed relevant variation when compared to the analytical values (TA: 5.0-6.5%; Ca: 0.4-4.8%; BT: 7.0-18.9%). However, the speciation and concentration of the carbonate system (CA, DIC, [Formula: see text], CO2(aq), ΩCalc, and ΩArag) obtained from the empirical values of TA, calcium and total boron did not differ significantly from those obtained analytically (0.0-6.1%). On the other hand, the parameters of pH, [Formula: see text], [Formula: see text], CO2(aq), ρCO2, ΩCalc, and ΩArag varied significantly within the different water masses (p < 0.05). This study supports and encourages acidification monitoring projects in the South Atlantic Ocean, based on modeling the carbonate system parameters generated in real-time.
Topics: Atlantic Ocean; Boron; Brazil; Calcium; Calcium Carbonate; Carbon Dioxide; Carbonates; Hydrogen-Ion Concentration; Seawater; Water
PubMed: 35881635
DOI: 10.1371/journal.pone.0271875 -
Current Biology : CB Feb 2022The freshwater aquatic larvae of the Chaoborus midge are the world's only truly planktonic insects, regulating their buoyancy using two pairs of internal air-filled...
The freshwater aquatic larvae of the Chaoborus midge are the world's only truly planktonic insects, regulating their buoyancy using two pairs of internal air-filled sacs, one in the thorax and the other in the seventh abdominal segment. In 1911, August Krogh demonstrated the larvae's ability to control their buoyancy by exposing them to an increase in hydrostatic pressure. However, how these insects control the volume of their air-sacs has remained a mystery. Gas is not secreted into the air-sacs, as the luminal gas composition is always the same as that dissolved in the surrounding water. Instead, the air-sac wall was thought to play some role. Here we reveal that bands of resilin in the air-sac's wall are responsible for the changes in volume. These bands expand and contract in response to changes in pH generated by an endothelium that envelops the air-sac. Vacuolar type H V-ATPase (VHA) in the endothelium acidifies and shrinks the air-sac, while alkalinization and expansion are regulated by the cyclic adenosine monophosphate signal transduction pathway. Thus, Chaoborus air-sacs function as mechanochemical engines, transforming pH changes into mechanical work against hydrostatic pressure. As the resilin bands interlaminate with bands of cuticle, changes in resilin volume are constrained to a single direction along the air-sac's longitudinal axis. This makes the air-sac functionally equivalent to a cross-striated pH muscle and demonstrates a unique biological role for resilin as an active structural element.
Topics: Animals; Fresh Water; Hydrogen-Ion Concentration; Larva; Water
PubMed: 35081331
DOI: 10.1016/j.cub.2022.01.018 -
International Journal of Biological... Jul 2022This study aimed to evaluate the properties of cellulose nanofibers (CNFs) with different hemicellulose contents and cellulose II polymorphs. A link was found between...
This study aimed to evaluate the properties of cellulose nanofibers (CNFs) with different hemicellulose contents and cellulose II polymorphs. A link was found between these polysaccharides and the properties of CNFs. A decrease in crystallinity (from 69 to 63%) and changes in the crystalline structure of cellulose subjected to an alkaline environment were observed, promoting the partial conversion of cellulose I to cellulose II (from 2 to 42%) and preventing CNFs production at NaOH concentrations higher than 5%. Most treatments showed pseudoplastic fluid behavior, except for the 10% NaOH treatment over 2 h, which showed Newtonian fluid behavior. The quality index of the reference CNFs (TEMPO-oxidized) was the highest (80 ± 3), followed by that of the 5% NaOH-treated (68 ± 3 and 22% energy savings compared to the untreated sample), and the untreated (63 ± 3) samples; and the 10% NaOH treatments had quality indices of 51 ± 3 and 32 ± 1, respectively.
Topics: Cellulose; Nanofibers; Polysaccharides; Sodium Hydroxide
PubMed: 35690158
DOI: 10.1016/j.ijbiomac.2022.06.012 -
Scientific Reports Oct 2023SARS-CoV-2 virus triggered a worldwide crisis, with world nations putting up massive efforts to halt its spread. Molnupiravir (MLN) was the first oral, direct-acting...
SARS-CoV-2 virus triggered a worldwide crisis, with world nations putting up massive efforts to halt its spread. Molnupiravir (MLN) was the first oral, direct-acting antiviral drug approved for nasopharyngeal SARS-CoV-2 infection with favorable safety and tolerability profile. This study aims at determination of MLN and N4-hydroxycytidine (NHC), its main degradation product and its main metabolite, using sensitive, simple, and green HPLC-DAD method. Moreover, under different stress conditions using NaOH, HCl, neutral, HO, dry heat and sun light, the method was applied for MLN assay along with kinetics degradation investigation. The linearity range for MLN and NHC were both 0.1-100 µg/mL with LOD and LOQ of 0.013 & 0.043 and 0.003 & 0.011 µg/mL, for MLN and NHC, respectively. MLN was found to be extremely vulnerable to alkali hydrolysis compared with acid and dry heat degradation. In contrast, MLN was stable under conditions of oxidative, neutral, and sunlight-induced deterioration. Acid and alkali-induced degradation followed pseudo first-order kinetics model. In addition, LC-MS-UV was used to suggest the mechanism of the stress-induced degradation route and to characterize the eluted degradation products. Toxicities of both MLN and its degradation products were evaluated using ProTox-II and they were found to be negligibly harmful. The proposed HPLC-DAD was effectively used for the analysis of MLN in commercial pharmaceutical formulations. The proposed method for MLN determination after greenness and whiteness appraisal was found to be superior compared to the reported methods for MLN analysis.
Topics: Humans; Antiviral Agents; Hydrogen Peroxide; Hepatitis C, Chronic; Chromatography, High Pressure Liquid; Acids; Alkalies; Drug Stability
PubMed: 37863912
DOI: 10.1038/s41598-023-44756-6 -
Scientific Reports Feb 2023Denitrification, as the main nitrogen (N) removal process in farmland drainage ditches in coastal areas, is significantly affected by saline-alkali conditions. To...
Denitrification, as the main nitrogen (N) removal process in farmland drainage ditches in coastal areas, is significantly affected by saline-alkali conditions. To elucidate the effects of saline-alkali conditions on denitrification, incubation experiments with five salt and salt-alkali gradients and three nitrogen addition levels were conducted in a saline-alkali soil followed by determination of denitrification rates and the associated functional genes (i.e., nirK/nirS and nosZ Clade I) via N/Ar technique in combination with qPCR. The results showed that denitrification rates were significantly decreased by 23.83-50.08%, 20.64-57.31% and 6.12-54.61% with salt gradient increasing from 1 to 3‰, 8‰, and 15‰ under 0.05‰, 0.10‰ and 0.15‰ urea addition conditions, respectively. Similarly, denitrification rates were significantly decreased by 44.57-63.24% with an increase of the salt-alkali gradient from 0.5 to 8‰. The abundance of nosZ decreased sharply in the saline condition, while a high salt level significantly decreased the abundance of nirK and nirS. In addition, the increase of nitrogen concentration attenuated the reduction of nirK, nirS and nosZ gene abundance. Partial least squares regression (PLSR) models demonstrated that salinity, dissolved oxygen (DO) in the overlying water, N concentration, and denitrifying gene abundance were key determinants of the denitrification rate in the saline environment, while pH was an additional determinant in the saline-alkali environment. Taken together, our results suggest that salinity and high pH levels decreased the denitrification rates by significantly inhibiting the abundance of the denitrifying genes nirK, nirS, and nosZ, whereas increasing nitrogen concentration could alleviate this effect. Our study provides helpful information on better understanding of reactive N removal and fertilizer application in the coastal areas.
Topics: Soil; Denitrification; Alkalies; Salinity; Hydrogen-Ion Concentration; Nitrogen; Soil Microbiology
PubMed: 36750752
DOI: 10.1038/s41598-023-29311-7 -
Drug Discoveries & Therapeutics May 2022The detergency of special electrolytic-reduction ion water (S-100) was evaluated in comparison with typical synthetic surfactants. Furthermore, to examine the cleaning...
The detergency of special electrolytic-reduction ion water (S-100) was evaluated in comparison with typical synthetic surfactants. Furthermore, to examine the cleaning mechanism of S-100, various physicochemical characteristics of S-100 were measured and a comprehensive evaluation of cleaning was performed. S-100 (10%) had a detergency comparable to that of various surfactants, such as sodium dodecyl sulfate and sodium dodecyl benzene sulfonate, which are generally blended or mixed in residential detergents. In addition, concentrated aqueous solutions of 10% or more of S-100 showed stronger detergency. The cleaning mechanism of S-100 is mainly attributed to the effect of surface tension reduction due to dissolved hydrogen or hydrogen nanobubbles in S-100, and the alkalinity generated by electrolysis charged the surface of the dirt or adherend, resulting in a peeling effect.
Topics: Detergents; Electrolysis; Hydrogen; Surface-Active Agents; Water
PubMed: 35474181
DOI: 10.5582/ddt.2022.01027 -
Proceedings of the National Academy of... Nov 2023Biological ice nucleation plays a key role in the survival of cold-adapted organisms. Several species of bacteria, fungi, and insects produce ice nucleators (INs) that...
Biological ice nucleation plays a key role in the survival of cold-adapted organisms. Several species of bacteria, fungi, and insects produce ice nucleators (INs) that enable ice formation at temperatures above -10 °C. Bacteria and fungi produce particularly potent INs that can promote water crystallization above -5 °C. Bacterial INs consist of extended protein units that aggregate to achieve superior functionality. Despite decades of research, the nature and identity of fungal INs remain elusive. Here, we combine ice nucleation measurements, physicochemical characterization, numerical modeling, and nucleation theory to shed light on the size and nature of the INs from the fungus . We find ice-binding and ice-shaping activity of IN, suggesting a potential connection between ice growth promotion and inhibition. We demonstrate that fungal INs are composed of small 5.3 kDa protein subunits that assemble into ice-nucleating complexes that can contain more than 100 subunits. INs retain high ice-nucleation activity even when only the ~12 kDa fraction of size-excluded proteins are initially present, suggesting robust pathways for their functional aggregation in cell-free aqueous environments. We conclude that the use of small proteins to build large assemblies is a common strategy among organisms to create potent biological INs.
Topics: Ice; Freezing; Water; Temperature; Bacterial Outer Membrane Proteins
PubMed: 37943838
DOI: 10.1073/pnas.2303243120