Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 256
Filtrar
1.
Nat Prod Res ; : 1-7, 2024 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-38785383

RESUMEN

Preliminary pharmacological studies revealed that the EtOAc fraction (BGEA) might be the main active fraction with anti-inflammatory and antinociceptive effects in Beaumontia grandiflora Wall. Further assays on BGEA at doses of 200, 400, and 800 mg/kg using four animal models showed that it could inhibit the xylene-induced ear edema, carrageenan-induced paw edema, and acetic acid-induced writhing and prolong the latency time in the hot-plate test. ELISA analysis revealed that the anti-inflammatory activity of BGEA might be associated with the decrease of TNF-α, IL-1ß, and IL-6 levels and the increase of the IL-10 level. The acute toxicity test showed that except for the n-BuOH fraction, the LD50 values of the extract and other three fractions were higher than 2000 mg/kg bw. Finally, 14 compounds were identified from BGEA by LC-MS. This research provides some basis for the folk use of B. grandiflora in the treatment of inflammation and pain-related diseases.

2.
Sci Total Environ ; 930: 172843, 2024 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-38685421

RESUMEN

In modern industries, rare earth elements (REEs) are considered as essential metals and invaluable natural resources. Ion-adsorption deposits (IADs) are repositories of REE in the weathering crust soils, in which REEs are adsorbed on clay minerals. In the last few decades, the mining of REEs from IADs has caused substantial environmental damage owing to the overuse of leaching agents for the desorption and transport of REEs in weathering crust soils. These environmental issues have sparked extensive research interest in modeling REE transport dynamics in weathering crust soils. Nevertheless, because current models treat REE adsorption and transport independently, they do not accurately describe REE transport dynamics. Therefore, in this study, a unified workflow that synergizes adsorption and transport dynamics is proposed to predict REE transport. The adsorption of REEs on IADs was found to follow the Freundlich isotherm with the coefficient of determination exceeding 0.9826. The adsorption capacities of La3+, Sm3+, Er3+, and Y3+ reach 1.3127, 1.4423, 1.5793, and 1.1061 mg g-1 at 300 ppm, respectively. For the breakthrough curve, an advection-dispersion-adsorption-equation (ADAE) model was developed and utilized to accurately and reliably predict REE transport dynamics in soil columns. It was found the saturation time of REEs in soils is 39.22, 44.15, 50.64, and 32.17 h, respectively at 2 mL min-1 and decreased with the increase of flow velocity. The upper and lower limits of REE transport are ADAE-Freundlich and ADAE-Toth. More importantly, the model was applied to simulate REEs transport in field-scale weathering crusts over 100 years and predict REE accumulation in the highly weathered layered, which is found in natural weathering crusts. The qualitative prediction of REE transport dynamics in weathering crusts may help fundamentally lower the usage of leaching agents and mitigate concomitant the environmental impacts of mining.

3.
J Asian Nat Prod Res ; : 1-9, 2024 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-38602500

RESUMEN

Four new tirucallane-type triterpenoids, polystanins H-K (1-4), were obtained from the stems and leaves of Aphanamixis polystachya. Their structures were elucidated by analysis of the spectroscopic data and comparison with literature data. Compounds 1 and 2 showed week inhibitory effects against NO production in LPS-stimulated RAW264.7 cells. All the isolates were investigated for their antifungal activities against drug-resistant Candida albicans.

5.
Redox Biol ; 71: 103111, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38521703

RESUMEN

Recent research has hypothesized that hydrogen peroxide (H2O2) may have emerged from abiotic geochemical processes during the Archean eon (4.0-2.5 Ga), stimulating the evolution of an enzymatic antioxidant system in early life. This eventually led to the evolution of cyanobacteria, and in turn, the accumulation of oxygen on Earth. In the latest issue of Redox Biology, Koppenol and Sies (vol. 29, no. 103012, 2024) argued against this hypothesis and suggested instead that early organisms would not have been exposed to H2O2 due to its short half-life in the ferruginous oceans of the Archean. We find these arguments to be factually incomplete because they do not consider that freshwater or some coastal marine environments during the Archean could indeed have led to H2O2 generation and accumulation. In these environments, abiotic oxidants could have interacted with early life, thus steering its evolutionary course.


Asunto(s)
Peróxido de Hidrógeno , Hierro , Hierro/química , Peróxido de Hidrógeno/química , Oxígeno/química , Fotosíntesis , Océanos y Mares , Compuestos Ferrosos
6.
Inorg Chem ; 63(2): 1367-1377, 2024 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-38174702

RESUMEN

Oriented attachment (OA), that is, the coalescence of crystals through attachment on coaligned crystal faces, is a nonclassical crystal growth process. Before attachment, a mesocrystal consisting of coaligned parallel crystals but with liquid separating them was observed. Fundamental questions such as why OA is kinetically favored and whether a mesocrystal stage is a prerequisite for OA are raised. Through combining brute-force molecular dynamics simulations and path samplings based on extensive umbrella simulations, we address these questions with a case study on the OA of a mica nanocrystal onto a mica crystal substrate in water. Brute-force simulations show that if two mica crystals are attached but largely misaligned, coalignment hardly appears. Thus, if OA is possible, then coalignment must appear before the attachment between crystals. Electrophoresis of the nanocrystal toward the substrate surface is spontaneous, but mesocrystal formation is occasional, also shown by brute-force simulations. Free energies along different pathways show that OA is spontaneous and kinetically favored over non-OA, and a mesocrystal formation is just a bifurcation in the pathway. OA is through a pathway in which the nanocrystal is tilted with respect to the substrate. Part of the nanocrystal is attached to the substrate first, and then, OA is gradually completed. Once a mesocrystal is occasionally formed, then a jump event is needed for the nanocrystal to get back to the OA pathway. The sampling technique here can hopefully guide the design of nanostructured materials facilitated by OA.

7.
Environ Sci Process Impacts ; 26(2): 288-297, 2024 Feb 21.
Artículo en Inglés | MEDLINE | ID: mdl-38258502

RESUMEN

Alkaline media widely exist in natural and engineered systems such as semiarid/arid areas, radioactive waste sites, and mine tailings. In these settings, the commonly occurring iron (oxyhydr)oxides differed in their ability to influence the fate of nutrients and contaminants. Due to the substantially increased atmospheric carbon dioxide (CO2) concentration, carbonate stands to increase in these media. However, how increasing carbonate affects the transformation of poorly crystalline iron (oxyhydr)oxides (e.g., two-line ferrihydrite) under alkaline conditions still remains unclear. Here, kinetics of ferrihydrite transformation were evaluated at pH ∼10 as a function of [carbonate] = 0-286 mM using synchrotron-based X-ray and vibrational spectroscopic techniques. The results showed that carbonate slowed down ferrihydrite transformation slightly and suppressed goethite formation, but promoted hematite formation regardless of its concentration. At low carbonate concentration (11.42 mM), the effect of carbonate on product formation was obvious due to the weak inner-sphere complex; however, at high carbonate concentration (80-286 mM), the effect was retarded because of the adsorption equilibrium of carbonate as well as the initial carbonate adsorption followed by desorption. Moreover, carbonate modified the morphology of hematite from rhombic to ellipsoidal to honeycomb and goethite from rod-like to needle-like to spindle-like due to the inner-sphere adsorption-desorption of carbonate and adsorption of hydroxyl ions on reactive sites of iron (oxyhydr)oxides in alkaline media. The results suggest that the concurrently increasing carbonate with enhanced atmospheric CO2 could control the transformation and occurrence of iron (oxyhydr)oxides in natural and engineered environments and have important implications for the biogeochemical cycles of iron and carbon.


Asunto(s)
Dióxido de Carbono , Compuestos Férricos , Compuestos de Hierro , Compuestos Férricos/química , Minerales/química , Hierro/química , Óxidos , Carbonatos , Adsorción , Oxidación-Reducción
8.
Spectrochim Acta A Mol Biomol Spectrosc ; 310: 123884, 2024 Apr 05.
Artículo en Inglés | MEDLINE | ID: mdl-38237501

RESUMEN

The current methods for determining high-concentration As(III) in the high-acid matrix from the copper smelting industry are complex, time-consuming, and costly. This limits effective modulation of sulfurizing agent dosage for As(III) removal via sulfurization, aggravating hazardous waste generation. Herein, a simple, rapid, and nondestructive UV high-reference differential absorption spectroscopy was developed to directly determine high-concentration As(III) in simulated high-acid wastewater. Time-dependent density functional theory calculations indicated that the spectral curve redshift with As(III) concentration increasing was related to the decrease of electron transition energies and energy gaps. When using high-reference solutions, the least redshift in the maximum absorption wavelength and the highest upper limit of linear fitting concentration could be obtained. Therefore, the piecewise quantitative linear model of differential absorbance and concentration was established under high-reference. The quantitative range of the model within 0.06-20.00 g/L As(III) with a mean relative error of < 5.0 % and standard recovery rates within 98.0 %-104.0 % indicated high accuracy. Additionally, the relative standard deviations of < 1.5 % (n = 5) revealed good precision. All results indicated the high feasibility of the developed method in alleviating linear deviation caused by redshift and absorption saturation. Furthermore, it has potential significance in saving sulfurizing agent dosage and reducing hazardous waste generation from the source, thereby facilitating a cleaner process for removing As(III) via sulfurization.

9.
Nat Prod Res ; 38(6): 1036-1043, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-37221665

RESUMEN

Aralianudaside A, a triterpene saponin with an unusual skeleton of pentacyclic triterpenoid, along with a new triterpene glycoside and six known compounds were obtained from the buds of Aralia elata. Their structures were determined through extensive spectral analysis, including HRESIMS, IR, 1D and 2D NMR, glycolysis and GC. All compounds were evaluated for anti-airway inflammatory activity in lipopolysaccharides (LPS)-induced airway epithelial cells (16HBE), compounds 1, 3, 5, 7 and 8 significantly decreased the expression of pro-inflammatory cytokines IL-1ß and IL-4.


Asunto(s)
Aralia , Saponinas , Triterpenos , Aralia/química , Saponinas/química , Triterpenos/farmacología , Triterpenos/química , Lipopolisacáridos/farmacología , Esqueleto/química
10.
Environ Res ; 245: 118017, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38157965

RESUMEN

As the largest beer producer and consumer in the world, China's endeavors to reduce solid waste generation (SWG) and carbon emissions (CEs) in the course of beer production assume paramount significance. This study aims to assess the SWG and CEs in beer production within China at both national and provincial levels, and further delves into the spatial distribution characteristics and evolving patterns across the country. Key findings of the study include:(1) Peak SWG and CEs were recorded in 2013, reaching 861.62 million tons and 2315.10 tCO2e, respectively, followed by a consistent decline. (2) Among the three types of solid waste, spent grain exhibited the highest generation rate, contributing to 94.38% of the total. (3) The emergence of China's beer industry dates back to the 1980s in the northeastern region, expanding to the southeastern and the Yangtze River Basin during the 1990s, ultimately extending nationwide. (4) The spatial distribution of beer production revealed significant regional disparities and notable industry concentration. Notably, many provinces witnessed reduced CEs from beer production starting in 2015, although the extent of reduction varied in different provinces. These findings serve as a scientific foundation for formulating emission reduction strategies in beer producing and offer insights for other food industries in China.


Asunto(s)
Carbono , Residuos Sólidos , Residuos Sólidos/análisis , Carbono/análisis , Cerveza/análisis , Industrias , China , Dióxido de Carbono/análisis , Desarrollo Económico
11.
Zhongguo Zhong Yao Za Zhi ; 48(21): 5817-5821, 2023 Nov.
Artículo en Chino | MEDLINE | ID: mdl-38114177

RESUMEN

Eight compounds were isolated from ethyl acetate fraction of 80% ethanol extract of the hulls of Garcinia mangostana by silica gel, Sephadex LH-20 column chromatography, as well as prep-HPLC methods. By HR-ESI-MS, MS, 1D and 2D NMR spectral analyses, the structures of the eight compounds were identified as 16-en mangostenone E(1), α-mangostin(2), 1,7-dihydroxy-2-(3-methy-lbut-2-enyl)-3-methoxyxanthone(3), cratoxyxanthone(4), 2,6-dimethoxy-para-benzoquinone(5), methyl orselinate(6), ficusol(7), and 4-(4-carboxy-2-methoxyphenoxy)-3,5-dimethoxybenzoic acid(8). Compound 1 was a new xanthone, and compound 4 was a xanthone dimer, compound 5 was a naphthoquinone. All compounds were isolated from this plant for the first time except compounds 2 and 3. Cytotoxic bioassay suggested that compounds 1, 2 and 4 possessed moderate cytotoxicity, suppressing HeLa cell line with IC_(50) va-lues of 24.3, 35.5 and 17.1 µmol·L~(-1), respectively. Compound 4 also could suppress K562 cells with an IC_(50) value of 39.8 µmol·L~(-1).


Asunto(s)
Antineoplásicos , Garcinia mangostana , Garcinia , Xantonas , Humanos , Garcinia mangostana/química , Células HeLa , Espectroscopía de Resonancia Magnética , Xantonas/farmacología , Garcinia/química , Extractos Vegetales/química , Estructura Molecular
12.
Fitoterapia ; 171: 105709, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37866422

RESUMEN

Nineteen triterpenoids, including five previously unknown (four triucallane-type derivatives and one highly oxidized A, B-seco limonoids), together with fourteen known triterpenoids, were isolated from the fruits of Aphanamixis polystachya. Their structures were elucidated by extensive spectroscopic analysis. All isolates were evaluated their anti-inflammatory activities. The result showed that all compounds inhibit LPS-induced nitric oxide production in RAW264.7 macrophages with their IC50 value ranging from 95 to 1332 uM, and compound 6 exhibited obvious anti-inflammatory activity comparable to that of the positive control, with IC50 values of 94.96 uM.


Asunto(s)
Meliaceae , Triterpenos , Frutas/química , Triterpenos/farmacología , Óxido Nítrico , Estructura Molecular , Meliaceae/química , Antiinflamatorios/farmacología
13.
J Hazard Mater ; 460: 132374, 2023 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-37683350

RESUMEN

Various combined processes with pre-coagulation have been developed for biologically treated landfill leachate, but the microscopic-level processes occurring during coagulation remain largely unknown. Herein, dissolved organic matter (DOM) fate using fluorescence excitation emission matrix spectroscopy combined with parallel factor analysis and electrospray ionization coupled Fourier transform-ion cyclotron resonance mass spectrometry and concomitant heavy metal (HM) behaviors were explored at the molecular level. In addition, AlCl3 and two polyaluminum chloride (PACl) species (dominated by [AlO4Al12(OH)24(H2O)12]7+ and [(AlO4)2Al28(OH)56(H2O)26]18+, respectively) were used. The results show that all coagulants are efficient at removing DOM. PACl was found to be advantageous over AlCl3 in overcoming pH fluctuation, which is ascribed to the different dominant mechanisms, namely, entrapment and sweep flocculation for AlCl3 and charge neutralization for PACl. Consequently, PACl was more effective at removing humic substances, usually high-molecular-weight, oxygen-rich and unsaturated, than protein substances. For HM removal, PACl was likewise better and more stable, where As, Cu, Ni, Co and Hg were removed predominantly via adsorption, and Cr, Zn, Pb, Cd and Mn were removed via coprecipitation. Correlation analysis showed that humic substances tended to complex with HMs and be removed synergistically due to the ubiquitous occurrences of aromatic structures and oxygen-containing functional groups.

14.
Sci Total Environ ; 905: 167344, 2023 Dec 20.
Artículo en Inglés | MEDLINE | ID: mdl-37751840

RESUMEN

The issue of ion-adsorption type rare earth deposits (IADs) in urban areas of South China has garnered significant attention due to its environmental implications. Hyperaccumulator-based phytoremediation is a potentially effective solution for reducing the environmental impact of IADs in urban areas, particularly using ferns as they are known to be REE hyperaccumulators. However, the ability of different fern species to accumulate REEs in urban areas remains unknown. In this study, four fern species, including known hyperaccumulators (Dicranopteris linearis and Blechnum orientale) and other ferns (Pteris ensiformis and Cibotium barometz), were studied to investigate their REE accumulation abilities in the Guangzhou urban area. The aboveground parts of Dicranopteris linearis (848.7 µg g-1) and Blechum orientale (1046.8 µg g-1) have been found to accumulate high concentrations of REEs, demonstrating they probably can be applied for phytoremediation in the natural environments. Despite having lower REE concentrations than REE hyperaccumulators, Pteris ensiformis and Cibotium barometz still probably have the function as phytostabilizers in urban areas, as REEs can be enriched in their roots beyond the normal levels of plants. The enrichment of REEs in ferns is influenced by the availability of various nutrients (K, Ca, Fe, and P), which probably can be associated with different growth processes. The four fern species show LREE enrichment, moderate Eu anomalies and different Ce anomalies. It is difficult to absorb and transfer Ce to the aboveground parts of Blechnum orientale and Cibotium barometz. The study also identified selective enrichment of Ce in Pteris ensiformis, which has potential for comprehensive extraction of REEs when combined with other REE hyperaccumulators. REE fractionations are probably determined by the specific characteristics of different fern parts. Overall, these findings provide insights for addressing potential environmental problems related to IADs and offer guidelines for phytoremediation technology in addressing high REE levels in urban areas.


Asunto(s)
Helechos , Metales de Tierras Raras , Tracheophyta , Metales de Tierras Raras/análisis , China , Raíces de Plantas/química
15.
Interv Neuroradiol ; : 15910199231182850, 2023 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-37309134

RESUMEN

BACKGROUND: Clot analogs are essential in animal and in vitro experiments on mechanical thrombectomy devices for treating acute ischemic stroke. Clot analogs should be capable of reproducing a variety of arterial clots observed in clinical practice in terms of histological composition and mechanical properties. METHODS: Bovine blood with added thrombin was stirred in a beaker so that clots could be formed under the condition of dynamic vortical flow. Static clots were also prepared without stirring, and the properties of the static clots and dynamic clots were compared. Histological and scanning electron microscopy experiments were performed. Compression and relaxation tests were performed to evaluate the mechanical properties of the two types of clots. Thromboembolism and thrombectomy tests were conducted in an in vitro circulation model. RESULTS: Compared to the static clots, the dynamic clots prepared under vortical flow displayed a higher fibrin content, and their fibrin network was denser and sturdier than that of the static clots. The stiffness of the dynamic clots was significantly higher than that of the static clots. The stress of both types of clots could decay quickly under large sustained strain. The static clots could break at the bifurcation in the vascular model, while the dynamic clots could be firmly stuck in the vascular model. CONCLUSIONS: Dynamic clots generated in dynamic vortical flow differ significantly from static clots in terms of their composition and mechanical properties, which may be beneficial information for preclinical research on mechanical thrombectomy devices.

17.
Nat Prod Bioprospect ; 13(1): 13, 2023 Apr 12.
Artículo en Inglés | MEDLINE | ID: mdl-37043142

RESUMEN

Uncarialines A-E (1-5), five undescribed monoterpene indole alkaloids, together with five known analogues were obtained from the stems of Uncaria rhynchophylla. Alkaloids 1-3 were unique 3,4-seco-tricyclic alkaloids with a 6/5/10 ring system, while 4 and 5 possessed a rare rearranged scaffold originated from corynantheine-type alkaloids with C-2/C-7 oxidation. Their structures were characterized by a comprehensive analysis of MS, NMR, and ECD. Their effects on blood clotting times of human plasma were evaluated and alkaloid 5 had a slight prolongation effect on both thrombin time and activated partial thromboplastin time (p < 0.001).

18.
J Hazard Mater ; 445: 130542, 2023 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-37055960

RESUMEN

Landfills contain significant amounts of plastic waste (PW) and microplastics (MPs). However, the contributions of various PW fragmentation processes to the quality and quantity of MPs in landfills are unclear. In this study, LDPE and EPS pieces were mixed with sand to simulate landfilled solid waste, which experienced one-dimensional abiotic compression under vertical stress of 100-800 kPa for 1-300 days. The generated MPs were stained and quantified with a fluorescent microscope. The numbers and masses of the fragmented MPs increase with the increasing compression stress and duration following linear or exponential trends. EPS has a lower stiffness than LDPE, thus generates more MPs under the same compression conditions. Stress-dependent and time-dependent fragmentation mechanisms are distinguished, the former is driven by sand-plastic porosity reduction and the latter is due to microscopic interfacial creep with minimal porosity reduction. Most of the mechanically fragmented MPs have diameters < 100 µm. The MPs size distributions follow an established power-law model, which are dependent on stress, duration, porosity reduction, and fragmentation mechanism. Our results serve as conservative estimations on long-term MPs generation in real landfills, which provide confirmative and quantitative evidence to support the previous studies reporting the varied MPs abundances and properties within landfills.

19.
Proc Natl Acad Sci U S A ; 120(13): e2221984120, 2023 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-36940327

RESUMEN

Terrestrial reactive oxygen species (ROS) may have played a central role in the formation of oxic environments and evolution of early life. The abiotic origin of ROS on the Archean Earth has been heavily studied, and ROS are conventionally thought to have originated from H2O/CO2 dissociation. Here, we report experiments that lead to a mineral-based source of oxygen, rather than water alone. The mechanism involves ROS generation at abraded mineral-water interfaces in various geodynamic processes (e.g., water currents and earthquakes) which are active where free electrons are created via open-shell electrons and point defects, high pressure, water/ice interactions, and combinations of these processes. The experiments reported here show that quartz or silicate minerals may produce reactive oxygen-containing sites (≡SiO•, ≡SiOO•) that initially emerge in cleaving Si-O bonds in silicates and generate ROS during contact with water. Experimental isotope-labeling experiments show that the hydroxylation of the peroxy radical (≡SiOO•) is the predominant pathway for H2O2 generation. This heterogeneous ROS production chemistry allows the transfer of oxygen atoms between water and rocks and alters their isotopic compositions. This process may be pervasive in the natural environment, and mineral-based production of H2O2 and accompanying O2 could occur on Earth and potentially on other terrestrial planets, providing initial oxidants and free oxygen, and be a component in the evolution of life and planetary habitability.

20.
Nat Prod Bioprospect ; 13(1): 7, 2023 Feb 23.
Artículo en Inglés | MEDLINE | ID: mdl-36813988

RESUMEN

Five new toosendanin limonoids with highly oxidative furan ring walsurobustones A-D (1-4), and one new furan ring degraded limonoid walsurobustone E (5) together with one known compound toonapubesic acid B (6) were isolated from the leaves of Walsura robusta. Their structures were elucidated by NMR and MS data. Especially, the absolute configuration of toonapubesic acid B (6) was confirmed by X-ray diffraction study. Compounds 1-6 exhibited good cytotoxicity against the cancer cell lines HL-60, SMMC-7721, A-549, MCF-7, and SW480.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...