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Open access

Najeeb Ur Rehman, Samia Ahmed Al-Riyami, Hidayat Hussain, Amjad Ali, Abdul Latif Khan and Ahmed Al-Harrasi

Abstract

Oxidative stress is often considered detrimental for cellular processes and damaging for the lipid bi-layer. Counteracting such stresses with the aid of nature-based chemical constituents can be an ideal therapeutic approach. The current study aimed to investigate the chemical constituents of resins derived from the well-known Aloe vera and less known Commiphora mukul trees and their effect in mitigating the lipid peroxidation (LPO) process. The bio-guided isolation of bio-active fractions from both resins afforded 20 chemical constituents (17 from A. vera and 3 from C. mukul). These compounds belonged to anthraquinones, anthraquinone glycosides, quinones, coumarins, polypodane-type terpenoids and benzene derivatives. Major chemical constituents of the resins of A. vera and C. mukul were from the classes of quinones and terpenoids. Feroxidin (4, from A. vera) showed slightly higher inhibition (IC 50 = 201.7 ± 0.9 µmol L−1) than myrrhanone C (18, from C. mukul: IC 50 = 210.7 ± 0.0 µmol L−1) and methyl 3-(4-hydroxyphenyl) propionate from A. vera (13, IC 50 = 232.9 ± 0.2 µmol L−1) compared to the other compounds. Structure-activity relationship showed that the existence of hydroxyl, methoxy and ether groups might play a major role in countering oxidative stress. To the best of our knowledge, anti-LPO activities of compounds 14, 14, 18 and 20 are reported for the first time. Such chemical constituents with high anti-lipid peroxidation activity could be helpful in synthesizing candidate drugs.

Open access

Lei Gao, Yaji Wang, Josie Geris, Paul D. Hallett and Xinhua Peng

Abstract

Subtropical regions have clay-rich, weathered soils, and long dry periods followed by intense rainfall that produces large fluctuations in soil water content (SWC) and hydrological behavior. This complicates predictions of spatio-temporal dynamics, as datasets are typically collected at too coarse resolution and observations often represent a duration that is too short to capture temporal stability. The aim of the present study was to gain further insights into the role of temporal sampling scale on the observed temporal stability features of SWC order to aid the design of optimal SWC sampling strategies. This focused on both sampling frequency and total monitoring duration, as previous analyses have not considered both of these sampling aspects simultaneously. We collected relatively high resolution data of SWC (fortnightly over 3.5 years) for various soil depths and under contrasting crops (peanuts and citrus) at the red soil region of southeast China. The dataset was split into a three-year training period and a six-month evaluation period. Altogether 13 sampling frequencies (intervals ranging from 15 to 240 days) and eight monitoring duration periods (between three and 36 months) were derived from the training period to identify temporal stability features and the most time stable location (MTSL). The prediction accuracies of these MTSLs were tested using the independent evaluation data. Results showed that vegetation type did affect the spatio-temporal patterns of SWC, whereby the citrus site exhibited a stronger temporal variation and weaker temporal stability than the peanut site. However, the effects of both sampling frequency and observation duration were more pronounced, irrespective of the role of vegetation type or soil depth. With increasing sampling interval or decreasing monitoring duration, temporal stability of SWC was generally overestimated; by less than 10% when sampling interval increased from every 15 to 240 days and by up to 40% with duration decreasing from 36 to 3 months. Our results suggest that sampling strategies and trade-offs between sampling interval and duration should focus on capturing the main variability in hydro-climatological conditions. For subtropical conditions, we found that sampling once every 45 days over 24 months to be the minimum sampling strategy to ensure errors in SWC temporal stability of less than 10%.

Open access

Faisal Al-Otaibi

Abstract

There are several limited approaches to treat epilepsy in hospitals, for example, using medicines, surgery, electrical stimulation and dietary interventions. Despite the availability of all these new and old approaches, seizure is particularly difficult to manage. The quest for new antiepileptic molecules with more specificity and less CNS toxicity continues for medicinal chemists until a new and ideal drug arrives. This review covers new antiseizure molecules of different chemical classes, the exact mode of action of which is still unidentified. Newer agents include sulfonamides, thiadiazoles, semi- and thiosemicarbazones, pyrrolidine-2,5-diones, imidazoles, benzothiazoles and amino acid deriva tives. These new chemical entities can be useful for the design and development of forthcoming antiseizure agents.

Open access

Karolina Słoczyńska, Agnieszka Gunia-Krzyżak, Paulina Koczurkiewicz, Katarzyna Wójcik-Pszczoła, Dorota Żelaszczyk, Justyna Popiół and Elżbieta Pękala

Abstract

Determination of metabolic profiles of new chemical entities is a key step in the process of drug discovery, since it influences pharmacokinetic characteristics of therapeutic compounds. One of the main challenges of medicinal chemistry is not only to design compounds demonstrating beneficial activity, but also molecules exhibiting favourable pharmacokinetic parameters. Chemical compounds can be divided into those which are metabolized relatively fast and those which undergo slow biotransformation. Rapid biotransformation reduces exposure to the maternal compound and may lead to the generation of active, non-active or toxic metabolites. In contrast, high metabolic stability may promote interactions between drugs and lead to parent compound toxicity. In the present paper, issues of compound metabolic stability will be discussed, with special emphasis on its significance, in vitro metabolic stability testing, dilemmas regarding in vitro-in vivo extrapolation of the results and some aspects relating to different preclinical species used in in vitro metabolic stability assessment of compounds.

Open access

Yufang Ni, Zhixian Cao and Qingquan Liu

Abstract

A 2D hydrodynamic (labeled as CAR) model has been proposed in a rectangular Cartesian coordinate system with two axes within the horizontal plane and one axis along the vertical direction (global coordinates), considering the effects of bed slope on both pressure distribution and bed shear stresses. The CAR model satisfactorily reproduces the analytical solutions of dam-break flow over a steep slope, while the traditional Saint-Venant Equations (labeled as SVE) significantly overestimate the flow velocity. For flood events with long duration and large mean slope, the CAR and the SVE models present distinguishable discrepancies. Therefore, the proposed CAR model is recommended for applications to real floods for its facility of extending from 1D to 2D version and ability to model shallow-water flows on steep slopes.

Open access

Rui Liu, Runze Yu, Yuxin Cui, Mengying Fan, Bo Wang and Yanmin Zhang

Abstract

The aim of this study was to investigate the inhibitory effect of TAD1822-7, a synthesized taspine derivative, on cancer through its effects on tumor cell growth and angiogenesis via suppression of EphrinB2. The obtained data showed that TAD1822-7 decreased Bel-7402 cell viability and colony formation ability and suppressed cell migration. TAD1822-7 effectively inhibited blood vessel formation in an aortic ring assay to examine angiogenesis. Moreover, it also down regulated the expression of VEGFR2, VEGFR3, CD34, PLCγ, Akt, MMP2, MMP9, and CXCR4, and suppressed the expression of EphrinB2 and its PDZ protein, PICK1, in Bel-7402 cells. These results indicate that TAD1822-7 is a potential anti-angiogenic agent that can inhibit the viability and migration of Bel-7402 cells via suppression of EphrinB2 and the related signaling pathways.

Open access

Jitka Kofroňová, Miroslav Tesař and Václav Šípek

Abstract

Longwave radiation, as part of the radiation balance, is one of the factors needed to estimate potential evapotranspiration (PET). Since the longwave radiation balance is rarely measured, many computational methods have been designed. In this study, we report on the difference between the observed longwave radiation balance and modelling results obtained using the two main procedures outlined in FAO24 (relying on the measured sunshine duration) and FAO56 (based on the measured solar radiation) manuals. The performance of these equations was evaluated in the April–October period over eight years at the Liz experimental catchment and grass surface in the Bohemian Forest (Czech Republic). The coefficients of both methods, which describe the influence of cloudiness factor and atmospheric emissivity of the air, were calibrated. The Penman-Monteith method was used to calculate the PET. The use of default coefficient values gave errors of 40–100 mm (FAO56) and 0–20 mm (FAO24) for the seasonal PET estimates (the PET was usually overestimated). Parameter calibration decreased the FAO56 error to less than 20 mm per season (FAO24 remained unaffected by the calibration). The FAO56 approach with calibrated coefficients proved to be more suitable for estimation of the longwave radiation balance.

Open access

Mohammad Reza Namaee and Jueyi Sui

Abstract

In the present study, experiments were conducted in a large-scale flume to investigate the issue of local scour around side-by-side bridge piers under both ice-covered and open flow conditions. Three non-uniform sediments were used in this experimental study. Analysis of armour layer in the scour holes around bridge piers was performed to inspect the grain size distribution curves and to study the impact of armour layer on scour depth. Assessments of grain size of deposition ridges at the downstream side of bridge piers have been conducted. Based on data collected in 108 experiments, the independent variables associated with maximum scour depth were assessed. Results indicate that the densi-metric Froude number was the most influential parameter on the maximum scour depth. With the increase in grain size of the armour layer, ice cover roughness and the densimetric Froude number, the maximum scour depth around bridge piers increases correspondingly. Equations have been developed to determine the maximum scour depth around bridge piers under both open flow and ice covered conditions.

Open access

Feliciana Licciardello, Salvatore Barbagallo and Francesc Gallart

Abstract

Increasing our understanding of the main processes acting in small Mediterranean catchments is essential to planning effective soil and water conservation practices in semi-arid areas. A monitoring program of a Sicilian catchment started in 1996 and ended in 2006. The factors driving the hydrological response for 170 events with runoff generation and 46 with sediment production were specified. The catchment response varied greatly over the year. Rainfall intensity was a poor driver of runoff generation, whereas both the simulations made with the Thornthwaite-Mather water balance model and hydrograph recession analyses, pointed to the chief importance of wet antecedent conditions and soil saturation processes in runoff generation. The influence of rainfall spatial variability was also examined. SSC-Q relationships, classified by following their shapes for all sediment production events, suggested that the principal role of small poorly vegetated hillslope patches was as sediment sources and confirmed the complexity of the hydrological response in this small Mediterranean catchment.

Open access

Corina Bubueanu, Rasit Iuksel and Minerva Panteli

Abstract

Lamium album and Lamium purpureum are species belonging to the genus Lamium. Aerial parts of the two species and roots of Lamium album have applications in human and veterinary traditional medicine. Haemostatic properties of butanolic extracts of Lamium species were investigated by two experimental models in Wistar rats: haemostatic test by tail bleeding time determination and acenocoumarolcarrageenan test. Results of the haemostatic test by tail bleeding determination demonstrated haemostatic activity of both extracts. In the acenocoumarol-carrageenan test, only the Lamium album extract showed haemostatic activity, comparable to that of vitamin K. Based on the qualitative chemical data on iridoid glycosides (HPTLC), 8-acetylshanzhiside methyl ester might be assumed to be responsible for haemostatic activity. Based on the acute toxicity test, none of the extracts showed toxicity.