Structure-activity relationship

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Quantitative structure-activity relationship of some 1-benzylbenzimidazole derivatives as antifungal agents

Quantitative structure-activity relationship of some 1-benzylbenzimidazole derivatives as antifungal agents

Quantitative structure-activity relationship (QSAR) has been used to study the relationships between the antifungal activity and lipophilicity parameter, logP, calculated by using CS C[r]

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Calculation of Quantitative Structure-Activity Relationship Descriptors  of Artemisinin Derivatives

Calculation of Quantitative Structure-Activity Relationship Descriptors of Artemisinin Derivatives

Artemisinin and its derivatives are only the group of compounds that is still effective against drug- resistant P. falciparum strains, and has the ability to quickly reduce parasite level (Krishna, 2004). From the other side, it has short plasma half-life, limited bioavailability, poor solubility in oil and water, and the low yield from natural sources (Woodrow, 2005). These reasons prompted to develop new chemotherapeutic artemisinin derivatives. By the chemical modifi cation of artemisinin at the position of C10 semisynthetic derivatives as artesunate, artemether, artelinic acid and dihydroartemisinin were produced, which have more antimalarial activities in vitro than artemisinin itself (Pinheiro, 2003). Many derivatives have been synthesized using dihydroartemisinin by adding different radicals on its rings. But, the development of a new drug is a very long and expensive process. To overcome these diffi culties scientists start to use a variety of computational methods to identify novel compounds, design compounds with increased selectivity, effi cacy and safety and develop compounds into clinical trial candidates. One of these methods is the Quantitative Structure- Activity Relationship (QSAR) technique. The present work is related to the design of a new antimalarial active artemisinin analog.
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2,3-Diarylxanthones as strong scavengers of reactive oxygen and nitrogen species: A structure–activity relationship study

2,3-Diarylxanthones as strong scavengers of reactive oxygen and nitrogen species: A structure–activity relationship study

in the aryl groups. However, in this assay, the presence of phenol groups seems to be extremely important for the scavenging effect. The highest ORAC value was obtained for compound 2b, a xan- thone bearing two phenol groups as substituents. The introduction of an additional OH substituent drastically decreases the scaveng- ing activity as it is evident by the results of compounds 3a–c. 2,3-Diarylxanthone 3c, a derivative with two ortho-dihydroxyl groups, provided the lowest ORAC value from all the tested hydroxyxanthone. These observations are not in accordance to the knowledge about structureactivity relationship of flavonoids and phenolic compounds. The ortho-dihydroxyl substitution is particularly important to the ROO  absorbing activity of those
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Unbalance Quantitative Structure Activity Relationship Problem Reduction in Drug Design

Unbalance Quantitative Structure Activity Relationship Problem Reduction in Drug Design

Abstract: Problem statement: Activities of drug molecules can be predicted by Quantitative Structure Activity Relationship (QSAR) models, which overcome the disadvantage of high cost and long cycle by employing traditional experimental methods. With the fact that number of drug molecules with positive activity is rather fewer than that with negatives, it is important to predict molecular activities considering such an unbalanced situation. Approach: Asymmetric bagging and feature selection was introduced into the problem and Asymmetric Bagging of Support Vector Machines (AB-SVM) was proposed on predicting drug activities to treat unbalanced problem. At the same time, features extracted from structures of drug molecules affected prediction accuracy of QSAR models. Hybrid algorithm named SPRAG was proposed, which applied an embedded feature selection method to remove redundant and irrelevant features for AB-SVM. Results: Numerical experimental results on a data set of molecular activities showed that AB-SVM improved AUC and sensitivity values of molecular activities and SPRAG with feature selection further helps to improve prediction ability. Conclusion: Asymmetric bagging can help to improve prediction accuracy of activities of drug molecules, which could be furthermore improved by performing feature selection to select relevant features from the drug.
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Quantitative Structure Activity Relationship and Risk Analysis of Some Pesticides in the Goat milk

Quantitative Structure Activity Relationship and Risk Analysis of Some Pesticides in the Goat milk

The detection and quantification of different pesticides in the goat milk samples collected from different localities of Faisalabad, Pakistan was performed by HPLC using solid phase microextraction. The analysis showed that about 50% milk samples were contaminated with pesticides. The mean±SEM levels (ppm) of cyhalothrin, endosulfan, chlorpyrifos and cypermethrin were 0.34±0.007, 0.063±0.002, 0.034±0.002 and 0.092±0.002, respectively; whereas, methyl parathion was not detected in any of the analyzed samples. Quantitative structure activity relationship (QSAR) models were suggested to predict the residues of unknown pesticides in the goat milk using their known physicochemical
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Design of Novel N-Myristoyltransferase Inhibitors of Leishmania donovani Using Four-Dimensional Quantitative Structure-Activity Relationship Analysis

Design of Novel N-Myristoyltransferase Inhibitors of Leishmania donovani Using Four-Dimensional Quantitative Structure-Activity Relationship Analysis

N-Myristoylation protein is catalyzed by N-myristoyltransferase (NMT), an essential target in Leishmania donovani, the causative agent of kala-azar. Four-dimensional quantitative structure- activity relationship (4D-QSAR) analysis was applied to a series of 77 Leishmania donovani NMT inhibitors. Then, three new compounds were proposed using QSAR models. In addition, molecular docking was performed to predict the binding affinities and interaction modes among the proposed compounds and the NMT active site. In silico absorption, distribution, metabolism and excretion (ADME) evaluation was performed and potential inhibitors demonstrated satisfactory pharmacokinetic properties.
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Quantum chemical properties used in structure-activity relationship studies.

Quantum chemical properties used in structure-activity relationship studies.

Este trabalho teve como objetivo demonstrar a variedade dos tipos de descritores moleculares baseados em cálculos químico-quânticos deriva- dos das funções de onda e distribuição de car[r]

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Evaluation of cytotoxic activity of synthetic bis-indolyl methanes: structure-activity relationship

Evaluation of cytotoxic activity of synthetic bis-indolyl methanes: structure-activity relationship

During the last years, the cellular origin of Hodgkin Lymphomas has been clarified. Due to the silencing of regulators of B cell differentiation (ABF-1, ID2 and NOTCH1, for example) or the disruption of B-cell specific gene expression (BCL6, NOTCH1 inhibition, for example), Reed-Sternberg cells, the tumour cells of HL, seem to result from a defect in the cytokinesis of cells. Some mechanisms responsible for Hodgkin-Reed-Sternberg cells include NF-κB activity encouraged by TNF/death-receptor family members, constitutive IκB kinase (IKK) complex and NF-κB inducing kinase (NIK). The disruption of JAK/STAT Signalling (Janus kinase/signal transducers and activators of transcription pathway) and deregulation of the AP-1/CREB complex are other drivers to HL pathology (38).
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Anti-Parasite and Cytotoxic Activities of Chloro and Bromo L-Tyrosine Derivatives

Anti-Parasite and Cytotoxic Activities of Chloro and Bromo L-Tyrosine Derivatives

Due to the emerging resistance against current drugs, it is mandatory to develop new, safer and more effective antiparasitic agents. For that reason, in the present study, the potentials of marine natural products derivatives compounds, based on bioactive L-bromotyrosines, were evaluated as new antiparasitic compounds. The syntheses of novel chloro and bromo L-tyrosine derivatives, with different grade of methylation of the amino group, lead us to realize a structure-activity relationship between the halogenations patterns in the aromatic ring of the L-tyrosine and the substitution of the amino group, looking for the best structural parameters for the development of new antiparasitic compounds.
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J. Braz. Chem. Soc.  vol.24 número1

J. Braz. Chem. Soc. vol.24 número1

studies were employed to find a possible structure-activity relationship and allowed to establish some important features for the chalcones to be active. For instance, the best activity against C. cladosporioides IMI 178517 was obtained with three descriptors: dihedral angle between atoms, HOMO density on atom 13 (PsiH-13) and refractivity index (Ref) and two components (PC1 and PC2) were necessary to discriminate the chalcones into active and inactive. In the case of S. aureus ATCC 6538, only one component (PC2) was needed and the descriptors responsible for the discrimination were the bond angle (A12-2-3), PsiL-2, and bond order between atoms (b7,14). Future efforts to optimize the structures of this class of compounds may involve design, as well as the study of the effect of some groups strategically placed in positions in the structure of chalcones that may influence some properties such as solubility.
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The effect of Cratylia floribunda lectin on renal hemodynamics and ion transport

The effect of Cratylia floribunda lectin on renal hemodynamics and ion transport

In respect to renal efects of Diocleinae lectins, our group demonstrated that the lectin of Canavalia brasiliensis (ConBr) (Teixeira et al., 2001), DguiL and ConA (Havt et al., 2003) distinctly alter physiological parameters in ex vivo rat kidneys. Considering that kidneys are responsible for the maintenance and excretion of electrolytes in the human body and the structure-activity relationship among Diocleinae lectins, the direct renal effects promoted by the seed lectin of Cratylia loribunda in isolated perfused kidneys and mesenteric bed of rats were investigated.
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Braz. J. Pharm. Sci.  vol.49 número1

Braz. J. Pharm. Sci. vol.49 número1

A survey of the literature revealed that slight modi- ications in the structure can result in qualitative as well as quantitative changes in activity, which prompted us to undertake the synthesis of various 2-phenitidine deriva- tives and to study their structure-activity relationship by screening them against DPPH, AChE, BChE, and lipoxy- genase (LOX), and these were found to be active against BChE, and were also possible entrants for the treatment of Alzheimer’s disease.

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Phenolic Acids and Derivatives:  Studies on the Relationship among Structure, Radical Scavenging Activity, and Physicochemical Parameters†

Phenolic Acids and Derivatives:  Studies on the Relationship among Structure, Radical Scavenging Activity, and Physicochemical Parameters†

Among naturally occurring phenolic compounds, phe- nolic acids and flavonoids are of particular interest because of their potential biological properties, such as anti-inflammatory, antiallergic, antimicrobial, anticar- cinogenic, and antiviral activities (Castellucio et al., 1996; Rice-Evans et al., 1996; Laranjinha et al., 1994). Many phenolic acids (e.g., cinnamic acids) are also known to be potent antioxidants, probably through their radical scavenging activity, although other mechanisms may be involved. The antiradical activity of phenolic compounds depends on their molecular structure, that is, on the availability of phenolic hydrogens and on the possibility for stabilization of the resulting phenoxyl radicals formed by hydrogen donation (Mathiesen et al., 1997; Rice-Evans et al., 1996). In fact, preliminary structure-activity relationship studies on cinnamic acids and derivatives have pointed out the importance of the catechol group to the antiradical efficacy (Moon and Terao, 1998; Chen and Ho, 1997; Brand- Williams et al., 1995; Graf, 1992). The role of the ethylenic side
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JISTEM J.Inf.Syst. Technol. Manag.  vol.14 número1

JISTEM J.Inf.Syst. Technol. Manag. vol.14 número1

The relevance of studies into IT Governance mechanisms is evident in the international academic scenario. This is apparent in the various researchers who have dedicated themselves to studying these arrangements and practices in recent years. As an example, Bowen, Cheung and Rohde (2007) explored the factors influencing the IT Governance mechanisms. They indicate that the IT Governance is associated with mechanisms such as shared understanding of the objectives between business and IT, the active involvement of IT committees in the management and decision making, strategies and policies shared and communicated between business and IT. Weill and Ross (2004), in a survey of 250 companies from different countries, demonstrated that the adoption of IT Governance mechanisms, especially the mechanisms of decision-making and relationship structure, could be a profitable investment. Table 1 shows the mechanisms cited in the study by Peterson (2001).
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prod 27 spe e20162207

prod 27 spe e20162207

The student-mentee is usually paired with the faculty-mentor from the first year. This marks the initiation phase. However the subsequent phases are not clearly demarcated into cultivation, separation and redefinition as described by Kram (1983). The relationship is planned to last the duration of each mentee’s university career which is currently four years for undergraduate studies (almost six years for those who enrol in the Master’s programme). In practice, there is high participation of the first year mentees in the mentoring programme being the period of transition from high school to the university. It could be said that the initiation phase is well demarcated. Nevertheless, once they overcome the academic challenges of the first year and obtain satisfactory grades there is a tendency for some of them to abandon the mentoring programme going directly to the separation phase. There seems to be no cultivation phase in many of the mentoring relationships. Although some of the mentees in their final year sometimes return to their mentors to seek advice on their professional career, elective courses, industrial placements and the Erasmus programme, the early separation from their mentors constrains the engineering university from achieving all the goals of the mentoring programme.
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Novel chromone and xanthone derivatives: Synthesis and ROSRNS scavenging activities

Novel chromone and xanthone derivatives: Synthesis and ROSRNS scavenging activities

scavenging activity of phenolic compounds, delaying or preventing lipid peroxidation [21,30]. All of compounds achieved similar ORAC values which were apparently superior to the value presented by the water-soluble vitamin E analogue trolox, used as standard. In fact, if we consider that compounds 12a-12c and 13a-13c are ex- pected to trap 4 peroxyl radicals similar to quercetin while trolox only traps 2 [31], the tested compounds are slightly less effective than trolox and clearly less effective than quercetin (Table 2). The results indicate that chromone 12c (1.63 ± 0.09) has higher scav- enging effect, followed by chromones 12a (1.44 ± 0.01) and 12b (1.40 ± 0.05), with similar ORAC values. Considering that chro- mones 12a-12c are less active than the 2-styrylchromones studied by Gomes et al. we can conclude that the additional double bond at C-2 decreases the scavenging effect against this ROS [29]. Analysing the results of xanthones, compounds 13a (1.5 ± 0.1) and 13c (1.58 ± 0.09) are the most active ones, followed by compound 13b (1.1 ± 0.1). An interesting feature common to all the ROS described is the fact that 6-OH xanthone 13c was shown to have improved scavenging activity when compared to the 8-OH xanthone 13b. Similar to the H 2 O 2 scavenging assays, the ROO  scavenging effects
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Analysis of epistemic practices in reports of higher education students groups in carrying out the inquiry-based activity of immunology

Analysis of epistemic practices in reports of higher education students groups in carrying out the inquiry-based activity of immunology

In our study, we observed that both undergraduate and postgraduate students group correctly concluded the investigative proposed activity, by reaching the correct answer to the set of experimental data that the groups were intended to solve the problem situation, prays stem cell, prays cells in the pre-B stage or prays to the fully differentiated B cell. Thus, which was the "path" covered by the students of the groups for the implementation of investigative activity? To pursue the path of this construction of the conclusions of activity by groups of students, we take the propose formulated by Jimenez-Aleixandre et al. (2008), Kelly (2008) and Sandoval (2000) who developed categories to search the epistemic practices in the classroom, and which are classified into three major keys inspired by scientific research procedure: 1) the data production; 2) data evaluation; and 3) the communication of the data collected.
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Relationship Between Bilirubin Level  and Disease Activity in Crohns Disease

Relationship Between Bilirubin Level and Disease Activity in Crohns Disease

CD diagnosis was made based on endoscopic and histopatho- logic criteria. Clinical activity was determined using the Crohn’s Disease Activity Index (CDAI). It was deined as the active phase of the disease if the CDAI was ≥ 150 and as remission if the CDAI was < 150 [7]. Subjects with elevations in any of the liver function tests (deined as alanine aminotransferase 40 U/L, as- partate aminotransferase 30 U/L, gamma glutamyl transferase 70 U/L, and alkaline phosphatase 120 U/L) were excluded from the study.

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Mechanism for determining the ecology-economic activity of cluster structure

Mechanism for determining the ecology-economic activity of cluster structure

business and, as a consequence – to increase the investment attractiveness of the region. For the ecological and economic evaluation of the enterprises activity within the cluster structure prompted the concept of «level of environmental and economic activity cluster». The level of environmental and economic activity cluster refers to the degree of investment attractiveness of the region at different stages of cluster operation taking into account environmental, social, economic and environmental and economic factors. The sequence of ecological and economic evaluation of processes in the enterprises to determine the level of environmental and economic activity takes place in 13 stages. The article describes the key aspects of innovative regional development, namely clustering. The emphasis is on the mathematical evaluation model of ecological-economic activity in cluster formation and determination of integral indicator vectors of ecological and economic activity. The mathematical evaluation model of ecological-economic activity of cluster consists of four vectors: social, economic, environmental, and ecological and economic.
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