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5 record(s) found

Two New isoquinoline alkaloids from the bark of Alphonsea cylindrica King and their antioxidant activity

Abstract

Two new isoquinoline alkaloids, iraqiine (1) and kareemine (2), along with five known alkaloids, muniranine (3), kinabaline (4), O-methylmoschatoline (5), atherospermidine (6) and N-methylouregidione (7), were purified from the dichloromethane crude extract of Alphonsea cylindrica bark. The structures of these compounds were elucidated through extensive 1D and 2D NMR, IR and LC–MS studies and comparison with previously reported data. Compounds (1–5 and 7) were tested for their antioxidant activity using in vitro DPPH radical scavenging assay, and 1, 3 and 4 showed the highest antioxidant activities with IC50 values of 48.77 ± 1.01, 44.51 ± 1.12 and 64.28 ± 0.93 μg/ml, respectively ..

Article Published 2019 5282 hits Limited

Secondary metabolites from three species of annonaceae plants and their biological activities

Obaid, Ahmed Kareem

Abstract

The study aimed to investigate the chemical constituents from Polyalthia lateriflora, Alphonsea elliptica and Alphonsea cylindrica as well as their cytotoxic, antioxidant and xanthine oxidase inhibitory activities. These samples were collected from Peninsular Malaysia and then extracted sequentially using hexane, dichloromethane and methanol. The chemical compounds were isolated and purified by various chromatographic techniques and their structures were elucidated via spectroscopic method especially Nuclear Magnetic Resonance, Mass Spectrometry, Infrared, Ultraviolet and comparison with literature. Cytotoxic activity was analysed on MCF-7 human breast cancer cells while antioxidant activity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH). Study on P. lateriflora has yielded six compounds which were lupeol, stigmasterol, Omethylmoschotaline, atherospermidine, lysicamine and liriodenine. Meanwhile, five compounds namely kinabaline, atherospermidine, liriodenine, N-met.....

Thesis Published 2019 3185 hits Available

The effects of strategic and employee factors on the project performance of Iraqi public construction projects:the role of knowledge transfer, experience and safety

Obaid, Mohammed Hatem

Abstract

The purpose of this study is to examine the effect of strategic and employee factors on the project performance of Iraqi public construction projects. The study also aims to determine the mediating effect of knowledge transfer and the moderating effect of safety and experience. A total of 221 responses were collected from project managers, civil engineers, site managers, and architects. The findings indicated that strategic factor and their dimensions (β = 0.300, t=4.889,p..

Thesis Published 2019 1513 hits Available

The effects of pragmatic instruction on Iraqi undergraduate English as a foreign language students usage of the speech act of request

Hussein, Nadhim Obaid

Abstract

The study aimed to investigate whether pragmatic instruction has an effect on Iraqi students' usage of request and whether male and female students differ in their usage of overall strategy and strategy patterns. This study also explored Iraqi EFL learners' perceptions of learning speech act of request and investigate whether Iraqi students were able to present the appropriate linguistic and pragmatic forms in performing speech act of request. Experimental design was adopted in this study. A discourse completion test (DCT) and a questionnaire were used for data collection. 80 undergraduate students participated in the study and they were divided into two groups; the control group consisted of 40 learners who did not receive any pragmatic instruction, and the experimental group that composed of 40 learners who were taught request strategies via pragmatic instruction. The results revealed that the experimental group showed a significant improvement in the scores of four compon.....

Thesis Published 2021 1354 hits Available

Effects of organizational commitment, employee motivation and employee participation on employee performance in the United Arab Emirates banking sector

Obaid, Alantali Ali

Abstract

This study aimed to investigate the effects of organizational commitment, employee motivation, and employee participation on employee performance in the United Arab Emirates banking sector and examine the mediating effects of intrinsic and extrinsic motivation as well as the moderating effect of employee participation on relationships. Using a simple random sampling technique, a sample of 350 UAE bank employees was selected. This study adopted a quantitative approach and questionnaires were used to collect data from the respondents. Partial Least Squares Structural Equation Modeling (PLS-SEM) was used to analyse the data. The findings revealed that at 0.05 significance level, affective commitment (β=0.408, t-value=6.840, p=0.001), continuance commitment (β=0.223, t-value=4.914, p=0.001), intrinsic motivation (β=0.174, tvalue= 2.344, p=0.001), and extrinsic motivation (β=0.185, t-value=2.912, p=0.001) have significant and positive effects on employee performance, but not .....

Thesis Published 2023 1842 hits Available

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