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Title: Phytochemical and antimicrobial studies on selected medicinal plants from the Iraqi flora : Citrus grandis, Citrus sinensis and Ruta chalepensis
Author: Al-Majmaie, S. H. A.
ISNI:       0000 0004 8501 7265
Awarding Body: Liverpool John Moores University
Current Institution: Liverpool John Moores University
Date of Award: 2019
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This study was founded on traditional medicinal information and local traditional uses of three Iraqi medicinal plants from the Rutaceae family, namely, Citrus grandis (leaves), Citrus sinensis (leaves and peel) and Ruta chalepensis (fruits, leaves, stems and roots). A bioassay-guided approach was adopted to study the phytochemicals and antimicrobial activity of these plants. The n-hexane, DCM and MeOH extracts of all plants and plant parts, obtained from successive Soxhlet extraction, were assessed for their antimicrobial proprieties using the microtitre resazurin assay involving two Gram-positive bacterial strains, Micrococcus luteus and Staphylococcus aureus, two Gram-negative strains, Escherichia coli and Pseudomonas aeruginosa and one fungal strain, Candida albicans. The DCM extracts of C. grandis (leaves) and C. sinensis (leaves) showed notable antimicrobial activity against the microbes used in this study with different MIC values. Both DCM and MeOH extracts of C. sinensis (peel) also revealed significant activity. All R. chalepensis extracts exhibited antimicrobial activity except for the root extract, which did not show any antimicrobial activity with the maximum concentration of 10 mg/mL. Thirty three compounds including two novel ones, mainly coumarins and flavonoids, were isolated from the active extracts/fractions using a combination of thin layer chromatography (TLC), solid-phase extraction and reversed-phase high-performance liquid chromatography (HPLC). 1D and 2D nuclear magnetic resonance (NMR) and mass spectrometric techniques were employed to identify and confirm the structures of the isolated compounds. Twenty of 33 isolated compounds were evaluated for their anti-MRSA activity against five methicillin-resistant Staphylococcus aureus strains (SA1199B, XU212, MRSA340702, EMRSA-15MRSA274819) and the standard strain (ATCC25923). The mechanism of action of six compounds were investigated by scanning electronic microscopic (SEM) method to detect any morphological changes or damage caused by the tested compounds. This study generated the first phytochemical and antimicrobial report of R. chalepensis fruits and Iraqi C. grandis leaves. To study the mechanism of action of compounds selected from the resazurin assay, a SEM protocol was developed.
Supervisor: Sarker, S. ; Nahar, L. ; Sharples, G. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: RM Therapeutics. Pharmacology ; RV Botanic, Thomsonian, and eclectic medicine