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United Arab Emirates University (2018)

PHYTOCHEMICAL SCREENING, ELEMENTAL COMPOSITION AND IN VITRO ANTIOXIDANT ASSESSMENT OF SELECTED UAE MEDICINAL PLANTS

Mukhtar Dirir, Amina,

Titre : PHYTOCHEMICAL SCREENING, ELEMENTAL COMPOSITION AND IN VITRO ANTIOXIDANT ASSESSMENT OF SELECTED UAE MEDICINAL PLANTS

Auteur : Mukhtar Dirir, Amina,

Université de soutenance : United Arab Emirates University

Grade : Master of Science (MS) 2018

Résumé
Medicinal herbs have been used since prehistoric times to alleviate pain and to treat many different diseases. In recent decades, there has been a growing interest in natural product research, particularly on herbal plants and their bioactive constituents. The resurgence of interest in medicinal plants is primarily attributed to the inefficacy of synthetic medicines in combating many diseases as well as to their toxic and side effects. The flora of the UAE is rich with various medicinal plants that were utilized by the indigenous people for different therapeutic purposes. Unfortunately, there are still gaps of knowledge, research and development on the phytochemical and pharmacological aspects of the UAE medicinal plants. Therefore, this thesis is aimed to perform phytochemical screening, to determine the content of phenolic and flavonoid compounds, to determine the content of thirteen chemical elements and to evaluate the in vitro antioxidant activities of the crude extracts of six UAE medicinal plants. The medicinal plants examined in this work were : Acridocarpus Orientalis, Leptadenia pyrotechnica, Calotropis procera, Tecomella undulate, Euphorbia larica and Cyperus conglomerates. The phytochemical screening was performed using preliminary chemical tests. The total phenolic and flavonoid contents were determined by Folin Ciocalteau and aluminium chloride colourimetric methods, respectively. The elemental analysis was performed using inductively coupled plasma-optical emission spectrometry (ICP-OES). The DPPH, ABTS and FRAP assays were used to assess the antioxidant activities of the selected medicinal plants. Results revealed the presence of phenols, flavonoids and terpenoids in all six medicinal plants. Different amounts of phenolic and flavonoid contents were recorded in the different plant extracts. The phenolic content was found to be highest in Acridocarpus Orientalis extract (506.42 mg GAE/g DE) and the lowest in Cyperus conglomerates extract (61 mg GAE/g DE). Similarly, the highest total flavonoid content was revealed in Acridocarpus Orientalis (454.37 mg QE/g DE), while Cyperus conglomerates had the least total flavonoid content (9.54 mg QE/g DE). The average concentrations of macro-elements were ranged from 3175 to 37,596 ; 567.49 to 13,472 ; 4452.16 to 15,562 and 205.31 to 6837.46 mg/kg for Ca, Mg, K and Na, respectively. All the plants crossed the allowable levels set for iron, manganese, copper, chromium and aluminium.

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