Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Suisse → Mining Sudanese Medicinal Plants for Natural Compounds against Malaria and Neglected Tropical Diseases

University of Basel (2020)

Mining Sudanese Medicinal Plants for Natural Compounds against Malaria and Neglected Tropical Diseases

Mahmoud, Abdelhalim Babiker Mohamed

Titre : Mining Sudanese Medicinal Plants for Natural Compounds against Malaria and Neglected Tropical Diseases

Auteur : Mahmoud, Abdelhalim Babiker Mohamed

Université de soutenance : University of Basel

Grade : Doctor of Philosophy (PhD) 2020

Résumé partiel
Tropical parasitic diseases such as malaria, human African trypanosomiasis, Chagas disease, mycetoma, and leishmaniasis affect more than a billion people worldwide and have devastating consequences. There is no vaccine for any of these diseases, and the current drugs are problematic given their serious adverse effects and the emergence of drug-resistant parasites. Thus, there is an urgent need for the development of new, efficacious, safe, and cost-effective drugs. Natural products have in many instances provided new leads to combat neglected tropical diseases. The aim of this work was to systemically evaluate Sudanese medicinal plants for their antiparasitic activity along with their cytotoxicity profile ; followed by phytochemical investigation to identify bioactive compounds. A library of 235 plant extracts was prepared from over 60 plants used in Sudanese traditional medicine, and it was assessed for antiprotozoal activity against Trypanosoma brucei rhodesiense, Trypanosoma cruzi, Leishmania donovani, and Plasmodium falciparum. Dereplication was performed for active extracts to enable a rapid identification of known active compounds and prioritization for follow-up isolation. Plants that displayed interesting activities, namely Croton gratissimus, Cuscuta hyalina, and Haplophyllum tuberculatum, were further pursued. HPLC-based activity profiling led to localization of activity and identification of the types of compounds in these plant extracts. Compound isolation and structure elucidation were achieved by a combination of analytical, preparative, and semipreparative chromatographic techniques such as HPLC-PDA-ELSD-MS and microprobe NMR. HPLC-based activity profiling of Croton gratissimus allowed the identification of flavonoids, mainly quercetin derivatives, as responsible for the antileishmanial activity of the chloroform fraction of the crude ethanolic extract. Of these compounds, quercetin-3,7-dimethylether and ayanin were the most active against the protozoan parasites and with the highest selectivity indices.

Présentation

Version intégrale (5 Mb)

Page publiée le 27 mai 2021