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University of Surrey (2015)

Phytochemical investigation of members of the Asparagaceae and Euphoriaceae families

Alqahtani, Alaa

Titre : Phytochemical investigation of members of the Asparagaceae and Euphoriaceae families

Auteur : Alqahtani, Alaa

Université de soutenance : University of Surrey

Grade : Doctor of Philosophy (PhD) 2015

Résumé
The Asparagaceae family is richly represented in the southern African region and has approximately 900 species. It consists of four tribes, the Hyacintheae, Urgineeae, Ornithogaleae, and Oziroeeae. Members of the Asparagaceae are widely used in traditional remedies for the treatment of several ailments, such as infections, rheumatism, inflammation and disorders associated with the central nervous system. Different species belonged to Urgineeae tribe (Rhodocodon campanulatus, R. calcicola), Hyacintheae tribe (Chionodoxa luciliae (Gigantea Hort)), Ornithogaleae tribe (Ornithogalum pyramidale and Avonsera convallarioides) have been selected for the present phytochemical study. The bulbs of R. campanulatus yielded five new compounds, a bufadienolide (RC.1), a homoisoflavonoid (RC.2) and two acetylated derivatives of a homosoflavonoid (RC.2a & RC.2b) and an acetylated neolignan (RC.3a). The bulbs of R. calcicola gave two known bufadienolides (RA.1 & RA.2). C. luciliae yielded ten compounds, including scillascillin-type homoisoflavonoids (CL.1-CL.5a), 4-chromanone (CL.4), p-hydroxybenzaldehyde (CL.6), 3-benzyl-chromanone type (CL.7-CL.9) and 3-benzylidene-4-chromanone (CL.10). O. pyramidale yielded new cardenolide glycosides (OP.1). A. convallarioides gave a known polyhydroxylated compound, polybotrin (AV.1), a purine nucleoside, adenosine (AV.2) and trans N-p-coumaroyloctopamine (AV.3). The Euphorbiaceae family is a large and diverse family which comprises 340 genera. Several species belonging to the Croton genus are employed as traditional medicinal agents in Africa, Asia and South America. The Croton species are popularly used to treat cancer, hypertension, inflammation, rheumatism, bleeding gums, malaria, asthma, diabetes and ulcers. In this study, three Croton species, C. megalocarpus, C. menyhartii and C. rivularis have been investigated for their chemistries. The roots of C. megalocarpus gave ten compounds, six diterpenoid compounds belonged to ent-clerodane (CP.1-CP.6), halimane (CP.7) and ent-abietane (CP.8-CP.9) and a triterpenoid, lupeol (CP.10). The leaves of C. menyhartii gave two flavonoids : (CM.1-CM.2) and 4-hydroxy-1-methyl-2-pyrrolidinone (CM.3) as well as large quantities of sitosterol. The leaves of C. rivularis gave one acyclic triterpene, squalene (CR.1) and an acyclic diterpenoids, phytol (CR.2). The structures of these compounds were determined using FTIR, MS, 1D, 2D NMR studies and CD analysis. Compounds RC.1 and RC.3a, and compound OP.1, were screened against the NCI60 cancer cell lines. Compound OP.1 showed significant growth inhibition of cancer cell lines at five dose concentration level with good responses at the GI50, TGI and LC50 parameters. The homoisoflavonoids isolated in this study from C. luciliae and R. campanulatus were tested for their anti-angiogenic inhibition ability, CL.10 and RC.2b showed significant anti-angiogenic inhibition with GI50 values of 40.4 and 128 μM respectively.

Présentation

Page publiée le 26 octobre 2018