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Abstract The aim of this thesis deals with the study of the chemical structure of polyphenolic constituents and their glycosides isolated from aerial part of Anithacanthus virgularis and Barleria cristata leaves (Acanthaceace). These plants have been selected to be the subject of this thesis due to its economic importance in folk medicine or in pharmacological uses and their scarce reports in the current literature. The aerial part of Anithacanthus virgularis were air-dried, ground and extracted with water. The water extract was applied on to a polyamide column, whereby seven fractions were obtained. The first fraction showed to contain mainly free sugars which were identified as: glucose, galactose and rhamnose. Investigation of the second fraction showed to contain complex pattern of polyphenolic constituents in minute amounts which could not be easily identified. From the third fraction, apigenin 6,8-di-C-β-D-glucopyranoside (vicenin II) (A1) and a new natural compound 6,8-dihydroxyapigenin-6-O-α-L-rhamnopyra- noside-8-O--D-galactopyranoside (A2) were isolated and identified. Detailed studies of the fourth fraction led to the isolation and identification of three glycosidic flavonoids namely:- chrysoeriol 7-O-β-D-glucopyranoside (A3), apigenin 4`-O--D-glucopyranoside (A4), acacetin-7-O--D-glucopyranoside (A5). From the fraction five two luteolin glycosides were isolated and identified the first as the new natural compound 6-OH-8,3’-dimethylether luteolin 6-rhamno-pyranoside (A6) and the second as luteolin 7-O-rutinoside (A7). Three compounds namely luteolin 7-O--D-galactopyranoside (A8), luteolin 8-C-β-D-glucopyrano-side (orientin) (A9) and acacetin (A10) were isolated from fraction six while apigenin (A11), luteolin (A12) and chrysoeriol (A13) from fraction seven. |