الفهرس 
A phytochemical and biological study of certain Ziziphus species growing in Egypt
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Abstract
Genus Ziziphus (Rhamnaceae) is well characterized for its multi benefits aside from its fruit nutritive value, its leaf decoction is a common healthy beverage in many cultures. Albeit, no detailed metabolites characterization is reported for its leaf till now, with most research focused on its fruits. Here we have employed UHPLC/PDA/ESI-MS technique to characterize the secondary metabolites profile of three traditionally used Ziziphus leaf taxa including: Z. spina-christi, Z. mauritiana and Z. jujuba revealing the first full insight onto Ziziphus leaf metabolome. A total of 102 metabolites were characterized including several novel flavonoids and cyclopeptide alkaloids first time to be reported from the genus. Additionally, fragmentation pattern for cyclopeptide alkaloids was proposed via ESI-MS. Principal component analysis (PCA) revealed close metabolite resemblance among Z. spina-christi and Z. mauritiana leaf specimens found enriched in saponins and distinct from that of Z. jujuba in which quercetin-3-O-(2-pentosyl)-rhamnoside was most abundant. In-vitro antioxidant, Ü-glucosidase, COX-1 and tyrosinase inhibitory assays revealed for Z. spina-christi and Z. mauritiana strong effects compared to Z. jujuba and in correlation with their metabolites repertoire supporting their medicinal values. Isolation of 4 triterpenic acids, 1 flavonoid and 1 saponin was achieved from Z. mauritiana Lam. leaf revealed as one of the most active investigated species. Further, antidiabetic effectiveness of Z. mauritiana on streptozocin induced diabetic rats was also investigated