Mohamed Gamaleldin Elsadig Karar

• In Sudan, a tropical country rich in biodiversity and biological resources, medicinal plants have been used for the treatment of several diseases and microbial infections in traditional medicine. However, the actual compounds responsible for the biological effects are still poorly characterized. In this project, extracts prepared from traditional medicinal plants native to Sudan and Europe were investigated for their phytoconstituents and biological effects. 457 phenolic compounds were unambiguously assigned to their regioisomeric level using LC–MSn. 332 of them were extracted for the first time from their sources, and 46 of them were not reported previously in nature. Chlorogenic acids, chlorogenic acid glycosides, phenolic acids, hydroxycinnamates, proanthocyanidins, flavonoid glycosides, flavonoid aglycones and derivatives thereof were identified as major phytoconstituents. Next, using preparative HPLC, 18 bioactive compounds including chlorogenic acids, flavonoid glycosides, coumarins and derivatives were isolated and identified in the plant extracts. Concerning the biological activities, various extracts showed antibacterial, antiparasitic and antioxidant activities. For example Acacia nilotica, Ocimum basilicam, Ziziphus spina-christi, Balanites aegyptiaca, Sonchus oleraceus, Punica granatum, Mimosa pigra and Ixora coccinea were the most interesting ones with antioxidative, antiplasmodial, antitrypanosomal and antibacterial activities. Moreover, the antibacterial activities of some naturally occurring phenolic compounds were investigated. Among the tested individual phytochemicals, phloretin, resveratrol, luteolin 7-O-glucoside and epigallocatechin gallate showed the highest antimicrobial activities. Most importantly, we investigated the influenza virus neuraminidase (NA) inhibitory activities of naturally occurring chlorogenic acids and synthesized derivatives against several viral NAs. The enzyme inhibition results indicated that chlorogenic acids and caffeic acid derivatives exhibited high antiviral effects. This study provides a detailed molecular level understanding of the phytoconstituents in a wide selection of Sudanese medicinal plants. Consequently, the phytochemical and pharmacological knowledge is better understood in support of the use of such plants in traditional medicine. As a highlight, the project presents a comprehensive LC-MS analysis for model mono and oligosaccharides based on their binding behavior to the sodium ion. This contribution shows that the modern MS methods such as UPLC-ESI-Q-TOF-MS/MS and HPLC-ESI-MSn can be used as unambiguously assignment of regioisomers of flavonoids glycosides and phenolic natural products. They can also be applied as predictive reliable techniques in the assignment of mono and oligosaccharide relative stereochemistry.