Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Pharmacognosy

Opuntia ficus-indica is the most economically important cactus species belonging to family Cactaceae. Its importance arises from its nutritional values and various biological activities such as antioxidant, anticancer and antimicrobial. This study attempts to characterize the metabolic profile of three O. ficus-indica cultivars having different colors i.e., red {u2018}Rose{u2019}, greenish white {u2018}Bianca{u2019} and yellow-orange represented by peels and pulp tissues via UPLC-QTOF-MS. 45 Metabolites were identified with flavonoids; mainly isorhamnetin conjugates and phenolic acids amounting for the major classes, whereas betaxanthins and coumarins were present at lower levels. Multivariate data analyses were employed to assess metabolites heterogeneity with dihydroxy psoralen-O-hexoside and ferulic acid and their glycosidic conjugates being the discriminatory metabolites among the peels and pulps within the different cultivars, while the level of flavonoids was comparable among cultivars. The antioxidant activity of peels and pulps extracts were further evaluated using DPPH and ABTS assays, with {u2018}{u2019}Rose{u2019}{u2019} cultivar peel exhibiting the highest antioxidant activity in both in vitro assays suggesting that though present at low levels coumarins present in addition to flavonoids mediate for the high antioxidant activity of O. ficus-indica fruits. Extracts prepared from O. ficus-indica were further administered to a gut consortium culture encompassing 8 microbes, which are major representatives of gut bacteria. Samples were harvested at 0.5 and 24 h post addition of O. ficus-indica extract and from blank culture in parallel and analyzed for its metabolites composition using gas chromatography coupled to mass spectrometry detection (GC/MS)

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