Thesis (M.Sc.) - Cairo University - Faculty of Science - Department of Botany - Microbiology

Aqueous and methanolic seed extracts of Citrullus colocynthis from different geographical habitats, namely Sinai, ElWadi ElGedid, and Wadi Qena, were screened for antimicrobial activities.The tested microorganisms include 18 species, of which 6 bacteria, 6 Candida, and 6 dermatophyte fungi. The methanolic extract was more effective than aqueous extract for all microorganisms.The extracts were variably effective with more significant inhibition towards dermatophytes, particularly the seeds from Sinai.The effect of methanol seed extract from Sinai combined with 0.5 og/ml fluconazole act as a synergistic factor in decreasing spore viability, reduction of keratinase, elastase, lipase, phospholipase, and protease was more pronounced. The phytochemical analyses of the methanolic seed extracts from the three localities shows the presence of Hexadecanoic acid, methyl ester, 9,12- Octadecadienoic acid (Z,Z), and 9,12-Octadecadienoic acid (Z,Z)-, 2-hydroxy-1- (hydroxymethyl) ethyl ester as common compounds.The in-silico docking activity of 9,12-Octadecadienoic acid (Z,Z), Methyl 9-cis,11-trans-octadecadienoate, and 9,12-Octadecadienoic acid, methyl ester, (E,E) toward keratinase and lipase enzymes of Microsporum canis and Trichophyton mentagrophytes showed a high affinity of binding between 9,12-Octadecadienoic acid (Z,Z) and lipase enzyme of Microsporum canis and Trichophyton mentagrophytes as it forms 3 H-bonds with Gln 106, Ser 107, and Thr 102 of Microsporum canis lipase, in addition, it forms 4 H-bonds with Gln 129, Gly 124, Ile 128, and Ser 130 of Trichophyton mentagrophytes lipase

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