Supervisors info:
Κόκοτος Γεώργιος Καθηγητής ΕΚΠΑ (επιβλέπων), Καλογεροπούλου Θεοδώρα Διευθύντρια Ερευνών ΕΙΕ, Μαυρομούστακος Θωμάς Καθηγητής ΕΚΠΑ
Summary:
The present thesis involves the design and synthesis of new
1,4-benzoxazine/acyl hydrazone hybrids with antibacterial and antifungal
activity. The preparation of the final products was performed by two methods,
a) using acid catalysis at room temperature and b) using microwave-assisted
synthesis. Subsequently, we performed the identification of all possible
isomers of the new compounds due to the different conformations of the amide
bond, using 1D and 2D Nuclear Magnetic Resonance (NMR) spectroscopy (COSY,
HSQC, HMBC). Geometrical isomers of the final products were not observed. In
addition, dynamic 1H NMR spectroscopy, was employed to study the conformer
interchange and/or to determine the coalescence of duplicated signals using a
temperature range of 25 oC – 85 oC (spectra were collected every 10 oC).
Furthermore, conformational analysis of the active analog
3,4-dihydro-2H-1,4-benzoxazine-2-hydroxy-phenyl-2-carbo-hydrazone (3) was
performed in support to NMR NOE data. The antimicrobial activity of the new
compounds was evaluated against gram positive and negative bacteria and various
pathogenic fungal strains. The majority of new compounds were more active than
the corresponding reference compounds with
3,4-dihydro-2H-1,4-benzoxazine-2-hydroxy-phenyl-2-carbo-hydrazone (3) being the
most active.
To get an insight on the mechanism of action of the new compounds we
investigated their interaction with cytochrome P450 (CYP51) of Candida albicans
using a spectrophotometric method and Saturation Transfer Difference NMR (STD
NMR). Finally, in silico docking studies of the new compounds were performed at
the active site of the enzyme, using the software package Glide SP of
Schrodinger. The criteria for selection was the binding energy, the distance of
the heteroatom of the acyl hydrazone aromatic ring from the Fe2+ cation,
interactions with active site amino acids (AA) in comparison to the reference
compound ketoconazole.
Keywords:
Microwave-assisted synthesis, 1, 4-benzoxazines, Two-dimensional NMR Spectroscopy (2D NMR), Conformational analysis, Molecular docking
