Gholap, Ashok V. (Professor)Belay, Abebe (PhD)Abraha, Ataklti2019-11-252023-11-092019-11-252023-11-092018-06-22http://10.90.10.223:4000/handle/123456789/20250Drug-drug/food interactions are major source of patient’s inconvenience and non-adherence through disruption in a patient’s daily schedule. Hence, lack of knowledge of potentially significant drug-drug/food interactions lead to poor clinical outcomes. Thus, investigation of different incompatibilities of drugs using spectroscopic techniques is most important inquiry of solving these problems. For this reason, the optical transition probabilities and interactions of some drugs (nicotinamide (NIC), neomycin sulfate (NOMS), norfloxacin (NOR) and ciprofloxacin (CIP)) with biologically active compounds of coffee beans (chlorogenic acid (CGA) and caffeine (CAF)) have been investigated using Ultraviolet visible (UV-Vis) absorption and fluorescence spectroscopic techniques. From the UV-Vis spectroscopic technique, the self-, hetero-association, thermodynamic properties, and optical transition probabilities of the drugs were investigated in aqueous solution. The parameters were analysed using Dimer model and Bensi-Hildebrand equations respectively for the self-and hetero-associations. The obtained equilibrium dimerization constant (KC) values are 2.379 _ 104, 1.06 _ 105, 5.424 _ 103, 4.377 _ 103, 4.3135 _ 103 and 6.67 _ 103M􀀀1 for NIC, NOMS, NOR, CIP, interaction of nicotinamide with chlorogenic acid (NIC-CGA), and interaction of norfloxacin with caffeine (NOR-CAF) respectively. In order to understand the interaction mechanisms of the self and heteroassociations, thermodynamic properties were determined using Vant’s Hoff’s equation. The molar enthalpy changes were found to be 4.826_0.415, 3.76_0.66, 􀀀(5.35_0.459), 􀀀(1.98 _ 0.25),􀀀(16.927 _ 0.836) and 􀀀(1.277 _ 0.103)kJ.mol􀀀1 for NIC, NOMS, NOR, CIP, NIC-CGA and NOR-CAF respectively. Thus, hydrophobic interactions are dominant for the interaction of NIC and NOMS molecules, and electrostatic forces play the major role in the interactions of NOR, CIP, NIC-CGA and NOR-CAF molecules. The op- (Copyright C Ataklti Abraha June 22, 2018) vi vii tical transition probabilities of the drugs were determined using integrating absorption technique from the absorption spectra of the drugs. The values of the oscillator strengths are 0.07, 0.1,0.37 and 0.46 for NIC, NOMS, NOR and CIP respectively. Besides, the binding of CAF with NIC using fluorescence quenching technique was analysed at temperatures of 295 and 303 K and it was confirmed with the absorption spectra of the binding molecules. From this fluorescence quenching spectral analysis the quenching constant (1.775_104L/mol), quenching rate constant (5.052_1013L/mol/s) and number of binding sites 0.88 were determined at 295 K. The thermodynamic properties of interaction of nicotinamide with caffeine (NIC-CAF) indicates that electrostatic forces play the major rule in the binding of the molecules. The effect of solvent polarity on the absorption and fluorescence spectra of NIC were investigated. The ground state and excited state dipole moments of NIC are estimated from solvatochromic shifts of absorption and fluorescence spectra as a function of the dielectric constant and refractive index functions. Thus, the ground and excited dipole moments were found to be 0.02D and 0.268D respectively using Bilot-Kawski method. The excited state dipole moment is found to be higher than those of ground state for all of the used methods, and the higher values are attributed to more polar excited state of NIC. Therefore, the results of the study are very important for understanding the binding reaction in biological system, nature and strength of the transition, absorption spectral interpretation, and in providing stringent test of atomic and molecular structure calculations for theoretical work of the compounds. Thus, understanding the interaction properties of the drugs may help in the field of pharma technology and food companies in improving the efficiency and the capabilities of absorption of the drugs in biological system and in induce rapid recovery of patient’s.enSpectroscopicTechniques to Study the Optical PropertiesInteractionSome Drugs With BioactiveCompound of Coffee BeansThesis