Fluorescence is a phenomenon in which light is emitted after a substance (fluorophore) absorbed light and entered an excited state. The described phenomenon is exploited by a number of techniques, used for both basic research and daily routine diagnostics. Regardless of the reasoning for their use, a fluorophore component is an essential part. It has to meet a number of requirements to be usable for a particular application, which limits the range of suitable fluorophores and probes. Therefore, with the increasingly rapid development of techniques that exploit the phenomenon of fluorescence, we need new fluorophores and probes for its use. The main purpose of the master 's thesis was to optimize the synthesis of fluorophore based on the coumarin derivative merocyanine by adapting the reaction conditions of the synthesis, primarily by changing solvents and base. We wanted to increase lipophilicity, as basic merocyanine was very poorly soluble in various organic solvents. Thus, the prepared merocyanine might serve as a probe for labeling lipid droplets or other lipophilic structures. We tried to prepare oxonol as the main product of the reaction, since a compound with an oxonol skeleton in its structure appeared as a by-product in the above-mentioned synthesis.
We found that the solvent does not significantly affect the course of the reaction, but the base has a great influence. With the addition of a base, it has been found that a larger amount of by-product is formed, so the absence of a base is more optimal for the reaction. Oxonols are a group of fluorophores, commonly used as a basis for various fluorescent probes. However, in our case, the prepared oxonol did not show fluorescence, so we did not continue with the research in our master's degree. The first step in the synthesis of merocyanin involved the synthesis of (Z)-3-aryl-3-chloropropenal. It is a reactive fragment, therefore we were interested in whether it could be used as a warhead in non-covalent inhibitors. We prepared a small group of (Z)-3-aryl-3-chloropropenales, which were then tested by a colleague from the Department of Pharmaceutical Chemistry on human enzymes called Mao-A, Mao-B, AChE and BChE. Some compounds inhibited the activity of enzymes to a certain degree, but after preincubation of enzymes with inhibitors, the catalytic activity was not reduced further. This means that the inhibitory effect is not due to the formation of a covalent bond between the enzyme and the inhibitor. (Z)-3-Aryl-3-chloropropenales are not suitable for the development of covalent inhibitors of said enzymes.
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