Evaluation of antimicrobial activity and cytotoxic effects of nanoliposomal formulation of ethanol extract of Melissa Officinalis L.

The aim of this thesis study is to evaluate the antimicrobial effects and cytotoxic effects of the formulation resulting from the encapsulation of the ethanol extract obtained from the Melissa officinalis L. plant with liposome structures that will increase the stabilization, absorption and dispersion effect. M. officinalis, which is widely grown in Turkey, is a perennial Mediterranean herb that has been used as an herbal medicine for about 2000 years in the treatment of various diseases. There are phenolic compounds with antioxidant properties belonging to many different classes in the leaves of the plant and these compounds provide direct antimicrobial effect and show proliferation-reducing and migration-reducing effects on different cancer cell lines. It is widely used in traditional medicine, food industry, and aromatherapy. Liposomes, on the other hand, are non-toxic, biodegradable, biocompatible phospholipid vesicles and are used in anticancer drug design, gene transfer, vaccine formulations, wound healing, dermatological diseases because of their function as a drug carrier system. Composition, physical properties, preparation method of liposomes may vary in different application areas. Liposomes can make controlled drug release depending on a certain release profile. In biological studies, liposomes increase the integration between the active substance and the target cell. In this thesis study; ethanol extraction was made from M.officinalis leaves. Subsequently, an extract formulation was created with liposome prepared by two-step homogenization. For characterization determination of total phenolic content in the extract, morphological characterization of the formulation, antimicrobial activity experiments, cytotoxicity experiments were performed. In order to have high encapsulation efficiency, smaller sized empty liposome dispersions were prepared by two-step homogenization. The ratio of incorporation the extract with liposomes providing high encapsulation efficiency was found to be 1: 1 (v/ v). The extract loaded liposome formulation prepared over this ratio was characterized by SEM. After characterization, disk diffusion and broth microdilution methods were performed against gram negative and gram positive bacterial strains to evaluate the antimicrobial activities of formulation. In the disk diffusion test, there was no statistically significant difference between extract and formulation, while in the broth microdilution test, the formulation was found to be more effective with less concentration against Staphylococcus aureus ATCC 25923 strain. MIC values of formulation and extract were found to be statistically the same against Escherichia coli ATCC 25922. In addition, dose-related cytotoxic effects of the extract and formulation on BEAS-2B and A549 cell lines were investigated by MTT test. The results showed that the IC50 value of the formulation was higher on healthy BEAS-2B cells and A549 cancer cells compared to that of the extract. This indicates that the formulation was less cytotoxic than the extract on the BEAS-2B cell line. Another point determined in the thesis study is that liposome alone has no antimicrobial and cytotoxic effects at all. According to the results of this study; a small amount of active compound to be formulated with liposomal formulation is sufficient for antimicrobial effect. It has also been demonstrated that the liposomal formulation is not cytotoxic.