PhD Scientific Days 2022

Pharmaceutical Sciences II. (Poster discussion will take place in the Aula during the Coffee Break)

Different Effects of Various Cyclodextrin Derivatives on Plasma Membrane Ganglioside and Cholesterol Level

Text of the abstract

Introduction: Gangliosides are membrane glycolipids and are highly abundant in neural tissues. They are enriched in membrane microdomains (lipid rafts, caveoles), along with cholesterol and sphingolipids serving as signaling platforms. Their role in the pathomechanism of several neurodegenerative diseases and insulin resistance is studied extensively. Our previous capillary electrophoresis (CE) experiments showed that several, pharmacologically relevant cyclodextrins (CDs) can form complexes with gangliosides. Beta CDs are widely used in vitro to manipulate membrane cholesterol level, however their effect on gangliosides is unclear.
Aims: Our aim was to examine the effect of various CDs on plasma membrane ganglioside and cholesterol levels. In addition, their effect on viability was also to be studied. CDs with different cavity size and substituents (DIMEB, HPBCD, RAMEA, HPACD) were tested.
Methods: CD treatments were carried out on rat cerebral synaptosomes by incubating them in physiological buffer containing CDs for 40 min at 37°C followed by analysis of membrane lipid fraction. Ganglioside composition was analyzed by using our previously published CE method. Cholesterol content and LDH release were measured by fluorescent assays.
Results: DIMEB depleted not only membrane cholesterol (IC50=8mM) but gangliosides (IC50=10mM) to a similar extent. HPBCD also depleted cholesterol (IC50=33mM) and gangliosides (IC50=83mM) and showed lower cytotoxicity than DIMEB. On the contrary, cholesterol depletion was not observed with ACD derivatives, which was associated with lower cytotoxicity than with BCDs. RAMEA was found to be more potent (IC50=26mM) than HPACD (IC50=85mM) in ganglioside extraction.
Conclusion: Cavity size of CDs plays a crucial role in cholesterol extraction. According to our present results HPBCD may be a better option than DIMEB for selective cholesterol depletion, due to the significant difference between its IC50 values for cholesterol and ganglioside depletion. Both ACD derivatives are able to extract gangliosides but not cholesterol therefore, they can be suitable to study ganglioside function in pharmacological studies. Methlyated CDs are more potent lipid extracting agents than hydroxypropylated ones.
Funding: This study was supported by the EFOP-3.6.3-VEKOP-16-2017-00009 grant and the School of PhD Studies, Semmelweis University.