Low-density lipoprotein and alkaloid Methyl cysteine complex: interaction characterization and evaluation of protective agent against lipid oxidation

BUCCI, ANTONELLA; FRIAS, M.A.; LEDESMA, A. E

Congreso; L Reunión Anual SAB; 2022

Hyperlipidemia is a condition caused by high or abnormal levels of lipids or lipoproteins in blood. An elevated level of low-density lipoprotein (LDL) in blood circulation, is one of the main risk factors for atherosclerosis and coronary artery disease. Due to the fact that lipoproteins present a variation in their density, their extraction was carried out from human plasma of healthy adult volunteers. The LDL were isolated based on separation by ultracentrifugation, at 40,000 rpm for 2 h at 4 ºC. The total protein content in said fraction was quantitatively characterized, by means of Bradford assay, and it was analyzed using the polyacrylamide gel electrophoresis technique at 8% resolution. Furthermore, the size was measured using dynamic light scattering (DLS) technique and the characteristic bands attributed to functional groups of the lipoproteins in the isolated fraction wereobserved by Fourier Transform Infrared Spectroscopy (FTIR). Finally, the interaction of lipoprotein and their oxidation in the presence of the Isoquinoline-type alkaloids named Methyl cytisine (NMC) was studied. The results indicate an average concentration of the LDL protein of 22.5 ± 2.1 mg/mL by extract with mean size measurement by DLS was 24 ± 3 nm. FTIR spectrum shows two differenced regions corresponding to lipids and protein bands. The bands analysis give about 30 % of b-sheet, 28 % of a-Helix, 21 % Random coil and 20 % of b-turn structures. Also, Fluorescence analysis showed a decreasing in the Trp emission intensity under of LDL protein by continuously adding of NMC up to 6.5 mg/mL. The oxidized LDL sample shows a decreasing in absorbance at 280 nm with respect to the LDL sample with an unincubated NMC. The a-Helix is degraded accompanied with an increasing in unordered structure by oxidation, observing this behavior in presence of NMC unincubated. When the LDL is previously incubated with NMC and them oxidized an increasing in b-sheet and b-turn structures were observed. The results indicate that the NMC modified the secondary structure of protein increasing in b-sheet and b-turn structures and prevents lipoperoxidation of the LDL protein observing a higher effect at high concentration of alkaloid