Study of mechanisms on vason-strengthening action of flavonoids

Based on the analysis of the spectra, it has been found that compounds of flavonoid nature, binding to cell membranes, change not in all cases the fluidity of membrane lipids depending on the cell type. Obviously, vascular tissue cells are a kind of "target cells" for these substances, i.e. there is a selectivity of flavonoids to certain tissues of organs. A particularly noticeable increase in the lipid fluidity of membranes was observed due to the addition of flavonoid glycosides - hyperoside, stachanoaceside and liquiritin to segments of venous tissue, which correlated with the high affinity of these substances to liposomes. The addition to the vessels of the metabolite quercetin - chalcone also led to a sharp increase in the lipid fluidity of cells of arterial and venous tissue, what suggests the presence of biological activity in flavonoid metabolites. One of the mechanisms of increasing the resistance of arterial and venous vessels under the action of flavonoid substances is an increase in the lipid fluidity of cell membranes of these vessels, which reduces the fragility of blood vessels and increases their flexibility and elasticity. The apparent contradiction between the rapid metabolism of many flavonoids in animals and the prolonged pharmacological action can be explained by the capability of their metabolites, such as chalcone, to increase the lipid fluidity of vascular cell membranes, changing their resistance to external influences. Reducing the fragility of the pulmonary vessels and increasing their flexibility and elasticity can have a positive effect on a human body in the fight against coronavirus.

The Impact of Surface Drug Distribution on the Acoustic Behavior of DOX-Loaded Microbubbles

Previous studies have reported substantial improvement of microbubble (MB)-mediated drug delivery with ultrasound when drugs are loaded onto the MB shell compared with a physical mixture. However, drug loading may affect shell properties that determine the acoustic responsiveness of MBs, producing unpredictable outcomes. The aim of this study is to reveal how the surface loaded drug (doxorubicin, DOX) affects the acoustic properties of MBs. A suitable formulation of MBs for DOX loading was first identified by regulating the proportion of two lipid materials (1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-distearoyl-sn-glycero-3-phospho-rac-glycerol sodium salt (DSPG)) with distinct electrostatic properties. We found that the DOX loading capacity of MBs was determined by the proportion of DSPG, since there was an electrostatic interaction with DOX. The DOX payload reduced the lipid fluidity of MBs, although this effect was dependent on the spatial uniformity of DOX on the MB shell surface. Loading DOX onto MBs enhanced acoustic stability 1.5-fold, decreased the resonance frequency from 12–14 MHz to 5–7 MHz, and reduced stable cavitation dose by 1.5-fold, but did not affect the stable cavitation threshold (300 kPa). Our study demonstrated that the DOX reduces lipid fluidity and decreases the elasticity of the MB shell, thereby influencing the acoustic properties of MBs.

Probe-location dependent resonance energy transfer at lipid/water interfaces: comparison between the gel- and fluid-phase of lipid bilayer

Effect of dielectric environment and lipid fluidity/rigidity in multi-chromophoric FRET from a series of donors to acceptors at lipid/water interfaces are monitored by tailored donor–acceptor pairs.