Protective Effect of Field Horsetail Polyphenolic Extract on Erythrocytes and Their Membranes

Abstract

Field horsetail (Equisetum arvense L.) is widely utilized in traditional medicine and is a rich source of bioactive compounds such as flavonoids, phenolic acids, and silica. This study investigates the protective effect of the polyphenolic extract from field horsetail (HLE) on erythrocytes and their cell membranes. The content of polyphenolic compounds in the extract was determined using the HPLC-DAD and Folin-Ciocalteu methods. The extract's hemolytic activity, toxicity, antioxidant activity, and its impact on the physical properties of erythrocytes and lipid membrane were investigated. The antioxidant properties were evaluated using erythrocytes and isolated erythrocyte membranes oxidized by UVC radiation and AAPH. The impact of the extract on the ordering and fluidity of erythrocyte and model lipid membranes was studied. Furthermore, the transmembrane potential, shape of erythrocytes and the dipole potential of the lipid membranes under the influence of HLE were evaluated. The results indicated that HLE extract exhibited no toxicity to erythrocytes and HMEC-1 cells. HLE components effectively protect erythrocytes and their membranes against oxidation. They interact with the outer, polar surface of the erythrocyte membrane and reduce both erythrocyte membrane potential and lipid membrane dipole potential. The HLE polyphenols decrease the concentration of free radicals at the surface of the membrane, where they are located, and serve as a protective barrier, preventing penetration into the membrane.

Keywords: HMEC-1; antioxidant activity; cytotoxicity; dipole potential; fluidity; horsetail; plant extracts; transmembrane potential.

Figure 1

The percentage of hemolysis of erythrocytes modified with 50 µg/mL and 100 µg/mL HLE extract versus NaCl concentration (a). Concentration of reduced glutathione (GSH) in red blood cells modified with horsetail leaf extract and exposed to oxidizing agent AAPH (b). The percentage of inhibition of erythrocyte oxidation generated by free radicals induced by the AAPH compound (c) * Statistically significant results are denoted (α < 0.05).

Figure 2

(a) The value of the hydrodynamic diameter (D_h) (nm) and polydispersity index (PDI) of the large monolayer lipid vesicles (LUVs) formed from RBCLs modified with HLE extract, (b) changes in dipole potential (Ψ_d) of liposomes formed from RBCL induced by HLE extract. * Statistically significant results are denoted (α < 0.05).

Figure 3

Values of generalized polarization (GP) of the Laurdan probe (a), anisotropy (A) of the DPH (b), and TMA-DPH probe (c) for erythrocytes membrane (ghost, RBCG) and RBCL liposomes modified with the different concentrations (5.0–50.0 µg/mL) of HLE extract at 37 °C. * Statistically significant results are denoted (α < 0.05).

Figure 4

An example of dependencies between (a) relative florescence intensity of TMA-DPH probe and time of erythrocyte membrane (RBCG) oxidation induced by AAPH for control and tested samples that contained HLE extract at a concentration range of 7.5–17.5 µg/mL; (b) absorbance vs. time of erythrocyte membrane (ghost) oxidation induced by UVC radiation in the presence of HLE extract over a concentration range of 10–100 µg/mL.