Influence of flavonoids' lipophilicity on platelet aggregation

Is there an interplay between the SARS-CoV-2 spike protein and Platelet-Activating factor?

Previous publications have reported a potent effect of COVID-19 on platelet function and that the Spike protein enhances washed human platelet aggregation induced by various agonists. This study aims to evaluate whether mRNA vaccination for COVID-19 affects human platelet-rich plasma (hPRP) aggregation response, whether a recombinant Spike protein modulates PAF-induced aggregation in hPRP and in washed rabbit platelets (WRP), and to investigate the effect of recombinant Spike protein on the PAF production in the U-937 cell line. Our results showed that PRP from vaccinated individuals exhibited ex vivo lower EC₅₀ values in response to PAF, ADP, and collagen. Platelet incubation with the Spike protein alone did not induce aggregation either in hPRP or in WRP, but resulted in augmentation of in vitro PAF-induced aggregation in hPRP from non-vaccinated individuals and in WRP. When PRP from vaccinated individuals was incubated with the Spike protein and PAF was subsequently added, elimination of the secondary wave of the biphasic aggregation curve was recorded compared with the aggregation induced by PAF alone. Collagen-induced in vitro aggregation was dose-dependently reduced when platelets were pre-incubated with the Spike protein in all tested aggregation experiments. Stimulation of U-937 by the Spike protein induced an increase in intracellular PAF production accompanied by elevation of the activities of all three PAF biosynthetic enzymes. In conclusion, since the Spike protein appears to modulate PAF production and activity, the use of compounds that act as PAF inhibitors, could be considered at least in mild cases of patients infected with SARS-CoV-2.

Development of the whole tomato and olive-based food supplement enriched with anti-platelet aggregating nutrients

Background

Platelet dysfunctions are shared by cardiovascular diseases and a wide range of inflammatory diseases.

Aims

To determine the ability of a new whole tomato-based food supplement (WTBFS) containing carotenoid and olive polyphenols to inhibit platelet aggregation.

Methods

Aggregation was evaluated in platelet-rich plasma using microtiter plates and a plate reader.

Results

Platelets treated with WTBFS showed a >70% reduction of 5 µM adenosine diphosphate (ADP)-induced platelet aggregation; at 10 µM of ADP, the inhibitory effect of WTBFS was reduced of about 50%. Similarly, 78% and 48% reduction were obtained using 5 µg/mL and 10 µg /mL of collagen as an agonist

Conclusion

Since the compounds in WTBFS share the ability to inhibit STAT3, the inhibition of its signaling pathway may represent the mechanism underlying the antiplatelet activities. The activity of a lipophilic solution prepared from WTBS was in vitro tested on the platelet aggregation in response to ADP agonists and Collagen.

Identification of lactoferrin-derived peptides as potential inhibitors against the main protease of SARS-CoV-2

COVID-19 is a global health emergency that causes serious concerns. A global effort is underway to identify drugs for the treatment of COVID-19. One possible solution to the present problem is to develop drugs that can inhibit SARS-CoV-2 main protease (M^pro), a coronavirus protein that been considered as one among many drug targets. In this work, lactoferrin from Bos taurus L. was in silico hydrolyzed. The bioactivity, water solubility, and ADMET properties of the generated peptides were predicted using various online tools. The molecular interactions between M^pro and the peptides were studied using molecular docking and molecular dynamic simulation. The results demonstrated that peptide GSRY was predicted to have better physicochemical properties, and the value of '-C DOCKER interaction energy' between peptide GSRY and M^pro was 80.8505 kcal/mol. The interaction between the peptide GSRY and the native ligand N3 co-crystallized with M^pro had overlapped amino acids, i.e., HIS163, GlY143, GLU166, GLN189 and MET165. Molecular dynamic simulation revealed that M^pro/GSRY complexes were stable. Collectively, the peptide GSRY may be a potential candidate drug against M^pro of SARS-CoV-2.

Effects of lead exposure on blood electrical impedance spectroscopy of mice

Background

Lead is a nonessential heavy metal, which can inhibit heme synthesis and has significant cytotoxic effects. Nevertheless, its effect on the electrical properties of red blood cells (RBCs) remains unclear. Consequently, this study aimed to investigate the electrical properties and the electrophysiological mechanism of lead exposure in mouse blood using Electrical Impedance Spectroscopy (EIS) in 0.01–100 MHz frequency range. Data characteristic of the impedance spectrum, Bodes plot, Nyquist plot and Nichols plot, and Constant Phase Element (CPE) equivalent circuit model were used to explicitly analyze the differences in amplitude–frequency, phase–frequency, and the frequency characteristics of blood in electrical impedance properties.

Results

Compared with the healthy blood in control mice, the changes in blood exposed to lead were as follows: (i) the hematocrit decreased; (ii) the amplitude–frequency and phase–frequency characteristics of electrical impedance decreased; (iii) the characteristic frequencies (f₀) were significantly increased; (iv) the electrical impedance of plasma, erythrocyte membrane, and hemoglobin decreased, while the conductivity increased. (v) The pseudo-capacitance of cell membrane (CPE_Tm) and the intracellular pseudo-capacitance (CPE-Ti) were decreased.

Conclusions

Therefore, EIS can be used as an effective method to monitor blood and RBC abnormalities caused by lead exposure. The electrical properties of the cells can be applied as an important observation in the evaluation of the toxic effects of heavy metals.

Antithrombotic activity of flavonoids and polyphenols rich plant species

Cardiovascular diseases represent one of the most notable health problems of the modern civilization. Stroke and heart attack often lead to lethal outcome; essential problem underneath being thrombus formation. Prophylactic approaches include acetylsalicylic acid and clopidogrel therapy on the level of primary hemostasis, i.e., primary clot formation. In the last five years, in the USA, health care expenses related to cardiovascular diseases have increased 50 %, to over 350 billion dollars. Thus, application of plant species and medicinal plants rich in polyphenols in prevention of thrombus formation are of interest. This is supported by the fact that the number of publications on antiaggregatory effect of polyphenols has doubled in the last decade. In this review we focus on antiaggregatory effect of most abundant polyphenols - flavonoids, the effect of plant extracts rich in polyphenols (propolis, species Salvia sp., Calamintha nepeta L., Lavandula angustifolia Mill., Melissa officinalis L, Mentha x piperita L., Ocimum basilicum L., Origanum vulgare L., Rosmarinus officinalis L.) on platelet aggregation, association of chemical composition and antioxidant properties with the observed biological effect, and possible clinical significance of the published results.