Glycan Epitopes and Potential Glycoside Antagonists of DC-SIGN Involved in COVID-19: In Silico Study

The Effect of Select SARS-CoV-2 N-Linked Glycan and Variant of Concern Spike Protein Mutations on C-Type Lectin-Receptor-Mediated Infection

The SARS-CoV-2 virion has shown remarkable resilience, capable of mutating to escape immune detection and re-establishing infectious capabilities despite new vaccine rollouts. Therefore, there is a critical need to identify relatively immutable epitopes on the SARS-CoV-2 virion that are resistant to future mutations the virus may accumulate. While hACE2 has been identified as the receptor that mediates SARS-CoV-2 susceptibility, it is only modestly expressed in lung tissue. C-type lectin receptors like DC-SIGN can act as attachment sites to enhance SARS-CoV-2 infection of cells with moderate or low hACE2 expression. We developed an easy-to-implement assay system that allows for the testing of SARS-CoV-2 trans-infection. Using our assay, we assessed how SARS-CoV-2 Spike S1-domain glycans and spike proteins from different strains affected the ability of pseudotyped lentivirions to undergo DC-SIGN-mediated trans-infection. Through our experiments with seven glycan point mutants, two glycan cluster mutants and four strains of SARS-CoV-2 spike, we found that glycans N17 and N122 appear to have significant roles in maintaining COVID-19's infectious capabilities. We further found that the virus cannot retain infectivity upon the loss of multiple glycosylation sites, and that Omicron BA.2 pseudovirions may have an increased ability to bind to other non-lectin receptor proteins on the surface of cells. Taken together, our work opens the door to the development of new therapeutics that can target overlooked epitopes of the SARS-CoV-2 virion to prevent C-type lectin-receptor-mediated trans-infection in lung tissue.

Pharmacological properties and derivatives of saikosaponins-a review of recent studies

OBJECTIVES

Saikosaponins (SSs) constitute a class of medicinal monomers characterised by a triterpene tricyclic structure. Despite their potential therapeutic effects for various pathological conditions, the underlying mechanisms of their actions have not been systematically analysed. Here, we mainly review the important anti-inflammatory, anticancer, and antiviral mechanisms underlying SS actions.

METHODS

Information from multiple scientific databases, such as PubMed, the Web of Science, and Google Scholar, was collected between 2018 and 2023. The search term used was saikosaponin.

KEY FINDINGS

Numerous studies have shown that Saikosaponin A exerts anti-inflammatory effects by modulating cytokine and reactive oxygen species (ROS) production and lipid metabolism. Moreover, saikosaponin D exerts antitumor effects by inhibiting cell proliferation and inducing apoptosis and autophagy, and the antiviral mechanisms of SSs, especially against SARS-CoV-2, have been partially revealed. Interestingly, an increasing body of experimental evidence suggests that SSs show the potential for use as anti-addiction, anxiolytic, and antidepressant treatments, and therefore, the related molecular mechanisms warrant further study.

CONCLUSIONS

An increasing amount of data have indicated diverse SS pharmacological properties, indicating crucial clues for future studies and the production of novel saikosaponin-based anti-inflammatory, efficacious anticancer, and anti-novel-coronavirus agents with improved efficacy and reduced toxicity.

Pharmacological activities and pharmacokinetics of liquiritin: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Liquiritin is a flavonoid derived from Radix et Rhizoma Glycyrrhizae, which is a widely used traditional Chinese medicine with the effects of invigorating spleen qi, clearing heat, resolving toxins, and dispelling phlegm to stop coughs.

AIM OF THE STUDY

In this review,the pharmacokinetics and pharmacological activities of liquiritin have been summarized.

MATERIALS AND METHODS

The information on liquiritin up to 2021 was collected from PubMed, Web of Science, Springer Link, and China National Knowledge Infrastructure databases. The key words were "liquiritin", "nerve", "tumor", "cardiac", etc. RESULTS: The absorption mechanism of liquiritin conforms to the passive diffusion and first-order kinetics while with low bioavailability. Liquiritin can penetrate the blood-brain-barrier. Besides, liquiritin displays numerous pharmacological effects including anti-Alzheimer's disease, antidepressant, antitumor, anti-inflammatory, cardiovascular protection, antitussive, hepatoprotection, and skin protective effects. In addition, the novel preparations, new pharmacological effects,and cdusafty of liquiritin are also discussed in this review.

CONCLUSION

This review provides a comprehensive state of knowledge on the pharmacokinetics and pharmacological activities of liquiritin, and makes a forecast for its research directions and applications in clinic.