Target-Specific Drug Discovery of Natural Products against SARS-CoV-2 Life Cycle and Cytokine Storm in COVID-19

Research Progress of Immunomodulation on Anti-COVID-19 and the Effective Components from Traditional Chinese Medicine

SARS-CoV-2 has posed a threat to the health of people around the world because of its strong transmission and high virulence. Currently, there is no specific medicine for the treatment of COVID-19. However, for a wide variety of medicines used to treat COVID-19, traditional Chinese medicine (TCM) plays a major role. In this paper, the effective treatment of COVID-19 using TCM was consulted first, and several Chinese medicines that were frequently used apart from their huge role in treating it were found. Then, when exploring the active ingredients of these herbs, it was discovered that most of them contained flavonoids. Therefore, the structure and function of the potential active substances of flavonoids, including flavonols, flavonoids, and flavanes, respectively, are discussed in this paper. According to the screening data, these flavonoids can bind to the key proteins of SARS-CoV-2, 3CLpro, PLpro, and RdRp, respectively, or block the interface between the viral spike protein and ACE2 receptor, which could inhibit the proliferation of coronavirus and prevent the virus from entering human cells. Besides, the effects of flavonoids on the human body systems are expounded on in this paper, including the respiratory system, digestive system, and immune system, respectively. Normally, flavonoids boost the body's immune system. However, they can suppress the immune system when over immunized. Ultimately, this study hopes to provide a reference for the clinical drug treatment of COVID-19 patients, and more TCM can be put into the market accordingly, which is expected to promote the development of TCM on the international stage.

Lancemaside A from Codonopsis lanceolata: Studies on Antiviral Activity and Mechanism of Action against SARS-CoV-2 and Its Variants of Concern

Several plant-derived natural products with anti-SARS-CoV-2 activity have been evaluated for the potential to serve as chemotherapeutic agents for the treatment of COVID-19. Codonopsis lanceolata (CL) has long been used as a medicinal herb in East Asian countries to treat inflammatory diseases of the respiratory system but its antiviral activity has not been investigated so far. Here, we showed that CL extract and its active compound lancemaside A (LA) displayed potent inhibitory activity against SARS-CoV-2 infection using a pseudotyped SARS-CoV-2 entry assay system. We demonstrated that this inhibitory effect of LA was due to the alteration of membrane cholesterol and blockade of the membrane fusion between SARS-CoV-2 and host cells by filipin staining and cell-based membrane fusion assays. Our findings also showed that LA, as a membrane fusion blocker, could impede the endosomal entry pathway of SARS-CoV-2 and its variants of concern (VOCs), including Alpha (B.1.1.7), Beta (B.1.351), Delta (B.1.617.2), and Omicron (B.1.1.529), in Vero cells with similar of IC₅₀ values ranging from 2.23 to 3.37 μM as well as the TMPRSS2-mediated viral entry pathway in A549 cells overexpressing ACE2 and TMPRSS2 with IC₅₀ value of 3.92 μM. We further demonstrated that LA could prevent the formation of multinucleated syncytia arising from SARS-CoV-2 spike protein-mediated membrane fusion. Altogether, the findings reported here suggested that LA could be a broad-spectrum anti-SARS-CoV-2 therapeutic agent by targeting the fusion of viral envelope with the host cell membrane.