Oridonin inhibits SARS-CoV-2 replication by targeting viral proteinase and polymerase

Advances in COVID-19 Therapeutics: Exploring the role of lectins and protease inhibitors

The rapid global spread of SARS-CoV-2 has demanded innovative approaches to treatment and prevention. This article reviews the current landscape of COVID-19 therapeutics and vaccines, emphasizing the role of biotechnological products, particularly lectins and protease inhibitors. SARS-CoV-2, a single-stranded RNA virus, infects host cells via its spike (S) protein, which binds to the angiotensin-converting enzyme 2 (ACE2) receptor. This interaction is facilitated by host proteases like TMPRSS2, which are critical for viral entry. Treatments for COVID-19 primarily focus on antiviral drugs, anti-inflammatory agents, and monoclonal antibodies. Protease inhibitors that target viral enzymes like Mpro and PLpro have demonstrated potential. Additionally, vaccines, including mRNA-based, DNA-based, and those using viral vectors or inactivated viruses, are essential for preventing new infections. Lectins, proteins that bind specifically to carbohydrates, have emerged as potential antiviral agents. They can impede viral entry by binding to glycoproteins on the virus's surface or modulate immune responses. Studies indicate that lectins like cyanovirin-N and griffithsin exhibit significant antiviral activity against SARS-CoV-2. While most of the research on these biotechnological products is still in preclinical or early stages, their potential for treating and preventing COVID-19 is substantial. Further investigation and clinical trials are crucial to validate their efficacy and safety. This article underscores the need for continued exploration of novel therapeutic strategies to combat the evolving COVID-19 pandemic. However, the review is limited by the scarcity of clinical data on these products, highlighting the need for translational research.

Regorafenib as a potential drug for severe COVID-19: inhibition of inflammasome activation in mice

SARS-CoV-2 infection can lead to severe COVID-19, particularly in elderly individuals and those with compromised immunity. Cellular senescence has been implicated as a key pathogenic mechanism. This study investigated the therapeutic potential of regorafenib, a previously characterized senomorphic drug, for severe COVID-19. SARS-CoV-2 virus-infected K18-hACE2 mice, overexpressing the human ACE2 receptor, exhibited 100% mortality by 10 days post infection. Regorafenib treatment significantly improved survival rates, approximately 43% remaining alive. Mechanistically, regorafenib effectively suppressed type I and II interferon and cytokine signaling. Notably, regorafenib inhibited NLR family pyrin domain containing 3 (NLRP3) inflammasome activation, a key driver of the cytokine storm associated with severe COVID-19. Our findings elucidate the molecular mechanisms underlying therapeutic effects of regorafenib and suggest its potential use as a promising treatment option for severe COVID-19.

Oridonin inhibits SGIV infection by regulating glycolipid metabolism and inflammatory response

Singapore grouper iridovirus (SGIV) is a significant infectious disease in the grouper aquaculture industry. Currently, there is no effective drug available to prevent or treat SGIV. Oridonin (Ori) is a naturally occurring compound derived from Rabdosia rubescens, exhibiting various biological activities, including anti-tumor, anti-inflammatory, and antioxidant properties. In this study, we examined the anti-SGIV activity of Ori and its potential mechanism of action in vitro. The study results indicate that Ori effectively inhibits SGIV infection at various concentrations. Further studies reveal that Ori inhibits the formation of lipid droplets induced by SGIV infection. Additionally, Ori suppresses the SGIV-induced up-regulation of fatty acid synthesis-related genes (SREBP1, ACC1, SCD1, FASN) and glycolysis-related genes (GLUT1, GLUT2, HK2, PDHX). The mTOR pathway plays a crucial role in regulating glycolipid metabolism. Our findings indicate that Ori suppresses the phosphorylation of AKT and mTOR proteins. Further research revealed that the activation or inhibition of mTOR significantly impacts SGIV protein production and the expression of genes related to glycolipid metabolism. In addition, Ori effectively inhibits the up-regulation of NLRP3, ASC, Caspase-1, and pro-inflammatory cytokines induced by SGIV infection. In conclusion, our experimental findings indicate that Ori effectively inhibits SGIV infection by regulating glycolipid metabolism through the AKT/mTOR pathway and by suppressing the inflammatory responses triggered by SGIV infection.

CRTC3 restricts SARS-CoV-2 replication and is antagonized by CREB

Virus-encoding RNA-dependent RNA polymerase (RdRp) is essential for genome replication and gene transcription of human coronaviruses (HCoVs), including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We previously identified the interaction between the catalytic subunit NSP12 of SARS-CoV-2 RdRp and the host protein CREB-regulated transcription coactivator 3 (CRTC3), a member of the CRTC family that regulates cyclic AMP response element-binding protein (CREB)-mediated transcriptional activation. Currently, the implication of CRTC3 in the pathogenesis of HCoVs is poorly understood. Herein, we demonstrated that CRTC3 attenuates RdRp activity and SARS-CoV-2 genome replication, therefore reducing the production of progeny viruses. The interaction of CRTC3 with NSP12 contributes to its inhibitory effect on RdRp activity. Furthermore, we expanded the suppressive effects of two other CRTC family members (CRTC1 and CRTC2) on the RdRp activities of lethal HCoVs, including SARS-CoV-2 and Middle East respiratory syndrome coronavirus (MERS-CoV), along with the CREB antagonization. Overall, our research suggests that CRTCs restrict the replication of HCoVs and are antagonized by CREB, which not only provides new insights into the replication regulation of HCoVs, but also offers important information for the development of anti-HCoV interventions.

Targeting viral suppressor of RNAi confers anti-coronaviral activity

Infections caused by coronaviruses are persistent threats to human health in recent decades, necessitating the development of innovative anti-coronaviral therapies. RNA interference (RNAi) is a conserved cell-intrinsic antiviral mechanism in diverse eukaryotic organisms, including mammals. To counteract, many viruses encode viral suppressors of RNAi (VSRs) to evade antiviral RNAi, implying that targeting VSRs could be a promising strategy to develop antiviral therapies. Here, we designed a series of peptides specifically targeting the SARS-CoV-2-encoded VSR, nucleocapsid (N) protein. Among these peptides, one designated GL directly interacts with N protein and inactivates its VSR activity, which unlocks a potent RNAi response and effectively inhibits severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) replication. Moreover, GL exhibited RNAi-dependent antiviral effects not only against various SARS-CoV-2 variants, including Delta, Omicron BA.5, XBB, and JN.1, but also against other coronaviruses such as human coronavirus (HCoV)-229E, HCoV-OC43, and mouse hepatitis virus. The in vivo anti-coronaviral activity of GL was also confirmed. Our findings indicate that the VSR-targeting peptide GL has the potential to be further developed as a broad-spectrum anti-coronaviral treatment, highlighting the functional importance and therapeutic potential of antiviral RNAi.

Z-Ligustilide restricts rabies virus replication by inducing ferroptosis through the ACSL4-LPCAT3-POR pathway

Rabies, induced by rabies virus (RABV), still threaten global health all over the world, and no effective therapy is available for rabies currently. Recently, a series of natural plant components have been found to inhibit virus production. In this study, Z-Ligustilide, a natural component of Ligusticum chuanxiong Hort, was found to inhibit RABV replication. Initially, the concentration of cytotoxicity 50 % (CC50) of Z-Ligustilide in N2a and BSR cells were 429.9 μM and 335.5 μM, respectively, which both significantly restrict RABV production in a concentration-dependent manner. Moreover, Z-Ligustilide was found to mainly inhibit the replication stage of RABV. Specifically, Z-Ligustilide can suppress lipid droplet (LD) formation via directly inhibiting diacylglycerol acyltransferase 1/2 (DGAT1/2) expression, which can further promote cellular lipid peroxidation, Fe2+ concentration, reactive oxygen species (ROS), and induce ferroptosis ultimately. Furthermore, Z-Ligustilide was demonstrated to increase ferroptosis via Acyl-CoA synthetase long-chain family member 4 (ACSL4)- Lysophosphatidylcholine Acyltransferase 3 (LPCAT3)- Cytochrome P450 Oxidoreductase (POR) pathway. Above all, this study explored the antiviral function of Z-Ligustilide, which provides a novel insight for developing anti-RABV drugs.

Relationship between creatinine-cystatin C ratio and all-cause mortality in hospitalized patients with COVID-19: A prospective study in China

Background

This study was conducted to investigate whether baseline creatinine-cystatin C ratio is associated with all-cause mortality in adult Chinese patients hospitalized with coronavirus disease 2019.

Methods

This study included 933 patients with coronavirus disease 2019 who were admitted to The Affiliated Hospital of Guangdong Medical University between December 2022 and March 2023. All-cause mortality was determined by telephone follow-up after 28 days. Multivariate Cox proportional risk models were used to investigate the relationship between baseline creatinine-cystatin C ratio and all-cause mortality. Restricted cubic spline and two-piecewise Cox proportional hazards risk models were used to identify non-linear correlations.

Results

Of the 933 patients, 128 died during the 28 days follow-up. The restricted cubic spline analysis of hospitalized patients with coronavirus disease 2019 revealed an L-shaped association between baseline creatinine-cystatin C ratio and all-cause mortality, with a threshold creatinine-cystatin C ratio of ≤0.93 predicting all-cause mortality. Specifically, a baseline creatinine-cystatin C ratio below this threshold value was negatively correlated with mortality (hazard ratio 0.12, 95 % confidence interval 0.03-0.48), but a creatinine-cystatin C ratio >0.93 was not correlated with mortality (hazard ratio 1.29, 95 % confidence interval 0.65-2.55).

Conclusions

In Chinese adult patients hospitalized with coronavirus disease 2019, an L-shaped relationship was observed between the baseline creatinine-cystatin C ratio and all-cause mortality.

Recent advancements in the discovery of small-molecule non-nucleoside inhibitors targeting SARS-CoV-2 RdRp

The RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 plays a pivotal role in the life cycle of the novel coronavirus and stands as a significant and promising target for anti-SARS-CoV-2 drugs. Non-nucleoside inhibitors (NNIs), as a category of compounds directed against SARS-CoV-2 RdRp, exhibit a unique and highly effective mechanism, effectively overcoming various factors contributing to drug resistance against nucleoside inhibitors (NIs). This review investigates various NNIs, including both natural and synthetic inhibitors, that closely interacting with the SARS-CoV-2 RdRp with valid evidences from in vitro and in silico studies.

The Natural Product Oridonin as an Anticancer Agent: Current Achievements and Problems

Oridonin, an active diterpenoid isolated from traditional Chinese herbal medicine, has received a rising attention for its remarkable roles in cancer therapy. In recent years, increasing evidences have revealed that oridonin inhibits the occurrence and development of tumor cells through multiple mechanisms, including induction of apoptosis and autophagy, cell cycle arrest, and inhibition of angiogenesis as well as migration and invasion. In addition, several molecular signal targets have been identified, including ROS, EGFR, NF-κB, PI3K/Akt, and MAPK. In this paper, we review considerable knowledge about the molecular mechanisms and signal targets of oridonin, which has been studied in recent years. It is expected that oridonin may be developed as a novel anti-tumor herbal medicine in human cancer treatment.