Antiviral activity of oleandrin and a defined extract of Nerium oleander against SARS-CoV-2
ABSTRACT: With continued expansion of the coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome 2 (SARS-CoV-2), both antiviral drugs as well as effective vaccines are desperately needed to treat patients at high risk of life-threatening disease. Here, we present in vitro evidence for significant inhibition of SARS-CoV-2 by oleandrin and a defined extract of N. oleander (designated as PBI-06150). Using Vero cells, we found that prophylactic (pre-infection) oleandrin (as either the pure compound or as the active principal ingredient in PBI-06150) administration at concentrations as low as 0.05 µg/ml exhibited potent antiviral activity against SARS-CoV-2, with an 800-fold reduction in virus production, and a 0.1 µg/ml concentration resulted in a greater than 3000-fold reduction in infectious virus production. The half maximal effective concentration (EC50) values were 11.98 ng/ml when virus output was measured at 24 h post-infection, and 7.07 ng/ml measured at 48 h post-infection. Therapeutic (post-infection) treatment up to 24 h after SARS-CoV-2 infection of Vero cells also reduced viral titers, with 0.1 µg/ml and 0.05 µg/ml concentrations causing greater than 100-fold reduction as measured at 48 h, and the 0.05 µg/ml concentration resulting in a 78-fold reduction. Concentrations of oleandrin up to 10 µg/ml were well tolerated in Vero cells. We also present in vivo evidence of the safety and efficacy of defined N. oleander extract (PBI-06150), which was administered to golden Syrian hamsters in a preparation containing as high as 130 µg/ml of oleandrin. In comparison to administration of control vehicle, PBI-06150 provided a statistically significant reduction of the viral titer in the nasal turbinates (nasal conchae). The potent prophylactic and therapeutic antiviral activities demonstrated here, together with initial evidence of its safety and efficacy in a relevant hamster model of COVID-19, support the further development of oleandrin and/or defined extracts containing this molecule for the treatment of SARS-CoV-2 and associated COVID-19 disease and potentially also for reduction of virus spread by persons diagnosed early after infection.
Project description:We previously reported neuroprotective activity of the botanical anti-cancer drug candidate PBI-05204, a supercritical CO2 extract of Nerium oleander, in brain slice and in vivo models of ischemic stroke. We showed that one component of this neuroprotective activity is mediated through its principal cardiac glycoside constituent, oleandrin, via induction of the potent neurotrophic factor brain-derived neurotrophic factor (BDNF). However, we also noted that the concentration-relation for PBI-05204 in the brain slice oxygen-glucose deprivation (OGD) model is considerably broader than that for oleandrin as a single agent. We thus surmised that PBI-05204 contains an additional neuroprotective component(s), distinct from oleandrin. We report here that neuroprotective activity is also provided by the triterpenoid constituents of PBI-05204, notably oleanolic acid. We demonstrate that a sub-fraction of PBI-05204 (Fraction 0-4) containing oleanolic and other triterpenoids, but without cardiac glycosides, induces the expression of cellular antioxidant gene transcription programs regulated through antioxidant transcriptional response elements (AREs). Finally, we show that Fraction 0-4 provides broad neuroprotection in organotypic brain slice models for neurodegeneration driven by amyloid precursor protein (APP) and tau implicated in Alzheimer's disease and frontotemporal dementias, respectively, in addition to ischemic injury modeled by OGD.
Project description:The coronavirus disease 2019 (COVID-19) has become a serious problem for public health since it was identified in the province of Wuhan (China) and spread around the world producing high mortality rates and economic losses. Nowadays, the WHO recognizes traditional, complementary, and alternative medicine for treating COVID-19 symptoms. Therefore, we investigated the antiviral potential of the hydroalcoholic extract of <i>Uncaria tomentosa</i> stem bark from Peru against SARS-CoV-2 <i>in vitro</i>. The antiviral activity of <i>U. tomentosa</i> against SARS-CoV-2 <i>in vitro</i> was assessed in Vero E6 cells using cytopathic effect (CPE) and plaque reduction assay. After 48?h of treatment, <i>U. tomentosa</i> showed an inhibition of 92.7% of SARS-CoV-2 at 25.0?<i>?</i>g/mL (<i>p</i> < 0.0001) by plaque reduction assay on Vero E6 cells. In addition, <i>U. tomentosa</i> induced a reduction of 98.6% (<i>p</i>=0.02) and 92.7% (<i>p</i>=0.03) in the CPE caused by SARS-CoV-2 on Vero E6 cells at 25?<i>?</i>g/mL and 12.5?<i>?</i>g/mL, respectively. The EC50 calculated for the <i>U. tomentosa</i> extract by plaque reduction assay was 6.6?<i>?</i>g/mL (4.89-8.85?<i>?</i>g/mL) for a selectivity index of 4.1. The EC50 calculated for the <i>U. tomentosa</i> extract by TCID50 assay was 2.57?<i>?</i>g/mL (1.05-3.75?<i>?</i>g/mL) for a selectivity index of 10.54. These results showed that U. tomentosa, known as cat's claw, has an antiviral effect against SARS-CoV-2, which was observed as a reduction in the viral titer and CPE after 48 h of treatment on Vero E6 cells. Therefore, we hypothesized that <i>U. tomentosa</i> stem bark could be promising in the development of new therapeutic strategies against SARS-CoV-2.
Project description:COVID-19 has become a global pandemic and there is an urgent call for developing drugs against the virus (SARS-CoV-2). The 3C-like protease (3CL<sup>pro</sup>) of SARS-CoV-2 is a preferred target for broad spectrum anti-coronavirus drug discovery. We studied the anti-SARS-CoV-2 activity of <i>S. baicalensis</i> and its ingredients. We found that the ethanol extract of <i>S. baicalensis</i> and its major component, baicalein, inhibit SARS-CoV-2 3CL<sup>pro</sup> activity <i>in vitro</i> with IC<sub>50</sub>'s of 8.52 µg/ml and 0.39 µM, respectively. Both of them inhibit the replication of SARS-CoV-2 in Vero cells with EC<sub>50</sub>'s of 0.74 µg/ml and 2.9 µM, respectively. While baicalein is mainly active at the viral post-entry stage, the ethanol extract also inhibits viral entry. We further identified four baicalein analogues from other herbs that inhibit SARS-CoV-2 3CL<sup>pro</sup> activity at µM concentration. All the active compounds and the <i>S. baicalensis</i> extract also inhibit the SARS-CoV 3CL<sup>pro</sup>, demonstrating their potential as broad-spectrum anti-coronavirus drugs.
Project description:During the recent severe acute respiratory (SARS) outbreak, the etiologic agent was identified as a new coronavirus (CoV). We have isolated a SARS-associated CoV (SARS-CoV) strain by injecting Vero cells with a sputum specimen from an Italian patient affected by a severe pneumonia; the patient traveled from Vietnam to Italy in March 2003. Ultrastructural analysis of infected Vero cells showed the virions within cell vesicles and around the cell membrane. The full-length viral genome sequence was similar to those derived from the Hong-Kong Hotel M isolate. By using both real-time reverse transcription-polymerase chain reaction TaqMan assay and an infectivity plaque assay, we determined that approximately 360 viral genomes were required to generate a PFU. In addition, heparin (100 microg/mL) inhibited infection of Vero cells by 50%. Overall, the molecular and biologic characteristics of the strain HSR1 provide evidence that SARS-CoV forms a fourth genetic coronavirus group with distinct genomic and biologic features.
Project description:LESSONS LEARNED:This trial evaluating a novel plant extract, PBI-05204, did not meet its primary endpoint of overall survival but did show signals of efficacy in heavily pretreated mPDA. PBI-05204 was generally well tolerated, with the most common side effects related to treatment being vomiting (23.7%), nausea (18.4%), decreased appetite (18.4%), and diarrhea (15.8%). Additional trials are needed to explore the role of PBI-05204 in cancer treatment. BACKGROUND:Survival for metastatic pancreatic ductal adenocarcinoma (mPDA) is dismal, and novel agents are needed. PBI-05204 is a modified supercritical carbon dioxide extract of Nerium oleander leaves. Oleandrin, the extract's major cytotoxic component, is a cardiac glycoside that has demonstrated antitumor activity in various tumor cell lines with a mechanism involving inhibition of Akt phosphorylation and through downregulation of mTOR. METHODS:A phase II, single-arm, open-label study to determine the efficacy of PBI-05204 in patients with refractory mPDA therapy was conducted. The primary endpoint was overall survival (OS), with the hypothesis that 50% of patients would be alive at 4.5 months. Secondary objectives included safety, progression-free survival (PFS), and overall response rate. Patients received oral PBI-05204 daily until progressive disease (PD), unacceptable toxicity, or patient withdrawal. Radiographic response was assessed every two cycles. RESULTS:Forty-two patients were enrolled, and 38 were analyzed. Ten patients were alive at 4.5 months (26.3%) with a median PFS of 56?days. One objective response (2.6%) was observed for 162?days. Grade ??3 treatment-emergent adverse events occurred in 63.2% of patients with the most common being fatigue, vomiting, nausea, decreased appetite, and diarrhea. CONCLUSION:PBI-05204 did not meet its primary endpoint for OS in this study. Recent preclinical data indicate a role for PBI-05204 against glioblastoma multiforme when combined with chemotherapy and radiotherapy. A randomized phase II trial is currently being designed.
Project description:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads worldwide and leads to an unprecedented medical burden and lives lost. Neutralizing antibodies provide efficient blockade for viral infection and are a promising category of biological therapies. Here, using SARS-CoV-2 spike receptor-binding domain (RBD) as a bait, we generate a panel of humanized single domain antibodies (sdAbs) from a synthetic library. These sdAbs reveal binding kinetics with the equilibrium dissociation constant (KD) of 0.99-35.5?nM. The monomeric sdAbs show half maximal neutralization concentration (EC50) of 0.0009-0.07?µg/mL and 0.13-0.51?µg/mL against SARS-CoV-2 pseudotypes, and authentic SARS-CoV-2, respectively. Competitive ligand-binding experiments suggest that the sdAbs either completely block or significantly inhibit the association between SARS-CoV-2 RBD and viral entry receptor ACE2. Fusion of the human IgG1 Fc to sdAbs improve their neutralization activity by up to ten times. These results support neutralizing sdAbs as a potential alternative for antiviral therapies.
Project description:Oleandrin, the main component of Nerium oleander L. extracts, is a cardiotoxic glycoside with multiple pharmacological implications, having potential anti-tumoral and antiviral characteristics. Although it is accepted that the main mechanism of oleandrin action is the inhibition of Na+/K+-ATPases and subsequent increase in cell calcium, many aspects which determine oleandrin cytotoxicity remain elusive. In this study, we used the model Saccharomyces cerevisiae to unravel new elements accounting for oleandrin toxicity. Using cells expressing the Ca2+-sensitive photoprotein aequorin, we found that oleandrin exposure resulted in Ca2+ influx into the cytosol and that failing to pump Ca2+ from the cytosol to the vacuole increased oleandrin toxicity. We also found that oleandrin exposure induced Mn2+ accumulation by yeast cells via the plasma membrane Smf1 and that mutants with defects in Mn2+ homeostasis are oleandrin-hypersensitive. Our data suggest that combining oleandrin with agents which alter Ca2+ or Mn2+ uptake may be a way of controlling oleandrin toxicity.
Project description:Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread worldwide through person-to-person contact, causing a public health emergency of international concern. At present, there is no specific antiviral treatment recommended for SARS-CoV-2 infection. Liu Shen capsule (LS), a traditional Chinese medicine, has been proven to have a wide spectrum of pharmacological properties, such as anti-inflammatory, antiviral and immunomodulatory activities. However, little is known about the antiviral effect of LS against SARS-CoV-2. Herein, the study was designed to investigate the antiviral activity of SARS-CoV-2 and its potential effect in regulating the host's immune response. The inhibitory effect of LS against SARS-CoV-2 replication in Vero E6 cells was evaluated by using the cytopathic effect (CPE) and plaque reduction assay. The number of virions of SARS-CoV-2 was observed under transmission electron microscope after treatment with LS. Proinflammatory cytokine expression levels upon SARS-CoV-2 infection in Huh-7 cells were measured by real-time quantitative PCR assays. The results showed that LS could significantly inhibit SARS-CoV-2 replication in Vero E6 cells, and reduce the number of virus particles and it could markedly reduce pro-inflammatory cytokines (TNF-?, IL-6, IL-1?, IL-8, CCL-2/MCP-1 and CXCL-10/IP-10) production at the mRNA levels. Moreover, the expression of the key proteins in the NF-?B/MAPK signaling pathway was detected by western blot and it was found that LS could inhibit the expression of p-NF-?B p65, p-I?B? and p-p38 MAPK, while increasing the expression of I?B?. These findings indicate that LS could inhibit SARS-CoV-2 virus infection via downregulating the expression of inflammatory cytokines induced virus and regulating the activity of NF-?B/MAPK signaling pathway in vitro, making its promising candidate treatment for controlling COVID-19 disease.
Project description:PURPOSE:Lianhuaqingwen (LH) as traditional Chinese medicine (TCM) formula has been used to treat influenza and exerted broad-spectrum antiviral effects on a series of influenza viruses and immune regulatory effects Ding et al. (2017). The goal of this study is to demonstrate the antiviral activity of LH against the novel SARS-CoV-2 virus and its potential effect in regulating host immune response. METHODS:The antiviral activity of LH against SARS-CoV-2 was assessed in Vero E6 cells using CPE and plaque reduction assay. The effect of LH on virion morphology was visualized under transmission electron microscope. Pro-inflammatory cytokine expression levels upon SARS-CoV-2 infection in Huh-7 cells were measured by real-time quantitative PCR assays. RESULTS:LH significantly inhibited SARS-CoV-2 replication in Vero E6 cells and markedly reduced pro-inflammatory cytokines (TNF-?, IL-6, CCL-2/MCP-1 and CXCL-10/IP-10) production at the mRNA levels. Furthermore, LH treatment resulted in abnormal particle morphology of virion in cells. CONCLUSIONS:LH significantly inhibits the SARS-COV-2 replication, affects virus morphology and exerts anti-inflammatory activity in vitro. These findings indicate that LH protects against the virus attack, making its use a novel strategy for controlling the COVID-19 disease.
Project description:The open reading frame 3 of the severe acute respiratory syndrome coronavirus (SARS-CoV) genome encodes a predicted protein 3a, consisting of 274 amino acids, that lacks any significant similarities to any known protein. We generated specific antibodies against SARS protein 3a by using a synthetic peptide (P2) corresponding to amino acids 261-274 of the putative protein. Anti-P2 antibodies and the sera from SARS patients could specifically detect the recombinant SARS protein 3a expressed in Escherichia coli and in Vero E6 cells. Expression of SARS protein 3a was detected at 8-12 h after infection and reached a higher level after approximately 24 h in SARS-CoV-infected Vero E6 cells. Protein 3a was also detected in the alveolar lining pneumocytes and some intra-alveolar cells of a SARS-CoV-infected patient's lung specimen. Recombinant protein 3a expressed in Vero E6 cells and protein 3a in the SARS-CoV-infected cells was distributed over the cytoplasm in a fine punctate pattern with partly concentrated staining in the Golgi apparatus. Our study demonstrates that SARS-CoV indeed expresses a novel protein 3a, which is present only in SARS-CoV and not in other known CoVs.