The Hydroalcoholic Extract of Uncaria tomentosa (Cat's Claw) Inhibits the Infection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) In Vitro

Plant-derived compounds as potential leads for new drug development targeting COVID-19

COVID-19, which was first identified in 2019 in Wuhan, China, is a respiratory illness caused by a virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although some patients infected with COVID-19 can remain asymptomatic, most experience a range of symptoms that can be mild to severe. Common symptoms include fever, cough, shortness of breath, fatigue, loss of taste or smell and muscle aches. In severe cases, complications can arise including pneumonia, acute respiratory distress syndrome, organ failure and even death, particularly in older adults or individuals with underlying health conditions. Treatments for COVID-19 include remdesivir, which has been authorised for emergency use in some countries, and dexamethasone, a corticosteroid used to reduce inflammation in severe cases. Biological drugs including monoclonal antibodies, such as casirivimab and imdevimab, have also been authorised for emergency use in certain situations. While these treatments have improved the outcome for many patients, there is still an urgent need for new treatments. Medicinal plants have long served as a valuable source of new drug leads and may serve as a valuable resource in the development of COVID-19 treatments due to their broad-spectrum antiviral activity. To date, various medicinal plant extracts have been studied for their cellular and molecular interactions, with some demonstrating anti-SARS-CoV-2 activity in vitro. This review explores the evaluation and potential therapeutic applications of these plants against SARS-CoV-2. This review summarises the latest evidence on the activity of different plant extracts and their isolated bioactive compounds against SARS-CoV-2, with a focus on the application of plant-derived compounds in animal models and in human studies.

Antiviral and Virucidal Activities of Uncaria tomentosa (Cat's Claw) against the Chikungunya Virus

Uncaria tomentosa (UT) is a medicinal plant popularly known as cat's claw belonging to the Rubiaceae family that has been reported to display antiviral and anti-inflammatory activities. The chikungunya virus (CHIKV) outbreaks constitute a Brazilian public health concern. CHIKV infection develops an abrupt onset of fever, usually accompanied by a skin rash, besides incapacitating polyarthralgia. There is no vaccine available or treatment for CHIKV infection. The present study evaluates the hydroalcoholic extract of UT bark as a potential antiviral against CHIKV. The in vitro antiviral activity of the UT extract against the Brazilian CHIKV strain was assessed using quantitative reverse transcription polymerase chain reaction, flow cytometry, and plaque assay. Results obtained demonstrated that UT inhibits CHIKV infection in a dose-dependent manner. At the non-cytotoxic concentration of 100 µg/mL, UT exhibited antiviral activity above 90% as determined by plaque reduction assay, and it reduced the viral cytopathic effect. Similarly, a significant virucidal effect of 100 µg/mL UT was observed after 24 and 48 h post-infection. This is the first report on the antiviral activity of UT against CHIKV infection, and the data presented here suggests UT as a potential antiviral to treat CHIKV infection.

Effectiveness of Drug Repurposing and Natural Products Against SARS-CoV-2: A Comprehensive Review

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a betacoronavirus responsible for the COVID-19 pandemic, causing respiratory disorders, and even death in some individuals, if not appropriately treated in time. To face the pandemic, preventive measures have been taken against contagions and the application of vaccines to prevent severe disease and death cases. For the COVID-19 treatment, antiviral, antiparasitic, anticoagulant and other drugs have been reused due to limited specific medicaments for the disease. Drug repurposing is an emerging strategy with therapies that have already tested safe in humans. One promising alternative for systematic experimental screening of a vast pool of compounds is computational drug repurposing (in silico assay). Using these tools, new uses for approved drugs such as chloroquine, hydroxychloroquine, ivermectin, zidovudine, ribavirin, lamivudine, remdesivir, lopinavir and tenofovir/emtricitabine have been conducted, showing effectiveness in vitro and in silico against SARS-CoV-2 and some of these, also in clinical trials. Additionally, therapeutic options have been sought in natural products (terpenoids, alkaloids, saponins and phenolics) with promising in vitro and in silico results for use in COVID-19 disease. Among these, the most studied are resveratrol, quercetin, hesperidin, curcumin, myricetin and betulinic acid, which were proposed as SARS-CoV-2 inhibitors. Among the drugs reused to control the SARS-CoV2, better results have been observed for remdesivir in hospitalized patients and outpatients. Regarding natural products, resveratrol, curcumin, and quercetin have demonstrated in vitro antiviral activity against SARS-CoV-2 and in vivo, a nebulized formulation has demonstrated to alleviate the respiratory symptoms of COVID-19. This review shows the evidence of drug repurposing efficacy and the potential use of natural products as a treatment for COVID-19. For this, a search was carried out in PubMed, SciELO and ScienceDirect databases for articles about drugs approved or under study and natural compounds recognized for their antiviral activity against SARS-CoV-2.

Dengue havoc: overview and eco-friendly strategies to forestall the current epidemic

Dengue fever is a mosquito-borne viral illness that affects over 100 nations around the world, including Africa, America, the Eastern Mediterranean, Southeast Asia, and the Western Pacific. Those who get infected by virus for the second time are at greater risk of having persistent dengue symptoms. Dengue fever has yet to be treated with a long-lasting vaccination or medication. Because of their ease of use, mosquito repellents have become popular as a dengue prevention technique. However, this has resulted in environmental degradation and harm, as well as bioaccumulation and biomagnification of hazardous residues in the ecosystem. Synthetic pesticides have caused a plethora of serious problems that were not foreseen when they were originally introduced. The harm caused by the allopathic medications/synthetic pesticides/chemical mosquito repellents has paved the door to employment of eco-friendly/green approaches in order to reduce dengue cases while protecting the integrity of the nearby environment too. Since the cases of dengue have become rampant these days, hence, starting the medication obtained from green approaches as soon as the disease is detected is advisable. In the present paper, we recommend environmentally friendly dengue management strategies, which, when combined with a reasonable number of vector control approaches, may help to avoid the dengue havoc as well as help in maintaining the integrity of the ecosystem.

Activation of PXR causes drug interactions with Paxlovid in transgenic mice

Paxlovid is a nirmatrelvir (NMV) and ritonavir (RTV) co-packaged medication used for the treatment of coronavirus disease 2019 (COVID-19). The active component of Paxlovid is NMV and RTV is a pharmacokinetic booster. Our work aimed to investigate the drug/herb-drug interactions associated with Paxlovid and provide mechanism-based guidance for the clinical use of Paxlovid. By using recombinant human cytochrome P450s (CYPs), we confirmed that CYP3A4 and 3A5 are the major enzymes responsible for NMV metabolism. The role of CYP3A in Paxlovid metabolism were further verified in Cyp3a-null mice, which showed that the deficiency of CYP3A significantly suppressed the metabolism of NMV and RTV. Pregnane X receptor (PXR) is a ligand-dependent transcription factor that upregulates CYP3A4/5 expression. We next explored the impact of drug- and herb-mediated PXR activation on Paxlovid metabolism in a transgenic mouse model expressing human PXR and CYP3A4/5. We found that PXR activation increased CYP3A4/5 expression, accelerated NMV metabolism, and reduced the systemic exposure of NMV. In summary, our work demonstrated that PXR activation can cause drug interactions with Paxlovid, suggesting that PXR-activating drugs and herbs should be used cautiously in COVID-19 patients receiving Paxlovid.

Potential pharmacokinetic interactions with concurrent use of herbal medicines and a ritonavir-boosted COVID-19 protease inhibitor in low and middle-income countries

The COVID-19 pandemic sparked the development of novel anti-viral drugs that have shown to be effective in reducing both fatality and hospitalization rates in patients with elevated risk for COVID-19 related morbidity or mortality. Currently, nirmatrelvir/ritonavir (Paxlovid™) fixed-dose combination is recommended by the World Health Organization for treatment of COVID-19. The ritonavir component is an inhibitor of cytochrome P450 (CYP) 3A, which is used in this combination to achieve needed therapeutic concentrations of nirmatrelvir. Because of the critical pharmacokinetic effect of this mechanism of action for Paxlovid™, co-administration with needed medications that inhibit or induce CYP3A is contraindicated, reflecting concern for interactions with the potential to alter the efficacy or safety of co-administered drugs that are also metabolized by CYP3A. Some herbal medicines are known to interact with drug metabolizing enzymes and transporters, including but not limited to inhibition or induction of CYP3A and P-glycoprotein. As access to these COVID-19 medications has increased in low- and middle-income countries (LMICs), understanding the potential for herb-drug interactions within these regions is important. Many studies have evaluated the utility of herbal medicines for COVID-19 treatments, yet information on potential herb-drug interactions involving Paxlovid™, specifically with herbal medicines commonly used in LMICs, is lacking. This review presents data on regionally-relevant herbal medicine use (particularly those promoted as treatments for COVID-19) and mechanism of action data on herbal medicines to highlight the potential for herbal medicine interaction Herb-drug interaction mediated by ritonavir-boosted antiviral protease inhibitors This work highlights potential areas for future experimental studies and data collection, identifies herbal medicines for inclusion in future listings of regionally diverse potential HDIs and underscores areas for LMIC-focused provider-patient communication. This overview is presented to support governments and health protection entities as they prepare for an increase of availability and use of Paxlovid™.

Medicinal Plants in Peru as a Source of Immunomodulatory Drugs Potentially Useful Against COVID-19

The current COVID-19 pandemic, characterized by a highly contagious severe acute respiratory syndrome, led us to look for medicinal plants as an alternative to obtain new drugs, especially those with immunomodulatory abilities, capable of acting against the pulmonary infection caused by coronavirus 2 (SARS-CoV-2). Despite medical advances with COVID-19 drugs and vaccines, plant-based compounds could provide an array of suitable candidates to test against this virus, or at the very least, to alleviate some symptoms. Therefore, this review explores some plants widely used in Peru that show immunomodulatory properties or, even more, contain phytoconstituents potentially useful to prevent or alleviate the COVID-19 infection. More interestingly, the present review highlights relevant information from those plants to support the development of new drugs to boost the immune system. We used three criteria to choose nine vegetal species, and a descriptive search was then conducted from 1978 to 2021 on different databases, using keywords focused on the immune system that included information such as pharmacological properties, phytochemical, botanical, ethnobotanical uses, and some clinical trials. From these literature data, our results displayed considerable immunomodulation activity along with anti-inflammatory, antiviral, antioxidant, and antitumoral activities. Noticeably, these pharmacological activities are related with a wide variety of bioactive phytoconstituents (mixtures or isolated compounds) which may be beneficial in modulating the overt inflammatory response in severe COVID-19. Further scientific research on the pharmacological activities and clinical utilization of these potential plants are warranted.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-023-00367-w.

Bioactive compounds as potential angiotensin-converting enzyme II inhibitors against COVID-19: a scoping review

OBJECTIVE AND DESIGN

The current study aimed to summarize the evidence of compounds contained in plant species with the ability to block the angiotensin-converting enzyme 2 (ACE-II), through a scoping review.

METHODS

PubMed and Scopus electronic databases were used for the systematic search and a manual search was performed RESULTS: Studies included were characterized as in silico. Among the 200 studies retrieved, 139 studies listed after the exclusion of duplicates and 74 were included for the full read. Among them, 32 studies were considered eligible for the qualitative synthesis. The most evaluated class of secondary metabolites was flavonoids with quercetin and curcumin as most actives substances and terpenes (isothymol, limonin, curcumenol, anabsinthin, and artemisinin). Other classes that were also evaluated were alkaloid, saponin, quinone, substances found in essential oils, and primary metabolites as the aminoacid L-tyrosine and the lipidic compound 2-monolinolenin.

CONCLUSION

This review suggests the most active substance from each class of metabolites, which presented the strongest affinity to the ACE-II receptor, what contributes as a basis for choosing compounds and directing the further experimental and clinical investigation on the applications these compounds in biotechnological and health processes as in COVID-19 pandemic.

Computational Study of the Phytochemical Constituents from Uncaria tomentosa Stem Bark against SARS-CoV-2 Omicron Spike Protein

The SARS-CoV-2 Omicron variant has spread rapidly and is considered the predominant variant in the world, and its main characteristic is related to evade immunity from natural infection or vaccines, due to its multiple mutations in the spike protein. On the other hand, medicinal plants have been used as alternatives therapies to ameliorate some signs and symptoms in COVID-19, and in our previous work, the cat’s claw (Uncaria tomentosa) stem bark has been studied in vitro and showed antiviral activity on SARS-CoV-2 as well as in silico studies on the 3CLpro protein and as disruptor between the ACE-2 human receptor and the spike protein. The aim in this computational study was to determine the main phytochemical constituents from U. tomentosa stem bark against the SARS-CoV-2 Omicron spike protein based on molecular modeling. A molecular docking was carried out on the isolated phytochemicals in a previous work against the SARS-CoV-2 Omicron spike protein-binding domain (PDB ID: 7T9K). Next, a molecular dynamic study was carried out to monitor the stability during the MD simulations. As results proanthocyanidin-C1 (-10.76 kcal/mol), quinovic acid-type 2 (-9.86 kcal/mol), and proanthocyanidin-B2 (-9.82 kcal/mol) were the constituents with the best binding free energy on the SARS-CoV-2 Omicron spike protein, and the best compound was stable during the dynamic simulation under physiological conditions. It is concluded that the anthocyanidin-based compounds determined in the stem bark ethanol extract could be responsible for the potential antiviral activity on SARS-CoV-2 Omicron variant, and the proanthocyanidin-C1 emerged as a powerful candidate to combat new variants.

Atorvastatin Effectively Inhibits Ancestral and Two Emerging Variants of SARS-CoV-2 in vitro

This article evaluated the in vitro antiviral effect of atorvastatin (ATV) against SARS-CoV-2 and identified the interaction affinity between this compound and two SARS-CoV-2 proteins. The antiviral activity of atorvastatin against this virus was evaluated by three different treatment strategies [(i) pre-post treatment, (ii) pre-infection treatment, and (iii) post-infection treatment] using Vero E6 and Caco-2 cells. The interaction of atorvastatin with RdRp (RNA-dependent RNA polymerase) and 3CL protease (3-chymotrypsin-like protease) was evaluated by molecular docking. The CC50s (half-maximal cytotoxic concentrations) obtained for ATV were 50.3 and 64.5 μM in Vero E6 and Caco-2, respectively. This compound showed antiviral activity against SARS-CoV-2 D614G strain in Vero E6 with median effective concentrations (EC50s) of 15.4, 12.1, and 11.1 μM by pre-post, pre-infection, and post-infection treatments, respectively. ATV also inhibited Delta and Mu variants by pre-post treatment (EC50s of 16.8 and 21.1 μM, respectively). In addition, ATV showed an antiviral effect against the D614G strain independent of the cell line (EC50 of 7.4 μM in Caco-2). The interaction of atorvastatin with SARS-CoV-2 RdRp and 3CL protease yielded a binding affinity of -6.7 kcal/mol and -7.5 kcal/mol, respectively. Our study demonstrated the in vitro antiviral activity of atorvastatin against the ancestral SARS-CoV-2 D614G strain and two emerging variants (Delta and Mu), with an independent effect of the cell line. A favorable binding affinity between ATV and viral proteins by bioinformatics methods was found. Due to the extensive clinical experience of atorvastatin use, it could prove valuable in the treatment of COVID-19.

Pharmacogenetics and Precision Medicine Approaches for the Improvement of COVID-19 Therapies

Many drugs are being administered to tackle coronavirus disease 2019 (COVID-19) pandemic situations without establishing clinical effectiveness or tailoring safety. A repurposing strategy might be more effective and successful if pharmacogenetic interventions are being considered in future clinical studies/trials. Although it is very unlikely that there are almost no pharmacogenetic data for COVID-19 drugs, however, from inferring the pharmacokinetic (PK)/pharmacodynamic(PD) properties and some pharmacogenetic evidence in other diseases/clinical conditions, it is highly likely that pharmacogenetic associations are also feasible in at least some COVID-19 drugs. We strongly mandate to undertake a pharmacogenetic assessment for at least these drug-gene pairs (atazanavir-UGT1A1, ABCB1, SLCO1B1, APOA5; efavirenz-CYP2B6; nevirapine-HLA, CYP2B6, ABCB1; lopinavir-SLCO1B3, ABCC2; ribavirin-SLC28A2; tocilizumab-FCGR3A; ivermectin-ABCB1; oseltamivir-CES1, ABCB1; clopidogrel-CYP2C19, ABCB1, warfarin-CYP2C9, VKORC1; non-steroidal anti-inflammatory drugs (NSAIDs)-CYP2C9) in COVID-19 patients for advancing precision medicine. Molecular docking and computational studies are promising to achieve new therapeutics against SARS-CoV-2 infection. The current situation in the discovery of anti-SARS-CoV-2 agents at four important targets from in silico studies has been described and summarized in this review. Although natural occurring compounds from different herbs against SARS-CoV-2 infection are favorable, however, accurate experimental investigation of these compounds is warranted to provide insightful information. Moreover, clinical considerations of drug-drug interactions (DDIs) and drug-herb interactions (DHIs) of the existing repurposed drugs along with pharmacogenetic (e.g., efavirenz and CYP2B6) and herbogenetic (e.g., andrographolide and CYP2C9) interventions, collectively called multifactorial drug-gene interactions (DGIs), may further accelerate the development of precision COVID-19 therapies in the real-world clinical settings.

Curcumin Inhibits In Vitro SARS-CoV-2 Infection In Vero E6 Cells through Multiple Antiviral Mechanisms

Due to the scarcity of therapeutic approaches for COVID-19, we investigated the antiviral and anti-inflammatory properties of curcumin against SARS-CoV-2 using in vitro models. The cytotoxicity of curcumin was evaluated using MTT assay in Vero E6 cells. The antiviral activity of this compound against SARS-CoV-2 was evaluated using four treatment strategies (i. pre-post infection treatment, ii. co-treatment, iii. pre-infection, and iv. post-infection). The D614G strain and Delta variant of SARS-CoV-2 were used, and the viral titer was quantified by plaque assay. The anti-inflammatory effect was evaluated in peripheral blood mononuclear cells (PBMCs) using qPCR and ELISA. By pre-post infection treatment, Curcumin (10 µg/mL) exhibited antiviral effect of 99% and 99.8% against DG614 strain and Delta variant, respectively. Curcumin also inhibited D614G strain by pre-infection and post-infection treatment. In addition, curcumin showed a virucidal effect against D614G strain and Delta variant. Finally, the pro-inflammatory cytokines (IL-1β, IL-6, and IL-8) released by PBMCs triggered by SARS-CoV-2 were decreased after treatment with curcumin. Our results suggest that curcumin affects the SARS-CoV-2 replicative cycle and exhibits virucidal effect with a variant/strain independent antiviral effect and immune-modulatory properties. This is the first study that showed a combined (antiviral/anti-inflammatory) effect of curcumin during SARS-CoV-2 infection. However, additional studies are required to define its use as a treatment for the COVID-19.

Uncaria tomentosa extract (AC-11) improves pregnancy hypertension together with suppression of sFlt-1 and sEng

Disruption of well-controlled reproductive functions leads to pregnancy complications such as hypertensive disorders of pregnancy (HDP). Uncaria tomentosa (Wild), known as cat's claw, is widely used for the treatment of a various types of health problems; AC-11 (AC-11®, hot-water extract of U. tomentosa) is unique phytochemical compound and has potential roles as anti-inflammatory or anti-oxidant processes. We investigated whether AC-11 has a protective effect on pathogenesis of HDP in vivo and production of anti-angiogenic factors (sFlt-1 and sEng, major factors for the onset of HDP) in in vitro. Non-pregnant or pregnant mice were administered AC-11 (4 mg/mL), then, angiotensin II (Ang II) was subcutaneously infused to increase blood pressure. Human placental tissues or human umbilical vein endothelial cells (HUVECs) were incubated with or without AC-11. Treatment with AC-11 significantly reduced blood pressure induced by Ang II infusion. The population of CD8⁺T cells, the ratio of CD8/CD4, and plasma interleukin-6 levels were increased by Ang II infusion, and were decreased by AC-11 both in pregnant and non-pregnant mice. In pregnant mice, plasma levels of sFlt-1 and sEng were decreased by AC-11. In in vitro cell culture of HUVECs or placental tissue culture, treatment with AC-11 significantly inhibited secretion of sFlt-1 and sEng. We suggest a novel role of AC-11 in regulating blood pressure by controlling the balance of T cell population and inflammatory cytokine production both in non-pregnant and pregnant conditions. In addition, AC-11 inhibits HDP-related factors, including sFlt-1 and sEng, suggesting that AC-11 may useful for relieving HDP.