Role of herbal medicines in the management of patients with COVID-19: A systematic review and meta-analysis of randomized controlled trials

Pontes CL, de O. Costa G, F. de Sousa N, Tizziani T, E. Pollo LA, Dambrós BP, Scotti MT, Steindel M, Braga AL, Schirmeister T, F. de Assis F, Sandjo LP. Inhibitory Effects of Mangifera indica Secondary Metabolites and Their Synthetic Derivatives against SARS-CoV-2 Mpro and NS2B/NS3 (ZIKV and DENV-2)

Chemical studies of Mangifera indica twigs yielded two compounds, identified as taraxerol (1) and methyl gallate (2). The galloyl moiety was suggested as a potential scaffold that can interfere with proteases by previous biological investigations on SARS-CoV-2 main protease (Mpro) inhibitors in combination with docking studies. Therefore, a series of 13 gallate esters were prepared by treating gallic acid with natural and non-natural alcohols. Their inhibitory effects were evaluated against Mpro and NS2B/NS3 of Zika and Dengue viruses. Among the obtained compounds, 2e and 2i were the most potent against Mpro with IC50 values of 2.60 and 4.0 μM, respectively. Compounds 2f and 2g were more potent than others against ZIKV protease with IC50 values of 2.7 and 1.9 μM, respectively. The bioactivity profile against DENV NS2B/NS3 was different with 2e and 2f showing moderate inhibition with IC50 values of 66.0 and 59.29 μM, respectively. It was found that 2f and 2g inhibited ZIKV NS2B/NS3 via a noncompetitive mechanism. The study also showed that 2e and 2f could exert noncompetitive inhibition at the previously described allosteric pocket of flaviviral NS2B/NS3 proteases. Molecular docking revealed different types of interactions among the most prominent were hydrogen bonding with the galloyl moiety.

Alliaceae-Derived Supplementation Improves the Severity of COVID-19 Symptoms among Elderly Nursing Home Residents

This study investigates the effect of daily consumption of a concentrated garlic and onion extract on COVID-19 symptoms among elderly nursing home residents. Volunteers consumed a daily capsule of the concentrated powder rich in organosulfur compounds over 36 weeks during lunch. The incidence and severity of COVID-19 symptoms between the treatment and control groups were compared, along with monitoring the safety of consumption, incidence of other diseases, and medicine usage. The treatment group showed a significant reduction in both the number and severity of COVID-19 symptoms compared to the control group, with no significant adverse effects observed. No significant reduction in symptom duration was detected. This study provides preliminary evidence that concentrated garlic and onion extract may aid in the treatment of COVID-19 among older adults. These findings suggest potential public health benefits, emphasizing the need for further research to explore the immunomodulatory properties of these natural compounds.

Ayush [Indian System of Medicines] Prophylaxis Against COVID-19: A Living Systematic Review and Meta-Analysis (Second Update)

Background: Ayush (Ayurveda, Yoga and Naturopathy, Unani, Siddha, and Homeopathy) system of medicine has been extensively used in India for the prevention and management of coronavirus disease 2019 (COVID-19). The present report is the second update of a living systematic review and meta-analysis and has been intended to assess the preventive potential and safety of Ayush drugs against COVID-19. Methods: A search of databases such as PubMed, the Cochrane central register of controlled trials, the World Health Organization (WHO) COVID-19 database, the clinical trial registry-India, the AYUSH research portal, and preprint repositories was performed till March 1, 2023. Randomized controlled trials or analytical observational studies were included. Incidences of COVID-19 infections and mortality were taken as primary outcome measures; and symptomatic severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) infection, incidences of hospital admissions, and adverse events were taken as secondary outcomes. The risk of bias was evaluated by version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB-2) and the Risk of Bias in Non-Randomized Studies-of Interventions (ROBINS-I) tool. Data were synthesized through the RevMan 5.4 tool, and the certainty of the evidence was ranked through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Results: Out of 2350 articles, 15 studies were included in the review. The pooled estimate of Guduchi [Tinospora cordifolia (Thunb.) Miers], Chyawanprasha, and Ayuraksha kit was obtained. Meta-analysis of the data suggested that Guduchi may reduce the incidences of COVID-19 infections (risk ratio [RR]: 0.67 [95% confidence interval, CI: 0.48-0.95]) and the symptom development among the infected (RR: 0.88 [95% CI: 0.73-1.08]), however, no change was observed in hospital admissions (RR: 0.96 [95% CI: 0.20-4.53]). It is uncertain that Chyawanprasha reduces the incidence of COVID-19 infection (RR: 0.28; [95% CI: 0.07-1.08]). Ayuraksha kit as chemoprophylaxis may reduce the incidences of COVID-19 infections (RR: 0.49; [95% CI: 0.32-0.77]). The certainty of the evidence was low to moderate mainly due to the serious risk of bias. Conclusion: Prophylactic use of Ayush medicines for populations at risk may help to prevent COVID-19 infection by reducing incidence and severity. However, considering the certainty and fewer studies, high-quality studies are still desired to confirm the efficacy and safety of Ayush chemoprophylaxis for COVID-19. Nevertheless, this update will serve as a torchbearer for policymakers, physicians, and other stakeholders for their decision-making through evidence-based medicine.

Traditional Formulations for Managing COVID-19: A Systematic Review

Background: The advancing etiopathogenesis, diagnosis, and treatment of the global coronavirus disease 2019 (COVID-19) pandemic have prompted the medical community to consider Ayurveda, Siddha, and Unani as add-on preventive and therapeutic options. Objective: To explore the effect of standalone or integrative Traditional Formulations (TFs) on selected clinical symptoms and biomarkers of COVID-19. Search strategy: Out of 465 articles identified from PubMed, ScienceDirect, and Scopus, 17 randomized controlled trials (RCTs) with 1646 COVID-19 patients published from January 2020 to February 2022 were included in the study. Inclusion criteria: RCTs that compared the effect of standalone/integrative TFs in decoction, tablet, and powder forms with placebo plus standard care (SC)/placebo/SC as controls involving mild to severe symptomatic COVID-19 patients were included. Data extraction and analysis: Three reviewers independently assessed the titles and abstracts of each article based on the inclusion after deleting duplicates. The relevant full texts were retrieved and examined, and then their data were extracted and double-checked by three independent reviewers using prepared data extraction forms. The primary outcome variables were reverse transcription polymerase chain reaction, fever, cough, dyspnea, myalgia, headache, C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and D-dimer. Results: The effect of different TFs or integrative TFs was more to inhibit severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) than the controls. There was an increase in fever and cough, a decrease in dyspnea, myalgia, headache, and ESR, no change in CRP, and a slight increase in D-dimer as an effect of TFs. Conclusions: Integrative or standalone TF may be the inexpensive preventive and therapeutic option to inhibit SARS-CoV-2 and its clinical symptoms.

In silico anti-viral assessment of phytoconstituents in a traditional (Siddha Medicine) polyherbal formulation - Targeting Mpro and pan-coronavirus post-fusion Spike protein

Background and aim

Novel nature of the viral pathogen SARS-CoV-2 and the absence of standard drugs for treatment, have been a major challenge to combat this deadly infection. Natural products offer safe and effective remedy, for which traditional ethnic medicine can provide leads. An indigenous poly-herbal formulation, Kabasura Kudineer from Siddha system of medicine was evaluated here using a combination of computational approaches, to identify potential inhibitors against two anti-SARS-CoV-2 targets - post-fusion Spike protein (structural protein) and main protease (Mpro, non-structural protein).

Experimental procedure

We docked 32 phytochemicals from the poly-herbal formulation against viral post-fusion Spike glycoprotein and Mpro followed by molecular dynamics using Schrodinger software. Drug-likeness analysis was performed using machine learning (ML) approach and pkCSM.

Results

The binding affinity of the phytochemicals in Kabasura Kudineer revealed the following top-five bioactives: Quercetin > Luteolin > Chrysoeriol > 5-Hydroxy-7,8-Dimethoxyflavone > Scutellarein against Mpro target, and Gallic acid > Piperlonguminine > Chrysoeriol > Elemol > Piperine against post-fusion Spike protein target. Quercetin and Gallic acid exhibited binding stability in complexation with their respective viral-targets and favourable free energy change as revealed by the molecular dynamics simulations and MM-PBSA analysis. In silico predicted pharmacokinetic profiling of these ligands revealed appropriate drug-likeness properties.

Conclusion

These outcomes provide: (a) potential mechanism for the anti-viral efficacy of the indigenous Siddha formulation, targeting Mpro and post-fusion Spike protein (b) top bioactive lead-molecules that may be developed as natural product-based anti-viral pharmacotherapy and their pleiotropic protective effects may be leveraged to manage co-morbidities associated with COVID-19.

Biological Importance of Phellodendrine in Traditional and Modern Medicines: An Update on Therapeutic Potential in Medicine

BACKGROUND

Herbal medicines have been used for the preparation of numerous pharmaceutical products for the treatment of human disorders. Plant-derived products have been used in medicine, nutraceuticals, perfumery, beverages, and cosmetics industries for different purposes. Herbal medicines are mainly derived from different parts of plant materials. Phellodendron bark has been widely known as one of the fundamental herbs of traditional Chinese medicine. Phellodendron bark contains phellodendrine as a main active phytochemical. Phellodendrine ((7S,13aS)-3,10-dimethoxy-7-methyl-6,8,13,13atetrahydro-5H-isoquinolino[2,1-b]isoquinolin-7- ium-2,11-diol), is a quaternary ammonium alkaloid.

METHODS

This present study aimed to investigate the biological potential and therapeutic effectiveness of phellodendrine in medicine through scientific data analysis of different research works on phellodendrine. The therapeutic value of phellodendrine was analyzed in the present work through scientific data available in Google, Google Scholar, ScienceDirect, and PubMed. All the scientific data on phellodendrine were collected from these databases using the terms herbal drugs and phellodendrine. Pharmacological and analytical data of phellodendrine were analyzed in the present work in order to know the medicinal importance of phellodendrine.

RESULTS

Scientific data analysis of phellodendrine in the present work signified the biological importance of phellodendrine in medicine. Phellodendrine has numerous beneficial aspects in medicine due to its potential benefits in ulcerative colitis, inflammation, pancreatic cancer, nephritis, immune response, acetylcholinesterase activity, psoriasis, arthritis, atopic dermatitis, and oxidative stress. However, it also has significant effects on eicosanoid generation, neuraminidase-1, inflammasome generation, cytochrome p450, taste receptors, and hepatic gluconeogenesis. Furthermore, scientific data has indicated the presence of phellodendrine in different natural sources, including Phellodendri cortex. Analytical data on phellodendrines has signified their importance in the isolation and separation of pure phytochemicals in medicine. Pharmacokinetic parameters have highlighted the tissue distribution of phellodendrine in different tissue of human beings and higher animals.

CONCLUSION

In the present work, scientific data analysis has indicated the biological importance, pharmacological activities, and analytical aspects of phellodendrine in medicine.

AYUSH (Indian System of Medicines) Therapeutics for COVID-19: A Living Systematic Review and Meta-Analysis (First Update)

Background: In India, alternative and complementary therapies (Ayurveda, Yoga and Naturopathy, Unani, Siddha, and Homeopathy [AYUSH] medicines) are extensively utilized in COVID-19 management, and some were investigated clinically. This study assessed the effectiveness of AYUSH therapeutic on COVID-19 through a living systematic review and meta-analysis approach. Methods: Databases like PubMed; the Cochrane central register of controlled trials; WHO COVID-19 database; the central trial registry-India; Digital Helpline for Ayurveda Research Articles and AYUSH research portal, and preprint repositories were searched till August 1, 2021. Randomized controlled trials or analytical observational studies were included only. Primary outcomes selected were clinical improvement, WHO ordinal scale, viral clearance, and mortality, whereas secondary outcomes were the use of O₂ therapy or mechanical ventilator, admission to high dependency unit or emergency unit, duration of hospitalization, the time to symptom resolution, and adverse events. The risk of bias was evaluated by Version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB-2) and Risk of Bias in Nonrandomized Studies-of Interventions (ROBINS-I) tools; data were synthesized through RevMan 5.4 tool, and the certainty of the evidence was ranked through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Results: Of 3609 studies retrieved, 17 were included in the systematic review, and 3 AYUSH therapeutics were meta-analyzed. Meta-analysis suggested that add-on AYUSH-64 likely provides therapeutic benefits by reducing time to symptom resolution (mean difference [MD] 2.35 days lower [95% confidence interval, CI; 4.05 lower to 0.65 lower]) and hastening clinical improvement (365 more per 1000 [95% CI; 4 more to 1000 more]) in mild-to-moderate COVID-19 patients. Kabasura Kudineer adjuvant to standard care is likely to reduce symptom resolution (MD; 1.93 days lower [95% CI; 2.28 lower to 1.58 lower]) and hospital stay (MD; 4.2 days lower [95% CI; 4.97 lower to 3.43 lower]) in mild-to-moderate COVID-19 patients. Co-administration of Guduchi (Tinospora cordifolia [Willd.] Miers.) to standard care may reduce the duration of hospitalization (MD; 3.93 days, lower [95% CI; 8.83 lower to 0.97 higher]) in mild-to-moderate COVID-19 patients. Furthermore, all three agents seemed safe in adjunct usage to standard care. The certainty of evidence for most outcomes was moderate to low, primarily due to the high risk of bias or imprecision owing to the small sample size. Conclusion: Rational use of integrated or standalone AYUSH interventions in mild-to-moderate COVID-19 patients is safe and may provide therapeutic benefits. The effect estimates may be changed with additional evidence in upcoming updates.

Attitudes and beliefs regarding the use of herbs and supplementary medications with COVID-19: A systematic review

BACKGROUND AND AIM

There is growing interest in using herbs and supplementary medications to treat and/or prevent COVID-19, evidenced by multiple reports exploring their effectiveness and safety. From a health psychology perspective, the desire to use herbs and supplementary medications to prevent and/or treat COVID-19 is a health behavior which is attributed to attitudes and beliefs. This systematic review critically appraised and synthesized the data from studies investigating these attitudes and beliefs.

METHODS

EMBASE, PubMed, ScienceDirect, Scopus, Cochrane (library), and WebOfScience were searched from inception to December 13, 2021 for studies investigating attitudes and beliefs on the use of herbs and supplementary medications to treat and/or prevent COVID-19.

RESULTS

A total of 17 articles were identified for inclusion. All except one were of cross-sectional design. Participants across most studies had a positive attitude towards using herbs and supplementary medications. They believed that herbs and supplementary medications were effective and were confident in their value in preventing and/or treating COVID-19 symptoms. The majority of included studies had significant flaws in study design and reporting, including inconsistent definitions of herbs and supplementary medications, a lack of theoretical models and conceptual frameworks underpinning the study of beliefs and attitudes, in addition to methodological issues of robustness affecting the validity and reliability of data.

CONCLUSION

The use of herbs and supplementary medicines to prevent and/or treat COVID-19 could well be driven by a positive attitude stemming from beliefs of effectiveness and safety. There is a need for well-designed studies on attitudes and beliefs that are driven by health behavior theories to permit generalizability of findings and establish more conclusive relationships between beliefs, attitudes and the decision to use herbs and supplementary medications to treat and/or prevent COVID-19.

The Efficacy and Safety of Imusil® Tablets in the Treatment of Adult Patients With Mild COVID-19: A Prospective, Randomized, Multicenter, Open-Label Study

Introduction Coronavirus disease 2019 (COVID-19) is a serious concern of the new era. Along with antiviral synthetic medications, there is a need to discover efficacious herbal antiviral medicines with minimum side effects in patients against COVID-19. This study aimed to assess the efficacy and safety of Imusil® among patients with mild COVID-19. Methods A prospective, randomized, multicenter, open-label, interventional study was conducted in patients with mild COVID-19 infection. Patients received either Imusil one tablet four times a day (seven days) along with the standard of care (SoC) or only SoC. The study endpoints were reverse transcription-polymerase chain reaction (RT-PCR) negativity, changes in cycle threshold (CT), clinical improvement, change in blood inflammatory indexes, and safety assessment. Results A total of 100 patients were enrolled, and 98 received at least one dose of treatment. The median age of patients was 36.0 years, and 58 were males. By day 4, 85.4% of patients in the Imusil+SoC group tested negative for RT-PCR compared to 64% of patients exhibiting the same outcome in the SoC group (P=0.0156). After eight days, clinical improvement was observed in all patients from the Imusil+SoC group, while in the SoC group, clinical improvement was observed in 94.0% of patients (P=0.4947). During follow-up visits, the average C-reactive protein (CRP) levels decreased from baseline in both treatment groups. The decrease in the levels of CRP (-7.3 mg/dL versus -5.5 mg/dL), D-dimer (-231.0 ng/mL versus -151.6 ng/mL), and interleukin 6 (IL-6) (-2.3 pg/mL versus -2.0 pg/mL) at eight days was comparatively higher in the Imusil+SoC group versus the SoC group. There were no serious treatment-emergent adverse events in the drug arm. Conclusion Imusil provides effective antiviral activity and safety in mild COVID-19 patients. Imusil ensures faster RT-PCR negativity and clinical improvement and ensures effective reduction of inflammatory markers such as CRP, D-dimer and interleukin 6.

Cytotoxic Activity of Herbal Medicines as Assessed in Vitro: A Review

Since time immemorial, human beings have sought natural medications for treatment of various diseases. Weighty evidence demonstrates the use of chemical methodologies for sensitive evaluation of cytotoxic potentials of herbal agents. However, due to the ubiquitous use of cytotoxicity methods, there is a need for providing updated guidance for the design and development of in vitro assessment. The aim of this review is to provide practical guidance on common cell-based assays for suitable assessment of cytotoxicity potential of herbal medicines and discussing their advantages and disadvantages Relevant articles in authentic databases, including PubMed, Web of Science, Science Direct, Scopus, Google Scholar and SID, from 1950 to 2022 were collected according to selection criteria of in vitro cytotoxicity assays and protocols. In addition, the link between cytotoxicity assay selection and different factors such as the drug solvent, concentration and exposure duration were discussed.

Prospect of herbal medication as prevention against COVID variants

Personal immunity frolicked an essential role in combating COVID-19 impacts on human health individually and collectively in community. Literature represented the fact about food or nutritional supplements are certified to protect against diseases; this was the reason behind public trust on certain plants and other commercial products to boost up immunity against coronavirus disease. Present study was conducted to observe the attitude of common public towards natural herbs in treating various diseases and to assess the possible potential of herbal medication in prevention of negative impacts of different variants of COVID-19 on human health at herbal clinic named "Pakistan Matab". Results concluded that most of the patients (About 80%) avoided COVID-19 testing even on experiencing major symptoms and they preferred herbal medication. Patients who died by COVID-19 were also experiencing different diseases like liver and Kideny malfunctioning; old age was another significant factor in this case. About 90% of patients were COVID symptomatic and 10% were carrying other diseases during observational study period at herbal clinic. Study represented that patients who visited clinic, have a faith on herbal medication with about 60% of patients in favor of vaccine and allopathic medication in combination with herbal treatment. Study investigated that vaccine was only for one type of variant and use of herbal medicines could be better option to boost up immunity against various COVID variants.

Panax ginseng as a potential therapeutic for neurological disorders associated with COVID-19; Toward targeting inflammasome

Coronavirus disease 2019 (COVID-19) is a highly infectious respiratory disease caused by a severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). SARS-CoV-2 infection may cause clinical manifestations of multiple organ damage, including various neurological syndromes. There are currently two oral antiviral drugs-Paxlovid and molnupiravir-that are recognized to treat COVID-19, but there are still no drugs that can specifically fight the challenges of SARS-CoV-2 variants. Nucleotide-binding oligomerization domain-like receptor pyrin domain-containing-3 (NLRP3) inflammasome is a multimolecular complex that can sense heterogeneous pathogen-associated molecular patterns associated with neurological disorders. The NLRP3 activation stimulates the production of caspase-1-mediated interleukin (IL)-1β, IL-18, and other cytokines in immune cells. Panax (P.) ginseng is a medicinal plant that has traditionally been widely used to boost immunity and treat various pathological conditions in the nervous system due to its safety and anti-inflammatory/oxidant/viral activities. Several recent reports have indicated that P. ginseng and its active ingredients may regulate NLRP3 inflammasome activation in the nervous system. Therefore, this review article discusses the current knowledge regarding the pathogenesis of neurological disorders related to COVID-19 and NLRP3 inflammasome activation and the possibility of using P. ginseng in a strategy targeting this pathway to treat neurological disorders.

Phase III randomized clinical trial of BV ‐4051, an Ayurvedic polyherbal formulation in moderate SARS‐CoV ‐2 infections and its impact on inflammatory biomarkers

SARS-CoV-2 virus and its variants continue to be a challenge inspite of widespread vaccination and preventive measures. We hypothesized an oral, safe polyherbal formulation with antiinflammatory properties may improve the clinical outcome of this disease. BV-4051, a formulation from four Ayurvedic plants namely Ashwagandha, Boswellia, Ginger and Turmeric was used for the treatment of hospitalized moderate COVID-19 patients along with standard of care (SOC). Patients were randomly assigned to receive BV-4051 or placebo tablets for 14 days, at four sites in India during late 2020 to early 2021. Among 208 randomized subjects, 175 completed the study. In BV-4051 group the mean reduction in duration of illness (p = 0.036), alleviation and severity scores of several symptoms like fever, cough, smell, and taste disorders were statistically significant (p ≤ 0.05). A sub-set analysis of subjects treated with or without Remdesivir as SOC showed mean reduction in duration of illness in BV-4051 (p = 0.030), and severity scores (p ≤ 0.05). Mean difference in Interleukin-6 was statistically significant (p = 0.042) on BV-4051 without Remdesivir. BV-4051 may reduce duration of illness, symptoms severity, Interleukin-6, and prevent the incidence of COVID-19 complications. It may have an adjunctive effect with other SOC. Larger extensive clinical testing may give a better understanding of its effect.

Online Yoga and Ayurveda Intervention as Tertiary Prevention of Psychological Comorbidities in COVID-19 Survivors: A Randomized Controlled Trial

Background and Purpose

About 56% of symptomatic COVID-19 survivors have been found with neuropsychological comorbidities, such as depression, anxiety, posttraumatic stress disorders (PTSD), and impaired quality of life (QoL). Alongside, antimicrobial, anti-inflammatory, neuroprotective, regenerative, immunomodulatory, cardio-pulmonary health promotive, and psychological benefits of yogic and Ayurvedic intervention are well documented. Therefore, this study aimed to assess the effect of online Yoga (OYI) and Yoga cum Ayurveda intervention (OYAI) on COVID-19-induced depression, anxiety, PTSD, and poor QoL.

Method

Seventy-two participants (males/females: 33/26) with at least a 3-month back history of symptomatic COVID-19 infection and age (mean ± SD: 32.33 ± 9.9 and 33.04 ± 12.9 for males and females, respectively) were recruited from Patanjali Ayurveda Hospital, Haridwar, India, and All India Institute of Medical Sciences, Rishikesh, Uttarakhand, India, before random allocation into an equal-sized control group (CG), Yoga group (YG) and Yoga cum concoction (YCG) group. Split-plot analysis of variance and Kruskal–Wallis tests with Bonferroni adjusted post hoc comparisons were computed for normal and nonnormal data using IBM SPSS (25th Version, SPSS South Asia Private Limited, Bangalore, India).

Results

Both the treatments—the 30-day OYI and OYAI, significantly improved depression ( P < .002, ES: -0.99 and P < .001, ES: -2.11), anxiety ( P < .001, ES: -1.32 and -1.89), PTSD ( P < .001, ES: -1.8 and -1.83) and QoL related constructs ( P < .001, ES: 0.63 and 0.76; 0.71 and 0.93 for each OYI and OYAI versus general health and physical health; P < .001, ES: 0.65 for OYAI versus psychological health; and P < .003, ES: 0.54 for OYI versus environment) of the participants compared to the controls.

Conclusion

OYAI may better ameliorate COVID-19-induced psychological comorbidities than OYI with no adverse effects.

The Therapeutic and Prophylactic Potential of Quercetin against COVID-19: An Outlook on the Clinical Studies, Inventive Compositions, and Patent Literature

Quercetin is a phenolic flavonol compound with established antioxidant, anti-inflammatory, and immuno-stimulant properties. Recent studies demonstrate the potential of quercetin against COVID-19. This article highlighted the prophylactic/therapeutic potential of quercetin against COVID-19 in view of its clinical studies, inventions, and patents. The literature for the subject matter was collected utilizing different databases, including PubMed, Sci-Finder, Espacenet, Patentscope, and USPTO. Clinical studies expose the potential of quercetin monotherapy, and also its combination therapy with other compounds, including zinc, vitamin C, curcumin, vitamin D3, masitinib, hydroxychloroquine, azithromycin, and ivermectin. The patent literature also examines claims that quercetin containing nutraceuticals, pharmaceuticals, and dietary supplements, alone or in combination with other drugs/compounds, including favipiravir, remdesivir, molnupiravir, navitoclax, dasatinib, disulfiram, rucaparib, tamarixin, iota-carrageenan, and various herbal extracts (aloe, poria, rosemary, and sphagnum) has potential for use against COVID-19. The literature reveals that quercetin exhibits anti-COVID-19 activity because of its inhibitory effect on the expression of the human ACE2 receptors and the enzymes of SARS-CoV-2 (MPro, PLPro, and RdRp). The USFDA designated quercetin as a “Generally Recognized as Safe” substance for use in the food and beverage industries. It is also an inexpensive and readily available compound. These facts increase the possibility and foreseeability of making novel and economical drug combinations containing quercetin to prevent/treat COVID-19. Quercetin is an acidic compound and shows metabolic interaction with some antivirals, antibiotics, and anti-inflammatory agents. Therefore, the physicochemical and metabolic drug interactions between quercetin and the combined drugs/compounds must be better understood before developing new compositions.