Antiviral Essential Oils Incorporated in Nanocarriers: Strategy for Prevention from COVID-19 and Future Infectious Pandemics

Role of ethno-phytomedicine knowledge in healthcare of COVID-19: advances in traditional phytomedicine perspective

Background

Since the outbreak of the COVID-19 virus, ethnomedicinal plants have been used in diverse geographical locations for their purported prophylactic and pharmacological effects. Medicinal plants have been relied on by people around the globe for centuries, as 80% of the world’s population rely on herbal medicines for some aspect of their primary health care needs, according to the World Health Organization.

Main body

This review portrays advances in traditional phytomedicine by bridging the knowledge of ethno-phytomedicine and COVID-19 healthcare. Ethnomedicinal plants have been used for symptoms related to COVID-19 as antiviral, anti-infective, anti-inflammatory, anti-oxidant, antipyretic, and lung–gut immune boosters. Traditionally used medicinal plants have the ability to inhibit virus entry and viral assembly, bind to spike proteins, membrane proteins, and block viral replications and enzymes. The efficacy of traditional medicinal plants in the terms of COVID-19 management can be evaluated by in vitro, in vivo as well as different in silico techniques (molecular docking, molecular dynamics simulations, machine learning, etc.) which have been applied extensively to the quest and design of effective biotherapeutics rapidly. Other advances in traditional phytomedicines against COVID-19 are controlled clinical trials, and notably the roles in the gut microbiome. Targeting the gut microbiome via medicinal plants as prebiotics is also found to be an alternative and potential strategy in the search for a COVID-19 combat strategy.

Conclusions

Since medicinal plants are the sources of modern biotherapeutics development, it is essential to build collaborations among ethnobotanists, scientists, and technologists toward developing the most efficient and the safest adjuvant therapeutics against the pandemic of the twenty-first century, COVID-19.

Risk assessment of in vitro cytotoxicity, antioxidant and antimicrobial activities of Mentha piperita L. essential oil

The objective of this study was to determine the chemical composition as well as antioxidant, antibacterial, and cytotoxic properties of the essential oil of Mentha piperita L. (peppermint). Fifteen chemical constituents were identified in the essential oil, for a total of 99.99% of the compounds. The essential oil exhibited antimicrobial activity against two Gram-positive bacteria Staphylococcus aureus and Listeria monocytogenes. The minimum inhibitory concentration (MIC) of essential oil of Mentha piperita L. for Staphylococcus aureus and Listeria monocytogenes was 1.84 μg/ml, whereas the minimum bactericidal concentration (MBC) values were 3.7 and 7.43 μg/ml, respectively. The oil displayed potent antioxidant activity inhibiting up to approximately73% of 2,2'-azinothiobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals. In the cytotoxicity assay, the highest essential oil concentration (100 μg/ml) resulted in viability of approximately 90% human epidermal keratinocyte (HaCaT) cells. With respect to antitumor activity in C6 rat glioma cells, there was significant reduction in cell viability: 56-74% in 24 hr, and 71-77% in 48 hr. Data suggest that in presence of the essential oil of Mentha piperita L. antioxidant, antibacterial, antitumor and non-cytotoxic properties were noted.

Virucidal Activity of Essential Oils From Citrus x aurantium L. Against Influenza A Virus H1N1:Limonene as a Potential Household Disinfectant Against Virus

This work explored the compositions of a crude extract of peels of Citrus x aurantium using a gas chromatography-mass spectrometry (GC-MS) technique. The crude extract of peels of C. ×  aurantium was analyzed by GC-MS revealing the presence of limonene as the major compound, accounting for 93.7% of the total. Virucidal activity of the oil of C. x aurantium peels against influenza A virus H1N1 was evaluated by the ASTM E1053-20 method. Moreover, the virucidal activity was also investigated of D-limonene, the major terpene in essential oils of C. x aurantium, and its enantiomer L-limonene. The essential oil of the C. x aurantium peels produced a log reduction of 1.9 to 2.0, accounting for 99% reduction of the virus, while D- and L-limonene exhibited virucidal activity with a log reduction of 3.70 to 4.32 at concentrations of 125 and 250.0 µg/mL, thus reducing the virus by 99.99%. Previous work found that D-limonene exhibited antiviral activity against herpes simplex virus, but L-limonene, an enantiomer of D-limonene, has never been reported for antiviral activity. This work demonstrates the antiviral activity of L-limonene for the first time. Moreover, this work suggests that concentrations of 0.0125% to 0.025% of either D- or L-limonene can possibly be used as a disinfectant against viruses, probably in the form of essential oil sprays, which may be useful disinfectants against the airborne transmission of viruses, such as influenza and COVID-19.

Biomedical Applications of Chinese Herb-Synthesized Silver Nanoparticles by Phytonanotechnology

Recent advances in nanotechnology have opened up new avenues for the controlled synthesis of nanoparticles for biomedical and pharmaceutical applications. Chinese herbal medicine is a natural gift to humanity, and it has long been used as an antibacterial and anticancer agent. This study will highlight recent developments in the phytonanotechnological synthesis of Chinese herbal medicines to utilize their bioactive components in biomedical and therapeutic applications. Biologically synthesized silver nanoparticles (AgNPs) have emerged as a promising alternative to chemical and physical approaches for various biomedical applications. The comprehensive rationale of combinational or synergistic effects of Chinese herb-based AgNPs synthesis was investigated with superior physicochemical and biological properties, and their biomedical applications, including antimicrobial and anticancer activity and wound healing properties. AgNPs can damage the cell ultrastructure by triggering apoptosis, which includes the formation of reactive oxygen species (ROS), DNA disintegration, protein inactivation, and the regulation of various signaling pathways. However, the anticancer mechanism of Chinese herbal medicine-based AgNPs is more complicated due to the potential toxicity of AgNPs. Further in-depth studies are required to address Chinese herbs' various bioactive components and AgNPs as a synergistic approach to combat antimicrobial resistance, therapeutic efficiency of drug delivery, and control and prevention of newly emerged diseases.

Recent Advances on Nanomaterials to COVID-19 Management: A Systematic Review on Antiviral/Virucidal Agents and Mechanisms of SARS-CoV-2 Inhibition/Inactivation

The current pandemic of coronavirus disease 2019 (COVID-19) is recognized as a public health emergency of worldwide concern. Nanomaterials can be effectively used to detect, capture/inactivate or inhibit coronavirus cell entry/replication in the human host cell, preventing infection. Their potential for nanovaccines, immunoengineering, diagnosis, repurposing medication, and disinfectant surfaces targeting the novel coronavirus (SARS-CoV-2) is highlighted. In this systematic review the aim is to present an unbiased view of which and how nanomaterials can reduce the spread of COVID-19. Herein, the focus is on SARS-CoV-2, analyzing 46 articles retrieved before December 31, 2020. The interface between nanomaterials is described, and the main mechanisms to inhibit SARS-CoV-2 pathogenesis and viral inactivation are also discussed. Nanocarbons, biopolymeric, copper, and silver nanoparticles are potential antiviral and virucidal agents toward self-cleaning and reusable filter media and surfaces (e.g., facial masks), drug administration, vaccines, and immunodiagnostic assays. Trends in toxicology research and safety tests can help fill the main gaps in the literature and overcome health surveillance's challenges. Phytochemicals delivery by nanocarriers also stand out as candidates to target and bio-friendly therapy. Nanocellulose might fill in the gaps. Future research using nanomaterials targeting novel therapies/prophylaxis measures to COVID-19 and future outbreaks is discussed.

Drug Repurposing in the COVID-19 Era: Insights from Case Studies Showing Pharmaceutical Peculiarities

COVID-19 may lead to severe respiratory distress syndrome and high risk of death in some patients. So far (January 2021), only the antiviral remdesivir has been approved, although no significant benefits in terms of mortality and clinical improvement were recently reported. In a setting where effective and safe treatments for COVID-19 are urgently needed, drug repurposing may take advantage of the fact that the safety profile of an agent is already well known and allows rapid investigation of the efficacy of potential treatments, at lower costs and with reduced risk of failure. Furthermore, novel pharmaceutical formulations of older agents (e.g., aerosolized administration of chloroquine/hydroxychloroquine, remdesivir, heparin, pirfenidone) have been tested in order to increase pulmonary delivery and/or antiviral effects of potentially active drugs, thus overcoming pharmacokinetic issues. In our review, we will highlight the importance of the drug repurposing strategy in the context of COVID-19, including regulatory and ethical aspects, with a specific focus on novel pharmaceutical formulations and routes of administration.