Forest-bathing and physical activity as weapons against COVID-19: a review.

Strengthening the immune system in order to better withstand the threat of COVID-19 is an important way to ensure the protection of our health against the current pandemic associated with SARS-CoV-2. There are many ways to achieve this, but with current circumstances, certain modalities stand out as being the most valid and are certainly worth greater consideration. Here we review the effects that particular immuno-strengthening activities can have on limiting the severity of COVID-19 disease as well as preventing virus infection. Physical activity, in particular, should not be discounted as an important method of prevention of viral diseases as it triggers many biological processes within the human body which in turn lead to heightened natural defences against viral infections. When exercise is performed in forested areas, these protective health benefits may be increased since many plant species emit biogenic volatile compounds (VOCs) which, when inhaled, have many protective properties. These VOCs have been shown in particular to have immunostimulatory effects on the human body and, thus, they could be of use in the prevention and/or treatment of COVID-19. Being amongst trees may also help to alleviate stress and anxiety, lowering cortisol levels and consequently helping the proper functioning of the immune system. In the following work, we have performed an analysis of the available scientific literature which looks at the effects of physical exercise as well as 'forest-bathing' on the immune system's ability to fight disease, especially of course as it relates to COVID-19. Our review aims at shedding light on the benefits of exercising outdoors in green areas and suggests reforestation as a protective measure against future outbreaks.

Potential Anti-SARS-CoV-2 Molecular Strategies.

Finding effective antiviral molecular strategies was a main concern in the scientific community when the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged at the end of 2019 as an easily transmissible and potentially deadly ß-coronavirus able to cause the coronavirus disease 19 (COVID-19), which famously led to one of the most worrying pandemics in recent times. Other members of this zoonotic pathogenic family were already known before 2019, but apart from the SARS-CoV, which was responsible of severe acute respiratory syndrome (SARS) pandemic in 2002/2003, and Middle East respiratory syndrome coronavirus (MERS-CoV), whose main impact on humans is geographically restricted to Middle Eastern countries, the other human ß-coronaviruses known at that time were those typically associated with common cold symptoms which had not led to the development of any specific prophylactic or therapeutic measures. Although SARS-CoV-2 and its mutations are still causing illness in our communities, COVID-19 is less deadly than before and we are returning to normality. Overall, the main lesson learnt after the past few years of pandemic is that keeping our bodies healthy and immunity defenses strong using sport, nature-inspired measures, and using functional foods are powerful weapons for preventing the more severe forms of illness caused by SARS-CoV-2 and, from a more molecular perspective, that finding drugs with mechanisms of action involving biological targets conserved within the different mutations of SARS-CoV-2-and possibly within the entire family of ß-coronaviruses-gives more therapeutic opportunities in the scenario of future pandemics based on these pathogens. In this regard, the main protease (Mpro), having no human homologues, offers a lower risk of off-target reactivity and represents a suitable therapeutic target in the search for efficacious, broad-spectrum anti-ß-coronavirus drugs. Herein, we discuss on the above points and also report some molecular approaches presented in the past few years to counteract the effects of ß-coronaviruses, with a special focus on SARS-CoV-2 but also MERS-CoV.

Evaluating In Silico the Potential Health and Environmental Benefits of Houseplant Volatile Organic Compounds for an Emerging 'Indoor Forest Bathing' Approach.

The practice of spending time in green areas to gain the health benefits provided by trees is well known, especially in Asia, as 'forest bathing', and the consequent protective and experimentally detectable effects on the human body have been linked to the biogenic volatile organic compounds released by plants. Houseplants are common in houses over the globe and are particularly appreciated for aesthetic reasons as well for their ability to purify air from some environmental volatile pollutants indoors. However, to the best of our knowledge, no attempt has been made to describe the health benefits achievable from houseplants thanks to the biogenic volatile organic compounds released, especially during the day, from some of them. Therefore, we performed the present study, based on both a literature analysis and in silico studies, to investigate whether the volatile compounds and aerosol constituents emitted by some of the most common houseplants (such as peace lily plant, Spathiphyllum wallisii, and iron plant, Aspidistra eliator) could be exploited in 'indoor forest bathing' approaches, as proposed here for the first time not only in private houses but also public spaces, such as offices, hospitals, and schools. By using molecular docking (MD) and other in silico methodologies for estimating vapor pressures and chemico-physical/pharmacokinetic properties prediction, we found that ß-costol is an organic compound, emitted in appreciable amounts by the houseplant Spathiphyllum wallisii, endowed with potential antiviral properties as emerged by our MD calculations in a SARS-CoV-2 Mpro (main protease) inhibition study, together with sesquirosefuran. Our studies suggest that the anti-COVID-19 potential of these houseplant-emitted compounds is comparable or even higher than known Mpro inhibitors, such as eugenol, and sustain the utility of houseplants as indoor biogenic volatile organic compound emitters for immunity boosting and health protection.

In Silico Investigation on the Interaction of Chiral Phytochemicals from Opuntia ficus-indica with SARS-CoV-2 Mpro

Opuntia ficus-indica is a cactaceous plant native to America but, nowadays, widely found worldwide, having been the most common domesticated species of cactus grown as a crop plant in semiarid and arid parts of the globe, including several Mediterranean basin countries. Opuntia ficus-indica can be regarded as a medicinal plant, being source of numerous bioactive phytochemicals such as vitamins, polyphenols, and amino acids. The urgent need for therapeutic treatments for the COronaVIrus Disease 19 (COVID-19), caused by the Severe Acute Respiratory Syndrome (SARS)-Coronavirus (CoV)-2, justifies the great attention currently being paid not only to repurposed antiviral drugs, but also to natural products and herbal medications. In this context, the anti-COVID-19 utility of Opuntia ficus-indica as source of potential antiviral drugs was investigated in this work on the basis of the activity of some of its phytochemical constituents. The antiviral potential was evaluated in silico in docking experiments with Mpro, i.e., the main protease of SARS-CoV-2, that is one of the most investigated protein targets of therapeutic strategies for COVID-19. By using two web-based molecular docking programs (1-Click Mcule and COVID-19 Docking Server), we found, for several flavonols and flavonol glucosides isolated from Opuntia ficus-indica, good binding affinities for Mpro, and in particular, binding energies lower than −7.0 kcal/mol were predicted for astragalin, isorhamnetin, isorhamnetin 3-O-glucoside, 3-O-caffeoyl quinic acid, and quercetin 5,4′-dimethyl ether. Among these compounds, the chiral compound astragalin showed in our in silico studies the highest affinity for Mpro (−8.7 kcal/mol) and also a low toxicity profile, emerging, thus, as an interesting protease inhibitor candidate for anti-COVID-19 strategies.

Molecular Basis of the Therapeutical Potential of Clove (Syzygium aromaticum L.) and Clues to Its Anti-COVID-19 Utility.

The current COronaVIrus Disease 19 (COVID-19) pandemic caused by SARS-CoV-2 infection is enormously affecting the worldwide health and economy. In the wait for an effective global immunization, the development of a specific therapeutic protocol to treat COVID-19 patients is clearly necessary as a short-term solution of the problem. Drug repurposing and herbal medicine represent two of the most explored strategies for an anti-COVID-19 drug discovery. Clove (Syzygium aromaticum L.) is a well-known culinary spice that has been used for centuries in folk medicine in many disorders. Interestingly, traditional medicines have used clove since ancient times to treat respiratory ailments, whilst clove ingredients show antiviral and anti-inflammatory properties. Other interesting features are the clove antithrombotic, immunostimulatory, and antibacterial effects. Thus, in this review, we discuss the potential role of clove in the frame of anti-COVID-19 therapy, focusing on the antiviral, anti-inflammatory, and antithrombotic effects of clove and its molecular constituents described in the scientific literature.