Infection by coronavirus (CoV-19) has led to emergence of a pandemic called as Coronavirus Disease (COVID-19) that has so far affected about 210 countries. The dynamic data indicate that the pandemic by CoV-19 so far has infected 2,403,963 individuals, and among these 624,698 have recovered while, it has been fatal for 165,229. Without much experience, currently, the medicines that are clinically being evaluated for COVID-19 include chloroquine, hydroxychloroquine, azithromycin, tocilizumab, lopinavir, ritonavir, tocilizumab and corticosteroids. Therefore, countries such as Italy, USA, Spain and France with the most advanced health care system are partially successful to control CoV-19 infection. India being the 2nd largest populous country, where, the healthcare system is underdeveloped, major portion of population follow unhygienic lifestyle, is able to restrict the rate of both infection and death of its citizens from COVID-19. India has followed an early and a very strict social distancing by lockdown and has issued advisory to clean hands regularly by soap and/or by alcohol based sterilizers. Rolling data on the global index of the CoV infection is 13,306, and the index of some countries such as USA (66,148), Italy (175,055), Spain (210,126), France (83,363) and Switzerland (262,122) is high. The index of India has remained very low (161) so far, mainly due to early implementation of social lockdown, social distancing, and sanitizing hands. However, articles on social lockdown as a preventive measure against COVID-19 in PubMed

CO 2 and NO 2 emissions Environmental regeneration Pollution and wildlife Self nurturing nature Social lockdown Coronavirus Disease (COVID-19) has become the largest pandemic that has affected 210 countries. Rolling data indicate that 257,3605 people are infected by the disease, from which 701,838 have recovered and 178,562 have died. No specific medicine or vaccine is available yet to control the disease, hence, social distancing via lockdown is widely adopted as the only preventive measure. Social distancing is observed at different level of strictness in different counties but it almost made the world to stands still. Although scientific articles on this largest social move are scanty, it resulted in benefiting the deteriorated environment to revive back. Many environmental indices such as lowering NO 2 and CO 2 emissions and reduction in particulate matters in air as a result of less human activities have led to clean air and pollution free water in many countries. Undoubtedly, the world was experiencing pollution in several countries due to mainly human activities including urbanization, industrialization, fossil fuel exhaustion etc. Under such situation a special (natural) a protective measure was awaited to fix environmental issues. Probably, the lockdown is one of the natural effects expected by nature via introduction of COVID-19. It is because, introduction of COVID-19 to nature was an outcome of mutation from two of its pre-existing forms, although, debate on it is still continuing. Viability of CoV-19 virus found to have a lot of correlation with aquatic and terrestrial environmental parameters such as pH, surface type, temperature etc. Air pollution is found to increase the risk of COVID-19 infection, therefore, use of mask and alcohols based standard

Many major cities that witnessed heavy air pollution by nitrogen dioxide (NO 2) and particulate matter (PM) have experienced a high rate of infection and severity of the coronavirus disease pandemic (COVID-19). This phenomenon could be explained by the overexpression of the angiotensin converting enzyme 2 (ACE-2) on epithelial cell surfaces of the respiratory tract. Indeed, ACE-2 is a receptor for coronaviruses including the severe acute respiratory syndrome coronavirus 1 and 2 (SARS-CoV), and ACE-2 is overexpressed under chronic exposure to air pollution such as NO 2 and PM 2.5. In this review, we explain that ACE-2 acts as the sole receptor for the attachment of the SARS-CoV-2 via its spike protein. The fact that respiratory and vascular epithelial cells express ACE-2 has been previously observed during the 2003 epidemic of the SARS-CoV-1 in China, and during the 2012 Middle East respiratory syndrome in Saudi Arabia. High ACE-2 expression in respiratory epithelial cells under air pollution explains the positive correlation between the severity in COVID-19 patients and elevated air pollution, notably high NO 2 and PM 2.5 levels. Specific areas in India, China, Italy, Russia, Chile and Qatar that experience heavy air pollution also show high rates of COVID-19 infection and severity. Overall, we demonstrate a link between NO 2 emissions, PM 2.5 levels, ACE-2 expression and COVID-19 infection severity. Therefore, air pollution should be reduced in places where confirmed cases of COVID-19 are unexpectedly high.

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The outbreak of COVID-19 has made a global catastrophic situation that caused 1,039,406 deaths out of 35,347,404 infections, and it will also cause significant socioeconomic losses with poverty increasing from 17.1 to 25.9%. Although the spreading rate of COVID-19 is very high on October 6, 2020, the death rate is still less than 2.94%. Nonetheless, this review article shows that the lockdown has induced numerous positive impacts on the environment and on energy consumption. For instance, the lockdown has decreased the electricity demand by 30% in Italy, India, Germany, and the USA, and by 12-20% in France, Germany, Spain, India, and the UK. Additionally, the expenditure of the fuel supply has been decreased by 4% in 2020 as compared to the previous years (2012-2019). In particular, The global demand for coal fuel has been reduced by 8% in March and April 2020 as compared to the same time in 2019. In terms of harmful emissions, the lockdowns reduced the emissions of nitrous oxides by 20-30% in China, Italy, France, Spain, and by 77.3% in São Paulo, Brazil. Similarly, the particulate matter level has been reduced from 5-15% in Western Europe, to 200% in New Delhi, India, which in turn has enhanced the air quality in a never-seen manner in recent times. In some places, such as New York, USA, CO 2 emission was also reduced by 5-10%. The water quality, in several polluted areas, has also been remarkably enhanced, for example, the dissolved oxygen content in the Ganga River, India, has increased by about 80%. Traffic congestion has also been reduced worldwide, and in some areas, it has been reduced by 50%, such as New York and Los Angeles, USA. Overall, while the COVID-19 pandemic has shrinked the global economy by 13-32%, the pandemic has also clearly benefited to other sectors, which must be considered as the spotlight for the permanent revival of the global ecosystem.

Oxidative stress is implicated in both hypo- and hyper-thyroid conditions. In the present study an attempt has been made to elucidate possible interaction between vitamin E or/and curcumin (two established antioxidants) with active portion (redox signaling intervening region) of nuclear factor erythroid 2-related factor 2 (NRF2) as a mechanism to alleviate oxidative stress in rat heart under altered thyroid states. Fifty Wistar strain rats were divided into two clusters (Cluster A: hypothyroidism; Cluster B: hyperthyroidism). The hypo- (0.05% (w/v) propylthiouracil in drinking water) and hyper- (0.0012% (w/v) T4 in drinking water) thyroid rats in both clusters were supplemented orally with antioxidants (vitamin E or/and curcumin) for 30 days. Interactive least count difference and principal component analyses indicated increase in lipid peroxidation, reduced glutathione level, alteration in the activities and protein expression of antioxidant enzymes like superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase under altered thyroid states. However, the expression of stress survival molecules; nuclear factor κB (NFκB) and the serine-threonine kinase B (Akt), in hyper-thyroidism only points towards different mechanisms responsible for either condition. Co-administration of vitamin E and curcumin showed better result in attenuating expression of mammalian target for rapamycin (mTOR), restoration of total protein content and biological activity of Ca 2+ ATPase in hyperthyroid rats, whereas, their individual treatment showed partial restoration. Since NRF2 is responsible for activation of antioxidant response element and subsequent expression of antioxidant enzymes, possible interactions of both vitamin E or/and curcumin with the antioxidant enzymes, NRF2 and its regulator Kelch ECH associating protein (KEAP1) were studied in silico . For the first time, a modeled active portion of the zipped protein NRF2 indicated its interaction with both vitamin E and curcumin. Further, curcumin and vitamin E complex showed in silico interaction with KEAP1. Reduction of oxidative stress by curcumin and/or vitamin E may be due to modulation of NRF2 and KEAP1 function in rat heart under altered thyroid states.

Antioxidant defence system, a highly conserved biochemical mechanism, protects organisms from harmful effects of reactive oxygen species (ROS), a by-product of metabolism. Both invertebrates and vertebrates are unable to modify environmental physical factors such as photoperiod, temperature, salinity, humidity, oxygen content, and food availability as per their requirement. Therefore, they have evolved mechanisms to modulate their metabolic pathways to cope their physiology with changing environmental challenges for survival. Antioxidant defences are one of such biochemical mechanisms. At low concentration, ROS regulates several physiological processes, whereas at higher concentration they are toxic to organisms because they impair cellular functions by oxidizing biomolecules. Seasonal changes in antioxidant defences make species able to maintain their correct ROS titre to take various physiological functions such as hibernation, aestivation, migration, and reproduction against changing environmental physical parameters. In this paper, we have compiled information available in the literature on seasonal variation in antioxidant defence system in various species of invertebrates and vertebrates. The primary objective was to understand the relationship between varied biological phenomena seen in different animal species and conserved antioxidant defence system with respect to seasons.