The disease-preventive and medicinal properties of plant polyphenolic compounds have long been known. As active ingredients, they are used to prevent and treat many noncommunicable diseases. In recent decades, marine macroalgae have attracted the attention of biotechnologists and pharmacologists as a promising and almost inexhaustible source of polyphenols. This heterogeneous group of compounds contains many biopolymers with unique structure and biological properties that exhibit high anti-infective activity. In the present review, the authors focus on the antiviral potential of polyphenolic compounds (phlorotannins) from marine algae and consider the mechanisms of their action as well as other biological properties of these compounds that have effects on the progress and outcome of viral infections. Effective nutraceuticals, to be potentially developed on the basis of algal polyphenols, can also be used in the complex therapy of viral diseases. It is necessary to extend in vivo studies on laboratory animals, which subsequently will allow proceeding to clinical tests. Polyphenolic compounds have a great potential as active ingredients to be used for the creation of new antiviral pharmaceutical substances.

An epidemic of COVID-19 (Coronavirus disease 2019) etiologically associated with the SARS-CoV-2 (Severe acute respiratory syndrome-related coronavirus 2) that occurred at the turn of 2019–2020 firstly in Wuhan (Hubei province of China) and then spread to many countries around the world rose a new wave of interest to coronaviruses. The first coronaviruses – members of the Coronaviridae family belonging to the order Nidovirales — were discovered in the first half of the last century. The first human coronavirus, HCoV-B814, was isolated in 1965 that was not preserved in available virological collections. Over the last time, old-fashioned names and terms have been overlapped. By the beginning of the XXI century coronaviruses posed a serious veterinary problem but it was believed that epidemic coronaviruses were not among highly dangerous viruses. Scientific community had to revise such views first in 2002 when SARS-CoV (Severe acute respiratory syndrome-related coronavirus) was transferred to human population in the Southeast Asia from bats, and then in 2012 when natural foci of the MERS-CoV (Middle East respiratory syndrome-related coronavirus) were found on the territory of the Arabian Peninsula. Due to an increased interest in coronaviruses, a large number of new Coronaviridae members was discovered in the first two decades of the XXI century, which required to revise its taxonomic structure several times. This review is aimed at outlining a history of investigating coronaviruses and their current classification that was shaped in early 2020 in accordance to the last recommendations of the International Committee on Taxonomy of Viruses.

Inflammatory reactions are part of a complex biological response that plays a vital role in the appearance of various stimuli resulting from tissue and cell damage, the invasion of pathogenic bacteria, and the formation of the subsequent adaptive immune response. The production of many triggers and mediators of inflammation, which are inducers of pro-inflammatory factors, is controlled by numerous differentiation programs, through which inflammation is resolved and tissue homeostasis is restored. However, prolonged inflammatory responses or dysregulation of pro-inflammatory mechanisms can lead to chronic inflammation. Modern advances in biotechnology have made it possible to characterize the anti-inflammatory activity of phlorotannins, polyphenolic compounds from brown seaweed, and the mechanisms by which they modulate the inflammatory response. The purpose of this review is to analyze and summarize the results of numerous experimental in vitro and in vivo studies, illustrating the regulatory mechanisms of these compounds, which have a wide range of biological effects on the body. The results of these studies and the need for further research are discussed.

Whereas the XX century marked the history of acute respiratory disease investigation as a period for generating in-depth system of combating influenza viruses (Articulavirales: Orthomyxoviridae, Alpha-/Betainfluenzavirus) (based on environmental and virological monitoring of influenza A virus in its natural reservoir — aquatic and semi-aquatic birds — to supervising epidemic influenza), a similar system is necessary to build up in the XXI century with regard to especially dangerous betacoronaviruses (Nidovirales: Coronaviridae, Betacoronavirus): Severe acute respiratory syndrome-related coronavirus (SARS-CoV) (subgenus Sarbecovirus), Severe acute respiratory syndrome-related coronavirus 2 (SARSCoV-2) (Sarbecovirus), Middle East respiratory syndrome-related coronavirus (MERS-CoV) (Merbecovirus). This became particularly evident after pandemic potential has been revealed in 2020 by the SARS-CoV-2. This review provides an insight into the historic timeline of discovering this virus, its current taxonomy, ecology, virion morphology, life cycle, molecular biology, pathogenesis and clinical picture of the etiologically related COVID-19 (Coronavirus disease 2019) as well as data available in the scientific literature on the anti-SARS-CoV-2-effectiveness of passive immunotherapy and most debated drugs used to treat COVID-19: Chloroquine, Hydroxychloroquine, Nitazoxanide, Ivermectin, Lopinavir and Ritonavir, Camostat mesilate, Remdesivir, Ribavirin, Tocilizumab, Anakinra, corticosteroids, and type I interferons. The pathogenesis of SARS-CoV-2 infection implicates decreased efficacy of artificial respiration, which, in this case might be replaced by more efficient extracorporeal membrane blood oxygenation supplemented with nitrogen oxide and/or Heliox inhalations.

The structural diversity and unique physicochemical properties of sulphated polysaccharides of red algae carrageenans (CRGs), to a great extent, determine the wide range of their antiviral properties. This work aimed to compare the antiviral activities of different structural types of CRGs: against herpes simplex virus type 1 (HSV-1) and enterovirus (ECHO-1). We found that CRGs significantly increased the resistance of Vero cells to virus infection (preventive effect), directly affected virus particles (virucidal effect), inhibited the attachment and penetration of virus to cells, and were more effective against HSV-1. CRG1 showed the highest virucidal effect on HSV-1 particles with a selective index (SI) of 100. CRG2 exhibited the highest antiviral activity by inhibiting HSV-1 and ECHO-1 plaque formation, with a SI of 110 and 59, respectively, when it was added before virus infection. CRG2 also significantly reduced the attachment of HSV-1 and ECHO-1 to cells compared to other CRGs. It was shown by molecular docking that tetrasaccharides—CRGs are able to bind with the HSV-1 surface glycoprotein, gD, to prevent virus–cell interactions. The revealed differences in the effect of CRGs on different stages of the lifecycle of the viruses are apparently related to the structural features of the investigated compounds.