Abstract

COVID-19 infection, caused by the SARS-CoV-2 virus, is associated withsubstantial morbidity and mortality. COVID-19 infection has three distinct phases: 1,early infection phase; 2, pulmonary phase; and 3, the hyperinflammatory phase.Despite a major focus on vaccines and new therapeutics, existing drugs sharing someknown mechanistic with this virus, have also gained interest. The potential positioningof three mature innovative drugs, which could be of potential use in this pandemicenvironment, is discussed in this chapter: OM-85 and calcium dobesilate, and their saltform etamsylate, have revealed anti-viral and anti-inflammatory properties. OM-85, abacterial extract originating from 21 pathogenic strains isolated from human lungs andindicated for the prevention of recurrent respiratory tract infections, stimulates bothinnate and adaptive immunity, resulting in non-specific loco-regional immuneresponses. It has shown anti-viral activity in a number of virus infection models,including influenza H1N1, rhinovirus, and more recently, coronaviruses. It has alsoshown some immunoregulatory properties. Accordingly, there is a rationale for furtherinvestigations on OM-85 to be used as prophylaxis for other respiratory infections andpotentially in long-COVID. For calcium dobesilate, currently indicated for thetreatment of microvascular diseases while preserving microvascular integrity viaantioxidant and anti-inflammatory properties, there are cumulating data that couldpromote its potential use for the treatment during phase 2 to protect the vascularendothelium. Calcium dobesilate has anti-viral properties and was recently shown tointerfere with the SARS-CoV-2 spike-protein binding to the ACE2 receptor.Accordingly, one could also postulate to use it during phase 1. Etamsylate, an antihaemorrhagic and antiangiogenic agent that improves platelet adhesiveness andrestores capillary resistance, is indicated for the prevention and treatment of capillaryhaemorrhages. Considering its mechanism of action, etamsylate could be envisage foruse as potential treatment during phase 3 for viral-induced complications. Importantly, none of these afore mentioned drugs are currently approved for the prevention ortreatment of SARS-CoV-2 viral infection. Further, the conduction of well-designedclinical trials is warranted.

Abstract

Introduction: COVID -19, caused by the novel coronavirus or SARS-CoV2,has claimed thousands of lives across the world as well as in India as of now. There aremany antivirals available to treat COVID-19 at present. Some of them are safe andeffective, while many others have been banned by the World Health Organization.Hence, it is very important for clinicians and nurses to know accurately and preciselyabout the safe and effective antivirals to treat COVID-19. Materials and methods: Thepurpose of this chapter is to address the issues with available antivirals, their modes ofaction, adverse effects, and drug interactions. Literature search has been carried outmeticulously. Conclusion: Many options are available for treating COVID-19, buttreatment needs to be tailored according to the situation.

Abstract

The development of multidrug-resistant bacteria (MDRB) and theemergence of new lethal diseases have raised the need for potent anti-infective agentswith different killing action mechanisms that contribute to treating and/or supportingthe currently used drugs. For this purpose, bacteriocins are considered excellentcandidates with promising potential. Bacteriocins are ribosomally synthesizedantimicrobial peptides that are produced by many bacterial genera. They arecharacterized by high thermal stability, being active over a wide pH range, and havingspecificity against selected bacterial strains by employing specific receptors on theircell membrane, which encourages bacteriocins to use in clinical applications as supportand/or alternatives currently used antibiotics. Interestingly, bacteriocins have manyadvantages over antibiotics, such as the relative difficulty of developing resistancecompared to broad-spectrum antibiotics. Moreover, due to their simple biosyntheticmechanisms, bacteriocins can be easily bioengineered, which improves their activity orspecificity against selected microorganisms. Additionally, bacteriocins originating fromlactic acid bacteria have the extra safety advantage because many LAB and theirproducts are classified by the American Food and Drug Administration (FDA) to begenerally recognized as safe (GRAS). Bacteriocins have promising pharmaceuticalpotentials as anti-infective agents, anti-MDRB agents, antileishmanial, and antiviralagents. Moreover, bacteriocins have been used to treat many ulcers, tumors, andcancers. In this chapter, we highlight the importance of bacteriocins as anti-infectiveagents, describing their common action mechanisms and recent clinical andtherapeutical applications of bacteriocins. Finally, prospects in this field are discussedto discover and develop more diverse and efficient bacteriocins with potent antiinfective activities.

Abstract

The delicate balance between oxidants and antioxidants is a dynamicprocess, and when it hampers, oxidative stress occurs. Oxidative stress is nowsuggested to have a direct correlation with a viral infection, which in turn inducesseveral oxidants like nitric oxide radicals, superoxide anions, hydroxyl radicals andtheir by-products (viz. hydrogen peroxide). All of these oxidants and their by-productscontribute to viral pathogenesis and ultimately cause infectious diseases. Theconsequences of viral diseases account for considerable economic loss worldwide. Inresponse to this, the scientific fraternity throughout the world is investigating the basicmechanisms underlying such diseases, as well as identifying novel therapeuticstrategies for the prevention and treatment of such maladies. Over the last few decades,scientists oriented their research aims mostly towards elucidating the immunologicalbasis of viral replication and pathogenesis, but a little is written about the implicationsof such research for drug development, which provides the impetus behind the creationof the present chapter enabling the readers to have a comprehensive overview on theinvolvement of free radicals in viral diseases along with latest updates towardsdeveloping novel therapeutic strategies against these diseases. The present chaptersummarizes the relationship between oxidative stress, viral infection, and a variety oftherapeutic strategies conferred by antioxidants. Antiviral therapeutic strategies basedon antioxidants are considered to be a promising area of research against viralinfections.

Abstract

The immune response is an essential regulatory system designed to conferprotective ability to hosts against various foreign challenges, including bacteria andviruses. However, self-perpetuation and over-aggravation of the immune system arealso responsible for a variety of infectious diseases in humans. Phytochemicals arebiologically active, non-nutritive, low molecular weight secondary metabolites thatoccur in different parts of plants and are well known for their various health-beneficialeffects. The non-nutritional plant-based bioactive molecules are amongst the majorgroups responsible for a majority of immunomodulatory health benefits. Thesephytomolecules have been shown to possess a significant role in the regulation ofvarious vital cell signaling pathways involved in the pathogenesis of various infectiousdiseases such as tuberculosis, hepatitis, pneumonia and dengue. Bioactive moleculesmay play an essential protective role in infectious diseases by interfering with innateand adaptive immune cell regulation, especially proinflammatory cytokine synthesisand cell activation. Considering this, nowadays, most of the natural products areprocessed and developed as immunomodulators and immunosuppressants for differentinfectious diseases. In this chapter, we will discuss phytomolecules, their biologicalpotential, and how these molecules regulate innate and adaptive immune responses ininfectious diseases. We will also discuss and compare the depth of knowledge availablefrom previous works, which emphasize the importance of developing phytomoleculesbased preventive and therapeutic approaches as alternatives to synthetic counterparts ininfectious diseases.