Current Medicinal Chemistry - Volume 28, Issue 26, 2021

Respiratory infections caused by viruses such as influenza and coronavirus are a serious global problem due to their high infection rates and potential to spark pandemics, such as the current COVID-19 pandemic. Although preventing these infections by using vaccines has been the most successful strategy to date, effective vaccines are not always available. Therefore, developing broad-spectrum anti-viral drugs to treat such infections is essential, especially in the case of immunocompromised patients or for outbreaks of novel virus strains. Sialic acids have been highlighted as a key molecule in the viral infection cycle, with terminally sialylated glycans acting as a target for several viral proteins involved in infection, particularly respiratory infection. Inhibitors of one such protein, neuraminidase, are the only anti-influenza drugs currently on the market. Problems with neuraminidase inhibitors, including the development of resistance and a relatively narrow spectrum of activity, drive the need for an improved understanding of the viral infection cycle and the development of more resilient, broader-spectrum anti-viral treatments. Hence, this review outlines the various roles played by sialic acids in respiratory viral infection and provides examples of drugs that exploit sialic acids to inhibit viral infections. It has been concluded that drugs targeting host cell expression of sialic acid could be especially well suited to inhibiting a broad spectrum of respiratory infections. This warrants the continued design and improvement of such drugs in an attempt to lessen the burden of respiratory infections.

COVID-19, an infectious disease caused by a newly discovered enveloped virus (SARS-CoV-2), was first reported in Wuhan, China, in December 2019 and affected the whole world. The infected individual may develop symptoms such as high fever, cough, myalgia, lymphopenia, respiratory distress syndrome etc., or remain completely asymptomatic after the incubation period of two to fourteen days. As the virus is transmitted by inhaling infectious respiratory droplets that are produced by sneezing or coughing, so early and rapid diagnosis of the disease can prevent infection and transmission. In the current pandemic situation, the medical industry is looking for new technologies to monitor and control the spread of COVID-19. In this context, the current review article highlights the Artificial Intelligence methods that are playing an effective role in rapid, accurate and early diagnosis of the disease via pattern recognition, machine learning, expert system and fuzzy logic by improving cognitive behavior and reducing human error. Auto-encoder deep learning method, α-satellite, ACEMod and heterogeneous graph auto- encoder are AI approaches that determine the transfer rate of virus and are helpful in shaping public health and planning. In addition, CT scan, X-ray, MRI, and RT-PCR are some of the techniques that are being employed in the identification of COVID-19. We hope using AI techniques; the world can emerge from COVID-19 pandemic while mitigating social and economic crisis.

Coronaviruses (CoVs) belong to a large family of zoonotic supercapsid viruses, including about 40 species of RNA-containing viruses with several strains capable of causing damage to the lungs and respiratory tract. The severe acute respiratory syndrome coronavirus (SARS-CoV) was responsible for the worldwide SARS outbreak in 2003. The rapid global spread of SARS-CoV-2 has been the cause of significant health concerns and thousands of deaths in 2019-2020 and outlined the need for novel antivirals. The present review is devoted to the development of effective and selective nucleoside drugs for the treatment of coronavirus infections. To date, about half of antivirals have been created based on nucleosides. The majority of drugs based on nucleosides have been approved by FDA. This indicates a fruitful area for the development of novel antivirals based on nucleosides. The review describes the main features of pathogenic SARS-CoV, MERS-CoV, and SARS-CoV-2 strains, presents their comparison, considers promising approaches to creating nucleoside drugs for the treatment of coronavirus infections and provides a systematic evaluation of all the known nucleoside derivatives, which inhibit the reproduction of coronaviruses in cells. To date, two known nucleoside drugs (Remdesivir, Favipiravir) have been recommended for the treatment of SARS-CoV-2 infection and nine hit compounds based on nucleosides and their analogues have been found, one of which efficiently suppressing SARS-CoV-2 replication and eight others inhibiting SARS-CoV replication.

Coronaviruses (CoVs) are enveloped viruses with particle-like characteristics and a diameter of 60-140 nm, positively charged, and single-stranded RNA genomes, which caused a major outbreak of human fatal pneumonia in the beginning of the 21st century. COVID-19 is currently considered a continuous potential pandemic threat across the globe. Therefore, considerable efforts have been made to develop innovative methods and technologies for suppressing the spread of viruses as well as inactivating the viruses but COVID-19 vaccines are still in the development phase. This perspective focuses on the sensing, detection and therapeutic applications of CoVs using inorganic- based nanomaterials, metal complexes, and metal-conjugates. Synthetic inorganic- based nanoparticles interact strongly with proteins of viruses due to their morphological similarities, and therefore, numerous antivirals have been tested for efficacy against different viruses in vitro through colorimetric and electrochemical assays. Metal complexes- based agents such as bismuth complexes form an attractive class of drugs with a number of therapeutic applications, including the inhibition and duplex-unwinding activity of SARS-CoV helicase by quantitative real-time PCR (Q-RT-PCR), phosphate release assay and radioassay studies. Metal-conjugates show major effects on inhibiting the 3Clike protease of SARS-CoV and the replication of RNA-dependent RNA polymerase (RdRp). We anticipate that these approaches will provide rapid and accurate antiviral strategies in the development of these innovative sensors for the detection, inhibition and antiviral activities of coronaviruses.

A newly identified virus appeared in Wuhan, China, in December 2019, was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and caused the coronavirus disease 2019 (COVID-19). SARS-CoV-2 presents similarities with two previous coronavirus pandemics, MERS (Middle East Respiratory Syndrome) and SARSCoV, concerning phylogenetic origin, structural composition, and clinical symptoms, thus, leading to common pathogenic mechanisms. The purpose of this review is to declare the role of interleukin-6 (IL-6) in the pathogenesis, prognosis, and treatment of COVID-19 by comparing its effect on SARS-CoV and MERS cases. Increased levels of IL-6 comprise the key for the stimulation of cytokine storm and the progression of SARS, MERS, and COVID-19 cases. Especially, in COVID-19 patients, the overactivation of NF-k, which is caused by the binding of coronavirus spike protein S to alveolar epithelial cells, up-regulates IL-6 and promotes its systematic circulation, causing alveolar damage and extrapulmonary injury. Additionally, IL-6 can be used to evaluate respiratory failure and identify asymptomatic patients. Tocilizumab (TCZ), a monoclonal antibody which blocks IL-6 signaling, comprises a remedial option against COVID-19. TCZ improves oxygenation, reduces fever, and decreases levels of IL-6. IL-6 plays a major role in the pathogenesis of cytokine storm and the progression of COVID-19 and may be used as a therapeutic target against COVID-19. However, further research is needed concerning the relation of IL-6 in COVID-19 cases, and more clinical trials are required to declare TCZ as a treatment option.

Photodynamic therapy has emerged as an effective therapeutic alternative to treat oncological, cardiovascular, dermatological, infectious, and ophthalmic diseases. Photodynamic therapy combines the action of a photosensitizer with light in the presence of oxygen to generate reactive oxygen species, capable of reacting with cellular components, resulting in injury and, consequently, inducing cellular death. Phthalocyanines are considered good photosensitizers, although most of them are lipophilic, difficulting their administration for clinical use. A strategy to overcome the lack of solubility of phthalocyanines in aqueous media is to incorporate them into different delivery systems. The present review aimed to summarize the current status of the main drug delivery systems used for Zn and Al phthalocyanines and their effect in photodynamic therapy, reported in the last five years. Liposomes, polymeric micelles, polymeric nanoparticles, and goldnanoparticles constituted some of the most used carriers and were discussed in this review. The latest studies reported strongly suggest that the application of nanotechnologies as delivery systems allows an increase in photodynamic therapy efficacy and reduces side-effects associated with the phthalocyanine administration, which represents a hope for cancer treatments.

Diabetes strongly influences the patient’s quality of life. The incidence of type 2 diabetes (T2D) accounts for approximately 90% of diabetic patients. Natural polysaccharides have been widely used for diabetes management. Changes in gut microbiota can also be used for the prevention and treatment of diabetes. In this review, the effects of different natural polysaccharides on gut microbiota, as well as the relationship between diabetes and the gut microbiome are summarized. The intestine is the primary location in which natural polysaccharides exert their biological activities and plays an important role in maintaining healthy bodily functions. Polysaccharides change the composition of the gut microbiota, which inhibits pathogen invasion and promotes beneficial bacterial growth. In addition, the gut microbiota degrade polysaccharides and produce metabolites to further modify the intestinal environment. Interestingly, the metabolites (short chain fatty acids and other bioactive components) have been shown to improve gut health, control glycemia, lower lipids, reduce insulin resistance, and alleviate inflammation. Therefore, understanding the underlying mechanisms by which soluble polysaccharides improve T2D through regulating the gut microbiota and provide a future reference for the management of T2D and its associated complications.

Pathogenic Escherichia coli poses a serious threat to global public health and is especially dangerous with the increase of antibiotic resistance. β-Glucuronidase (GUS) and some other glycosidases can serve as useful biomarkers or indicators for the detection of E. coli. The probes made up of a glycosyl residue (recognition group), a label or reporter group, and a linkage that is generally a direct glycosidic bond, are powerful analytical tools. Upon hydrolysis of the glycosidic linkages by the corresponding glycosidases, these probes irreversibly release detectable labels or reporter molecules. A variety of such glycosidase probes have been developed and applied for the detection of E. coli or the development of various corresponding detection methods. This paper provides an overview of recent advances in this field, covering the development and applications of chromogenic, fluorogenic, luminogenic, and electrochemical glycosidase substrates. The challenges and opportunities in the probe development for detection of E. coli are also discussed.

Pancreatic Ductal Adenocarcinoma (PDA) is a highly metastatic tumor, and the liver is its first target, which restricts the use of medications. PDA is considered one of the most aggressive types of cancer in the world, with an extremely short survival time, depending on the stage of diagnosis. In non-surgical cases, chemotherapy alternatives are only effective in 40% to 60% of patients. The low efficiency of treatments occurs mainly due to the complex microenvironment in PDA, leading to chemoresistance to treatments and making it difficult to reach the affected tissue. A very important histological characteristic of PDA is the extremely dense stroma, which leads to low vascularization of tumor tissue. Consequently, the stroma environment causes less drug accumulation in tumor cells, even of selective and/or targeted drugs. Overcoming the stroma's microenvironment is a major challenge for therapies. Moreover, specific genes lead to direct chemoresistance in PDA due to their high progression. In this scenario, nanotechnology appears as an alternative to overcome these clinical challenges concerning two distinct ways: acting on the stroma or/and acting directly on the pancreatic tumor cells. Thus, this review aimed to highlight advances in the application of nanotechnology aiming to open up new landscapes against PDA. There are a huge number of nanoparticles carrying drugs in preclinical and clinical trials for the effective treatment of PDA. These works have been discussed, and based on the current scenario, the future prospects for an efficient treatment of PDA have been proposed.

Background: A growing body of evidence suggests that Hsp70, which is overexpressed in human breast tumors, plays a role in tumorigenesis and tumor progression in breast cancer as well as in its aggressive phenotypes. Hsp70 constitutes a potential therapeutic target in the treatment of this disease. Methods: We developed a new series of rhodacyanine-based Hsp70 inhibitors, represented by compounds 1 and 6, in which the cationic pyridin-1-ium or thiazol-3-ium ring of existing Hsp70 inhibitors (e.g., JG-40 and JG-98) was replaced by a corresponding benzo- fused N-heterocycle. Results: Several lines of evidence suggest that these benzo-fused derivatives may exert their antitumor activities, in part, by targeting Hsp70. These putative inhibitors displayed differential antiproliferative efficacy against breast cancer cells (IC50 as low as 0.25 μM) versus nontumorigenic MCF-10A breast epithelial cells (IC50 ≥ 5 μM). This was correlated with the corresponding Hsp70 expression levels. Using a protein refolding assay, we confirmed that these agents effectively inhibited the chaperone activity of Hsp70. Moreover, these inhibitors effectively suppressed the expression of well-known oncogenic client proteins of Hsp70’s, including FoxM1, HuR, and Akt, which paralleled their antiproliferative efficacy. Supporting the established role of Hsp70 in regulating protein refolding, these derivatives induced autophagy, as manifested by the conversion of LC3B-I to LC3B-II. Notably, these putative Hsp70 inhibitors did not cause a compensatory elevation in Hsp90 expression, contrasting with the previously reported effects of Hsp90 inhibitors on Hsp70 upregulation. Conclusion: Together with the finding that compounds 1 and 6 showed improved microsomal stability, these results suggest the translational potential of these putative Hsp70 inhibitors to foster new strategies for cancer therapy. However, whether these benzo-fused rhodacyanines act on kinases or other targets remains unclear. It is currently under investigation.