Phycobilins as Potent Food Bioactive Broad-Spectrum Inhibitors Against Proteases of SARS-CoV-2 and Other Coronaviruses: A Preliminary Study

Combining network pharmacology and experimental verification to study the anti-colon cancer effect and mechanism of sulforaphene

BACKGROUND

Sulforaphene is a derivative of glucosinolate and a potential bioactive substance used for treating colon cancer. This study aimed to evaluate the potential inhibitory effect and mechanisms of sulforaphene in human colon cancer Caco-2 cells. Network pharmacology, molecular docking, and experimental verification were performed to elucidate potential sulforaphene mechanisms in the treatment of this condition.

RESULT

Network pharmacology predicted 27 intersection target genes between sulforaphene and colon cancer cell inhibition. Key sulforaphene targets associated with colon cancer cell inhibition were identified as EGFR, MAPK14, MCL1, GSK3B, PARP1, PTPRC, NOS2, CTSS, TLR9, and CTSK. Gene ontology functional enrichment analysis revealed that the above genes were primarily related to the positive regulation of peptidase activity, cytokine production in the inflammatory response, and the cell receptor signaling pathway. Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that sulforaphene mainly inhibited the proliferation of cancer cells by affecting apoptosis as well as the signaling pathways of PD-1, Toll-like receptor, T cell receptor, and P13k-Akt. Molecular docking results further confirmed that CTSS, GSK3B, and NOS2 were significantly up-regulated and had good binding affinity with sulforaphene. In vitro experiments also indicated that sulforaphene had a significant inhibitory effect on human colon cancer Caco-2 cells.

CONCLUSION

This paper revealed the pharmacodynamic mechanism of sulforaphene in the treatment of colon cancer for the first time. It provides scientific insight into the development of sulforaphene as a medicinal resource. © 2024 Society of Chemical Industry.

Recent biotechnological applications of value-added bioactive compounds from microalgae and seaweeds

Microalgae and seaweed have been consumed as food for several decades to combat starvation and food shortages worldwide. The most famous edible microalgae species are Nostoc, Spirulina, and Aphanizomenon, in addition to seaweeds, which are used in traditional medicine and food, such as Nori, which is one of the most popular foods containing Pyropia alga as a major ingredient. Recently, many applications use algae-derived polysaccharides such as agar, alginate, carrageenan, cellulose, fucoidan, mannan, laminarin, ulvan, and xylan as gelling agents in food, pharmaceuticals, and cosmetics industries. Moreover, pigments (carotenoids particularly astaxanthins, chlorophylls, and phycobilins), minerals, vitamins, polyunsaturated fatty acids, peptides, proteins, polyphenols, and diterpenes compounds are accumulated under specific cultivation and stress conditions in the algal cells to be harvested and their biomass used as a feedstock for the relevant industries and applications. No less critical is the use of algae in bioremediation, thus contributing significantly to environmental sustainability.This review will explore and discuss the various applications of microalgae and seaweeds, emphasising their role in bioremediation, recent products with algal added-value compounds that are now on the market, and novel under-developing applications such as bioplastics and nanoparticle production. Nonetheless, special attention is also drawn towards the limitations of these applications and the technologies applied, and how they may be overcome.

Identification of antiviral phytochemicals from cranberry as potential inhibitors of SARS-CoV-2 main protease (Mpro)

Cranberry phytochemicals are known to possess antiviral activities. In the current study, we explored the therapeutic potential of cranberry against SARS-CoV-2 by targeting its main protease (Mpro) enzyme. Firstly, phytochemicals of cranberry origin were identified from three independent databases. Subsequently, virtual screening, using molecular docking and molecular dynamics simulation approaches, led to the identification of three lead phytochemicals namely, cyanidin 3-O-galactoside, β-carotene and epicatechin. Furthermore, in vitro enzymatic assays revealed that cyanidin 3-O-galactoside had the highest inhibitory potential with IC50 of 9.98 μM compared to the other two phytochemicals. Cyanidin 3-O-galactoside belongs to the class of anthocyanins. Anthocyanins extracted from frozen cranberry also exhibited the highest inhibitory potential with IC50 of 23.58 μg/ml compared to the extracts of carotenoids and flavanols, the class for β-carotene and epicatechin, respectively. Finally, we confirm the presence of the phytochemicals in the cranberry extracts using targeted LC-MS/MS analysis. Our results, therefore, indicate that the identified cranberry-derived bioactive compounds as well as cranberry could be used for therapeutic interventions against SARS-CoV-2.

Role of Natural Compounds Modulating Heme Catabolic Pathway in Gut, Liver, Cardiovascular, and Brain Diseases

The crucial physiological process of heme breakdown yields biliverdin (BV) and bilirubin (BR) as byproducts. BV, BR, and the enzymes involved in their production (the "yellow players-YP") are increasingly documented as endogenous modulators of human health. Mildly elevated serum bilirubin concentration has been correlated with a reduced risk of multiple chronic pro-oxidant and pro-inflammatory diseases, especially in the elderly. BR and BV per se have been demonstrated to protect against neurodegenerative diseases, in which heme oxygenase (HMOX), the main enzyme in the production of pigments, is almost always altered. HMOX upregulation has been interpreted as a tentative defense against the ongoing pathologic mechanisms. With the demonstration that multiple cells possess YP, their propensity to be modulated, and their broad spectrum of activity on multiple signaling pathways, the YP have assumed the role of an adjustable system that can promote health in adults. Based on that, there is an ongoing effort to induce their activity as a therapeutic option, and natural compounds are an attractive alternative to the goal, possibly requiring only minimal changes in the life style. We review the most recent evidence of the potential of natural compounds in targeting the YP in the context of the most common pathologic condition of adult and elderly life.

Broad-Spectrum Antivirals against Multiple Human and Animal Coronaviruses Infection

Among the seven coronaviruses that infect humans, HCoV-229E, HCoV-OC43, HCoV-NL63, and HCoV-HKU1 usually cause mild and common cold symptoms; however, infection with three coronaviruses, namely severe acute respiratory syndrome coronavirus [SARS-CoV], Middle East respiratory syndrome coronavirus [MERS-CoV], and the newly identified severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2], often results in respiratory distress, cytokine storm and multiorgan failure [...].

The nanomolar affinity of C-phycocyanin from virtual screening of microalgal bioactive as potential ACE2 inhibitor for COVID-19 therapy

The global pandemic of COVID-19 caused by SARS-CoV-2 has caused more than 400 million infections with more than 5.7 million deaths worldwide, and the number of validated therapies from natural products for treating coronavirus infections needs to be increased. Therefore, the virtual screening of bioactive compounds from natural products based on computational methods could be an interesting strategy. Among many sources of bioactive natural products, compounds from marine organisms, particularly microalgae and cyanobacteria, can be potential antiviral agents. The present study investigates bioactive antiviral compounds from microalgae and cyanobacteria as a potential inhibitor of SARS-CoV-2 by targeting Angiotensin-Converting Enzyme II (ACE2) using integrated in silico and in vitro approaches. Our in silico analysis demonstrates that C-Phycocyanin (CPC) can potentially inhibit the binding of ACE2 receptor and SARS-CoV-2 with the docking score of -9.7 kcal mol-1. This score is relatively more favorable than the native ligand on ACE2 receptor. Molecular dynamics simulation also reveals the stability interaction between both CPC and ACE2 receptor with a root mean square deviation (RMSD) value of 1.5 Å. Additionally, our in vitro analysis using the surface plasmon resonance (SPR) method shows that CPC has a high affinity for ACE2 with a binding affinity range from 5 to 125 µM, with KD 3.37 nM. This study could serve as a reference to design microalgae- or cyanobacteria-based antiviral drugs for prophylaxis in SARS-CoV-2 infections.

Antiviral effects of phytochemicals against severe acute respiratory syndrome coronavirus 2 and their mechanisms of action: A review

The worldwide spreading of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed a serious threat to health, economic, environmental, and social aspects of human lives. Currently, there are no approved treatments that can effectively block the virus although several existing antimalarial and antiviral agents have been repurposed and allowed use during the pandemic under the emergency use authorization (EUA) status. This review gives an updated overview of the antiviral effects of phytochemicals including alkaloids, flavonoids, and terpenoids against the COVID-19 virus and their mechanisms of action. Search for natural lead molecules against SARS-CoV-2 has been focusing on virtual screening and in vitro studies on phytochemicals that have shown great promise against other coronaviruses such as SARS-CoV. Until now, there is limited data on in vivo investigations to examine the antiviral activity of plants in SARS-CoV-2-infected animal models and the studies were performed using crude extracts. Further experimental and preclinical investigations on the in vivo effects of phytochemicals have to be performed to provide sufficient efficacy and safety data before clinical studies can be performed to develop them into COVID-19 drugs. Phytochemicals are potential sources of new chemical leads for the development of safe and potent anti-SARS-CoV-2 agents.

A Review on a Hidden Gem: Phycoerythrin from Blue-Green Algae

Phycoerythrin (PE) is a pink/red-colored pigment found in rhodophytes, cryptophytes, and blue-green algae (cyanobacteria). The interest in PE is emerging from its role in delivering health benefits. Unfortunately, the current cyanobacterial-PE (C-PE) knowledge is still in the infant stage. It is essential to acquire a more comprehensive understanding of C-PE. This study aimed to review the C-PE structure, up and downstream processes of C-PE, application of C-PE, and strategies to enhance its stability and market value. In addition, this study also presented a strengths, weaknesses, opportunities, and threats (SWOT) analysis on C-PE. Cyanobacteria appeared to be the more promising PE producers compared to rhodophytes, cryptophytes, and macroalgae. Green/blue light is preferred to accumulate higher PE content in cyanobacteria. Currently, the prominent C-PE extraction method is repeated freezing-thawing. A combination of precipitation and chromatography approaches is proposed to obtain greater purity of C-PE. C-PE has been widely exploited in various fields, such as nutraceuticals, pharmaceuticals, therapeutics, cosmetics, biotechnology, food, and feed, owing to its bioactivities and fluorescent properties. This review provides insight into the state-of-art nature of C-PE and advances a step further in commercializing this prospective pigment.

Focus on Marine Animal Safety and Marine Bioresources in Response to the SARS-CoV-2 Crisis

SARS-CoV-2 as a zoonotic virus has significantly affected daily life and social behavior since its outbreak in late 2019. The concerns over its transmission through different media directly or indirectly have evoked great attention about the survival of SARS-CoV-2 virions in the environment and its potential infection of other animals. To evaluate the risk of infection by SARS-CoV-2 and to counteract the COVID-19 disease, extensive studies have been performed to understand SARS-CoV-2 biogenesis and its pathogenesis. This review mainly focuses on the molecular architecture of SARS-CoV-2, its potential for infecting marine animals, and the prospect of drug discovery using marine natural products to combat SARS-CoV-2. The main purposes of this review are to piece together progress in SARS-CoV-2 functional genomic studies and antiviral drug development, and to raise our awareness of marine animal safety on exposure to SARS-CoV-2.

Molecular Docking and Dynamics Simulation of Several Flavonoids Predict Cyanidin as an Effective Drug Candidate against SARS-CoV-2 Spike Protein

The in silico method has provided a versatile process of developing lead compounds from a large database in a short duration. Therefore, it is imperative to look for vaccinations and medications that can stop the havoc caused by SARS-CoV-2. The spike protein of SARS-CoV-2 is required for the viral entry into the host cells, hence inhibiting the virus from fusing and infecting the host. This study determined the binding interactions of 36 flavonoids along with two FDA-approved drugs against the spike protein receptor-binding domain of SARS-CoV-2 through molecular docking and molecular dynamics (MD) simulations. In addition, the molecular mechanics generalized Born surface area (MM/GBSA) approach was used to calculate the binding-free energy (BFE). Flavonoids were selected based on their in vitro assays on SARS-CoV and SARS-CoV-2. Our pharmacokinetics study revealed that cyanidin showed good drug-likeness, fulfilled Lipinski's rule of five, and conferred favorable toxicity parameters. Furthermore, MD simulations showed that cyanidin interacts with spike protein and alters the conformation and binding-free energy suited. Finally, an in vitro assay indicated that about 50% reduction in the binding of hACE2 with S1-RBD in the presence of cyanidin-containing red grapes crude extract was achieved at approximately 1.25 mg/mL. Hence, cyanidin may be a promising adjuvant medication for the SARS-CoV-2 spike protein based on in silico and in vitro research.

Herbal medications and natural products for patients with covid-19 and diabetes mellitus: Potentials and challenges

BACKGROUND

The presence of diabetes mellitus (DM) among COVID-19 patients is associated with increased hospitalization, morbidity, and mortality. Evidence has shown that hyperglycemia potentiates SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection and plays a central role in severe COVID-19 and diabetes comorbidity. In this review, we explore the therapeutic potentials of herbal medications and natural products in the management of COVID-19 and DM comorbidity and the challenges associated with the preexisting or concurrent use of these substances.

METHODS

Research papers that were published from January 2016 to December 2021 were retrieved from PubMed, ScienceDirect, and Google Scholar databases. Papers reporting clinical evidence of antidiabetic activities and any available evidence of the anti-COVID-19 potential of ten selected natural products were retrieved and analyzed for discussion in this review.

RESULTS

A total of 548 papers (73 clinical trials on the antidiabetic activities of the selected natural products and 475 research and review articles on their anti-COVID-19 potential) were retrieved from the literature search for further analysis. A total of 517 articles (reviews and less relevant research papers) were excluded. A cumulative sum of thirty-one (31) research papers (20 clinical trials and 10 others) met the criteria and have been discussed in this review.

CONCLUSION

The findings of this review suggest that phenolic compounds are the most promising phytochemicals in the management of COVID-19 and DM comorbidity. Curcumin and propolis have shown substantial evidence against COVID-19 and DM in humans and are thus, considered the best potential therapeutic options.

Methodology-Centered Review of Molecular Modeling, Simulation, and Prediction of SARS-CoV-2

Despite tremendous efforts in the past two years, our understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), virus-host interactions, immune response, virulence, transmission, and evolution is still very limited. This limitation calls for further in-depth investigation. Computational studies have become an indispensable component in combating coronavirus disease 2019 (COVID-19) due to their low cost, their efficiency, and the fact that they are free from safety and ethical constraints. Additionally, the mechanism that governs the global evolution and transmission of SARS-CoV-2 cannot be revealed from individual experiments and was discovered by integrating genotyping of massive viral sequences, biophysical modeling of protein-protein interactions, deep mutational data, deep learning, and advanced mathematics. There exists a tsunami of literature on the molecular modeling, simulations, and predictions of SARS-CoV-2 and related developments of drugs, vaccines, antibodies, and diagnostics. To provide readers with a quick update about this literature, we present a comprehensive and systematic methodology-centered review. Aspects such as molecular biophysics, bioinformatics, cheminformatics, machine learning, and mathematics are discussed. This review will be beneficial to researchers who are looking for ways to contribute to SARS-CoV-2 studies and those who are interested in the status of the field.

Phycobiliproteins-A Family of Algae-Derived Biliproteins: Productions, Characterization and Pharmaceutical Potentials

Phycobiliproteins (PBPs) are colored and water-soluble biliproteins found in cyanobacteria, rhodophytes, cryptomonads and cyanelles. They are divided into three main types: allophycocyanin, phycocyanin and phycoerythrin, according to their spectral properties. There are two methods for PBPs preparation. One is the extraction and purification of native PBPs from Cyanobacteria, Cryptophyta and Rhodophyta, and the other way is the production of recombinant PBPs by heterologous hosts. Apart from their function as light-harvesting antenna in photosynthesis, PBPs can be used as food colorants, nutraceuticals and fluorescent probes in immunofluorescence analysis. An increasing number of reports have revealed their pharmaceutical potentials such as antioxidant, anti-tumor, anti-inflammatory and antidiabetic effects. The advances in PBP biogenesis make it feasible to construct novel PBPs with various activities and produce recombinant PBPs by heterologous hosts at low cost. In this review, we present a critical overview on the productions, characterization and pharmaceutical potentials of PBPs, and discuss the key issues and future perspectives on the exploration of these valuable proteins.

Advances in delivery methods of Arthrospira platensis (spirulina) for enhanced therapeutic outcomes

Arthrospira platensis (A. platensis) aqueous extract has massive amounts of natural products that can be used as future drugs, such as C-phycocyanin, allophycocyanin, etc. This extract was chosen because of its high adaptability, which reflects its resolute genetic composition. The proactive roles of cyanobacteria, particularly in the medical field, have been discussed in this review, including the history, previous food and drug administration (FDA) reports, health benefits and the various dose-dependent therapeutic functions that A. platensis possesses, including its role in fighting against lethal diseases such as cancer, SARS-CoV-2/COVID-19, etc. However, the remedy will not present its maximal effect without the proper delivery to the targeted place for deposition. The goal of this research is to maximize the bioavailability and delivery efficiency of A. platensis constituents through selected sites for effective therapeutic outcomes. The solutions reviewed are mainly on parenteral and tablet formulations. Moreover, suggested enteric polymers were discussed with minor composition variations applied for better storage in high humid countries alongside minor variations in the polymer design were suggested to enhance the premature release hindrance of basic drugs in low pH environments. In addition, it will open doors for research in delivering active pharmaceutical ingredients (APIs) in femtoscale with the use of various existing and new formulations.Abbrevations: SDGs; Sustainable Development Goals, IL-4; Interleukin-4, HDL; High-Density Lipoprotein, LDL; Low-Density Lipoprotein, VLDL; Very Low-Density Lipoprotein, C-PC; C-Phycocyanin, APC; Allophycocyanin, PE; Phycoerythrin, COX-2; Cyclooxygenase-2, RCTs; Randomized Control Trials, TNF-α; Tumour Necrosis Factor-alpha, γ-LFA; Gamma-Linolenic Fatty Acid, PGs; Polyglycans, PUFAs: Polyunsaturated Fatty Acids, NK-cell; Natural Killer Cell, FDA; Food and Drug Administration, GRAS; Generally Recognized as Safe, SD; Standard Deviation, API; Active Pharmaceutical Ingredient, DW; Dry Weight, IM; Intramuscular, IV; Intravenous, ID; Intradermal, SC; Subcutaneous, AERs; Adverse Event Reports, DSI-EC; Dietary Supplement Information Executive Committee, cGMP; Current Good Manufacturing Process, A. platensis; Arthrospira platensis, A. maxima; Arthrospira maxima, Spirulina sp.; Spirulina species, Arthrospira; Spirulina, Tecuitlatl; Spirulina, CRC; Colorectal Cancer, HDI; Human Development Index, Tf; Transferrin, TfR; Transferrin Receptor, FR; Flow Rate, CPP; Cell Penetrating Peptide, SUV; Small Unilamenar Vesicle, LUV; Large Unilamenar Vesicle, GUV; Giant Unilamenar Vesicle, MLV; Multilamenar Vesicle, COVID-19; Coronavirus-19, PEGylated; Stealth, PEG; Polyethylene Glycol, OSCEs; Objective Structured Clinical Examinations, GI; Gastrointestinal Tract, CAP; Cellulose Acetate Phthalate, HPMCP, Hydroxypropyl Methyl-Cellulose Phthalate, SR; Sustained Release, DR; Delay Release, Poly(MA-EA); Polymethyl Acrylic Co-Ethyl Acrylate, f-DR L-30 D-55; Femto-Delay Release Methyl Acrylic Acid Co-Ethyl Acrylate Polymer, MW; Molecular Weight, Tg; Glass Transition Temperature, SN2; Nucleophilic Substitution 2, EPR; Enhance Permeability and Retention, VEGF; Vascular Endothelial Growth Factor, RGD; Arginine-Glycine-Aspartic Acid, VCAM-1; Vascular Cell Adhesion Molecule-1, P; Coefficient of Permeability, PES; Polyether Sulfone, pHe; Extracellular pH, ζ-potential; Zeta potential, NTA; Nanoparticle Tracking Analysis, PB; Phosphate Buffer, DLS; Dynamic Light Scattering, AFM; Atomic Force Microscope, Log P; Partition Coefficient, MR; Molar Refractivity, tPSA; Topological Polar Surface Area, C log P; Calculated Partition Coefficient, CMR; Calculated Molar Refractivity, Log S; Solubility Coefficient, pka; Acid Dissociation Constant, DDAB; Dimethyl Dioctadecyl Ammonium Bromide, DOPE; Dioleoylphosphatidylethanolamine, GDP; Good Distribution Practice, RES; Reticuloendothelial System, PKU; Phenylketonuria, MS; Multiple Sclerosis, SLE; Systemic Lupus Erythematous, NASA; National Aeronautics and Space Administration, DOX; Doxorubicin, ADRs; Adverse Drug Reactions, SVM; Support Vector Machine, MDA; Malondialdehyde, TBARS; Thiobarbituric Acid Reactive Substances, CRP; C-Reactive Protein, CK; Creatine Kinase, LDH; Lactated Dehydrogenase, T2D; Type 2 Diabetes, PCB; Phycocyanobilin, PBP; Phycobiliproteins, PEB; Phycoerythrobilin, DPP-4; Dipeptidyl Peptidase-4, MTT; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide, IL-2; Interleukin-2, IL-6; Interleukin-6, PRISMA; Preferred Reporting Items for Systematic Reviews and Meta-Analyses, STATA; Statistics, HepG2; Hepatoblastoma, HCT116; Colon Cancer Carcinoma, Kasumi-1; Acute Leukaemia, K562; Chronic Leukaemia, Se-PC; Selenium-Phycocyanin, MCF-7; Breast Cancer Adenocarcinoma, A375; Human Melanoma, RAS; Renin-Angiotensin System, IQP; Ile-Gln-Pro, VEP; Val-Glu-Pro, Mpro; Main Protease, PLpro; Papin-Like Protease, BMI; Body Mass Index, IC50; Inhibitory Concentration by 50%, LD50; Lethal Dose by 50%, PC12 Adh; Rat Pheochromocytoma Cells, RNS; Reactive Nitrogen Species, Hb1Ac; hemoglobin A1c.

Efficient Synthesis of Phycocyanobilin by Combinatorial Metabolic Engineering in Escherichia coli

Phycocyanobilin (PCB) is a kind of light-harvesting pigment which naturally exists in algae and plays important roles in absorbing and transferring energy. Based on its antioxidant and optical properties, PCB has been applied in food, medicine, and cosmetics. Currently, PCB is mainly extracted from Spirulina through complicated steps; thus, the biosynthesis of PCB in Escherichia coli has attracted more attention. However, due to the lower catalytic efficiency of synthetic enzymes and the deficiency of precursors and cofactors, the titer of PCB remains at a low level. Here, we report the efficient synthesis of PCB by the expression of heme oxygenase-1 from Thermosynechococcus elongatus and PCB: ferredoxin oxidoreductase (PcyA) from Synechocystis sp. using a high-copy number plasmid with an inducible T7lac promoter and the assembly of these two enzymes at a suitable ratio of 2:1 with DNA scaffolds. Additionally, the synthesis of PCB was further enhanced by direct supplementation of 5-aminolevulinic acid (ALA), moderate overexpression of key enzymes in the heme biosynthetic pathway (hemB and hemH), and accelerated cycle of cofactors (NADPH) through the expression of NAD⁺ kinase and the addition of a reducing agent. Finally, based on the optimal conditions (Modified R medium with 200 mg/L ALA, 20 mg/L FeSO₄·7H₂O, and 5 g/L vitamin C induced by 0.8 mM isopropylthio-β-galactoside at 30 °C), the highest reported titer of PCB (28.32 mg/L) was obtained at the fermenter level by feeding glucose and FeSO₄·7H₂O. The strategies applied in this study will be useful for the synthesis of other natural pigments and PCB or heme derivatives in E. coli.

Rational Discovery of Antiviral Whey Protein-Derived Small Peptides Targeting the SARS-CoV-2 Main Protease

In the present work, and for the first time, three whey protein-derived peptides (IAEK, IPAVF, MHI), endowed with ACE inhibitory activity, were examined for their antiviral activity against the SARS-CoV-2 3C-like protease (3CL^pro) and Human Rhinovirus 3C protease (3C^pro) by employing molecular docking. Computational studies showed reliable binding poses within 3CL^pro for the three investigated small peptides, considering docking scores as well as the binding free energy values. Validation by in vitro experiments confirmed these results. In particular, IPAVF exhibited the highest inhibitory activity by returning an IC₅₀ equal to 1.21 μM; it was followed by IAEK, which registered an IC₅₀ of 154.40 μM, whereas MHI was less active with an IC₅₀ equal to 2700.62 μM. On the other hand, none of the assayed peptides registered inhibitory activity against 3C^pro. Based on these results, the herein presented small peptides are introduced as promising molecules to be exploited in the development of “target-specific antiviral” agents against SARS-CoV-2.

Phycobiliproteins: Structural aspects, functional characteristics, and biotechnological perspectives

Phycobiliproteins (PBPs) are fluorescent proteins of various colors, including fuchsia, purple-blue and cyan, that allow the capture of light energy in auxiliary photosynthetic complexes called phycobilisomes (PBS). PBPs have several highly preserved structural and physicochemical characteristics. In the PBS context, PBPs function is capture luminous energy in the 450-650 nm range and delivers it to photosystems allowing photosynthesis take place. Besides the energy harvesting function, PBPs also have shown to have multiple biological activities, including antioxidant, antibacterial and antitumours, making them an interesting focus for different biotechnological applications in areas like biomedicine, bioenergy and scientific research. Nowadays, the main sources of PBPs are cyanobacteria and micro and macro algae from the phylum Rhodophyta. Due to the diverse biological activities of PBPs, they have attracted the attention of different industries, such as food, biomedical and cosmetics. This is why a large number of patents related to the production, extraction, purification of PBPs and their application as cosmetics, biopharmaceuticals or diagnostic applications have been generated, looking less ecological impact in the natural prairies of macroalgae and less culture time or higher productivity in cyanobacteria to satisfy the markets and applications that require high amounts of these molecules. In this review, we summarize the main structural characteristics of PBPs, their biosynthesys and biotechnological applications. We also address current trends and future perspectives of the PBPs market.

Recent Development of Small Molecules for SARS-CoV-2 and the Opportunity for Fragment-Based Drug Discovery

Abstract:

The ongoing pandemic of Covid-19 caused by SARS-CoV-2 is a major threat to global public health, drawing attention to develop new therapeutics for treatment. Much research work is focused on identifying or repurposing new small molecules to serve as potential inhibitors by interacting with viral or host-cell molecular targets and understanding the nature of the virus in the host cells. Identifying small molecules as potent inhibitors at an early stage is advantageous to make a molecule with higher potency and then find a lead compound for the development of drug discovery. Small molecules can show their inhibition property by targeting either SARS-CoV-2 main protease (Mpro) enzyme, papain-like protease (PLpro) enzyme, or helicase (Hel), or blocking the spike (S) protein angiotensin-converting enzyme 2 (ACE2) receptor. A very recent outbreak of a new variant (B.1.617.2—termed as Delta variant) of SARS-CoV-2 worldwide posed a greater challenge as it is resistant to clinically undergoing vaccine trials. Thus, the development of new drug molecules is of potential interest to combat SARS-CoV-2 disease, and for that, fragment-based drug discovery (FBDD) approach could be one of the ways to bring out an effective solution. Two cysteine protease enzymes would be an attractive choice of target for fragment-based drug discovery to tune the molecular structure at an early stage with suitable functionality. In this short review, the recent development of small-molecule as inhibitors against Covid-19 are discussed and the opportunity for FBDD is envisioned optimistically to provide an outlook regarding Covid-19 that may pave the way in the direction of the Covid-19 drug development paradigm.