Lectins from plant and algae act as anti-viral against HIV, influenza and coronaviruses

Isolation and characterisation of stress tolerant divalent dependant lectin from insect pest of Corcyra cephalonica (Stainton) (Lepidoptera: Galleriidae) and its functional studies

This study aims to isolate and identify a lectin from an agricultural insect pest of Corcyra cephalonica (CC). The lectin exhibited strong hemagglutination in sheep and goat blood, particularly A+ and B+, influenced by metal ions Ca2+ and Mn2+. Its molecular mass was determined to be 225 kDa, comprising subunits of 95, 68, and 62 kDa. The lectin displayed high thermal stability up to 100 °C and maintained hemagglutination activity at pH 12.0. MALDI-TOF analysis confirmed its identity as a lectin. Notably, it displayed significant antioxidant activity, achieving 93.98% inhibition against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 97.59% against 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) at concentrations of 0.5 and 0.05 mg/mL, respectively. This is the first report of Corcyra cephalonica lectin exhibiting such potent antioxidant properties, suggesting its potential as an ingredient in drug development for free radical-mediated inflammatory diseases and cancer since it has high biophysical stability.

Modifying of non-nutritional compounds in legumes: Processing strategies and new technologies

Legumes are consumed worldwide, are notable for their nutritional quality, however, contain certain non-nutritional compounds (NNCs) that can affect the absorption of nutrients, though these may exhibit bioactive properties. Various processing methods can modify the concentration of NNCs, including soaking and germination. These methods can be combined with other thermal, non-thermal, and bioprocessing treatments to enhance their efficiency. The efficacy of these methods is contingent upon the specific types of NNCs and legume in question. This work examines the effectiveness of these processing methods in terms of modifying the concentration of NNCs present in legumes as well as the potential use of emerging technologies, to enhance the level of NNCs modification in legumes. These technologies could increase the functional use of legume flours, potentially leading to new opportunities for incorporating legume-based ingredients in a range of culinary applications, thereby enhancing the diets of many individuals worldwide.

First identification report for amino acid composition of red algae Gracilaria spp. obtained from Central Java, Indonesia

Gracilaria is a genus of red algae found mainly in Asia. Various species of Gracilaria are distributed throughout Indonesia's marine waters, especially in coastal areas, and are cultivated for research and economic purposes. Gracilaria mainly consists of polysaccharides and pigments, which have hindered protein identification. The unique protein expressions have never been analyzed using a proteomic approach, and no reports are available on Gracilaria spp. amino acid sequences in Central Java. Based on this background, we aimed to explore Gracilaria protein characterization using unique peptide sequence analysis via LC-HRMS. The usage of liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) has been growing in biomedical and environmental sciences, offering high accuracy in protein detection. We followed the LC-HRMS standard protocol with an optimized precipitation procedure. TCA/acetone precipitation was used for protein purification, after which the precipitate was subjected to protein digestion to obtain small peptide fractions. Protein analysis results are presented as protein concentrations, molecular models, and peptide sequences. This experiment identified four sequences derived from the Rhodophyta database: TKKILDK (845.5455 Da), TVKSLLTK (889.5717 Da), ILVKTLK (814.5761 Da), and TGcGRSKR (921.4683 Da). This study reveals peptide sequences for Gracilaria spp., showing similarities with other red algae species, along with the functions of the peptide sequences. Furthermore, amino acid models of secondary structures were provided to support our findings.

Omics-driven bioinformatics for plant lectins discovery and functional annotation - A comprehensive review

Lectins are known for their specific and reversible binding capacity to carbohydrates. These molecules have been particularly explored in plants due to their reported properties, highlighting antimicrobial, antiviral, anticancer, antiparasitic, insecticidal, and immunoregulatory actions. The increasing availability of lectin and lectin-like sequences in omics data banks provides an opportunity to identify important candidates, inferring their roles in essential signaling pathways and processes in plants. Bioinformatics enables a fast and low-cost scenario for elucidating sequences and predicting functions in the lectinology universe. Thus, this review addresses the state of the art of annotation, structural characterization, classification, and predicted applications of plant lectins. Their allergenic and toxic properties are also discussed, as well as tools for predicting such effects from the primary structure. This review uncovers a promising scenario for plant lectins and new study possibilities, particularly for studies in lectinology in the omics era.

Identification of a Novel Antiviral Lectin against SARS-CoV-2 Omicron Variant from Shiitake-Mushroom-Derived Vesicle-like Nanoparticles

Lectins are a class of carbohydrate-binding proteins that may have antiviral activity by binding to the glycans on the virion surface to interfere with viral entry. We have identified a novel lectin (named Shictin) from Shiitake mushroom (Lentinula edodes)-derived vesicle-like nanoparticles (VLNs, or exosomes) that exhibits strong activity against the SARS-CoV-2 Omicron variant with an IC50 value of 87 nM. Shictin contains 298 amino acids and consists of two unique domains (N-terminal and C-terminal domain). The N-terminal domain is the carbohydrate-binding domain (CBD) that is homologous with CBDs of other lectins, suggesting that Shictin inhibits SARS-CoV-2 infection by binding to the glycans on the virion surface to prevent viral entry. This finding demonstrates that exosomes of vegetables are a valuable source for the identification of antiviral lectins. Therefore, it is believed that lectins from vegetable VLNs have potential as antiviral therapeutic agents.

Lactic acid bacterial surface display of scytovirin inhibitors for anti-ebolavirus infection

Scytovirin (SVN) is a lectin from cyanobacteria which has a strong inhibitory activity against Ebola virus infection. We engineered scytovirin as the inhibitor for surface display of lactic acid bacteria to block Ebola virus infection. Two different bacterial strains (Lactobacillus casei and Lactococcus lactis) were successfully engineered for scytovirin expression on the bacterial surface. These bacteria were found to be effective at neutralizing pseudotyped Ebolavirus in a cell-based assay. This approach can be utilized for prophylactic prevention, as well as for treatment. Since lactic acid bacteria can colonize the human body, a long-term efficacy could be achieved. Furthermore, this approach is also simple and cost-effective and can be easily applied in the regions of Ebola outbreaks in the developing countries.

The Antiviral Potential of Algal Lectins

Algae have emerged as fascinating subjects of study due to their vast potential as sources of valuable metabolites with diverse biotechnological applications, including their use as fertilizers, feed, food, and even pharmaceutical precursors. Among the numerous compounds found in algae, lectins have garnered special attention for their unique structures and carbohydrate specificities, distinguishing them from lectins derived from other sources. Here, a comprehensive overview of the latest scientific and technological advancements in the realm of algal lectins with a particular focus on their antiviral properties is provided. These lectins have displayed remarkable effectiveness against a wide range of viruses, thereby holding great promise for various antiviral applications. It is worth noting that several alga species have already been successfully commercialized for their antiviral potential. However, the discovery of a diverse array of lectins with potent antiviral capabilities suggests that the field holds immense untapped potential for further expansion. In conclusion, algae stand as a valuable and versatile resource, and their lectins offer an exciting avenue for developing novel antiviral agents, which may lead to the development of cutting-edge antiviral therapies.

Bioactivity of Fucoidan-Rich Extracts from Fucus vesiculosus against Rotavirus and Foodborne Pathogens

Marine algae are sources of bioactive components with defensive properties of great value against microbial infections. This study investigated the bioactivity of extracts from brown algae Fucus vesiculosus against rotavirus, the worldwide leading cause of acute gastroenteritis in infants and young children. Moreover, one of the extracts was tested against four foodborne bacteria: Campylobacter jejuni, Escherichia coli, Salmonella Typhimurium, and Listeria monocytogenes, and the non-pathogenic: E. coli K12. In vitro tests using MA104 cells revealed that both whole algae extracts and crude fucoidan precipitates neutralized rotavirus in a dose-responsive manner. The maximum neutralization activity was observed when the rotavirus was incubated with 100 μg mL-1 of the hydrochloric acid-obtained crude fucoidan (91.8%), although crude fucoidan extracted using citric acid also demonstrated high values (89.5%) at the same concentration. Furthermore, molecular weight fractionation of extracts decreased their antirotaviral activity and high molecular weight fractions exhibited higher activity compared to those of lower molecular weight. A seaweed extract with high antirotaviral activity was also found to inhibit the growth of C. jejuni, S. Typhimurium, and L. monocytogenes at a concentration of 0.2 mg mL-1. Overall, this study expands the current knowledge regarding the antimicrobial mechanisms of action of extracts from F. vesiculosus.

Plants as Biofactories for Therapeutic Proteins and Antiviral Compounds to Combat COVID-19

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had a profound impact on the world's health and economy. Although the end of the pandemic may come in 2023, it is generally believed that the virus will not be completely eradicated. Most likely, the disease will become an endemicity. The rapid development of vaccines of different types (mRNA, subunit protein, inactivated virus, etc.) and some other antiviral drugs (Remdesivir, Olumiant, Paxlovid, etc.) has provided effectiveness in reducing COVID-19's impact worldwide. However, the circulating SARS-CoV-2 virus has been constantly mutating with the emergence of multiple variants, which makes control of COVID-19 difficult. There is still a pressing need for developing more effective antiviral drugs to fight against the disease. Plants have provided a promising production platform for both bioactive chemical compounds (small molecules) and recombinant therapeutics (big molecules). Plants naturally produce a diverse range of bioactive compounds as secondary metabolites, such as alkaloids, terpenoids/terpenes and polyphenols, which are a rich source of countless antiviral compounds. Plants can also be genetically engineered to produce valuable recombinant therapeutics. This molecular farming in plants has an unprecedented opportunity for developing vaccines, antibodies, and other biologics for pandemic diseases because of its potential advantages, such as low cost, safety, and high production volume. This review summarizes the latest advancements in plant-derived drugs used to combat COVID-19 and discusses the prospects and challenges of the plant-based production platform for antiviral agents.