Characterization of an Insecticidal Protein from Withania somnifera Against Lepidopteran and Hemipteran Pest

Mannose-specific plant and microbial lectins as antiviral agents: A review

Lectins are non-immunological carbohydrate-binding proteins classified on the basis of their structure, origin, and sugar specificity. The binding specificity of such proteins with the surface glycan moiety determines their activity and clinical applications. Thus, lectins hold great potential as diagnostic and drug discovery agents and as novel biopharmaceutical products. In recent years, significant advancements have been made in understanding plant and microbial lectins as therapeutic agents against various viral diseases. Among them, mannose-specific lectins have being proven as promising antiviral agents against a variety of viruses, such as HIV, Influenza, Herpes, Ebola, Hepatitis, Severe Acute Respiratory Syndrome Coronavirus-1 (SARS-CoV-1), Middle Eastern Respiratory Syndrome Coronavirus (MERS-CoV) and most recent Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). The binding of mannose-binding lectins (MBLs) from plants and microbes to high-mannose containing N-glycans (which may be simple or complex) of glycoproteins found on the surface of viruses has been found to be highly specific and mainly responsible for their antiviral activity. MBLs target various steps in the viral life cycle, including viral attachment, entry and replication. The present review discusses the brief classification and structure of lectins along with antiviral activity of various mannose-specific lectins from plants and microbial sources and their diagnostic and therapeutic applications against viral diseases.

Plant lectins as prospective antiviral biomolecules in the search for COVID-19 eradication strategies

Lectins or clusters of carbohydrate-binding proteins of non-immune origin are distributed chiefly in the Plantae. Lectins have potent anti-infectivity properties for several RNA viruses including SARS-CoV-2. The primary purpose of this review is to review the ability of lectins mediated potential biotherapeutic and bioprophylactic strategy against coronavirus causing COVID-19. Lectins have binding affinity to the glycans of SARS-COV-2 Spike glycoprotein that has N-glycosylation sites. Apart from this, the complement lectin pathway is a "first line host defense" against the viral infection that is activated by mannose-binding lectins. Mannose-binding lectins deficiency in serum influences innate immunity of the host and facilitates infectious diseases including COVID-19. Our accumulated evidence obtained from scientific databases particularly PubMed and Google Scholar databases indicate that mannose-specific/mannose-binding lectins (MBL) have potent efficacies like anti-infectivity, complement cascade induction, immunoadjuvants, DC-SIGN antagonists, or glycomimetic approach, which can prove useful in the strategy of COVID-19 combat along with the glycobiological aspects of SARS-CoV-2 infections and antiviral immunity. For example, plant-derived mannose-specific lectins BanLac, FRIL, Lentil, and GRFT from red algae can inhibit and neutralize SARS-CoV-2 infectivity, as confirmed with in-vitro, in-vivo, and in-silico assessments. Furthermore, Bangladesh has a noteworthy resource of antiviral medicinal plants as well as plant lectins. Intensifying research on the antiviral plant lectins, adopting a glyco-biotechnological approach, and with deeper insights into the "glycovirological" aspects may result in the designing of alternative and potent blueprints against the 21st century's biological pandemic of SARS-CoV-2 causing COVID-19.

Metabolomics of Withania somnifera (L.) Dunal: Advances and applications

ETHNOPHARMACOLOGICAL RELEVANCE

Withania somnifera L. (Solanaceae), commonly known as Ashwagandha or Indian ginseng, is used in Ayurveda (Indian system of traditional medicine) for vitality, cardio-protection and treating other ailments, such as neurological disorders, gout, and skin diseases.

AIM OF THE REVIEW

We present a critical overview of the information on the metabolomics of W. somnifera and highlight the significance of the technique for use in quality control of medicinal products. We have also pointed out the use of metabolomics to distinguish varieties and to identify best methods of cultivation, collection, as well as extraction.

MATERIAL AND METHODS

The relevant information on medicinal value, phytochemical studies, metabolomics of W. somnifera, and their applications were collected from a rigorous electronic search through scientific databases, including Scopus, PubMed, Web of Science and Google Scholar. Structures of selected metabolites were from the PubChem.

RESULTS

The pharmacological activities of W. somnifera were well documented. Roots are the most important parts of the plant used in Ayurvedic preparations. Stem and leaves also have a rich content of bioactive phytochemicals like steroidal lactones, alkaloids, and phenolic acids. Metabolomic studies revealed that metabolite profiles of W. somnifera depended on plant parts collected and the developmental stage of the plant, besides the season of sample collection and geographical location. The levels of withanolides were variable, depending on the morpho/chemotypes within the species of W. somnifera. Although studies on W. somnifera were initiated several years ago, the complexity of secondary metabolites was not realized due to the lack of adequate and fool-proof technology for phytochemical fingerprinting. Sophistications in chromatography coupled to mass spectrometry facilitated the discovery of several new metabolites. Mutually complementary techniques like LC-MS, GC-MS, HPTLC, and NMR were employed to obtain a comprehensive metabolomic profile. Subsequent data analyses and searches against spectral databases enabled the annotation of signals and dereplication of metabolites in several numbers without isolating them individually.

CONCLUSIONS

The present review provides a critical update of metabolomic data and the diverse application of the technique. The identification of parameters for standardization and quality control of herbal products is essential to facilitate mandatory checks for the purity of formulation. Such studies would enable us to identify the best geographical location of plants and the time of collection. We recommend the use of metabolomic analysis of herbal products based on W. somnifera for quality control as well as the discovery of novel bioactive compounds.

Structural insights into rice SalTol QTL located SALT protein

Salinity is one of the major stresses affecting rice production worldwide, and various strategies are being employed to increase salt tolerance. Recently, there has been resurgence of interest to characterize SalTol QTL harbouring number of critical genes involved in conferring salt stress tolerance in rice. The present study reports the structure of SALT, a SalTol QTL encoded protein by X-ray crystallography (PDB ID: 5GVY; resolution 1.66 Å). Each SALT chain was bound to one mannose via 8 hydrogen bonds. Compared to previous structure reported for similar protein, our structure showed a buried surface area of 900 Ų compared to only 240 Ų for previous one. Small-angle X-ray scattering (SAXS) data analysis showed that the predominant solution shape of SALT protein in solution is also dimer characterized by a radius of gyration and maximum linear dimension of 2.1 and 6.5 nm, respectively. The SAXS profiles and modelling confirmed that the dimeric association and relative positioning in solution matched better with our crystal structure instead of previously reported structure. Together, structural/biophysical data analysis uphold a tight dimeric structure for SALT protein with one mannose bound to each protein, which remains novel to date, as previous structures indicated one sugar unit sandwiched loosely between two protein chains.

Methanolic Extract of Winter Cherry Causes Morpho-Histological and Immunological Ailments in Mulberry Pyralid Glyphodes pyloalis

The effect of Withania somnifera a medicinal plant seed extract was tested against lesser mulberry pyralid, a potential pest of mulberry. The mulberry leaves were used for silk production in rural areas of northern Iran. The extract was administered orally by leaf dipping method in two lower (5%W/V) and higher (15%W/V) dosages to third instar larvae (<24 h) for biological assays and to fifth instar larvae (<24 h) for Physiological studies. The results showed formation of larvoids (Ls), larval-pupal intermediates (LPIs), pupoids (Ps) and pupal-adult intermediates (PAIs). The results showed increased larval duration by 1.7 and 2 folds in 5 and 15% treatment, respectively. Fecundity of resultant adults was decreased by 1.2 and 1.3 in 5 and 15% treatment, respectively. Except approximate digestibility (AD) and consumption index (CI) all other feeding indices showed reduction. The feeding deterrence was prominent at 15% (87%) and 5% showing 48% deterrence. Our enzymatic and non-enzymatic assessments upon treatment showed reduction in key components, except detoxifying enzymes. However, the activity of an important enzyme involved in cuticle hardening and immunity called phenoloxidase was reduced. We also investigated the histology of midgut for further analysis and found drastic changes in main cellular elements. Immunological changes following treatment was noticeable in reduced Total Hemocyte Count but surprisingly increased Differential Hemocyte Count. However, the hemocytes structure was extremely damaged. The reduced number of eggs in treated but survived adults indicated reduced ovaries, with vacuolization both in trophocytes and oocytes. The key chemical compounds showed reductions particularly at 15%. The present results are concomitant with few earlier studies on this medicinal plant and deserve further studies particularly in deriving key chemicals that alter metamorphosis similar to insect growth regulators.

Concanavalin A Toxicity Towards Potato Psyllid and Apoptosis Induction in Midgut Cells

Concanavalin A (ConA), a legume lectin, has been drawing increasing attention in recent years concerning its toxicity against insects and its potential application in pest management. In an attempt to evaluate the effect of ConA on potato psyllid (Bactericera cockerelli), an economically important pest of solanaceous crops, the effect of ConA on potato psyllid survival, psyllid gut nuclear morphology, and expression of psyllid caspase genes were evaluated. Our results determined that artificial diet-feeding assays using ConA had deleterious effects on potato psyllids, resulting in significant psyllid mortality following ingestion. We also found that an apoptotic response was induced by ConA in psyllid midgut cells, which was demonstrated by the DNA fragmentation and abnormal nuclear architecture in the midgut cells. Following ConA ingestion, there was also upregulation of caspase genes in the psyllid midguts. Therefore, a key mechanism behind ConA toxicity towards potato psyllid probably involves the induction of apoptosis in midgut cells. This study could provide a better understanding of the mechanisms underlying ConA toxicity in insects and be a stepping stone towards the development of new psyllid control strategies based on plant lectins.

Progress and prospects of arthropod chitin pathways and structures as targets for pest management

Chitin is a structural component of the arthropod cuticular exoskeleton and the peritrophic matrix of the gut, which play crucial roles in growth and development. In the past few decades, our understanding of the composition, biosynthesis, assembly, degradation, and regulation of chitinous structures has increased. Many chemicals have been developed that target chitin biosynthesis (benzoyphenyl ureas, etoxazole), chitin degradation (allosamidin, psammaplin), and chitin regulation (benzoyl hydrazines), thus resulting in molting deformities and lethality. In addition, proteins that disrupt chitin structures, such as lectins, proteases, and chitinases have been utilized to halt feeding and induce mortality. Chitin-degrading enzymes, such as chitinases are also useful for improving the efficacy of bio-insecticides. Transgenic plants, baculoviruses, fungi, and bacteria have been engineered to express chitinases from a variety of organisms for control of arthropod pests. In addition, RNA interference targeting genes involved in chitin pathways and structures are now being investigated for the development of environmentally friendly pest management strategies. This review describes the chemicals and proteins used to target chitin structures and enzymes for arthropod pest management, as well as pest management strategies based upon these compounds, such as plant-incorporated-protectants and recombinant entomopathogens. Recent advances in RNA interference-based pest management, and how this technology can be used to target chitin pathways and structures are also discussed.

Insect midgut structures and molecules as targets of plant-derived protease inhibitors and lectins

The midgut of insects is involved in digestion, osmoregulation and immunity. Although several defensive strategies are present in this organ, its organization and function may be disturbed by some insecticidal agents, including bioactive proteins like lectins and protease inhibitors (PIs) from plants. PIs interfere with digestion, leading to poor nutrient absorption and decreasing amino acid bioavailability. Intake of PIs can delay development, cause deformities and reduce fertility. Ingestion of PIs may lead to changes in the set of proteases secreted in the insect gut, but this response is often insufficient and results in aggravation of the malnutrition status. Lectins are proteins that are able to interact with glycoconjugates, including those linked to cell surfaces. Their effects on the midgut include disruption of the peritrophic matrix, brush border and secretory cell layer; induction of apoptosis and oxidative stress; interference with nutrient absorption and transport proteins; and damaging effects on symbionts. In addition, lectins can cross the intestinal barrier and reach the hemolymph. The establishment of resistant insect populations due to selective pressure resulting from massive use of a bioactive protein is an actual possibility, but this can be minimized by the multiple mode-of-action of these proteins, mainly the lectins. © 2018 Society of Chemical Industry.