White kidney bean lectin exerts anti-proliferative and apoptotic effects on cancer cells

Exploring the nutritional and health benefits of pulses from the Indian Himalayan region: A glimpse into the region's rich agricultural heritage

Pulses have been consumed worldwide for over 10 centuries and are currently among the most widely used foods. They are not economically important, but also nutritionally beneficial as they constitute a good source of protein, fibre, vitamins and minerals such as iron, zinc, folate and magnesium. Pulses, but particularly species such as Macrotyloma uniflorum, Phaseolus vulgaris L., Glycine max L. and Vigna umbellate, are essential ingredients of the local diet in the Indian Himalayan Region (IHR). Consuming pulses can have a favourable effect on cardiovascular health as they improve serum lipid profiles, reduce blood pressure, decrease platelet activity, regulate blood glucose and insulin levels, and reduce inflammation. Although pulses also contain anti-nutritional compounds such as phytates, lectins or enzyme inhibitors, their deleterious effects can be lessened by using effective processing and cooking methods. Despite their great potential, however, the use of some pulses is confined to IHR regions. This comprehensive review discusses the state of the art in available knowledge about various types of pulses grown in IHR in terms of chemical and nutritional properties, health effects, accessibility, and agricultural productivity.

Plant lectin: A promising future anti-tumor drug

Since the early discovery of plant lectins at the end of the 19th century, and the finding that they could agglutinate erythrocytes and precipitate glycans from their solutions, many applications and biological roles have been described for these proteins. Later, the observed erythrocytes clumping features were attributed to the lectin-cell surface glycoconjugates recognition. Neoplastic transformation leads to various cellular alterations which impact the growth of the cell and its persistence, among which is the mutation in the outer surface glycosylation signatures. Quite a few lectins have been found to act as excellent biomarkers for cancer diagnosis while some were presented with antiproliferative activity that initiated by lectin binding to the respective glycocalyx receptors. These properties are blocked by the hapten sugar that is competing for the lectin affinity binding site. In vitro investigations of lectin-cancer cell's glycocalyx interactions lead to a series of immunological reactions that result in autophagy or apoptosis of the transformed cells. Mistletoe lectin, an agglutinin purified from the European Viscum album is the first plant lectin employed in the treatment of cancer to enter into the clinical trial phases. The entrapment of lectin in nanoparticles besides other techniques to promote bioavailability and stability have also been recently studied. This review summarizes our up-to-date understanding of the future applications of plant lectins in cancer prognosis and diagnosis. With the provision of many examples of lectins that exhibit anti-neoplastic properties.

In Silico Analysis and Functional Characterization of Antimicrobial and Insecticidal Vicilin from Moth Bean (Vigna aconitifolia (Jacq.) Marechal) Seeds

Vicilin has nutraceutical potential and different noteworthy medicative health-promoting biotic diversions, and it is remarkable against pathogenic microorganisms and insects. In this study, Vigna aconitifolia vicilin (VacV) has been identified and characterized from the seed of Vigna aconitifolia (Jacq.) Marechal (Moth beans). LC-MS/MS analysis of VacV provided seven random fragmented sequences comprising 238 residues, showing significant homology with already reported Vigna radiata vicilin (VraV). VacV was purified using ammonium sulfate precipitation (60%) followed by size exclusion chromatography on Hi-Load 16/60 Superdex 200 pg column and anion-exchange chromatography (Hi trap Q FF column). Purified VacV showed a major ~50 kDa band and multiple lower bands on 12% sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) under both reduced and non-reduced conditions. After all, a three-dimensional molecular structure of VacV was predicted, which showed β-sheeted molecular conformation similar to crystallographic structure of VraV. All Vicilins from V. aconitifolia and other plants were divided into six sub-groups by phylogenetic analysis, and VacV shared a high degree of similarity with vicilins of Vigna radiata, Pisum sativum, Lupinus albus, Cicer arietinum and Glycine max. Additionally, VacV (20 μg) has significant growth inhibition against different pathogenic bacteria along strong antifungal activity (50 μg). Likewise, VacV (3.0 mg) produced significant growth reduction in Rice Weevil Sitophilus oryzae larvae after 9 days compared with control. Furthermore, by using MMT assay, the cytotoxicity effect of VacV on the growth of HepG2 liver cancerous cells was tested. VacV showed cytotoxicity against the HepG-2 line and the acquired value was 180 µg after 48 h. Finally, we performed molecular docking against caspase-3 protein (PDB ID: 3DEI) for VacV bioactive receptor interface residues. Hence, our results reveal that VacV, has nutraceutical potential and moth beans can be used as a rich resource of functional foods.

Research advances and prospects of legume lectins

Lectins are widely distributed proteins having ability of binding selectively and reversibly with carbohydrates moieties and glycoconjugates. Although lectins have been reported from different biological sources, the legume lectins are the best-characterized family of plant lectins. Legume lectins are a large family of homologous proteins with considerable similarity in amino acid sequence and their tertiary structures. Despite having strong sequence conservation, these lectins show remarkable variability in carbohydrate specificity and quaternary structures. The ability of legume lectins in recognizing glycans and glycoconjugates on cells and other intracellular structures make them a valuable research tool in glycomic research. Due to variability in binding with glycans, glycoconjugates and multiple biological functions, legume lectins are the subject of intense research for their diverse application in different fields such as glycobiology, biomedical research and crop improvement. The present review specially focuses on structural and functional characteristics of legume lectins along with their potential areas of application.

Effects of Low-pH Treatment on the Allergenicity Reduction of Black Turtle Bean (Phaseolus vulgaris L.) Lectin and Its Mechanism

A high content of potentially allergenic lectin in Phaseolus vulgaris L. beans is of increasing health concerns; however, understanding of the protein allergenicity mechanism on the molecular basis is scarce. In the present study, low-pH treatments were applied to modify black turtle bean lectin allergen, and a sensitization procedure was performed using the BALB/c mice for the allergenicity evaluation, while the conformational changes were monitored by the spectral analyses and the details were explored by the molecular dynamics simulation. Much milder anaphylactic responses were observed in BALB/c mice experiments. At the molecular level, the protein was unfolded in low acidic environments because of protonation, and α-helix was reduced with the exposure of trypsin cleavage sites, especially the improvement of protease accessibility for Lys121, 134, and 157 in the B cell epitope structural alterations. These results indicate that a low-pH treatment might be an efficient method to improve the safety of legume protein consumption.

Phaseolus vulgaris L. var. Venanzio Grown in Tuscany: Chemical Composition and In Vitro Investigation of Potential Effects on Colorectal Cancer

Phaseolus vulgaris L. (common bean) is a leguminous species that is an important dietary component due to its high content of proteins, unsaturated fatty acids, minerals, dietary fibers and vitamins. Due to the high content of polyphenols, several biological activities have been described for bean extracts, making it possible to include P. vulgaris among food with beneficial effects for human health. Moreover, more than 40,000 varieties of beans have been recognised with different nutraceutical properties, pointing out the importance of food biodiversity. In this work, we describe for the first time the chemical composition and biological activity of a newly recognized Italian variety of P. vulgaris grown in a restricted area of the Tuscany region and named “Fagiola di Venanzio”. Fagiola di Venanzio water extract is rich in proteins, sugars and polyphenols and displays antioxidant, anti-inflammatory and antiproliferative activities in in vitro assays on colon cancer cellular models. Our data indicate that this variety of P. vulgaris appears to be a promising source of bioactive compounds and encourage more in-depth studies to better elucidate the implications of its consumption for public health.

Improving Human Dietary Choices Through Understanding of the Tolerance and Toxicity of Pulse Crop Constituents

Chickpea, dry bean, dry pea, and lentil are prominent dietary grain legumes commonly referred to as pulses. Pulses have been a staple component of the human diet for more than 8,000 years; however, in the last 70 years they have virtually disappeared from most Western diets. Reduced intake has occurred concomitantly with inadequate dietary fiber consumption and the onset of the obesity pandemic. Misinformation about tolerance and toxicity of several pulse crop constituents remains a barrier to public health efforts to increase dietary intake. Of particular concern are lectins which participate in agglutination reactions with cell surface proteins and galacto-oligosaccharides which have been associated with intestinal discomfort and flatulence. The scientific basis of these concerns is reviewed.

Plant lectins in cancer therapeutics: Targeting apoptosis and autophagy-dependent cell death

Plant lectins are non-immunoglobin in nature and bind to the carbohydrate moiety of the glycoconjugates without altering any of the recognized glycosyl ligands. Plant lectins have found applications as cancer biomarkers for recognizing the malignant tumor cells for the diagnosis and prognosis of cancer. Interestingly, plant lectins contribute to inducing cell death through autophagy and apoptosis, indicating their potential implication in cancer inhibitory mechanism. In the present review, anticancer activities of major plant lectins have been documented, with a detailed focus on the signaling circuit for the possible molecular targeted cancer therapy. In this context, several lectins have exhibited preclinical and clinical significance, driving toward therapeutic potential in cancer treatment. Moreover, several plant lectins induce immunomodulatory activities, and therefore, novel strategies have been established from preclinical and clinical investigations for the development of combinatorial treatment consisting of immunotherapy along with other anticancer therapies. Although the application of plant lectins in cancer is still in very preliminary stage, advanced high-throughput technology could pave the way for the development of lectin-based complimentary medicine for cancer treatment.

Low-pH induced structural changes, allergenicity and in vitro digestibility of lectin from black turtle bean (Phaseolus vulgaris L.)

Lectin was incubated in corresponding acidic buffers (pH 1.0-3.5) for a certain period (0.5, 1, 2, 4, 8, 12 and 24 h) at 25 °C. Low-pH induced changes in structure, allergenicity and in vitro digestibility of lectin from black turtle bean (Phaseolus vulgaris L.) were investigated in the present study. Results indicated that the alteration in structure was a progressive unfolding process mainly depending on pH environment, and the treated lectin attained a stable state at 8 h. Electrophoretic, dynamic light scattering (DLS) and size exclusion chromatography (SEC) analyses suggested that lectin monomers appeared in the solutions of pH < 2.0. Differential scanning calorimetry (DSC) confirmed that thermal stability of lectin weakened in low pH environments. Furthermore, ELISA and in vitro digestion assay showed allergenicity and digestibility significantly decreased with the structural alterations. These results showed low-pH treatments have great potential to reduce the damage of legumes protein consumption.

Biochemical characterisation of lectin from wild chickpea (Cicer reticulatum L.) with potential inhibitory action against human cancer cells

A wild chickpea lectin (WCL) from the seeds of Cicer reticulatum L. was chromato-purified using DEAE-Cellulose and SP-Sephadex ion exchange chromatography. WCL was thermostable upto 60°C with broad pH optima (pH 5-9) and various divalent metal ions did not influence its activity. WCL demonstrated DNA protection in a dose-dependent manner. The lectin exerted antifungal activity against diverse fungal pathogens. WCL augmented the mitogenic response of mouse spleen cells at 10 µg/ml concentration and showed an inhibition of HIV-1 reverse transcriptase at IC₅₀ of 200 µM. Against human cancer cell lines, lectin demonstrated anticancer potential. The cell viability assay in HepG2, Ishikawa, MCF-7 and MDA-MB-231 cell line demonstrated IC₅₀ values of 61.8, 54.4, 37.5 and 44.2 µg/ml respectively. PRACTICAL APPLICATIONS: WCL exhibited distinct medicinal properties vis-à-vis antiproliferative, mitogenic, antifungal/bacterial and HIV-1 reverse transcriptase inhibiting activities. The potential of WCL can be a subject of exploration from a pharmacological standpoint.

Inhibitory Effects of Pulse Bioactive Compounds on Cancer Development Pathways

Previous studies suggest that pulses may have the potential to protect against cancer development by inhibiting pathways that result in the development of cancer. These pathways include those that result in inflammation, DNA damage, cell proliferation, and metastasis. Other studies have demonstrated extracts from pulses have the capacity to induce apoptosis specifically in cancer cells. Compounds reported to be responsible for these activities have included phenolic compounds, proteins and short chain fatty acids. The majority of the studies have been undertaken using in vitro cell culture models, however, there are a small number of in vivo studies that support the hypothesis that pulse consumption may inhibit cancer development. This review highlights the potential benefit of a diet rich in pulse bioactive compounds by exploring the anti-cancer properties of its polyphenols, proteins and short chain fatty acids.

Plant Lectins Targeting O-Glycans at the Cell Surface as Tools for Cancer Diagnosis, Prognosis and Therapy

Aberrant O-glycans expressed at the surface of cancer cells consist of membrane-tethered glycoproteins (T and Tn antigens) and glycolipids (Lewis a, Lewis x and Forssman antigens). All of these O-glycans have been identified as glyco-markers of interest for the diagnosis and the prognosis of cancer diseases. These epitopes are specifically detected using T/Tn-specific lectins isolated from various plants such as jacalin from Artocarpus integrifola, and fungi such as the Agaricus bisporus lectin. These lectins accommodate T/Tn antigens at the monosaccharide-binding site; residues located in the surrounding extended binding-site of the lectins often participate in the binding of more extended epitopes. Depending on the shape and size of the extended carbohydrate-binding site, their fine sugar-binding specificity towards complex O-glycans readily differs from one lectin to another, resulting in a great diversity in their sugar-recognition capacity. T/Tn-specific lectins have been extensively used for the histochemical detection of cancer cells in biopsies and for the follow up of the cancer progression and evolution. T/Tn-specific lectins also induce a caspase-dependent apoptosis in cancer cells, often associated with a more or less severe inhibition of proliferation. Moreover, they provide another potential source of molecules adapted to the building of photosensitizer-conjugates allowing a specific targeting to cancer cells, for the photodynamic treatment of tumors.

Physicochemical characterization, antioxidant and anticancer activities of proteins from four legume species

The physicochemical, functional, antioxidant and anticancer properties of protein isolates from the seeds of Soybean (SP), Black soybean (BSP), Adzuki bean (ABP), and Mung bean (MBP) were comparatively characterized. The difference was found in the protein composition and physicochemical properties of the four types of legume proteins, which affected the functional properties and bioactivities. BSP and SP had six predominant proteins with a molecular weight (M_W) range of 20-95 kDa, whereas ABP and MBP showed the most intense bands of 48 kDa. ABP with higher essential amino acids content and the highest solubility exhibited the highest antioxidant activities among the four types of proteins. While BSP with higher content of acidic amino acids, low content of the hydrophobic amino acids and higher WHC, may have potential nutraceutical uses.

Protein regulation and Apoptotic induction in human breast carcinoma cells (MCF-7) through lectin from G. beauts

Lectins are proteins that show a variety of biological activities. Nevertheless, information on lectin from Gluttonous beauts and their anticancer activities are very limited. In this study, we purified a lectin from hemolymph of G. beauts and identified its molecular weight to be 66kDa. The effect of lectin at different concentrations (μg/mL) on the cell growth and apoptosis were evaluated against MCF-7 and MCF-10A cells, whereas cytotoxicity to the MCF-7 cells mediated by lectin was observed and the mechanism of action of the lectin in including apoptosis in cancer cells via the intrinsic pathway was also proposed. The MCF-7 cells were employed for in vitro studies on cytotoxicity, induction of apoptosis and apoptotic DNA fragmentation. In MCF-10A cells lectin did not show any adverse effect even at higher concentration. Cell cycle analysis also showed a significant cell cycle arrest on selected cells after lectin treatment. Western blotting suggested that lectin up regulates the apoptotic protein expression in MCF-7 cells while it down regulates the level of Bcl-2 expression.