Lectins as Bioactive Plant Proteins: A Potential in Cancer Treatment

Bioactive peptides: an alternative therapeutic approach for cancer management

Cancer is still considered a lethal disease worldwide and the patients' quality of life is affected by major side effects of the treatments including post-surgery complications, chemo-, and radiation therapy. Recently, new therapeutic approaches were considered globally for increasing conventional cancer therapy efficacy and decreasing the adverse effects. Bioactive peptides obtained from plant and animal sources have drawn increased attention because of their potential as complementary therapy. This review presents a contemporary examination of bioactive peptides derived from natural origins with demonstrated anticancer, ant invasion, and immunomodulation properties. For example, peptides derived from common beans, chickpeas, wheat germ, and mung beans exhibited antiproliferative and toxic effects on cancer cells, favoring cell cycle arrest and apoptosis. On the other hand, peptides from marine sources showed the potential for inhibiting tumor growth and metastasis. In this review we will discuss these data highlighting the potential befits of these approaches and the need of further investigations to fully characterize their potential in clinics.

Purification and characterization of an asialofetuin specific lectin from the rhizome of Xanthosoma violaceum Schott

Lectins are proteins or glycoproteins that bind specifically and reversibly to the carbohydrate or glycoconjugates. A new lectin is purified from the rhizome of Xanthosoma violaceum Schott. by successive steps of ammonium sulfate fractionation and affinity chromatography with asialofetuin as ligand. The purified lectin was found to be a homotetramer of approximately 49 kDa with a subunit molecular weight of 12 kDa linked by non-covalent bonds. Characterization of the lectin shows that the hemagglutination activity is inhibited by asialofetuin and d-galacturonic acid. Hemagglutination activity is shown only in rabbit RBC but not in the human RBC of all blood groups. It is a metal ion-independent glycoprotein of 1.87% carbohydrate content, stable upto 40 °C and pH from 5.5 to 9. The lectin shows its optimum hemagglutination activity at 0 °C-40 °C and pH 6 to 8.5. From LC-MS/MS analysis it is confirmed that the purified lectin was not purified and characterized earlier.

Impairment of SK-MEL-28 Development-A Human Melanoma Cell Line-By the Crataeva tapia Bark Lectin and Its Sequence-Derived Peptides

Melanoma is difficult to treat with chemotherapy, prompting the need for new treatments. Protease inhibitors have emerged as promising candidates as tumor cell proteases promote metastasis. Researchers have developed a chimeric form of the Bauhinia bauhinioides kallikrein inhibitor, rBbKIm, which has shown negative effects on prostate tumor cell lines DU145 and PC3. Crataeva tapia bark lectin, CrataBL, targets sulfated oligosaccharides in glycosylated proteins and has also demonstrated deleterious effects on prostate and glioblastoma tumor cells. However, neither rBbKIm nor its derived peptides affected the viability of SK-MEL-28, a melanoma cell line, while CrataBL decreased viability by over 60%. Two peptides, Pep. 26 (Ac-Q-N-S-S-L-K-V-V-P-L-NH2) and Pep. 27 (Ac-L-P-V-V-K-L-S-S-N-Q-NH2), were also tested. Pep. 27 suppressed cell migration and induced apoptosis when combined with vemurafenib, while Pep. 26 inhibited cell migration and reduced nitric oxide and the number of viable cells. Vemurafenib, a chemotherapy drug used to treat melanoma, was found to decrease the release of interleukin 8 and PDGF-AB/BB cytokines and potentiated the effects of proteins and peptides in reducing these cytokines. These findings suggest that protease inhibitors may be effective in blocking melanoma cells and highlight the potential of CrataBL and its derived peptides.

Recombinant Phaseolus vulgaris phytohemagglutinin L-form expressed in the Bacillus brevis exerts in vitro and in vivo anti-tumor activity through potentiation of apoptosis and immunomodulation

Leukocyte phytohemagglutinin (PHA-L) is a tetrameric isomer of phytohemagglutinin (PHA) purified from the red kidney bean (Phaseolus vulgaris) and is a well-known human lymphocyte mitogen. Due to its antitumor and immunomodulatory effects, PHA-L may serve as a potential antineoplastic agent in future cancer therapeutics. However, various negative consequences of PHA have been reported in the literature as a result of the restricted acquisition methods, including oral toxicity, hemagglutinating activity, and immunogenicity. There is a critical need to explore a new method to obtain PHA-L with high purity, high activity and low toxicity. In this report active recombinant PHA-L protein was successfully prepared by Bacillus brevius expression system, and the antitumor and immunomodulatory activities of recombinant PHA-L were characterized by in vitro and in vivo experiments. The results showed that recombinant PHA-L protein had stronger antitumor effect, and its anti-tumor mechanism was realized through direct cytotoxicity and immune regulation. Importantly, compared with natural PHA-L, the recombinant PHA-L protein showed the lower erythrocyte agglutination toxicity in vitro and immunogenicity in mice. Altogether, our study provides a new strategy and important experimental basis for the development of drugs with dual effects of immune regulation and direct antitumor activity.

Chemopreventive and immunoadjuvant properties of standardised edible bird’s nest extract on human breast cancer cell line

The present work investigated the chemopreventive and immunoadjuvant properties of edible bird’s nest (EBN) extract on breast cancer cell line (MCF-7). Specifically, the cytotoxicity level of EBN extracts (HMG, EHMG, pHMG) against MCF-7, human immune cells of cytotoxic T cells, and monocytes (CD8+ and CD14+) were evaluated by measuring the production of pro-apoptotic and anti-apoptotic molecules released in single and co-culture of MCF-7, CD8+, and CD14+ cells, before and after EBN treatment. The highest cytotoxic effect towards MCF-7 using IC50 of 15 µg/mL was demonstrated by HMG but no effects on CD8+ and CD14+, with cell viability of more than 90%. At the mRNA level, activated CD8+ and CD14+ depicted increased pro-apoptotic gene expression after HMG treatment in co-culture. Additionally, HMG treatment increased apoptosis by down-regulating the regulation of anti-apoptotic genes and up-regulating the pro-apoptotic genes in MCF-7. ELISA and multiplex assay reflected increased pro-apoptotic factors, and decreased anti-apoptotic soluble factors, by non-activated and activated CD8+ and CD14+, in a single or co-culture with MCF-7 after HMG treatment. In conclusion, HMG extract possesses immunoadjuvant properties that can be a potential anticancer agent without causing any deleterious effects on the human immune cells.

Naturally Occurring Plant Food Toxicants and the Role of Food Processing Methods in Their Detoxification

Some plant foods evolve defense mechanisms to protect themselves from predators by producing inherent chemicals as secondary metabolites such as cyanogenic glycosides, glycoalkaloids, glucosinolates, pyrrolizidine alkaloids, and lectins. These metabolites are beneficial for the plant itself but toxic to other organisms, including human beings. Some of these toxic chemicals are believed to have therapeutic benefits and are therefore used to protect against chronic health complications such as cancer. Inversely, short- and long-term exposure to significant amounts of these phytotoxins may end up with chronic irreversible negative health problems in important organ systems, and in severe cases, they can be carcinogenic and fatal. A systematic literature search of relevant published articles indexed in Google Scholar®, PubMed®, Scopus®, Springer Link®, Web of Science®, MDPI®, and ScienceDirect databases was used to obtain the necessary information. Various traditional and emerging food-processing techniques have been found to considerably reduce most of the toxicants in the food to their safest level. Despite their ability to preserve the nutritional value of processed foods, emerging food processing methods have limited application and accessibility in middle- and low-income countries. As a consequence, much more work is recommended on the implementation of emerging technologies, with additional scientific work on food processing methods that are effective against these naturally occurring plant food toxicants, particularly pyrrolizidine alkaloids.

Recent advances in the use of legume lectins for the diagnosis and treatment of breast cancer

Poor lifestyle choices and genetic predisposition are factors that increase the number of cancer cases, one example being breast cancer, the third most diagnosed type of malignancy. Currently, there is a demand for the development of new strategies to ensure early detection and treatment options that could contribute to the complete remission of breast tumors, which could lead to increased overall survival rates. In this context, the glycans observed at the surface of cancer cells are presented as efficient tumor cell markers. These carbohydrate structures can be recognized by lectins which can act as decoders of the glycocode. The application of plant lectins as tools for diagnosis/treatment of breast cancer encompasses the detection and sorting of glycans found in healthy and malignant cells. Here, we present an overview of the most recent studies in this field, demonstrating the potential of lectins as: mapping agents to detect differentially expressed glycans in breast cancer, as histochemistry/cytochemistry analysis agents, in lectin arrays, immobilized in chromatographic matrices, in drug delivery, and as biosensing agents. In addition, we describe lectins that present antiproliferative effects by themselves and/or in conjunction with other drugs in a synergistic effect.

Potential Role of Bioactive Proteins and Peptides Derived from Legumes towards Metabolic Syndrome

Legumes have been widely consumed and used to isolate bioactive compounds, mainly proteins. The aim of this study was to review the beneficial actions of different legumes proteins and peptides updating the main findings that correlate legumes consumption and the effects on non-transmissible chronic diseases, specifically metabolic syndrome. An exhaustive revision of five relevant bioactivities (antioxidant, anti-inflammatory, antihypertensive, hypocholesterolemic -all of them linked to metabolic syndrome- and antitumoral) of proteins and peptides from legumes focused on isolation and purification, enzymatic hydrolysis and in vitro gastrointestinal digestion was carried out. The promising potential of bioactive hydrolysates and peptides from pulses has been demonstrated by in vitro tests. However, only a few studies validated these biological activities using animal models. No clinical trials have been carried out yet; so further research is required to elucidate their effective health implications.

Reprograming of Gene Expression of Key Inflammatory Signaling Pathways in Human Peripheral Blood Mononuclear Cells by Soybean Lectin and Resveratrol

Inflammation is linked to several human diseases like microbial infections, cancer, heart disease, asthma, diabetes, and neurological disorders. We have shown that the prototype inflammatory agonist LPS modulates the activity of Ubiquitin-Proteasome System (UPS) and regulates transcription factors such as NF-κB, leading to inflammation, tolerance, hypoxia, autophagy, and apoptosis of cells. We hypothesized that proteasome modulators resveratrol and soybean lectin would alter the gene expression of mediators involved in inflammation-induced signaling pathways, when administered ex vivo to human peripheral blood mononuclear blood cells (PBMCs) obtained from normal healthy controls. To test this hypothesis, analysis of RNA derived from LPS-treated human PBMCs, with or without resveratrol and soybean lectin, was carried out using Next Generation Sequencing (NGS). Collectively, the findings described herein suggest that proteasome modulators, resveratrol (proteasome inhibitor) and lectins (proteasome activator), have a profound capacity to modulate cytokine expression in response to proteasome modulators, as well as expression of mediators in multiple signaling pathways in PBMCs of control subjects. We show for the first-time that resveratrol downregulates expression of mediators involved in several key signaling pathways IFN-γ, IL-4, PSMB8 (LMP7), and a subset of LPS-induced genes, while lectins induced IFN-γ, IL-4, PSMB8, and many of the same genes as LPS that are important for innate and adaptive immunity. These findings suggest that inflammation may be influenced by common dietary components and this knowledge may be used to prevent or reverse inflammation-based diseases.

Isolation, partial characterization and in vitro digestion of starch from Ariopsis peltata and Lagenandra toxicaria tuber

The starch from two aroid tuber viz. Ariopsis peltata and Lagenandra toxicaria were isolated and evaluated for their morphological, physical and chemical properties. The tubers of these plants are used as food and medicine by the indigenous communities. The starch yield from A. peltata tuber was 25 ± 1.7% with an amylose content of 10 ± 0.9%, while the tuber of L. toxicaria contained 28 ± 6.5% starch with 15 ± 0.5% of apparent amylose in it. The starch isolated from both the tubers was highly pure (99%) starch exhibiting an A-type X-ray diffraction pattern. The starch granules of L. toxicaria were of various shapes and exhibited a smooth surface without any cleft or break. While the starch granules of A. peltata were spherical with smooth surface, as well as rough surface. The breaks and clefts were apparent on the rough-surfaced granules. The gelatinization temperature range for A. peltata and L. toxicaria starch is approximately 23 °C and 19 °C respectively. A. peltata starch showed higher thermal stability compared to L. toxicaria starch and either of the starch was rapidly digestible as evident from in vitro digestion study. The physicochemical properties of both the starches render them stable to withstand extreme processing. Besides they also mimic simple sugar in digestibility. So it can be utilized as a substitute for simple sugars in brewing and pharmaceutical industries.

Exploring the Phytochemicals and Anti-Cancer Potential of the Members of Fabaceae Family: A Comprehensive Review

Cancer is the second-ranked disease and a cause of death for millions of people around the world despite many kinds of available treatments. Phytochemicals are considered a vital source of cancer-inhibiting drugs and utilize specific mechanisms including carcinogen inactivation, the induction of cell cycle arrest, anti-oxidant stress, apoptosis, and regulation of the immune system. Family Fabaceae is the second most diverse family in the plant kingdom, and species of the family are widely distributed across the world. The species of the Fabaceae family are rich in phytochemicals (flavonoids, lectins, saponins, alkaloids, carotenoids, and phenolic acids), which exhibit a variety of health benefits, especially anti-cancer properties; therefore, exploration of the phytochemicals present in various members of this family is crucial. These phytochemicals of the Fabaceae family have not been explored in a better way yet; therefore, this review is an effort to summarize all the possible information related to the phytochemical status of the Fabaceae family and their anti-cancer properties. Moreover, various research gaps have been identified with directions for future research.

The Impact of Cereal Grain Composition on the Health and Disease Outcomes

Whole grains are a pivotal food category for the human diet and represent an invaluable source of carbohydrates, proteins, fibers, phytocompunds, minerals, and vitamins. Many studies have shown that the consumption of whole grains is linked to a reduced risk of cancer, cardiovascular diseases, and type 2 diabetes and other chronic diseases. However, several of their positive health effects seem to disappear when grains are consumed in the refined form. Herein we review the available literature on whole grains with a focus on molecular composition and health benefits on many chronic diseases with the aim to offer an updated and pragmatic reference for physicians and nutrition professionals.

Biological activity and development of functional foods fortified with okra (Abelmoschus esculentus)

The Abelmoschus esculentus plant, better known as okra, is an interesting crop from a nutritional standpoint. The okra plant is native to the African region but can now be found throughout tropical and subtropical areas of the world. This plant, known for its healing abilities, has been used as a traditional medicine to treat several diseases and external ailments, such as wounds or boils. This article reviews the potential health benefits from okra consumption, as well as the bioactive compounds that are suggested to be responsible. Furthermore, the okra plant and its derivatives have been evaluated in the formulation and manufacture of new functional food products. The latest advances in this direction, which includes characterizing the technical properties of functional foods fortified with okra are also presented in this review. A series of bioactive compounds such as flavonoids and catechins have been found in the okra plant, which were associated with numerous biological properties observed in research studies that reported potential anti-diabetic, anti-cancer, anti-hypertensive, and antimicrobial effects, among others, as a result of their consumption. These potential health benefits contribute to the development of new and useful functional foods, with okra (or its derivatives) being used as the highlighted ingredient.

Asparagus racemosus and Geodorum densiflorum lectins induce apoptosis in cancer cells by altering proteins and genes expression

A lectin (designated as ARL) was purified first time from the Asparagus racemosus root with the molecular weight of 14.0 kDa containing about 4.8% carbohydrate. ARL showed hemagglutination activity in both mice and human erythrocytes that were inhibited by three complex sugars among the 26 sugars tested. ARL was thermostable that mostly preserved activity at its optimum pH 8.0. Around 48% and 52.5% human colorectal cancer (HCT-116) cells growth was inhibited by 160 μg/ml of ARL and 256 μg/ml of previously purified Geodorum densiflorum rhizome lectin (GDL). Induction of apoptosis in HCT-116 cells was confirmed by Hoechst 33342 staining, caspase inhibitors, but ROS generation was only observed for ARL. The expression level of BAX and p53 genes increased with a decrease of PARP gene expression for both lectins. The expression of FAS and FADD were increased with the decrease of WNT after treatment with GDL. ARL inhibited 68% and 26% of Ehrlich ascites carcinoma cell growth in vivo in mice after treating with 3.0 and 1.5 mg/kg/day doses for five consecutive days. ARL increased the expression level of NFκB and arrested S cell cycle phase in EAC cells, in contrast, G₂/M phase was arrested by ARL and GDL in HCT-116.

Lectin Activity in Commonly Consumed Plant-Based Foods: Calling for Method Harmonization and Risk Assessment

Lectins are ubiquitous proteins characterized through their ability to bind different types of carbohydrates. It is well known that active lectins from insufficiently prepared legumes can cause adverse human health effects. The objective of this study was to determine the activity of lectins in samples across plant families representing commercially available edible plants, and the feasibility of inactivating lectins through soaking and boiling. Lectins were extracted from the plant families Adoxaceae, Amaranthaceae, Cannabaceae, Fabaceae, Gramineae, Lamiaceae, Linaceae, Pedaliaceae, and Solanaceae. A hemagglutination assay based on non-treated or trypsin treated rabbit erythrocytes was used to measure the lectin activity. The results showed the highest lectin activity in species from the Fabaceae family and demonstrated that soaking and boiling have an effect on the levels of active lectins. This is the first large study that combines lectin activity obtained from two different assays with raw and processed edible plants. In addition, we examined the current risk assessment, and regulations necessary for an adequate official reporting of results. We encourage the scientific community to further explore this field and agree on harmonized methods for analysis and interpretation, and hope that our methodology can initiate this development.

Rhizoctonia bataticola lectin induces apoptosis and inhibits metastasis in ovarian cancer cells by interacting with CA 125 antigen differentially expressed on ovarian cells

A N-glycan specific lectin from Rhizoctonia bataticola [RBL] was shown to induce growth inhibitory and apoptotic effect in human ovarian, colon and leukemic cells but mitogenic effect on normal PBMCs as reported earlier, revealing its clinical potential. RBL has unique specificity for high mannose tri and tetra antennary N-glycans, expressed in ovarian cancer and also recognizes glycans which are part of CA 125 antigen, a well known ovarian cancer marker. Hence, in the present study diagnostic and therapeutic potential of RBL was investigated using human ovarian epithelial cancer SKOV3 and OVCAR3 cells known for differentially expressing CA 125. RBL binds differentially to human ovarian normal, cyst and cancer tissues. Flow cytometry, western blot analysis of membrane proteins showed the competitive binding of RBL and CA 125 antibody for the same binding sites on SKOV3 and OVCAR3 cells. RBL has strong binding to both SKOV3 and OVCAR3 cells with MFI of 173 and 155 respectively. RBL shows dose and time dependent growth inhibitory effect with IC₅₀ of 2.5 and 8 μg/mL respectively for SKOV3 and OVCAR3 cells. RBL induces reproductive cell death, morphological changes, nuclear degradation and increased release of ROS in SKOV3 and OVCAR3 cells leading to cell death. This is also supported by increase in hypodiploid population, altered MMP leading to apoptosis possibly involving intrinsic pathway. Adhesion, wound healing, invasion and migration assays demonstrated anti-metastasis effect of RBL apart from its growth inhibitory effect. These results show the promising potential of RBL both as a diagnostic and therapeutic agent.

Lectins applied to diagnosis and treatment of prostate cancer and benign hyperplasia: A review

Environmental factors, as well as genetic factors, contribute to the increase in prostate cancer cases (PCa), the second leading cause of cancer death in men. This fact calls for the development of more reliable, quick and low-cost early detection tests to distinguish between malignant and benign cases. Abnormal cell glycosylation pattern is a promising PCa marker for this purpose. Proteins, such as lectins can decode the information contained in the glycosylation patterns. Several studies have reported on applications of plant lectins as diagnostic tools for PCa considering the ability to differentiate it from benign cases. In addition, they can be used to detect, separate and differentiate the glycosylation patterns of cells or proteins present in serum, urine and semen. Herein, we present an overview of these studies, showing the lectins that map glycans differentially expressed in PCa, as well as benign hyperplasia (BPH). We further review their applications in biosensors, histochemical tests, immunoassays, chromatography, arrays and, finally, their therapeutic potential. This is the first study to review vegetable lectins applied specifically to PCa.

3'-Sulfo-TF Antigen Determined by GAL3ST2/ST3GAL1 Is Essential for Antitumor Activity of Fungal Galectin AAL/AAGL

Many lectins have been reported to have antitumor activities; identifying the glycan ligands in tumor cells of lectins is crucial for lectin clinical application. An edible mushroom galectin, Agrocybe aegerita lectin (AAL/AAGL), that has a high antitumor activity has been reported. In this paper, based on the glycan array data, it is showed that the Thomsen-Friedenreich antigen (TF antigen)-related O-glycans were found to be highly correlated with the antitumor activity of AAL/AAGL. Further glycosyltransferase quantification suggested that the ratio between GAL3ST2 and ST3GAL1 (GAL3ST2/ST3GAL1), which determined the 3'-sulfo-TF expression level, was highly correlated with the antitumor activity of AAL/AAGL. Overexpressing the enzyme of GAL3ST2 in HL60 and HeLa cell lines could increase the growth inhibition ratio of AAL/AAGL from 22.7 to 43.9% and 27.8 to 39.1%, respectively. However, ST3GAL1 in Jurkat cells could decrease the growth inhibition ratio from 44.7 to 35.6%. All the data suggested that the 3'-sulfo-TF antigen is one of the main glycan ligands that AAL/AAGL recognizes in tumor cells. AAL/AAGL may potentially serve as a reagent for cancer diagnosis and a targeted therapy for the 3'-sulfo-TF antigen.

Three-dimensional structure and properties of the giant reed (Arundo donax) lectin (ADL)

Arundo donax lectin (ADL) is a 170 amino acid protein that can be purified from the rhizomes of the giant reed or giant cane exploiting its selective binding to chitin followed by elution with N-acetyl-D-glucosamine. The lectin is listed in the UniProt server, the largest protein sequence database, as an uncharacterized protein with chitin-binding domains (A0A0A9P802). This paper reports the purification, three-dimensional structure and ligand-binding properties of ADL. The lectin is a homodimer in which the two protomers are linked by two disulphide bridges. Each polypeptide chain presents four carbohydrate-binding modules that belong to family 18 (CBM18). A high degree of sequence similarity is observed among the modules present in each protomer. We have determined the X-ray structure of the apo-protein to a resolution of 1.70 Å. The carbohydrate-binding modules, that span a sequence of approximately 40 amino acids, present four internal disulfide bridges a very short antiparallel central beta sheet and three short alpha helices, two on one side of the beta sheet and one on the other. The structures of the complexes of the lectin with N-acetylglucosamine, N-acetyllactosamine, N-acetylneuraminic acid and N-N'diacetylchitobiose reveal that ADL has two primary and two secondary carbohydrate-binding sites per dimer. They are located at the interface between the two protomers and each binding site involves residues of both chains. The lectin presents structural similarity to the wheat germ agglutinin (WGA) family, in particular to isoform 3.

Trichosanthes dioica seed lectin inhibits Ehrlich ascites carcinoma cells growth in vivo in mice by inducing G0 /G1 cell cycle arrest

Trichosanthes dioica seed lectin (TDSL), having a molecular mass of 57 ± 2 kDa was purified in an alternative way. For the purification process, the galactose-sepharose-4B affinity column was used. The purified TDSL agglutinated human and mouse erythrocytes at the minimum concentration of 8  μg/ml. d-lactose and d-galactose were the most potent inhibitory sugars as observed. The purified lectin was a glycoprotein having 3.0% of a neutral sugar. The lectin exhibited maximum activity up to 60°C and pH range from 7.0 to 10.0 and stable up to 4.0 M urea as tested. The lectin demonstrated mild toxicity when administered against brine shrimp nauplii, and the LC₅₀ value was calculated to be 84.0 µg/ml. Minimum agglutination of Ehrlich ascites carcinoma (EAC) cells caused by the lectin was found at the protein concentration of 1.56 µg/ml. TDSL inhibited 7, 50.2%, and 60.3% of the EAC cells growth in vivo in mice when administered with 0.75, 1.5, and 3.0 mg kg^-1  day^-1 (i.p.), respectively, for five consecutive days. After lectin treatment, red blood cell (RBC) and hemoglobin levels were increased significantly toward the normal compared with EAC cells-bearing control and normal mice. The tumor burden reduced to 29.5% and 67% after treatment with 1.5 and 3.0 mg kg^-1  day^-1 of the lectin. TDSL triggered the cell cycle arrest at the G₀ /G₁ phase, which was observed using flow cytometry. In conclusion, TDSL can be a candidate for the potent anticancer agents that exerts low toxicity toward brine shrimp nauplii. PRACTICAL APPLICATIONS: A 57 ± 2 kDa lectin (designated TDSL) was purified from Trichosanthes dioica seeds using a galactose-sepharose-4B affinity column. The lectin demonstrated mild toxicity and agglutinated Ehrlich ascites carcinoma (EAC) cells. The lectin inhibited 50.2% and 60.3% of the EAC cell growth in vivo in mice when administered with 1.5 and 3.0 mg kg^-1  day^-1 (i.p.), respectively, for five consecutive days. The lectin increased RBC and hemoglobin level toward the normal compared with lectin-treated EAC cells-bearing, EAC cells-bearing control and normal mice. The tumor burden reduced to 29.5% and 67% after treatment with 1.5 and 3.0 mg kg^-1  day^-1 lectin. TDSL triggered the cell cycle arrest at the G₀ /G₁ phase. The lectin can be a candidate for potent anticancer agents.

Anticancer Activity of Lectins from Bauhinia purpurea and Wisteria floribunda on Breast Cancer MCF-7 Cell Lines

BACKGROUND

Individual and collaborative efforts are being made worldwide in search of effective chemical or natural drugs with less severe side-effects for treatment of cancer. Due to the specificity and selectivity properties of lectins for saccharides, several plant lectins are known to induce cytotoxicity into tumor cells.

OBJECTIVE

To study the antiproliferative activity of two N-acetyl galactosamine specific plant lectins from seeds of Bauhinia purpurea and Wisteria floribunda against MCF-7 Breast cancer cell lines.

METHODS

MTT, lactate dehydrogenase (LDH) leakage, reactive oxygen species (ROS), and caspase- 3 assays and flow cytometry for cell cycle analysis were performed.

RESULTS

The agglutinins BPL and WFL; 446 μgml-1 (2.2 μM) and 329 μgml-1 (2.8 μM), respectively caused remarkable concentration-dependent antiproliferative effect on MCF-7. The effect was seen to be a consequence of binding of the lectin to the cell surface and triggering S and G2 phase arrest. Apoptosis induced was found to be associated with LDH leakage, cell cycle arrest and ROS generation. The apoptotic signal was observed to be amplified by activation of caspase-3 resulting in cell death.

CONCLUSION

The study provides a base for detailed investigation and further use of lectins in cancer studies.

Functional Component Isolated from Phaseolus vulgaris Lectin Exerts In Vitro and In Vivo Anti-Tumor Activity Through Potentiation of Apoptosis and Immunomodulation

Phytohemagglutinin (PHA), the lectin purified from red kidney bean (Phaseolus vulgaris), is a well-known mitogen for human lymphocyte. Because it has obvious anti-proliferative and anti-tumor activity, PHA may serve as a potential antineoplastic drug in future cancer therapeutics. However, the literature is also replete with data on detrimental effects of PHA including oral toxicity, hemagglutinating activity, and immunogenicity. There is a critical need to evaluate the functional as well as the toxic components of PHAs to assist the rational designs of treatment with it. In this report, we performed SDS-PAGE to identify components of PHA-L, the tetrameric isomer of PHA with four identical L-type subunits, and then characterized biological function or toxicity of the major protein bands through in vitro experiments. It was found that the protein appearing as a 130 kD band in SDS-PAGE gel run under the condition of removal of β-mercaptoethanol from the sample buffer together with omission of a heating step could inhibit tumor cell growth and stimulate lymphocyte proliferation, while most of the 35 kD proteins are likely non-functional impurity proteins and 15 kD protein may be related to hemolytic effect. Importantly, the 130 kD functional protein exhibits promising in vivo anti-tumor activity in B16-F10 melanoma C57 BL/6 mouse models, which may be achieved through potentiation of apoptosis and immunomodulation. Altogether, our results suggest that PHA-L prepared from crude extracts of red kidney bean by standard strategies is a mixture of many ingredients, and a 130 kD protein of PHA-L was purified and identified as the major functional component. Our study may pave the way for PHA-L as a potential anticancer drug.

Genetic sequence analysis and characterization of bioactive compounds in mushroom-forming fungi

Mushroom-forming fungi produce unique bioactive compounds that have potential applications as medicines, supplements, and agrochemicals. Thus, it is necessary to clarify the biosynthetic pathways of these compounds using genome and transcriptome analyses. This review introduces some of our research on bioactive compounds isolated from mushrooms, as well as genetic analysis with next-generation sequencing.

In vitro assessment of dual (antiviral and antitumor) activity of a novel lectin produced by the newly cyanobacterium isolate, Oscillatoria acuminate MHM-632 MK014210.1

A novel lectin was purified from newly cyanobacterium isolate, Oscillatoria acuminate MHM-632 MK014210.1 using affinity chromatography with a molecular weight of 120 kDa under native-PAGE and 30 kDa on reducing-PAGE, represented tetramer nature of this lectin. Oscillatorial lectin showed stability at 60 °C for 30 min, pH-dependent, with the highest activities over the pH range of 6-8, and required zinc ions to express its full activity. Oscillatorial lectin is a glycan-binding protein with a neutral carbohydrate content of 7.0% as evaluated by the phenol-sulfuric acid method. Polyols and α- glycosides polymer of mannose sugar or sugars alcohol were completely inhibited oscillatorial lectin with MIC of 0.195 mM, while β-glycosides sugars did not show any inhibition effect. The oscillatorial lectin has anti-proliferative activity against Huh-7 and MCF-7 cancer cells and inhibited their proliferation with EC₅₀ values of 106.75 µg/ml and 254.14 µg/ml, respectively. Besides the anticancer effect, oscillatorial lectin also has potent antiviral activity against HSV-1 in a dose-dependent manner via virions neutralization and inhibition of viral replication with IC₅₀ values of 90.95 ng/ml and 131.3 ng/ml, respectively. The unique carbohydrate affinity of oscillatorial lectin provides insight into its use as a promising candidate in many biotechnological applications, like fighting viral infection and combating cancer disease.Communicated by Ramaswamy H. Sarma.

Exploring the multifocal role of phytochemicals as immunomodulators

A well-functioning immune system of the host body plays pivotal role in the maintenance of ordinary physiological and immunological functions as well as internal environment. Balanced immunity enhances defense mechanism against infection, diseases and unwanted pathogens to avoid hypersensitivity reactions and immune related diseases. The ideal immune responses are the results of corrective interaction between the innate immune cells and acquired components of the immune system. Recently, the interest towards the immune system increased as significant target of toxicity due to exposure of chemicals, drugs and environmental pollutants. Numerous factors are involved in altering the immune responses of the host such as sex, age, stress, malnutrition, alcohol, genetic variability, life styles, environmental-pollutants and chemotherapy exposure. Immunomodulation is any modification of immune responses, often involved induction, amplification, attenuation or inhibition of immune responses. Several synthetic or traditional medicines are available in the market which promptly have many serious adverse effects and create pathogenic resistance. Phytochemicals are naturally occurring molecules, which significantly play an imperative role in modulating favorable immune responses. The present review emphasizes on the risk factors associated with alterations in immune responses, and immunomodulatory activity of phytochemicals specifically, glycosides, alkaloids, phenolic acids, flavonoids, saponins, tannins and sterols and sterolins.

Tepary bean (Phaseolus acutifolius) lectin fraction provokes reversible adverse effects on rats' digestive tract

The Tepary bean (Phaseolus acutifolius) lectin fraction (TBLF) exhibits differential cytotoxicity on colon cancer cells and inhibition of early tumorigenesis in the colon (50 mg/kg, three times per week, for 6 weeks). TBLF showed low toxicity with the ability to activate the immune system; however, some adverse effects are the loss in body weight gain, intestinal atrophy, and pancreatic hyperplasia. After a recovery period of 2 weeks after treatment, reversion of pancreatic hyperplasia but no recovery of intestinal atrophy was observed. As TBLF has shown anticancer effects on the colon, it is important to characterize the adverse effects and how they can be reversed. Sprague Dawley rats were administered with TBLF (50 mg/kg) for 6 weeks, three times per week, and then allowed to recover for 6 weeks post-treatment. After TBLF administration, small intestine atrophy, villus atrophy, and cryptic hyperplasia were confirmed, as well as increased intestinal mucus production, increased permeability and a decrease in the apparent ileal digestibility of crude proteins. The colon showed damage in the simple prismatic tissue and decreased crypt depth, and changes in microbiota and a decrease in the apparent fecal digestibility of crude protein were determined. Our results show that the adverse effects provoked by TBLF were partially reversed after 6 weeks of recovery post-treatment, suggesting that increasing the recovery period it could be possible to reverse all adverse effects observed.

Is There Such a Thing as "Anti-Nutrients"? A Narrative Review of Perceived Problematic Plant Compounds

Plant-based diets are associated with reduced risk of lifestyle-induced chronic diseases. The thousands of phytochemicals they contain are implicated in cellular-based mechanisms to promote antioxidant defense and reduce inflammation. While recommendations encourage the intake of fruits and vegetables, most people fall short of their target daily intake. Despite the need to increase plant-food consumption, there have been some concerns raised about whether they are beneficial because of the various ‘anti-nutrient’ compounds they contain. Some of these anti-nutrients that have been called into question included lectins, oxalates, goitrogens, phytoestrogens, phytates, and tannins. As a result, there may be select individuals with specific health conditions who elect to decrease their plant food intake despite potential benefits. The purpose of this narrative review is to examine the science of these ‘anti-nutrients’ and weigh the evidence of whether these compounds pose an actual health threat.

Structure and properties of the oyster mushroom (Pleurotus ostreatus) lectin

Pleurotus ostreatus Lectin (POL) is a 353 amino acid chain lectin that can be purified from the fruiting bodies of the very well-known and widely diffused edible oyster mushrooms (P. ostreatus). The lectin has been partially characterized by different groups and, although it was crystallized about 20 years ago, its 3D structure and the details of its interactions with carbohydrates are still unknown. This paper reports the 3D structure and ligand-binding properties of POL. We have determined the X-ray structure of the apo-protein purified from the fruiting bodies of the mushroom and that of the recombinant protein in complex with melibiose to a resolution of about 2 Å. The lectin is a homodimer in which the two polypeptide chains are linked by a disulfide bridge. A POL monomer is composed of two highly homologous β-jellyroll domains each of which containing a calcium-dependent carbohydrate-binding site. A high degree of sequence similarity is observed between the two carbohydrate-binding modules present in each monomer. The structure of the lectin in complex with melibiose reveals that a POL dimer has four calcium-dependent carbohydrate-binding sites. The interaction with sugars in solution has been characterized by isothermal titration calorimetry and saturation transfer difference NMR and it sheds new light on the molecular determinants of POL specificity. The lectin exhibits in vitro antiproliferative effects against human cancer cell lines and presents structural similarity with the prototype member of the CBM67 family, the noncatalytic domain of Streptomyces avermitilis α-rhamnosidase.

Probabilistic identification of saccharide moieties in biomolecules and their protein complexes

The chemical composition of saccharide complexes underlies their biomedical activities as biomarkers for cardiometabolic disease, various types of cancer, and other conditions. However, because these molecules may undergo major structural modifications, distinguishing between compounds of saccharide and non-saccharide origin becomes a challenging computational problem that hinders the aggregation of information about their bioactive moieties. We have developed an algorithm and software package called "Cheminformatics Tool for Probabilistic Identification of Carbohydrates" (CTPIC) that analyzes the covalent structure of a compound to yield a probabilistic measure for distinguishing saccharides and saccharide-derivatives from non-saccharides. CTPIC analysis of the RCSB Ligand Expo (database of small molecules found to bind proteins in the Protein Data Bank) led to a substantial increase in the number of ligands characterized as saccharides. CTPIC analysis of Protein Data Bank identified 7.7% of the proteins as saccharide-binding. CTPIC is freely available as a webservice at (http://ctpic.nmrfam.wisc.edu).

Anticancer potentiality and mode of action of low-carbohydrate proteins and peptides from mushrooms

Severe side effects of chemotherapy as well as drug resistance highlight the ongoing need to discover novel natural bioactive compounds with anticancer potentiality. Mushroom-derived proteins are among the naturally occurring compounds that have been the subject of a body of research on their potentiality in cancer therapy. The greatest attention in relevant review articles has been paid to well-known mushroom-derived glycoproteins such as lectins and protein-bound polysaccharide complexes such as polysaccharide-K (PSK) or krestin and polysaccharopeptide (PSP), which contain substantial amounts of carbohydrates (50-90%). These complex compounds exert their anticancer activity mainly by binding to cell membranes leading to extrinsic (death receptor) apoptosis or intrinsic (mitochondrial) apoptotic pathways. However, several other research studies have reported pure, well-characterized, proteins or peptides from mushrooms, which are carbohydrate-free or have very low amounts of carbohydrate. These proteins may fall into four categories including fungal immunomodulatory proteins, ubiquitin-like proteins, enzymes, and unclassified proteins. Well-defined chemical structure, elucidated full amino acid or N-terminal sequences, purity, and having some distinct and specific pathways compared to glycoproteins have made these low-carbohydrate proteins attractive for cancer research. The aim of this review was therefore to improve the current understanding of mushroom-derived low-carbohydrate proteins and to consolidate the existing knowledge of the most promising mushroom species from which low-carbohydrate proteins have been derived, characterized, and examined for their anticancer activity. In addition, molecular targets and mechanisms of action of these proteins have been discussed. Key points • Mushroom-derived low-carbohydrate proteins lack or have low carbohydrate. • Low-carbohydrate proteins show potent anticancer activities in vitro and in vivo. • There are specific pathways for low-carbohydrate proteins to inhibit cancer cells.

A core fucose specific lectin from Cephalosporium curvulum induces cellular apoptosis in hepatocellular and pancreatic cancer cells and effective in detecting AFP

Cephalosporium curvulum lectin (CSL), a lectin from pathogenic fungus has exquisite specificity towards α1-6 linkage of core fucosylated glycans, expressed in hepatocellular and pancreatic cancer. Interaction and effect of CSL and other fucose specific lectins LCA and AOL on HepG2 and PANC-1 cells was investigated. CSL, LCA and AOL exhibited strong binding to PANC-1 cells which could be effectively blocked by competing glycoprotein mucin. Effect of CSL, LCA and AOL on PANC-1 and HepG2 cells was determined by MTT assay and all the three lectins inhibited the cell growth which could be blocked by mucin, cell cycle analysis revealed that CSL increased hypodiploid HepG2 cell population indicating cellular apoptosis. CSL induced apoptosis in HepG2 cells was confirmed by Annexin V/PI assay. CSL induced increase in early apoptotic HepG2 cell population, a time dependent increase in the expression of caspases-3, 9 and cytochrome-c was observed by western blotting suggesting the possible involvement of intrinsic caspase dependent apoptosis. Increase in ROS and decrease in MMP demonstrated involvement of intrinsic caspase dependent apoptosis. Quantification of AFP in HCC patients using CSL lectin-antibody sandwich ELISA, supports diagnostic potential of CSL.

Recombinant Lectin from Tepary Bean (Phaseolus acutifolius) with Specific Recognition for Cancer-Associated Glycans: Production, Structural Characterization, and Target Identification

Herein, we report the production of a recombinant Tepary bean lectin (rTBL-1), its three-dimensional (3D) structure, and its differential recognition for cancer-type glycoconjugates. rTBL-1 was expressed in Pichia pastoris, yielding 316 mg per liter of culture, and was purified by nickel affinity chromatography. Characterization of the protein showed that rTBL-1 is a stable 120 kDa homo-tetramer folded as a canonical leguminous lectin with two divalent cations (Ca2+ and Mn2+) attached to each subunit, confirmed in its 3D structure solved by X-ray diffraction at 1.9 Å resolution. Monomers also presented a ~2.5 kDa N-linked glycan located on the opposite face of the binding pocket. It does not participate in carbohydrate recognition but contributes to the stabilization of the interfaces between protomers. Screening for potential rTBL-1 targets by glycan array identified 14 positive binders, all of which correspond to β1-6 branched N-glycans' characteristics of cancer cells. The presence of α1-6 core fucose, also tumor-associated, improved carbohydrate recognition. rTBL-1 affinity for a broad spectrum of mono- and disaccharides was evaluated by isothermal titration calorimetry (ITC); however, no interaction was detected, corroborating that carbohydrate recognition is highly specific and requires larger ligands for binding. This would explain the differential recognition between healthy and cancer cells by Tepary bean lectins.

Identification of Cancerlectins Using Support Vector Machines With Fusion of G-Gap Dipeptide

The cancerlectin plays an important role in the initiation, survival, growth, metastasis, and spread of cancer. Therefore, to study the function of cancerlectin is greatly significant because it can help to identify tumor markers and tumor prevention, treatment, and prognosis. However, plenty of studies have generated a large amount of protein data. Traditional prediction methods have been unable to meet the needs of analysis. Developing powerful computational models based on these data to discriminate cancerlectins and non-cancerlectins on a large scale has been treated as one of the most important topics. In this study, we developed a feature extraction method to identify cancerlectins based on fusion of g-gap dipeptides. The analysis of variance was used to select the optimal feature set and a support vector machine was used to classify the data. The rigorous nested 10-fold cross-validation results, demonstrated that our method obtained the prediction accuracy of 83.91% and sensitivity of 83.15%. At the same time, in order to evaluate the performance of the classification model constructed in this work, we constructed a new data set. The prediction accuracy of the new data set reaches 83.3%. Experimental results show that the performance of our method is better than the state-of-the-art methods.

Concanavalin A Enhanced Proliferation and Osteogenic Differentiation of Dental Pulp Stem Cells

Objective  Dental pulp stem cells (DPSCs) can be used as a component in the formation of regenerative dentine during direct pulp capping therapy. Concanavalin A (ConA) is a type of lectin with a molecular weight of 26 kDa derived from the Canavalia ensiformis plant. Lectins possess strong proliferation and differentiation abilities in various animal cells including lymphocytes, osteoblasts, and chondrocytes. The aim of study was to determine the effect of ConA on the proliferation and osteogenic differentiation of DPSCs in vitro .

Materials and Methods  In this in vitro study, DPSCs were isolated from third molars before ConA induction was performed at concentrations of 5 and 10 μg/mL. The proliferation assay was determined by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Osteogenic differentiation was determined by means of mineralization.

Statistical Analysis  Data were analyzed using analysis of variance and a Student’s t -test. The p -value was set at 0.05.

Results  The addition of 5 and 10 µg/mL of ConA to DPSCs can significantly increase the proliferation and osteogenic differentiation of DPSCs ( p ≤0.05).

Conclusion  ConA can increase the proliferation and osteogenic differentiation of DPSCs.

BEL β-Trefoil Reduces the Migration Ability of RUNX2 Expressing Melanoma Cells in Xenotransplanted Zebrafish

RUNX2, a master osteogenic transcript ion factor, is overexpressed in several cancer cells; in melanoma it promotes cells migration and invasion as well as neoangiogenesis. The annual mortality rates related to metastatic melanoma are high and novel agents are needed to improve melanoma patients’ survival. It has been shown that lectins specifically target malignant cells since they present the Thomsen–Friedenreich antigen. This disaccharide is hidden in normal cells, while it allows selective lectins binding in transformed cells. Recently, an edible lectin named BEL β-trefoil has been obtained from the wild mushroom Boletus edulis. Our previous study showed BEL β-trefoil effects on transcription factor RUNX2 downregulation as well as on the migration ability in melanoma cells treated in vitro. Therefore, to better understand the role of this lectin, we investigated the BEL β-trefoil effects in a zebrafish in vivo model, transplanted with human melanoma cells expressing RUNX2. Our data showed that BEL β-trefoil is able to spread in the tissues and to reduce the formation of metastases in melanoma xenotransplanted zebrafish. In conclusion, BEL β-trefoil can be considered an effective biomolecule to counteract melanoma disease.

Quantum Dot Labelling of Tepary Bean (Phaseolus acutifolius) Lectins by Microfluidics

Lectins are bioactive proteins with the ability to recognize cell membrane carbohydrates in a specific way. Diverse plant lectins have shown diagnostic and therapeutic potential against cancer, and their cytotoxicity against transformed cells is mediated through the induction of apoptosis. Previous works have determined the cytotoxic activity of a Tepary bean (Phaseolus acutifolius) lectin fraction (TBLF) and its anti-tumorigenic effect on colon cancer. In this work, lectins from the TBLF were additionally purified by ionic-exchange chromatography. Two peaks with agglutination activity were obtained: one of them was named TBL-IE2 and showed a single protein band in two-dimensional electrophoresis; this one was thus selected for coupling to quantum dot (QD) nanoparticles by microfluidics (TBL-IE2-QD). The microfluidic method led to low sample usage, and resulted in homogeneous complexes, whose visualization was achieved using multiphoton and transmission electron microscopy. The average particle size (380 nm) and the average zeta potential (-18.51 mV) were determined. The cytotoxicity of the TBL-IE2 and TBL-IE2-QD was assayed on HT-29 colon cancer cells, showing no differences between them (p ≤ 0.05), where the LC50 values were 1.0 × 10-3 and 1.7 × 10-3 mg/mL, respectively. The microfluidic technique allowed control of the coupling between the QD and the protein, substantially improving the labelling process, providing a rapid and efficient method that enabled the traceability of lectins. Future studies will focus on the potential use of the QD-labelled lectin to recognize tumor tissues.

Tepary Bean (Phaseolus acutifolius) Lectins Induce Apoptosis and Cell Arrest in G0/G1 by P53(Ser46) Phosphorylation in Colon Cancer Cells

A Tepary bean lectin fraction (TBLF) has been studied because it exhibits differential cytotoxic and anticancer effects on colon cancer. The present work focuses on the evaluation of the apoptotic mechanism of action on colon cancer cells. Initially, lethal concentrations (LC₅₀) were obtained for the three studied cell lines (HT-29, RKO and SW-480). HT-29 showed the highest LC₅₀, 10 and 100 times higher than that of RKO and SW-480 cells, respectively. Apoptosis was evaluated by flow cytometry, where HT-29 cells showed the highest levels of early and total apoptosis, caspases activity was confirmed and necrosis was discarded. The effect on cell cycle arrest was shown in the G0/G1 phase. Specific apoptosis-related gene expression was determined, where an increase in p53 and a decrease in Bcl-2 were observed. Expression of p53 gene showed the maximum level at 8 h with an important decrease at 12 and 24 h, also the phosphorylated p53(ser46) increased at 8 h. Our results show that TBLF induces apoptosis in colon cancer cells by p-p53(ser46) involvement. Further studies will focus on studying the specific signal transduction pathway.

In-vivo antiproliferative activity of Morus latifolia leaf and bark extracts against Ehrlich's ascites carcinoma

Cancer is the second death causing disease all over the world and until today 100 different types of cancer have been identified whose treatment methods consist of serious side effects on human body. To reduce the frequency of adverse effects of cancer treatment, nowadays plant derived natural components are getting priority. The plant Morus latifolia is widely available in northern part of Bangladesh. The earlier researches suggested that popular varieties of some Morus sp. like Morus alba, Morus indica etc. have good anti-proliferative activity. Hence, this study was designed to evaluate the anti-proliferative activity of leaf and bark extracts of M. latifolia against Ehrlich's ascites carcinoma (EAC) in vivo. The leaf and bark extracts of M. latifolia were used in several bioassays including Brine shrimp lethality test, hemagglutination activity test, antioxidant activity test, and cell growth inhibition test. Besides, fluorescence microscopy was performed to study apoptotic features in EAC cells, and molecular analysis like real-time PCR were also conducted. The results of Brine shrimp lethality test, hemagglutination activity test, and antioxidant activity assay supported the cell growth inhibition capability of leaf and bark extracts which was confirmed by in vivo cell growth inhibition bioassay. Moreover, the experimental extracts were able to induce cell apoptotis through altering the expression pattern of Bcl-2 and Bax genes. All of the results of this study suggest that several noble compounds are present in M. latifolia plant extracts which are capable for healing cancer cells.

Seeds

A wide variety of plant species provide edible seeds. Seeds are the dominant source of human calories and protein. The most important and popular seed food sources are cereals, followed by legumes and nuts. Their nutritional content of fiber, protein, and monounsaturated/polyunsaturated fats make them extremely nutritious. They are important additions to our daily food consumption. When consumed as part of a healthy diet, seeds can help reduce blood sugar, cholesterol, and blood pressure.