Investigations on the Biological Activity of Allium sativum Agglutinin (ASA) Isolated from Garlic.

BACKGROUND: Garlic (Allium sativum) from the family Amaryllidaceae is widely used in culinary and is reported to have potential anticancer, anti-diabetic, antimicrobial, and cardioprotective activities. Allium sativum agglutinin (ASA) is a bulb-type lectin (BTL) domaincontaining lectin isolated from garlic and has been studied for its various biological functions. Previous studies have reported the anti-cancer effects of ASA on histiocytic lymphoma (U937), promyelocytic leukemia (HL60), and oral cancer (KB). METHODS: In this study, we have purified and characterized ASA and evaluated it for its anticancer effects on other cancer cell lines. MTT assay and FACS analysis was done to corroborate the anticancer findings against cervical (HeLa) and lung cancer (A549) cell lines. RESULTS: IC50 value of 37 µg/ml in HeLa and a weak activity (26.4 ± 1.9% cellular inhibition at 100µg/ml treatment) in A549 were found in the MTT assay. FACS analysis further corroborated these findings and showed the apoptotic effects of ASA in these cell lines. CONCLUSION: Anticancer activity for members of bulb-type lectin (BTL) domain-containing lectins has been widely reported, and we hope that our study forms a basis for the development of ASA as a therapeutic agent.

The Agglutinin of Common Nettle (Urtica dioica L.) Plant Effects on Gene Expression Related to Apoptosis of Human Acute Myeloid Leukemia Cell Line.

Treatment of acute myeloid leukemia (AML) requires new drugs as result of a rise in new cases and high disease relapse. Plant lectins with the ability to bind carbohydrates on the cell surface have the potential to treat cancer. Urtica dioica L. agglutinin (UDA) is a low weight lectin with anti-benign prostatic hyperplasia (BPH) impact. Here, we examine the impact of UDA on HL-60 cell line. Cytotoxicity and cytostatic effects were assessed in HL-60 cells treated with UDA and vincristine (positive control). The effects of the lectin on cell cycle phases and cell death mechanism were surveyed by propidium iodide (PI) staining and annexin V/PI, respectively. The activation status of the apoptosis pathway was determined by western blotting. Finally, the expression levels of 84 genes were examined by the Human cancer drug target gene PCR array kit. The results indicated that the increase in UDA concentration inhibited the proliferation of HL-60 cells as well as apoptosis induction. Cell cycle analysis showed that the number of sub G1 cells increased essentially. Experimental observations showed that UDA can induce cell apoptosis through a caspase 9-dependent pathway. The expression changes of 21 genes confirmed the apoptotic events in HL-60 cells treated with UDA. In this, we have presented the first investigation on the cytotoxic and apoptotic effects of a lectin isolated from rhizomes and roots of Urtica dioica L. on human AML cells. Generally, the results suggest that UDA may have therapeutic value for leukemia and would be studied further as a new drug for AML later on.

Angio-Suppressive Effect of Partially Purified Lectin-like Protein from Musa acuminata pseudostem by Inhibition of VEGF-Mediated Neovascularization and Induces Apoptosis Both In Vitro and In Vivo.

Lifestyle and nutritional changes have contributed much to the somatic genetic changes which have concurrently led to an increase cancer in humans. Hence the plant-based and nutritional involvements block oncogenic transformation are in good demand. We evaluate Phloem exudates of the dietary plant, Musa acuminate pseudostem, the initial domesticated plant species with the effective lectin activity for its functional role against the tumor development and its mechanism of action. Our experimental data exhibit that Musa acuminata Lectin Protein (MALP) shows a promising cytotoxic effect against the various human cancer cell lines. Supporting this, we evaluate the in vivo anti-tumor and anti-angiogenic activity of MALP in Ehrlich Ascites Carcinoma mice model (EAC). MALP treatment resulted in tumor growth inhibition and increased the lifespan of the EAC-bearing mice without showing any side effects on normal mice, as revealed by histological parameters. Further, a significant decrease in the ascites vascular endothelial growth factor (VEGF) secretion and microvessel density supports the anti-angiogenic property of the MALP. Apoptosis-inducing activity of MALP was revealed by DNA fragmentation assay, Caspase-3 inhibitor assay and cellular morphology were studied by fluorescence staining methods. Our study delivers the real evidence that MALP with a promising an anticancer potential expressively degenerates the tumor development by affecting angiogenesis and apoptosis.

Agglutinin isolated from Arisema heterophyllum Blume induces apoptosis and autophagy in A549 cells through inhibiting PI3K/Akt pathway and inducing ER stress.

Arisaema heterophyllum Blume is one of the three medicinal plants known as traditional Chinese medicine Rhizoma Arisaematis (RA). RA has been popularly used to treat patients with convulsions, inflammation, and cancer for a long time. However, the underlying mechanisms for RA effects are still unclear. The present study was designed to determine the cytotoxicity of agglutinin isolated from Arisema heterophyllum Blume (AHA) and explore the possible mechanisms in human non-small-cell lung cancer A549 cells. AHA with purity up to 95% was isolated and purified from Arisaema heterophyllum Blume using hydrophobic interaction chromatography. AHA dose-dependently inhibited the proliferation of A549 cells and induced G1 phase cell cycle arrest. AHA induced apoptosis by up-regulating pro-apoptotic Bax, decreasing anti-apoptotic Bcl-2, and activating caspase-9 and caspase-3. In A549 cells treated with AHA, the PI3K/Akt pathway was inhibited. Furthermore, AHA induced increase in the levels of ER stress markers such as phosphorylated eukaryotic initiation factor 2α (p-eIF2α), C/EBP-homologous protein (CHOP), inositol-requiring enzyme 1α (IRE1α), and phosphorylated c-Jun NH2-terminal kinase (p-JNK). AHA also induced autophagy in A549 cells. Staining of acidic vesicular organelles (AVOs) and increase in the levels of LC3II and ATG7 were observed in AHA-treated cells. These findings suggested that AHA might be one of the active components with anti-cancer effects in Arisaema heterophyllum Blume. In conclusion, cytotoxicity of AHA on cancer cells might be related to its effects on apoptosis and autophagy through inhibition of PI3K/Akt pathway and induction of ER stress.

Deciphering the mode of action of a mutant Allium sativum Leaf Agglutinin (mASAL), a potent antifungal protein on Rhizoctonia solani.

BACKGROUND: Mutant Allium sativum leaf agglutinin (mASAL) is a potent, biosafe, antifungal protein that exhibits fungicidal activity against different phytopathogenic fungi, including Rhizoctonia solani. METHODS: The effect of mASAL on the morphology of R.solani was monitored primarily by scanning electron and light microscopic techniques. Besides different fluorescent probes were used for monitoring various intracellular changes associated with mASAL treatment like change in mitochondrial membrane potential (MMP), intracellular accumulation of reactive oxygen species (ROS) and induction of programmed cell death (PCD). In addition ligand blot followed by LC-MS/MS analyses were performed to detect the putative interactors of mASAL. RESULTS: Knowledge on the mode of function for any new protein is a prerequisite for its biotechnological application. Detailed morphological analysis of mASAL treated R. solani hyphae using different microscopic techniques revealed a detrimental effect of mASAL on both the cell wall and the plasma membrane. Moreover, exposure to mASAL caused the loss of mitochondrial membrane potential (MMP) and the subsequent intracellular accumulation of reactive oxygen species (ROS) in the target organism. In conjunction with this observation, evidence of the induction of programmed cell death (PCD) was also noted in the mASAL treated R. solani hyphae. Furthermore, we investigated its interacting partners from R. solani. Using ligand blots followed by liquid chromatography tandem mass spectrometry (LC-MS/MS) analyses, we identified different binding partners including Actin, HSP70, ATPase and 14-3-3 protein. CONCLUSIONS: Taken together, the present study provides insight into the probable mode of action of the antifungal protein, mASAL on R. solani which could be exploited in future biotechnological applications.

Sensitivity of transmitted and founder human immunodeficiency virus type 1 envelopes to carbohydrate-binding agents griffithsin, cyanovirin-N and Galanthus nivalis agglutinin.

Human immunodeficiency virus type 1 (HIV-1) transmission often results from infection by a single transmitted/founder (T/F) virus. Here, we investigated the sensitivity of T/F HIV-1 envelope glycoproteins (Envs) to microbicide candidate carbohydrate-binding agents (CBAs) griffithsin (GRFT), cyanovirin-N (CV-N) and Galanthus nivalis agglutinin (GNA), showing that T/F Envs demonstrated different sensitivity to CBAs, with IC50 values ranging from 0.006 ± 0.0003 to >10 nM for GRFT, from 0.6 ± 0.2 to 28.9 ± 2.9 nM for CV-N and from 1.3 ± 0.2 to >500 nM for GNA. We further revealed that deglycosylation at position 295 or 448 decreased the sensitivity of T/F Env to GRFT, and at 339 to both CV-N and GNA. Mutation of all the three glcyans rendered a CBA-sensitive T/F Env largely resistant to GRFT, indicating that the sensitivity of T/F Env to GRFT is mainly determined by glycans at 295, 339 and 448. Our study identified specific T/F Env residues associated with CBA sensitivity.

Molecular mechanisms of Lycoris aurea agglutinin-induced apoptosis and G2 /M cell cycle arrest in human lung adenocarcinoma A549 cells, both in vitro and in vivo.

OBJECTIVES: Lycoris is aurea agglutinin (LAA) has attracted rising attention due to its remarkable bioactivities. Here, we aimed at investigating its anti-tumor activities. MATERIAL AND METHODS: In vitro methods including MTT, cellular morphology observation, FCM and immunoblotting were performed. In vivo methods like detection of tumor volume, body weight and survival ratio, as well as TUNEL staining were performed. RESULTS AND CONCLUSION: LAA triggers G2 /M phase cell cycle arrest via up-regulating p21expression as well as down-regulating cdk-1cyclinA singling pathway, and induces apoptotic cell death through inhibiting PI3K-Akt survival pathway in human lung adenocarcinoma A549 cells. While LAA has no significant cytotoxic effect toward normal human embryonic lung fibroblast HELF cells, and moreover, LAA could amplify the antineoplastic effects of cisplatin toward A549 cells. Lastly LAA also bears anti-cancer and apoptosis-inducing effects in vivo, and it could decrease the volume and weight of subcutaneous tumor mass obviously as well as expand lifespan of mice. These findings may provide a new perspective for elucidating the complicated molecular mechanisms of LAA-induced cancer cell growth-inhibition and death, providing a new opportunity of LAA as a potential candidate anti-neoplastic drug for future cancer therapeutics.

Compatibility of garlic (Allium sativum L.) leaf agglutinin and Cry1Ac δ-endotoxin for gene pyramiding.

δ-Endotoxins produced by Bacillus thuringiensis (Bt) have been used as bio-pesticides for the control of lepidopteran insect pests. Garlic (Allium sativum L.) leaf agglutinin (ASAL), being toxic to several sap-sucking pests and some lepidopteran pests, may be a good candidate for pyramiding with δ-endotoxins in transgenic plants for enhancing the range of resistance to insect pests. Since ASAL shares the midgut receptors with Cry1Ac in Helicoverpa armigera, there is possibility of antagonism in their toxicity. Our study demonstrated that ASAL increased the toxicity of Cry1Ac against H. armigera while Cry1Ac did not alter the toxicity of ASAL against cotton aphids. The two toxins interacted and increased binding of each other to brush border membrane vesicle (BBMV) proteins and to the two important receptors, alkaline phosphatase (ALP) and aminopeptidase N (APN). The results indicated that the toxins had different binding sites on the ALP and APN but influenced mutual binding. We conclude that ASAL can be safely employed with Cry1Ac for developing transgenic crops for wider insect resistance.

Pinellia ternata agglutinin expression in chloroplasts confers broad spectrum resistance against aphid, whitefly, Lepidopteran insects, bacterial and viral pathogens.

Broad spectrum protection against different insects and pathogens requires multigene engineering. However, such broad spectrum protection against biotic stress is provided by a single protein in some medicinal plants. Therefore, tobacco chloroplasts were transformed with the agglutinin gene from Pinellia ternata (pta), a widely cultivated Chinese medicinal herb. Pinellia ternata agglutinin (PTA) was expressed up to 9.2% of total soluble protein in mature leaves. Purified PTA showed similar hemagglutination activity as snowdrop lectin. Artificial diet with purified PTA from transplastomic plants showed marked and broad insecticidal activity. In planta bioassays conducted with T0 or T1 generation PTA lines showed that the growth of aphid Myzus persicae (Sulzer) was reduced by 89%-92% when compared with untransformed (UT) plants. Similarly, the larval survival and total population of whitefly (Bemisia tabaci) on transplastomic lines were reduced by 91%-93% when compared with UT plants. This is indeed the first report of lectin controlling whitefly infestation. When transplastomic PTA leaves were fed to corn earworm (Helicoverpa zea), tobacco budworm (Heliothis virescens) or the beet armyworm (spodoptera exigua), 100% mortality was observed against all these three insects. In planta bioassays revealed Erwinia population to be 10,000-fold higher in control than in PTA lines. Similar results were observed with tobacco mosaic virus (TMV) challenge. Therefore, broad spectrum resistance to homopteran (sap-sucking), Lepidopteran insects as well as anti-bacterial or anti-viral activity observed in PTA lines provides a new option to engineer protection against biotic stress by hyper-expression of an unique protein that is naturally present in a medicinal plant.

Purification, characterization, and molecular cloning of a novel antifungal lectin from the roots of Ophioglossum pedunculosum.

A novel mannan-specific lectin was isolated from the roots of a traditional Chinese herbal medicine, Ophioglossum pedunculosum through ion-exchange chromatography and gel filtration. With a molecular mass of 19,835.7 Da demonstrated by MALDI-TOF analysis, this novel agglutinin was designated as O. pedunculosum agglutinin (OPA), specifically agglutinating human O erythrocytes and rabbit erythrocytes. The hemagglutination could be strongly inhibited by mannan and thyroglobulin, the activity of which was stable in pH range of 4.0-8.0 and at temperatures below 50 °C. Chemical modification studies indicated that tryptophan and arginine residues were essential for its hemagglutinating activity. Meanwhile, it showed antifungal activities toward Sclerotium rolfsii and Fusarium graminearum. In addition, to amplify cDNA of OPA by 3'/5'-rapid amplification of cDNA ends (RACE), the N-terminal 30 amino acids sequence of OPA was determined, and degenerate primers were designed. The obtained full-length cDNA of OPA contained 885 bp with an open-reading frame of 600 bp encoding a precursor protein of 199 amino acids, while the mature protein had 170 amino acids.

Inhibition of hepatitis C virus 3a genotype entry through Glanthus Nivalis Agglutinin.

BACKGROUND: Hepatitis C Virus (HCV) has two envelop proteins E1 and E2 which is highly glycosylated and play an important role in cell entry. Inhibition of virus at entry step is an important target to find antiviral drugs against HCV. Glanthus Nivalis Agglutinin (GNA) is a mannose binding lectin which has tendency for specific recognition and reversible binding to the sugar moieties of a wide variety of glycoproteins of enveloped viruses. RESULTS: In the present study, HCV pseudoparticles (HCVpp) for genotype 3a were produced to investigate the ability of GNA to block the HCV entry. The results demonstrated that GNA inhibit the infectivity of HCVpp and HCV infected serum in a dose-dependent manner and resulted in 50% reduction of virus at 1 ± 2 µg concentration. Molecular docking of GNA and HCV glycoproteins (E1 and E2) showed that GNA inhibit HCV entry by binding N-linked glycans. CONCLUSION: These results demonstrated that targeting the HCV glycans is a new approach to develop antiviral drugs against HCV.

Mannose-specific plant lectins from the Amaryllidaceae family qualify as efficient microbicides for prevention of human immunodeficiency virus infection.

The plant lectins derived from Galanthus nivalis (Snowdrop) (GNA) and Hippeastrum hybrid (Amaryllis) (HHA) selectively inhibited a wide variety of human immunodeficiency virus type 1 (HIV-1) and HIV-2 strains and clinical (CXCR4- and CCR5-using) isolates in different cell types. They also efficiently inhibited infection of T lymphocytes by a variety of mutant virus strains. GNA and HHA markedly prevented syncytium formation between persistently infected HUT-78/HIV cells and uninfected T lymphocytes. The plant lectins did not measurably affect the antiviral activity of other clinically approved anti-HIV drugs used in the clinic when combined with these drugs. Short exposure of the lectins to cell-free virus particles or persistently HIV-infected HUT-78 cells markedly decreased HIV infectivity and increased the protective (microbicidal) activity of the plant lectins. Flow cytometric analysis and monoclonal antibody binding studies and a PCR-based assay revealed that GNA and HHA do not interfere with CD4, CXCR4, CCR5, and DC-SIGN and do not specifically bind with the membrane of uninfected cells. Instead, GNA and HHA likely interrupt the virus entry process by interfering with the virus envelope glycoprotein. HHA and GNA are odorless, colorless, and tasteless, and they are not cytotoxic, antimetabolically active, or mitogenic to human primary T lymphocytes at concentrations that exceed their antivirally active concentrations by 2 to 3 orders of magnitude. GNA and HHA proved stable at high temperature (50 degrees C) and low pH (5.0) for prolonged time periods and can be easily formulated in gel preparations for microbicidal use; they did not agglutinate human erythrocytes and were not toxic to mice when administered intravenously.

Immunomodulatory effects of Viscum album agglutinin-I on natural immunity.

In 24 h cultured human peripheral blood mononuclear cells, treated with various (1 microgram/ml to 1 ng/ml) concentrations of Viscum album agglutinin-I, quantitative assessment of DNA breaks labelled with terminal deoxynucleotidyl transferase revealed a dose-dependent Viscum album agglutinin-I-induced apoptosis above a lectin concentration of 10 ng/ml. After 24 h incubation of peripheral blood mononuclear cells with non-cytotoxic concentrations of Viscum album agglutinin-I (10 and 1 ng/ml), messenger (m)RNA expression and secretion of a panel of cytokines were evaluated by reverse polymerase chain reaction and by enzyme-linked immunosorbent assay (ELISA), respectively. The lectin induced expression of interleukin-1 alpha, interleukin-1 beta, interleukin-6, tumor necrosis factor-alpha, interferon-gamma, granulocyte-monocyte colony stimulating factor and interleukin-10 genes, but no expression of interleukin-2 or interferon-gamma production could be detected. In addition, cellular components of the natural immune system (such as monocytes and granulocytes) bound Viscum album agglutinin-I molecules to a higher degree than lymphocytes. To establish the modulatory potency of Viscum album agglutinin-I on the natural immunity of human subjects, four randomized, double-blind crossover trials were performed on healthy volunteers. In contrast to the significant lectin-induced increases in number and activity of natural killer cells observed in animal models, in the first and second trial human healthy individuals showed no significant differences between their natural killer responses following an injection of lectin-enriched preparation or saline. Due to considerable intrinsic fluctuation of these parameters, a third and fourth double-blind trial with freshly isolated Viscum album agglutinin-I was performed using a more rapidly detectable parameter, the priming of granulocytes. Here, significant lectin-induced increases were found.

Datura stramonium agglutinin released histamine from rat peritoneal mast cells that was inhibited by pertussis toxin, haptenic sugar and N-acetylglucosamine-specific lectins: involvement of glycoproteins with N-acetylglucosamine residues.

The N-acetyl glucosamine (GlcNAc)-specific lectin Datura stramonium agglutinin (DSA) rapidly and sugar-specifically released histamine from rat peritoneal mast cells, and pertussis toxin (IAP) inhibited it, suggesting that DSA activated mast cells via an IAP-sensitive G protein pathway. The additive effects of DSA and basic secretagogues such as compound 48/80 that activate IAP-sensitive G protein directly suggest that they shared the same mechanism of action including involvement of the IAP-sensitive G protein. Using lectin-blotting, blots of the corresponding glycoproteins detected by DSA diminished by haptenic sugar or pretreatment of the cells with N-glycosidase F, suggesting that the binding of DSA was responsible for the mast cell activation. The other GlcNAc-specific lectins such as Phytolacca americana mitogen, Solanum tuberosum agglutinin and wheat germ agglutinin (WGA) inhibited the histamine release induced by DSA, suggesting that these lectins were antagonists, but DSA was an agonist. Sialic acid-specific Macckia amurensis mitogen (MAM) inhibited the histamine release, and neuraminidase-treatment decreased mast cell activation induced by DSA. At least four mast cell glycoproteins that have affinity to DSA, WGA and MAM and are sensitive to neuraminidase-treatment were detected by lectin-blotting. Some of them may be binding sites coupled to histamine release including the IAP-sensitive G protein pathway. DSA is a useful tool for studying signal transduction of mast cells including the involvement of the IAP-sensitive G protein.

An initial signal of activation of rat peritoneal mast cells stimulated by Datura stramonium agglutinin: a confocal fluorescence microscopic analysis of intracellular calcium ion and cytoskeletal assembly.

A confocal fluorescence microscope using fluo-3 and 9-(dicyanovinyl)- julolidine (DCVJ) was used to study the mast cell activation by the N-acetyl glucosamine oligomer specific lectin Datura stramonium agglutinin (DSA) and inhibition by antagonist lectins having affinity to N-acetyl glucosamine (GlcNAc). DSA induced a transient increase in intracellular free calcium concentration ([Ca2+]i) followed by cytoskeletal disassembly and reassembly in rat peritoneal mast cells. These changes induced by DSA resulted in histamine release. The time course of fluorescence intensity in mast cells loaded with fluo-3- or DCVJ and activated by DSA resembled those activated by the basic polymer compound 48/80. Inhibition of [Ca2+]i rise by antagonist lectins was responsible for the inhibition of cytoskeletal assembly and the consequent histamine release induced by DSA. At the level of the individual cell, a mast cell stimulated by DSA responds in an all-or-none fashion. DSA possible induced intracellular calcium mobilization and cytoskeletal change by recognizing the GlcNAc-oligomer residues of specific glycoproteins of mast cells.

Preliminary observations on leukaemia specific agglutinins from seeds.

Semipurified saline extracts of seeds from Crotolaria juncea, Cassia marginata, Ficus racemosa, Cicer arietinum (L-532), Gossipium indicum (G-27), Melia composita, Acacia lenticularis, Meletia ovalifolia, Acacia catechu and Peltophorum ferrenginium were tested for leukoagglutinating activity against whole leukocytes and mononuclear cells from patients with chronic myeloid leukaemia (34), acute myeloblastic leukaemia (5), acute lymphoblastic leukaemia (7), chronic lymphocytic leukaemia (3), various lymphoproliferative/haematologic disorders (54), and normal healthy subjects (50). In addition, bone marrow cells from three patients undergoing diagnostic bone marrow aspiration and activated lymphocytes from mixed lymphocyte cultures (MLC) were also tested. All the seed extracts agglutinated white blood cells from patients with different types of leukaemia. But none of them reacted with peripheral blood cells of normal individuals, patients with various lymphoproliferative/haematologic disorders or cells from MLC. Leukoagglutination of leukaemic cells with each of the seed extracts was inhibited by simple sugars. Only in one instance, cells from bone marrow of an individual who had undergone diagnostic bone marrow aspiration for a non-malignant condition were agglutinated. It is felt that purification of these seed extracts may yield leukaemia-specific lectins.