Glycan-directed SARS-CoV-2 inhibition by leek extract and lectins with insights into the mode-of-action of Concanavalin A.

Four years after its outbreak, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remains a global challenge for human health. At its surface, SARS-CoV-2 features numerous extensively glycosylated spike proteins. This glycan coat supports virion docking and entry into host cells and at the same time renders the virus less susceptible to neutralizing antibodies. Given the high genetic plasticity of SARS-CoV-2 and the rapid emergence of immune escape variants, targeting the glycan shield by carbohydrate-binding agents emerges as a promising strategy. However, the potential of carbohydrate-targeting reagents as viral inhibitors remains underexplored. Here, we tested seven plant-derived carbohydrate-binding proteins, called lectins, and one crude plant extract for their antiviral activity against SARS-CoV-2 in two types of human lung cells: A549 cells ectopically expressing the ACE2 receptor and Calu-3 cells. We identified three lectins and an Allium porrum (leek) extract inhibiting SARS-CoV-2 infection in both cell systems with selectivity indices (SI) ranging between >2 and >299. Amongst these, the lectin Concanavalin A (Con A) exerted the most potent and broad activity against a panel of SARS-CoV-2 variants. We used multiplex super-resolution microscopy to address lectin interactions with SARS-CoV-2 and its host cells. Notably, we discovered that Con A not only binds to SARS-CoV-2 virions and their host cells, but also causes SARS-CoV-2 aggregation. Thus, Con A exerts a dual mode-of-action comprising both, antiviral and virucidal, mechanisms. These results establish Con A and other plant lectins as candidates for COVID-19 prevention and basis for further drug development.

Tripterygium wilfordii protects against an animal model of autoimmune hepatitis.

ETHNOPHARMACOLOGICAL RELEVANCE: Tripterygium wilfordii tablets (TWT) is widely used to treat autoimmune diseases such as rheumatoid arthritis. Celastrol, one main active ingredient in TWT, has been shown to produce a variety of beneficial effects, including anti-inflammatory, anti-obesity, anti-cancer, and immunomodulatory. However, whether TWT could protect against Concanavalin A (Con A)-induced hepatitis remains unclear. THE AIM OF THE STUDY: This study aims to investigate the protective effect of TWT against Con A-induced hepatitis and elucidate the underlying mechanism. MATERIALS AND METHODS: Metabolomic analysis, pathological analysis, biochemical analysis, qPCR and Western blot analysis and the Pxr-null mice were used in this study. RESULTS: The results indicated that TWT and its active ingredient celastrol could protect against Con A-induced acute hepatitis. Plasma metabolomics analysis revealed that metabolic perturbations related to bile acid and fatty acid metabolism induced by Con A were reversed by celastrol. The level of itaconate in the liver was increased by celastrol and speculated as an active endogenous compound mediating the protective effect of celastrol. Administration of 4-octanyl itaconate (4-OI) as a cell-permeable itaconate mimicker was found to attenuate Con A-induced liver injury through activation of the pregnane X receptor (PXR) and enhancement of the transcription factor EB (TFEB)-mediated autophagy. CONCLUSIONS: Celastrol increased itaconate and 4-OI promoted activation of TFEB-mediated lysosomal autophagy to protect against Con A-induced liver injury in a PXR-dependent manner. Our study reported a protective effect of celastrol against Con A-induced AIH via an increased production of itaconate and upregulation of TFEB. The results highlighted that PXR and TFEB-mediated lysosomal autophagic pathway may offer promising therapeutic target for the treatment of autoimmune hepatitis.

Koumine ameliorates concanavalin A-induced autoimmune hepatitis in mice: involvement of the Nrf2, NF-κB pathways, and gut microbiota.

Gelsemiumelegans(Gardner. & Chapm.) Benth. has long been considered a traditional Chinese medicine effective against rheumatoid pain, cancer, cirrhosis, and skin diseases. Koumine (KM), the most abundant alkaloid in G.elegans Benth., demonstrates a variety of biological effects, including antitumor, analgesic, anxiolytic, anti-inflammatory, antidepressant, antioxidant, immunoregulatory, and hepatoprotective effects. Furthermore, the relatively low toxicity of KM makes it a promising drug candidate. This study aimed to investigate the protective effects of KM and its possible mechanisms using a concanavalin A (Con A)-induced autoimmune hepatitis (AIH) model in mice. Mice were orally administered different doses of KM for 14 d before Con A tail vein injections. The effects of KM on serum biochemical markers and liver histopathology were then evaluated 12 h after Con A exposure. The Nrf2 and NF-κB signaling pathways and alterations in gut microbiota were determined using western blotting, immunohistochemistry, and 16S rRNA sequencing to explore the underlying mechanisms of KM exposure. KM pretreatment dose-dependently decreased serum liver injury markers (Alanine aminotransferase, and aspartate aminotransferase) and cytokine levels (Tumor necrosis factor-α and interleukin-6), as well as the liver pathological damage triggered by Con A. Furthermore, the results of the multi-technique analysis indicated that KM activated the Nrf2 pathway, upregulated the expression of anti-oxidation factors HO-1 and Nrf2, and downregulated the expression of Keap1. Moreover, the NF-κB signaling pathway was inhibited. Interestingly, pre-treatment with KM also significantly improved the composition of the gut microbiota probably because it increases the richness of probiotics. Our findings suggest that KM pretreatment could attenuate Con A-induced AIH, the Nrf2 and NF-κB signaling pathways, and that gut microbiota are involved in the process of the hepatoprotective effect. This study provides a theoretical basis for the development of KM as an effective agent against AIH.

Ethyl Acetate Extract from Artemisia argyi Prevents Liver Damage in ConA-Induced Immunological Liver Injury Mice via Bax/Bcl-2 and TLR4/MyD88/NF-κB Signaling Pathways.

BACKGROUND: Immunological liver injury (ILI) is a common liver disease and lacks potent drugs for treatment. Artemisia argyi Lévl. et Vant. (A. argyi), a medicinal and edible homologous plant usually used in diet therapy to cure various liver diseases, provides a great option for the prevention of ILI. PURPOSE: To investigate the effect that ethyl acetate extract of A. argyi (AaEA) on Concanavalin A (ConA)-induced ILI and the mechanism of regulating Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways. METHODS: The chemical components of AaEA were studied by LC-MS. In animal experiments, the positive control group was administrated diammonium glycyrrhizinate (DIG, 100 mg/kg), while different doses of AaEA groups (AaEA-H, AaEA-M, AaEA-L) were pretreated with AaEA 2.00, 1.00, and 0.50 g/kg, respectively, by intragastric for seven days, once every day. Then, ConA (12.00 mg/kg) was used through tail intravenous injection to establish the ILI model. The blood samples and livers were collected to test the degree of liver dysfunction, inflammation, oxidative stress, histopathological changes, and cell apoptosis. Real-time PCR and Western blotting analysis were used to explain the mechanism of regulating Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways. RESULTS: The way in which AaEA prevents liver damage in immunological liver injury (ILI) mice caused by ConA was investigated for the first time. Pretreatment with AaEA reduced the expression of ALT, AST, and inflammatory factors (TNF-α and IFN-γ). Meanwhile, AaEA also reduced MDA levels but upregulated the contents of IL-4, SOD, and GSH-px, alleviating oxidative stress induced by ILI. Western blotting and real-time PCR analysis demonstrated that AaEA could regulate the expression level and relative mRNA expression of key proteins on Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways. Finally, 504 components from AaEA were identified by LC-MS analysis, mainly including flavones, phenolic acids, and terpenoids with anti-inflammatory and liver protective activities, which highlights the potential of AaEA for diet treatment of ILI. CONCLUSION: AaEA can work against ConA-induced ILI in mice by regulating Bax/Bcl-2 and TLR4/MyD88/NF-κB signaling pathways, which has the potential to be a great strategy for the prevention of ILI.

Cucurbitacin E glucoside alleviates concanavalin A-induced hepatitis through enhancing SIRT1/Nrf2/HO-1 and inhibiting NF-ĸB/NLRP3 signaling pathways.

ETHNOPHARMACOLOGICAL RELEVANCE: Cucurbitacins are highly oxygenated tetracyclic triterpenoids, that represent the major metabolites reported from C. colocynthis (L.) Schrad.. Cucurbitacin E glucoside (CuE) is a tetracyclic triterpene glycoside separated from Cucurbitaceae plants. CuE has potent anti-inflammatory, immunomodulatory, and anti-tumor properties. AIM OF THE STUDY: The current study aimed at examining the hepatoprotective effect of CuE against concanavalin A (Con A)-produced hepatitis. MATERIALS AND METHODS: Mice were intravenously administered Con A (15 mg/kg) to induce AIH. CuE was orally administered at two different doses for five days preceding Con A injection. RESULTS: The results revealed that CuE pretreatment markedly attenuated the serum indices of hepatotoxicity and the severity of hepatic lesions. CuE depressed Con A-provoked increment in CD4+ T-cells in hepatic tissue. The antioxidant activity of CuE was evident through its ability to decrease markers of Con A-induced oxidative stress (malondialdehyde, 4-hydroxyenonanal, and protein carbonyl) and intensified the antioxidants in the hepatic tissue (SOD, GSH, and TAC). CuE increased mRNA expression of SIRT1 and Nrf2 as well as its binding capacity. Subsequently, CuE augmented mRNA expression of Nrf2 targeted genes as NQO1, GCL, and HO-1 and recovered its normal level. CuE inhibited the activation of NF-κB/downstream pro-inflammatory mediators signaling. Furthermore, CuE attenuated the mRNA expression of NLRP3 and its associated genes. CONCLUSION: Collectively, these results demonstrated the remarkable hepatoprotective potential of CuE towards Con A-induced AIH which was mediated via suppression of oxidative stress, enhancing SIRT1/Nrf2/HO-1, and prohibition of the NF-κB/NLRP3 signaling. CuE could be a candidate for hepatitis patients.

Acupuncture stimulation attenuates TNF-α production via vagal modulation in the concanavalin A model of hepatitis.

BACKGROUND: A growing body of evidence shows that neuronal activity is involved in modulating the efficacy of acupuncture therapy. However, it has been seldom investigated whether neuronal activity following acupuncture stimulation is effective at regulating hepatic inflammation. OBJECTIVE: Using the concanavalin A (ConA) model of hepatitis, we investigated the regulation of inflammatory cytokine tumor necrosis factor (TNF)-α in the liver tissue and the blood after acupuncture stimulation at ST36. METHODS: Mice were subjected to ConA injection, acupuncture stimulation at ST36 by manual acupuncture (MA) or electroacupuncture (EA) procedures, and vagotomy (VNX). Liver tissue and blood were collected for TNF-α analysis. TNF-α mRNA was analyzed by real-time polymerase chain reaction (PCR), and TNF-α, CD11b, CD68, and Erk1/2 proteins were analyzed by Western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assay. RESULTS: TNF-α mRNA and protein were induced in CD11b-positive hepatic cells and the plasma at 6-24 h after ConA injection. The application of MA or EA was very effective at attenuating the production of TNF-α. Anti-inflammatory effects of acupuncture were greatly suppressed by VNX in ConA-injected animals, suggesting the requirement of vagus nerve activity in acupuncture-mediated anti-inflammatory responses. Electrical stimulation of the sciatic nerve (SNS) resulted in an anti-inflammatory effect similar to acupuncture stimulation. In parallel with TNF-α, production of phospho-Erk1/2, which was induced in the liver tissue, was downregulated by MA and EA in liver cells. CONCLUSION: The regulatory effects of acupuncture stimulation on inflammatory responses in the liver may be modulated through the activation of the vagus nerve pathway.

ConBr, the Lectin from Canavalia brasiliensis Mart. Seeds: Forty Years of Research.

Lectins are defined as proteins or glycoproteins capable of specific and reversible binding to carbohydrates. Inside this group of proteins, the most well-studied lectins belong to the Leguminosae family, and inside this family, the Diocleinae subtribe includes the most characterized lectin Concanavalin A (ConA), as well as ConBr, the lectin from Canavalia brasiliensis, the subject of this review. Since 1979, several studies have been published in the literature regarding this lectin, from its isolation and characterization to its several biological activities. This year, 2019, will mark 40 years since researchers have begun to study ConBr and 100 years since the discovery of ConA, making 2019 a momentous year for lectinology. Owing to the abundance of studies involving ConBr, this review will focus on ConBr's purification, physicochemical properties, functional and structural analyses, biological activities and biotechnological applications. This will give researchers a broad glimpse into the potential of this lectin, as well as it characteristics, as we look ahead to its expanding applications in glycomics and biotechnology.

New Alkaloids from Green Vegetable Soybeans and Their Inhibitory Activities on the Proliferation of Concanavalin A-Activated Lymphocytes.

A comprehensive phytochemical study of the chemical constituents of green vegetable soybeans resulted in the isolation of two new alkaloids, soyalkaloid A, 1, and isoginsenine, 2, together with four known ones, ginsenine, 3, (1S,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid, 4, (1R,3S)-1-methyl-1,2,3,4-tetrahydro-ß-carboline-3-carboxylic acid, 5, and indole-3-carboxylic acid, 6. The structures of compounds 1-6 were elucidated on the basis of spectroscopic and chemical analyses. All of the alkaloids were isolated from soybeans for the first time, and compound 1 was a new indole-type alkaloid with a novel carbocyclic skeleton. Their inhibitory activities on the proliferation of concanalin A-activated lymphocytes were assessed by CCK8 assay.

CdTe quantum dots conjugated to concanavalin A as potential fluorescent molecular probes for saccharides detection in Candida albicans.

Semiconductor colloidal quantum dots (QDs) have been applied in biological analysis due to their unique optical properties and their versatility to be conjugated to biomolecules, such as lectins and antibodies, acquiring specificity to label a variety of targets. Concanavalin A (Con A) lectin binds specifically to α-d-mannose and α-d-glucose regions of saccharides that are usually expressed on membranes of mammalian cells and on cell walls of microbials. Candida albicans is the most common fungal opportunistic pathogen present in humans. Therefore, in this work, this fungus was chosen as a model for understanding cells and biofilm-forming organisms. Here, we report an efficient bioconjugation process to bind CdTe (Cadmium Telluride) QDs to Con A, and applied the bioconjugates to label saccharide structures on the cellular surface of C. albicans suspensions and biofilms. By accomplishing hemagglutination experiments and circular dichroism, we observed that the Con A structure and biochemical properties were preserved after the bioconjugation. Fluorescence microscopy images of yeasts and hyphae cells, as well as biofilms, incubated with QDs-(Con A) showed a bright orange fluorescence profile, indicating that the cell walls were specifically labeled. Furthermore, flow cytometry measurements confirmed that over 93% of the yeast cells were successfully labeled by QD-(Con A) complex. In contrast, non-conjugated QDs or QDs-(inhibited Con A) do not label any kind of biological system tested, indicating that the bioconjugation was specific and efficient. The staining pattern of the cells and biofilms demonstrate that QDs were effectively bioconjugated to Con A with specific labeling of saccharide-rich structures on C. albicans. Consequently, this work opens new possibilities to monitor glucose and mannose molecules through fluorescence techniques, which can help to optimize phototherapy protocols for this kind of fungus.

Dietary Curcuma longa enhances resistance against Eimeria maxima and Eimeria tenella infections in chickens.

The effects of dietary supplementation with an organic extract of Curcuma longa on systemic and local immune responses to experimental Eimeria maxima and Eimeria tenella infections were evaluated in commercial broiler chickens. Dietary supplementation with C. longa enhanced coccidiosis resistance as demonstrated by increased BW gains, reduced fecal oocyst shedding, and decreased gut lesions compared with infected birds fed a nonsupplemented control diet. The chickens fed C. longa-supplemented diet showed enhanced systemic humoral immunity, as assessed by greater levels of serum antibodies to an Eimeria microneme protein, MIC2, and enhanced cellular immunity, as measured by concanavalin A-induced spleen cell proliferation, compared with controls. At the intestinal level, genome-wide gene expression profiling by microarray hybridization identified 601 differentially expressed transcripts (287 upregulated, 314 downregulated) in gut lymphocytes of C. longa-fed chickens compared with nonsupplemented controls. Based on the known functions of the corresponding mammalian genes, the C. longa-induced intestinal transcriptome was mostly associated with genes mediating anti-inflammatory effects. Taken together, these results suggest that dietary C. longa could be used to attenuate Eimeria-induced, inflammation-mediated gut damage in commercial poultry production.

Antiviral effect of dietary germanium biotite supplementation in pigs experimentally infected with porcine reproductive and respiratory syndrome virus.

Germanium biotite (GB) is an aluminosilicate mineral containing 36 ppm germanium. The present study was conducted to better understand the effects of GB on immune responses in a mouse model, and to demonstrate the clearance effects of this mineral against Porcine reproductive and respiratory syndrome virus (PRRSV) in experimentally infected pigs as an initial step towards the development of a feed supplement that would promote immune activity and help prevent diseases. In the mouse model, dietary supplementation with GB enhanced concanavalin A (ConA)-induced lymphocyte proliferation and increased the percentage of CD3+CD8+ T lymphocytes. In pigs experimentally infected with PRRSV, viral titers in lungs and lymphoid tissues from the GB-fed group were significantly decreased compared to those of the control group 12 days post-infection. Corresponding histopathological analyses demonstrated that GB-fed pigs displayed less severe pathological changes associated with PRRSV infection compared to the control group, indicating that GB promotes PRRSV clearance. These antiviral effects in pigs may be related to the ability of GB to increase CD3+CD8+ T lymphocyte production observed in the mice. Hence, this mineral may be an effective feed supplement for increasing immune activity and preventing disease.

N-acetylglucosamine biofunctionalized CdSeTe quantum dots as fluorescence probe for specific protein recognition.

Hsp70 proteins are implicated in resistance to chemotherapy in cancers, the detection of which is important for cancer treatment and prognosis. In this work, we report the study on the detection of specific intracellular target protein in fixed cells using GlcNAc-conjugated CdSeTe QDs. The QDs were coupled with Con A via a carbodiimide reaction and then were further assembled with GlcNAc by lectin-carbohydrate interaction between Con A and GlcNAc. The obtained QDs-Con A-GlcNAc conjugates have an emission wavelength at 650 nm that is close to the near-infrared (NIR) regions and a specific recognition for Hsp70. These results show that the QDs-Con A-GlcNAc probe can be a promising tool for direct localization of the Hsp70 protein.

Antiviral effect of dietary germanium biotite supplementation in pigs experimentally infected with porcine reproductive and respiratory syndrome virus

Germanium biotite (GB) is an aluminosilicate mineral containing 36 ppm germanium. The present study was conducted to better understand the effects of GB on immune responses in a mouse model, and to demonstrate the clearance effects of this mineral against Porcine reproductive and respiratory syndrome virus (PRRSV) in experimentally infected pigs as an initial step towards the development of a feed supplement that would promote immune activity and help prevent diseases. In the mouse model, dietary supplementation with GB enhanced concanavalin A (ConA)-induced lymphocyte proliferation and increased the percentage of CD3+CD8+ T lymphocytes. In pigs experimentally infected with PRRSV, viral titers in lungs and lymphoid tissues from the GB-fed group were significantly decreased compared to those of the control group 12 days post-infection. Corresponding histopathological analyses demonstrated that GB-fed pigs displayed less severe pathological changes associated with PRRSV infection compared to the control group, indicating that GB promotes PRRSV clearance. These antiviral effects in pigs may be related to the ability of GB to increase CD3+CD8+ T lymphocyte production observed in the mice. Hence, this mineral may be an effective feed supplement for increasing immune activity and preventing disease.

Immunological adjuvant effect of Boswellia serrata (BOS 2000) on specific antibody and cellular response to ovalbumin in mice.

In this study, the biopolymeric fraction BOS 2000 from Boswellia serrata was evaluated for its potential ability as adjuvants on the immune responses to ovalbumin (OVA) in mice. Balb/c mice were immunized subcutaneously with OVA 100 µg alone or with OVA 100 µg dissolved in saline containing alum (200 µg) or BOS 2000 (10, 20, 40 and 80 µg) on Days 1 and 15. Two weeks later, OVA specific antibodies in serum; concanavalin A (Con A), OVA stimulated splenocyte proliferation, CD4/CD8/CD80/CD86 analysis in spleen cells and its estimation of cytokines (IL-2 and IFN gamma) from cell culture supernatant were measured. OVA specific IgG, IgG1 and IgG2a antibody levels in serum were significantly enhanced by BOS 2000 (80 µg) compared with OVA control group. Moreover, the adjuvant effect of BOS 2000 (80 µg) on the OVA-specific IgG, IgG1, and IgG2a antibody responses to OVA in mice were more significant than those of alum. BOS 2000 significantly enhanced the Con A and OVA induced splenocyte proliferation in the OVA immunized mice especially at a dose of 80 µg (p<0.001). However, no significant differences were observed among the OVA group and OVA/alum group. At a dose of 80 µg (p<0.001), there was a significant increase in the CD4/CD8 and CD80/CD86 analysis in spleen cells and cytokine (IL-2 and IFN-gamma) profile in the spleen cell culture supernatant was observed. In conclusion, BOS 2000 seems to be a promising balanced Th1 and Th2 directing immunological adjuvants which can enhance the immunogenicity of vaccine.

The lectin riddle: glycoproteins fractionated from complex mixtures have similar glycomic profiles.

One common method used for analyzing the glycoproteome is chromatography using multiple lectins that display different affinities toward oligosaccharide structures. Much has been done to determine lectin affinity using standard glycoproteins with known glycosylation; however, a knowledge of the selectivity and specificity of lectins exposed to complex mixtures of proteins is required if they are to be used as a means of studying the glycoproteome. In the present study, three lectins (Concanavalin A, Jacalin, and Wheat Germ Agglutinin) were used to fractionate glycoproteins from two different complex environments: (1) cell membranes and (2) plasma. Reproducible enrichment of glycoproteins from these samples has been shown to result from the combined use of these lectins. However, the global glycan profiles of the released N- and O-linked oligosaccharides from the glycoproteins retained by the lectins, and from those glycoproteins that did not bind, using both these complex samples, were found to be very similar. That is, although the lectins selectively and reproducibly retained some glycoproteins, other proteins with the same attached oligosaccharide structures did not bind. Some small N- and O-glycan differences were observed in the bound fractions but there was little absolute specificity toward individual oligosaccharide structures known to have high affinity to these lectins. These data indicate that lectins are useful for fractionating glycoproteins from complex mixtures, but that the overall glycoproteome is not isolated by this approach.

[Inhibition of panaxynol on experimental delayed type hypersensitivity].

OBJECTIVE: To evaluate the effect of panaxynol (PAN) on delayed type hypersensitivity and possible mechanism. METHOD: Allergic contact dermatitis (ACD) was induced by DNCB as a delayed type hypersensitivity (DTH) model to observe effect of PAN on auricle inflammation including pathological injury. Proliferation of T lymphocytes was induced by ConA and measured by MTf method. IFN-gamma secretion of splenocyte induced by ConA was detected by ELISA. RESULT: The swelling degree of auricle and pathological injury in ACD mice was reduced significantly by treated with PAN in induction phase. Proliferation of T lymphocytes induced by ConA in vitro was inhibited significantly by PAN, By contrast, no detectable effect was observed in resting splenocyte. IFN-y induced by ConA in splenocytes was inhibited markedly by PAN from 10 micromol x L(-1) and from 6 h. CONCLUSION: The results showed that DTH was inhibited by PAN mainly in induction phase and this effect may be related with the inhibition on T lymphocytes proliferation and secretion of IFN-gamma.

Effect of dietary garlic and onion on biliary proteins and lipid peroxidation which influence cholesterol nucleation in bile.

Formation of cholesterol gallstones in gallbladder is controlled by procrystallizing and anticrystallizing factors present in bile. Dietary garlic and onion have been recently observed to possess anti-lithogenic potential in experimental mice. In this investigation, the role of biliary proteins from rats fed lithogenic diet or garlic/onion-containing diet in the formation of cholesterol gallstones in model bile was studied. Cholesterol nucleation time of the bile from lithogenic diet group was prolonged when mixed with bile from garlic or onion groups. High molecular weight proteins of bile from garlic and onion groups delayed cholesterol crystal growth in model bile. Low molecular weight (LMW) proteins from the bile of lithogenic diet group promoted cholesterol crystal growth in model bile, while LMW protein fraction isolated from the bile of garlic and onion groups delayed the same. Biliary LMW protein fraction was subjected to affinity chromatography using Con-A and the lectin-bound and unbound fractions were studied for their influence on cholesterol nucleation time in model bile. Major portion of biliary LMW proteins in lithogenic diet group was bound to Con-A, and this protein fraction promoted cholesterol nucleation time and increased cholesterol crystal growth rate, whereas Con-A unbound fraction delayed the onset of cholesterol crystallization. Biliary protein from garlic/onion group delayed the crystallization and interfered with pronucleating activity of Con-A bound protein fraction. These data suggest that apart from the beneficial modulation of biliary cholesterol saturation index, these Allium spices also influence cholesterol nucleating and antinucleating protein factors that contribute to their anti-lithogenic potential.

Conformational behavior of alpha-D-mannopyranosyl-(1-->6)-alpha,beta-D-mannose complexed with two mannose-binding plant lectins, Allium sativam agglutinin I and concanavalin A, using NMR and molecular modeling techniques.

Herein, we report the intrinsic conformational preferences of alpha-d-Manp-(1-->6)-alpha,beta-d-Manp, (1) in the free state and as two (ASAI and ConA) lectin-bound forms. NMR spectroscopy and molecular dynamics techniques are used as 3D-structural determination tools. In free form disaccharide 1 displays a fair amount of conformational freedom, with one major (phi/psi 95 +/- 30 degrees/195 +/- 20 degrees and one minor (95 +/- 30 degrees/70 +/- 20 degrees) conformations around the glycosidic linkage and around the omega angle, both the gg and gt rotamers are almost equally populated. This is a first report of a three-dimensional structure of 1 bound with ASAI. Both lectins recognize a major phi/psi 95 +/- 30 degrees/200 +/- 30 degrees conformer with the ligand showing more flexibility in the binding site of ConA. Comparison of the mode of binding of the two lectins explains the differences in observed specificities.

Improvement of leucocyte functions in ovariectomised aged rats after treatment with growth hormone, melatonin, oestrogens or phyto-oestrogens.

Ageing is accompanied by an impairment of the physiological activity of the nervous, endocrine and immune system, as well as in neuroendocrine-immune communication. However, age-related changes in this communication axis have been scarcely studied. In mammals, the process of ageing is associated with an important decline in the secretion of several hormones, such as growth hormone (GH), melatonin (MEL) and oestrogens (Os). Ovariectomy, a model of menopause in rats, has been found to lead to premature immunosenescence. In the present study, the effect of ovariectomy and the role of replacement therapies with GH, MEL, O and natural phyto-oestrogens (POs) have been assessed on several functions in leucocytes from the spleen and the axillary nodes of intact and ovariectomised rats. Chemotaxis, lymphoproliferative response to the mitogen concanavalin A (Con A), the release of interleukin-2 (IL-2) and the natural killer (NK) cell activity have been investigated. Age-controlled rats were used to compare immune functions in hormone treated aged rats with those in younger untreated animals. In all experimental groups, the immune impairment caused by ageing and ovariectomy was partially or completely reversed by hormone treatments. Since the immune system is a marker of health and a predictor of longevity, the results suggest that treatment with hormones could slow down the effects of the ageing process.

Immunosuppressive effects of demethylzeylasteral in a rat kidney transplantation model.

In this study, we examined the immunosuppressive activity of demethylzeylasteral (T-96), isolated from the traditional Chinese herbal medicine, Tripterygium wilfordii Hook f. Its immunosuppressive effect was investigated using mouse splenocytes in vitro, and in an in vivo rat kidney transplant model. T-96 inhibited mouse splenocyte proliferation in a dose dependent manner. In the rat kidney transplant study, rats were randomly divided into eight groups following kidney transplantation, and different doses of T-96 or cyclosporin A (CsA) were administered to each group. T-96 alone at doses of 10 or 20 mg/kg/day significantly prolonged the survival of kidney-transplanted rats, compared with transplanted but untreated control rats. A combination of T-96 and prednisone also significantly prolonged survival: 10 mg/kg/day T-96 with 10 mg/kg/day prednisone increased the survival time to 31.8+/-6.5 days. Moreover, the combination of T-96 and prednisone was also effective in suppressing rejection of rat transplanted kidneys. These results demonstrate the strong immunosuppressive activity of T-96 and suggest a possible clinical use for T-96 as an immunosuppressive agent in the fields of organ transplantation and autoimmune disorders.