Anti-staphylococcal effects of Myracrodruon urundeuva lectins on nonresistant and multidrug resistant isolates.

AIMS: To evaluate the anti-staphylococcal effects of lectins isolated from bark (MuBL), heartwood (MuHL) and leaves (MuLL) of Myracrodruon urundeuva. METHODS AND RESULTS: The lectins were evaluated for: effects on growth, aggregation, haemolytic activity and biofilm-forming ability of Staphylococcus aureus clinical isolates nonresistant (8325-4) and multidrug resistant (LAC USA300); interference with the expression of virulence genes (hla, rnaIII and spa) of the Agr system of S. aureus; and synergistic effect with the antibiotics cefoxitin and cefotaxime. MuBL, MuHL and MuLL reduced growth (minimal inhibitory concentration (MIC): 12·5-50 µg ml-1 ) and viability (minimal bactericidal concentration (MBC): 100 µg ml-1 ) of 8325-4 and LAC USA300 cells. MuLL (at ½MIC and MIC) reduced LAC USA300 agglutination. The lectins did not interfere with haemolytic activity and expression of hla, rnaIII and spa genes. Only MuHL was able to reduce the biofilm production by 8325-4 (50-400 µg ml-1 ) and LAC USA300 (400 µg ml-1 ). CONCLUSION: The M. urundeuva lectins showed antibacterial activity against nonresistant and resistant clinical isolates of S. aureus and synergistic effects with antibiotics in reducing growth and biofilm formation. SIGNIFICANCE AND IMPACT OF THE STUDY: This work reports bioactive molecules capable of acting as anti-staphylococcal agents, since there are increasing reports of multiresistant isolates of this bacterium.

Anti-Candida activity of the water-soluble lectin from Moringa oleifera seeds (WSMoL).

This work reports the effects of the water-soluble lectin from Moringa oleifera seeds (WSMoL) on growth and survival of Candida species. In addition, cellular alterations linked to the antifungal effect were investigated. The minimal inhibitory (MIC) and fungicidal (MFC) concentrations were determined and 24-h growth curves in absence and presence of lectin were established. Flow cytometry was used to evaluate the induction of apoptosis/necrosis, alterations in mitochondrial membrane potential (ΔΨm), and occurrence of lysosomal damage. WSMoL inhibited the growth of C. albicans, C. glabrata, C. krusei and C. parapsilosis with MIC of 20µg/mL. The lowest MFC (20µg/mL) was detected for C. glabrata and the highest (80µg/mL) for C. albicans and C. parapsilosis. The inhibitory effect started from the ninth to nineteenth hour of incubation depending on the fungal species. Incubation with the lectin at the MIC for 24h increased the number of cells undergoing apoptosis and necrosis. Hyperpolarization of the mitochondrial membrane was detected after 12-h treatment, followed by reduction of ΔΨm or depolarization after 24h. No lysosomal damage was detected in treated cells. In conclusion, WSMoL is a fungistatic and fungicide agent against Candida with differential effects depending on the species.

Low circulating insulin-like growth factor-1 levels are associated with high serum uric acid in nondiabetic adult subjects.

BACKGROUND AND AIMS: Low insulin-like growth factor-1 (IGF-1) levels and high uric acid concentrations are associated with cardio-metabolic disorders. Acute IGF-1 infusion decreases uric acid concentration in healthy individuals. In this study, we aimed to examine the relationship between IGF-1 and uric acid levels. METHODS AND RESULTS: 1430 adult non diabetic subjects were stratified into quartiles according to their circulating IGF-1 values. Significant differences in uric acid concentration, measured by the URICASE/POD method were observed between low (quartile 1), intermediate (quartile 2 and 3), and high (quartile 4) IGF-1 levels groups after adjusting for age, gender, and body mass index (P = 0.02). These differences remained significant after adjustment for blood pressure, total cholesterol, high density lipoprotein, triglycerides, fasting and 2 h post-load glucose levels, HOMA-IR index (P = 0.005), liver enzymes (P = 0.03), glucose tolerance status (P = 0.02), growth hormone levels (GH) (P = 0.05), anti-hypertensive treatments (P = 0.04) or diuretics use (P = 0.04)). To clarify the molecular links between IGF-1 and uric acid, we performed an in vitro study, incubating human hepatoma cells with uric acid for 24 or 48 h in the presence of GH and observed a 21% and 26% decrease, respectively, in GH-stimulated IGF-1 mRNA expression (P = 0.02 and P = 0.012, respectively). This effect appears to be mediated by uric acid ability to down regulate GH intracellular signaling; in fact we observed a significant decrease of GH activated JAK2 and Stat5 phosphorylation. CONCLUSIONS: These data demonstrate an inverse relationship between IGF-1 and uric acid levels in adults and suggest that uric acid might affect hepatic IGF-1 synthesis.

Antimicrobial lectin from Schinus terebinthifolius leaf.

AIMS: Schinus terebinthifolius leaves are used for treating human diseases caused by micro-organisms. This work reports the isolation, characterization and antimicrobial activity of S. terebinthifolius leaf lectin (SteLL). METHODS AND RESULTS: The isolation procedure involved protein extraction with 0.15 mol l(-1) NaCl, filtration through activated charcoal and chromatography of the filtrate on a chitin column. SteLL is a 14-kDa glycopeptide with haemagglutinating activity that is inhibited by N-acetyl-glucosamine, not affected by ions (Ca(2+) and Mg(2+)) and stable upon heating (30-100 °C) as well as over the pH 5.0-8.0. The antimicrobial effect of SteLL was evaluated by determining the minimal inhibitory (MIC), bactericide (MBC) and fungicide (MFC) concentrations. Lectin was active against Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Salmonella enteritidis and Staphylococcus aureus. Highest bacteriostatic and bactericide effects were detected for Salm. enteritidis (MIC: 0.45 µg ml(-1)) and Staph. aureus (MBC: 7.18 µg ml(-1)), respectively. SteLL impaired the growth (MIC: 6.5 µg ml(-1)) and survival (MFC: 26 µg ml(-1)) of Candida albicans. CONCLUSIONS: SteLL, a chitin-binding lectin, purified in milligram quantities, showed antimicrobial activity against medically important bacteria and fungi. SIGNIFICANCE AND IMPACT OF THE STUDY: SteLL can be considered as a new biomaterial for potential antimicrobial applications.

Glucose tolerance, insulin sensitivity and insulin release in European non-diabetic carriers of a polymorphism upstream of CDKN2A and CDKN2B.

AIMS/HYPOTHESIS: The aim of this study was to investigate the association of the rs10811661 polymorphism near the CDKN2B/CDKN2A genes with glucose tolerance, insulin sensitivity and insulin release in three samples of white people with European ancestry. METHODS: Sample 1 comprised 845 non-diabetic offspring of type 2 diabetes patients recruited in five European centres participating in the EUGENE2 study. Samples 2 and 3 comprised, respectively, 864 and 524 Italian non-diabetic participants. All individuals underwent an OGTT. Screening for the rs10811661 polymorphism was performed using a TaqMan allelic discrimination assay. RESULTS: The rs10811661 polymorphism did not show a significant association with age, BMI and insulin sensitivity. Participants carrying the TT genotype showed a significant reduction in insulin release, measured by an OGTT-derived index, compared with carriers of the C allele, in the three samples. When these results were pooled with those of three published studies, and meta-analysed with a random-effects model, the T allele was significantly associated with reduced insulin secretion (-35.09 [95% CI 14.68-55.52], p = 0.0008 for CC+CT vs TT; and -29.45 [95% CI 9.51-49.38], p = 0.0038, for the additive model). In addition, in our three samples, participants carrying the TT genotype exhibited an increased risk for impaired glucose tolerance (IGT) compared with carriers of the C allele (OR 1.55 [95% CI 1.20-1.95] for the meta-analysis of the three samples). CONCLUSIONS/INTERPRETATION: Our data, together with the meta-analysis of previously published studies, show that the rs10811661 polymorphism is associated with impaired insulin release and IGT, suggesting that this variant may contribute to type 2 diabetes by affecting beta cell function.