Ecofriendly Synthesis of Silver Nanoparticles Using Potato Steroidal Alkaloids and Their Activity Against Phytopathogenic Fungi

ABSTRACT In order to reduce the excessive reliance on the toxic chemical fungicides, the present study aimed to isolate the total potato glycoalkaloids (TPAs), and the two steroidal alkaloids α-chaconine and α-solanine from potatoes, Solanum tuberosum L. Their structures were characterized using physical and spectroscopic methods including (UV, IR, 1H, 13C--NMR, 2D 1H-1H COSY, HMBC and NOESY). Silver nanoparticles (AgNPs) were prepared from potato alkaloids through a green synthesis approach. Potato alkaloids and their nanoparticles inhibited mycelial growth of the phytopathogenic fungi Alternaria alternate, Rhizoctonia solani, Botrytis cinerea and Fusarium oxysporum f. sp. lycopersici with low minimal inhibitory and minimal fungicidal concentrations. R. solani was the most susceptible, while F. oxysporum was the most resistant. TPAs was the most fungitoxic (EC50's were 19.8, 22.5, 26.5 and 32.3 µg/ml against R. solani, A. alternate, B. cinerea and F. oxysporum respectively). A mixture of α-solanine and α-chaconine (1:1) showed a marked antifungal activity. AgNPs (size 39.5-80.3 diameter) from alkaloids showed improved fungitoxic activity (EC50's of TPAs nanoparticles ranged between 10.9 and 16.1 µg/ml). Alkaloids exhibited no or a slight phytotoxicity against wheat and radish. Results recommend the potential of using potato alkaloids and their nanoparticles as biorational alternatives to conventional fungicides.

IL-33 Priming Enhances Peritoneal Macrophage Activity in Response to Candida albicans

IL-33 is a member of the IL-1 cytokine family and plays a role in the host defense against bacteria, viruses, and fungi. In this study, we investigated the function of IL-33 and its receptor in in vitro macrophage responses to Candida albicans. Our results demonstrate that pre-sensitization of isolated peritoneal macrophages with IL-33 enhanced their pro-inflammatory cytokine production and phagocytic activity in response to C. albicans. These macrophage activities were entirely dependent on the ST2-MyD88 signaling pathway. In addition, pre-sensitization with IL-33 also increased ROS production and the subsequent killing ability of macrophages following C. albicans challenge. These results indicate that IL-33 may increase anti-fungal activity against Candida through macrophage-mediated resistance mechanisms.

Granulocyte macrophage colony-stimulating factor enhances the modulatory effect of cytokines on monocyte-derived multinucleated giant cell formation and fungicidal activity against Paracoccidioides brasiliensis

Multinucleated giant cells (MGC) are cells present in characteristic granulomatous inflammation induced by intracellular infectious agents or foreign materials. The present study evaluated the modulatory effect of granulocyte macrophage colony-stimulating factor (GM-CSF) in association with other cytokines such as interferon-gamma (IFN-γ), tumour necrosis factor-alpha, interleukin (IL)-10 or transforming growth factor beta (TGF-β1) on the formation of MGC from human peripheral blood monocytes stimulated with Paracoccidioides brasiliensis antigen (PbAg). The generation of MGC was determined by fusion index (FI) and the fungicidal activity of these cells was evaluated after 4 h of MGC co-cultured with viable yeast cells of P. brasiliensis strain 18 (Pb18). The results showed that monocytes incubated with PbAg and GM-CSF plus IFN-γ had a significantly higher FI than in all the other cultures, while the addition of IL-10 or TGF-β1 had a suppressive effect on MGC generation. Monocytes incubated with both pro and anti-inflammatory cytokines had a higher induction of foreign body-type MGC rather than Langhans-type MGC. MGC stimulated with PbAg and GM-CSF in association with the other cytokines had increased fungicidal activity and the presence of GM-CSF also partially inhibited the suppressive effects of IL-10 and TGF-β1. Together, these results suggest that GM-CSF is a positive modulator of PbAg-stimulated MGC generation and on the fungicidal activity against Pb18.

Fungicidal activity of Eucalyptus tereticornis essential oil on the pathogenic fungus Fusarium oxysporum / Actividad antimicótica del aceite esencial a partir de Eucalyptus tereticornis sobre el hongo patógeno Fusarium oxysporum

The objective of present paper was to determine the antifungal activity of the Eucalyptus tereticornis (Myrtaceae) essential oil and two fractions on the Fusarium oxysporum mushroom, a pathogen with clinical and agricultural significance. The total citronelal (44.8 percent) and geraniol (9.78 percent) essential oil had a fungicidal effect at a 3 g/L concentration and a fungicidal activity at small concentrations. The A and B fractions composed most of p-mentane-3,8-diol (18.95 percent) and geraniol acetate (24.34 percent), respectively were more active than the total extract. The observations at microscopic level showed damages and changes in hyphae and chlamydospores, as well as a decrease in the number of conidia. The observed fungicidal activity and the morphologic damages were dependent on the concentration.

El objetivo de este trabajo fue determinar la actividad antifúngica del aceite esencial de Eucalyptus tereticornis (Myrtaceae) y 2 fracciones sobre el hongo Fusarium oxysporum, patógeno de importancia tanto clínica como agrícola. El aceite esencial total, compuesto principalmente por citronelal (44,8 por ciento), citronelol (9,78 por ciento) presentó un efecto fungicida a una concentración de 3 g/L y actividad fungistática a concentraciones menores. La fracciones A y B compuestas en su mayoría por p-mentano-3,8-diol (18,95 por ciento) y acetato de citronelol (24,34 por ciento) respectivamente fueron más activas que el extracto total. Las observaciones a nivel microscópico mostraron daños y cambios en hifas y clamidosporas, así como disminución en el número de conidias. La actividad fungistática observada y los daños morfológicos fueron dependientes de la concentración.

Antimicrobial activity and chemical composition of essential oil of Pelargonium odoratissimum

The chemical composition of the essential oil from the leaves of Pelargonium odoratissimum (L.) L'Hér., Geraniaceae, was determined and the antimicrobial activities against the Aspergillus flavus CML 1816, Aspergillus carbonarius CML1815 and Aspergillus parasiticus CMLA 817 fungi, as well the Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25 992 bacteria were evaluated. The essential oil was isolated by steam distillation using a modified Clevenger apparatus, and its constituents were identified and quantified by GC/MS and GC-FID analyses. In vitro bioanalytical testing was performed using a completely randomized design. The concentrations of essential oil employed ranged from 0.1 to 2 μL.mL-1 (in dimethyl sulfoxide) for the fungus species and from 1 to 500 μL.mL-1 for the bacteria. The diameters of the inhibition zones formed for bacteria and the mean diameters of mycelial growth in perpendicular directions for fungi were measured, followed by calculation of the percentage of inhibition. The essential oil from the leaves of P. odoratissimum furnished methyleugenol (96.80 percent), a phenylpropanoid. This essential oil inhibited the growth of fungi (100 percent inhibition) and exhibited a small effect on the bacteria at the concentrations tested.

Interleukin-15 augments oxidative metabolism and fungicidal activity of human monocytes against Paracoccidioides brasiliensis

Interleukin (IL)-15 is a pleiotropic cytokine that regulates the proliferation and survival of many cell types. IL-15 is produced by monocytes and macrophages against infectious agents and plays a pivotal role in innate and adaptive immune responses. This study analyzed the effect of IL-15 on fungicidal activity, oxidative metabolism and cytokine production by human monocytes challenged in vitro with Paracoccidioides brasiliensis (Pb18), the agent of paracoccidioidomycosis. Peripheral blood monocytes were pre-incubated with IL-15 and then challenged with Pb18. Fungicidal activity was assessed by viable fungi recovery from cultures after plating on brain-heart infusion-agar. Superoxide anion (O2-), hydrogen peroxide (H2O2), tumour necrosis factor-alpha (TNF-α), IL-6, IL-15 and IL-10 production by monocytes were also determined. IL-15 enhanced fungicidal activity against Pb18 in a dose-dependent pattern. This effect was abrogated by addition of anti-IL-15 monoclonal antibody. A significant stimulatory effect of IL-15 on O2- and H2O2 release suggests that fungicidal activity was dependent on the activation of oxidative metabolism. Pre-treatment of monocytes with IL-15 induced significantly higher levels of TNF-α, IL-10 and IL-15 production by cells challenged with the fungus. These results suggest a modulatory effect of IL-15 on pro and anti-inflammatory cytokine production, oxidative metabolism and fungicidal activity of monocytes during Pb18 infection.

Stimulation of Bactericidal and Fungicidal Activity of Neonatal Monocytes by Immunoactivating Peptide

PURPOSE: To evaluate the function of Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm) in human neonatal monocytes. METHODS: The peptide, Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm), was synthesized, purified, and prepared in the Peptide Library Support Facility at Pohang University of Science and Technology. Female Sprague-Dawley rats (200+/-10 g) were preinfected with S. aureus and treated with WKYMVm through femoral vein. At various time points, blood samples were obtained by puncture of femoral artery and the serum was plated on the nutrient agar plate. The number of viable bacteria was determined by counting the number of bacterial colonies. In addition, using S. aureus and C. albicans, we evaluated the bactericidal and fungicidal activities of neonatal monocytes, which were separated from umbilical cord blood by Ficoll gradient. RESULTS: The numbers of bacteria in the blood of WKYMVm-treated rats were rapidly decreased with time, as compared with those of the untreated rats. The peptide treatment enhanced the bactericidal activity in vivo within 10 minutes. In neonatal monocytes, WKYMVm stimulated the intracellular killing of S. aureus in a dose dependent manner, showing the maximum effect at 100 nM. WKYMVm stimulated the phagocytic and fungicidal activities against C. albicans in a dose dependent manner, with the maximum effect at the 100 nM. CONCLUSION: These results suggest that WKYMVm may be an effective agent against the neonatal infections.

Effects of tumor necrosis factor alpha(TNF-?) on the fungicidal activity of mouse peritoneal exudate cells / 中国免疫学杂志

Objective:To study the effect of TNF-? on the activation and fungicidal activity of mouse peritoneal exudate cells.Methods:The mouse peritoneal exudate cells and macrophage were stimulated with IL-12、IL-18、IFN-?、TNF-? or monoclonal antibody.Cytokines and nitric oxide(NO) levels in the medium supernatant were determined with ELISA and Griess method respectively.Detected the numbers of viable Cryptococcus neoformans in macrophage.Results:Combined with IL-12 and IL-18 synergistically induced the production of TNF-? by peritoneal exudate cells and this effect can be inhibited by neutralizing anti-IFN-? mAb.Combined with IFN-? and TNF-? synergistically induced the production of NO by macrophage and potentiate its activity against Cryptococcus neoformans.Conclusion:The result suggests that the TNF-? plays an important role in enhancement of the fungicidal activity of macrophages. [