Durcilene Alves da Silva

Development and Antibacterial Activity of Cashew Gum-Based Silver Nanoparticles

The present study describes the development of a green synthesis of silver nanoparticles reduced and stabilized by exuded gum from Anacardium occidentale L. and evaluates in vitro their antibacterial and cytotoxic activities. Characterization of cashew gum-based silver nanoparticles (AgNPs) was carried out based on UV–Vis spectroscopy, transmission electron microscopy and dynamic light scattering analysis which revealed that the synthesized silver nanoparticles were spherical in shape, measuring about 4 nm in size with a uniform dispersal. AgNPs presented antibacterial activity, especially against Gram-negative bacteria, in concentrations where no significant cytotoxicity was observed.

Collagen-based silver nanoparticles for biological applications: synthesis and characterization

BackgroundType I collagen is an abundant natural polymer with several applications in medicine as matrix to regenerate tissues. Silver nanoparticles is an important nanotechnology material with many utilities in some areas such as medicine, biology and chemistry. The present study focused on the synthesis of silver nanoparticles (AgNPs) stabilized with type I collagen (AgNPcol) to build a nanomaterial with biological utility. Three formulations of AgNPcol were physicochemical characterized, antibacterial activity in vitro and cell viability assays were analyzed. AgNPcol was characterized by means of the following: ultraviolet-visible spectroscopy, dynamic light scattering analysis, Fourier transform infrared spectroscopy, atomic absorption analysis, transmission electron microscopy and of X-ray diffraction analysis.ResultsAll AgNPcol showed spherical and positive zeta potential. The AgNPcol at a molar ratio of 1:6 showed better characteristics, smaller hydrodynamic diameter (64.34±16.05) and polydispersity index (0.40±0.05), and higher absorbance and silver reduction efficiency (0.645 mM), when compared with the particles prepared in other mixing ratios. Furthermore, these particles showed antimicrobial activity against both Staphylococcus aureus and Escherichia coli and no toxicity to the cells at the examined concentrations.ConclusionsThe resulted particles exhibited favorable characteristics, including the spherical shape, diameter between 64.34 nm and 81.76 nm, positive zeta potential, antibacterial activity, and non-toxicity to the tested cells (OSCC).

Antidiarrheal activity of cashew GUM, a complex heteropolysaccharide extracted from exudate of Anacardium occidentale L. in rodents.

ETHNOPHARMACOLOGICAL RELEVANCE Anacardium occidentale L. (Anacardiaceae) is commonly known as the cashew tree. It is native to tropical America and extracts of the leaves, bark, roots, chestnut net and exudate have been traditionally used in northeast Brazil for the treatment of various diseases. The exudate of the cashew tree (cashew gum) has been exploited by locals since ancient times for multiple applications, including the treatment of diarrheal diseases. AIM OF THE STUDY The primary aim of the present study is to evaluate the antidiarrheal activity of cashew gum (CG), a complex heteropolysaccharide from the exudate of the cashew tree, using various models. MATERIALS AND METHODS The antidiarrheal activity of cashew gum (CG) against acute diarrhea was investigated using the castor oil-induced diarrhea model. The effects of CG on gastrointestinal transit and castor oil- and PGE2- induced enteropooling were also examined in rodents. In addition, the effect of CG against secretory diarrhea was investigated using a model of fluid secretion in cholera toxin-treated intestinal closed loops in live mice. RESULTS Cashew gum (30, 60, and 90 mg/kg, p.o.) showed a significant (P<0.05-0.01) antidiarrheal effect in rats with castor oil-induced diarrhea, inhibiting the total amount of stool and diarrheal stools. The 60 mg/kg dose of CG exhibited excellent antidiarrheal activity and significantly reduced the severity of diarrhea (diarrhea scores) in rats. CG (60 mg/kg) significantly (P<0.05) decreased the volume of castor oil- and PGE2-induced intestinal fluid secretion (enteropooling). In addition, similar to loperamide (standard drug, 5 mg/kg, p.o.), CG treatment reduced the distance traveled by a charcoal meal in the 30-min gastrointestinal transit model by interacting with opioid receptors. In cholera toxin-induced secretory diarrhea, CG (60 mg/kg) significantly inhibited the intestinal fluid secretion and decreased Cl(-) ion loss in the cholera toxin(-)treated isolated loops model of live mice by competitively binding to cholera toxin-GM1 receptors. CONCLUSIONS In conclusion, our results indicate that a complex heteropolysaccharide extracted from the exudate of A. occidentale L. has antidiarrheal activity in acute, inflammatory, and secretory diarrhea models, which could justify its traditional use in the treatment of diarrhea in northeast Brazil. The antidiarrheal activity might be explained by the capacity of CG to inhibit gastrointestinal motility and thereby reduce the accumulation of intestinal fluid and the secretion of water and chloride ions in the lumen of the intestine.

Gastroprotective Properties of Cashew Gum, a Complex Heteropolysaccharide of Anacardium occidentale, in Naproxen-Induced Gastrointestinal Damage in Rats

Preclinical Research

Chitosan-based silver nanoparticles: A study of the antibacterial, antileishmanial and cytotoxic effects:

Silver nanoparticles have been studied as an alternative for treatment of microbial infections and leishmaniasis, without promoting induction of microbial or parasite resistance. In this study, chitosan-based silver nanoparticles were synthesized from silver nitrate (AgNO3), sodium borohydride as a reducing agent, and the biopolymer chitosan as a capping agent. The chitosan-based silver nanoparticles were characterized by ultraviolet–visible, Fourier transform infrared, dynamic light scattering, zeta potential, atomic force microscopy, and transmission electron microscope. The antibacterial assay was performed by determination of the minimum inhibitory concentration. The antileishmanial and the cytotoxic effects induced by AgNO3, chitosan, and chitosan-based silver nanoparticles were analyzed by resazurin and MTT colorimetric assays, respectively. AgNO3, chitosan, and chitosan-based silver nanoparticles induced a marked activity against all bacterial strains and promastigote forms of Leishmania amazonensis at minimum inhibitory concentrations ranging from 1.69 to 3.38 µg Ag/mL. Interestingly, the chitosan-based silver nanoparticles presented less cytotoxicity than the AgNO3 alone and were more active against L. amazonensis than solely chitosan. Furthermore, the cytotoxic concentrations (CC50) of both chitosan and chitosan-based silver nanoparticles against macrophages were significantly higher than the IC50 against promastigotes. Thus, the chitosan-based silver nanoparticles represent a promising alternative for the treatment of microbial infections and leishmaniasis.

Quaternized cashew gum: An anti-staphylococcal and biocompatible cationic polymer for biotechnological applications

Chemical modifications to cashew gum (CG) structure have been previously reported to obtain new physicochemical characteristics, however until now there were no reports of modifications by introduction of new functional groups to add cationic character. This study presents a quaternization route for CG using a quaternary ammonium reagent. The chemical features of the quaternized cashew gum derivatives (QCG) were analyzed by: FTIR, elemental analysis, degree of substitution, Zeta potential, 1H NMR and 1H-13C correlation (HSQC). QCG were evaluated for their anti-staphylococcal activity by determining minimum inhibitory and bactericidal concentrations against pathogenic Staphylococcus spp. and by imaging using atomic force microscopy. Moreover, the mammalian cell biocompatibility were also assessed through hemolytic and cell toxicity assays. QCG presented promising antimicrobial activity against methicillin-resistant S. aureus and biocompatibility on tested cells. These results show that QCG could be a promising tool in the development of biomaterials with an anti-septic action.

Orabase formulation with cashew gum polysaccharide decreases inflammatory and bone loss hallmarks in experimental periodontitis

This study aimed to investigate the chemical characteristics and the effects of an orabase gel with Cashew Gum Polysaccharide (CG-P) from Anacardium occidentale L. on alveolar bone loss and relative mRNA expression of TNF-α, IL-1β, RANK, RANKL, and OPG in the periodontal tissue of Wistar rats (Rattus norvegicus) subjected to ligature-induced periodontitis. Crude cashew gum was collected and purified by chemical processes; then, the CG-P was mixed with orabase gel. Female rats were randomly divided into four groups of six animals each: saline 0.9% (Sal Group); orabase gel (Gel Group); 50mg CG-P/1g orabase gel (CG-P50 Group) and 150mg CG-P/1g orabase gel (CG-P150 Group). Periodontitis was induced in the animals; they were treated for 20days with one daily topical application. The purification process of CG-P presented high yield and resulted in a protein-free product. The treatment with CG-P150 (150mg CG-P/1g orabase gel) significantly reduced alveolar bone loss, decreased the relative mRNA expression of TNF-α, IL-1β, RANKL and the RANKL/OPG ratio, and caused a significant decrease in myeloperoxidase activity of the gingival tissue. Thus, the CG-P in orabase represents a potential adjuvant drug for the treatment of periodontitis and possible source of new biotechnological discoveries.

Modified chitosan-based bioactive material for antimicrobial application: Synthesis and characterization

The search for natural antibacterial agents to treat diseases caused by resistant microorganisms has been gaining increasing attention. Chitosan has been studied in several areas due to its particular properties. The grafting of hydrophobic chains into the chitosan molecule, turning it amphiphilic, may improve its antimicrobial activity by increasing electrostatic interaction with the bacterial cell wall. The objective of this work was to enhance the antimicrobial activity of chitosan by the reaction of N-acylation with maleic anhydride. For this purpose, molar ratios of 1:2, 1:5 and 1:10 chitosan: anhydride were investigated, and the obtained derivatives were characterized by elemental analysis, FTIR, thermal analysis and XRD where it was possible to prove the chemical modification of chitosan. The modified materials presented excellent antibacterial action against Staphylococcus aureus and Escherichia coli, evidencing no activity against the protozoan Leishmania amazonensis. Cytotoxicity assays by the MTT analysis and hemolysis indicated that the derivatives did not show toxicity in mammalian cells. The proposed modified chitosan compounds showed to be promising for biomedical applications since they allied excellent antibacterial activity and absence of cytotoxicity.

Collagen-based silver nanoparticles: Study on cell viability, skin permeation, and swelling inhibition

Collagen is considered the most abundant protein in the animal kingdom, comprising 30% of the total amount of proteins and 6% of the human body by weight. Studies that examine the interaction between silver nanoparticles and proteins have been highlighted in the literature in order to understand the stability of the nanoparticle system, the effects observed in biological systems, and the appearance of new chemical pharmaceutical products. The objective of this study was to analyze the behavior of silver nanoparticles stabilized with collagen (AgNPcol) and to check the skin permeation capacity and action in paw edema induced by carrageenan. AgNPcol synthesis was carried out using solutions of reducing agent sodium borohydride (NaBH4), silver nitrate (AgNO3) and collagen. Characterization was done by using dynamic light scattering (DLS) and X-ray diffraction (XRD) and AFM. Cellular viability testing was performed by using flow cytometry in human melanoma cancer (MV3) and murine fibroblast (L929) cells. The skin permeation study was conducted using a Franz diffusion cell, and the efficiency of AgNPcol against the formation of paw edema in mice was evaluated. The hydrodynamic diameter and zeta potential of AgNPcol were 140.7±7.8nm and 20.1±0.7mV, respectively. AgNPcol failed to induce early apoptosis, late apoptosis, and necrosis in L929 cells; however, it exhibited enhanced toxicity in cancer cells (MV3) compared to normal cells (L929). AgNPcol demonstrated increased toxicological effects in cancer MV3 cells, promoting skin permeation, and preventing paw edema.

Topical protection of mice laryngeal mucosa using the natural product cashew gum

Evaluate the effect of in vitro exposure of mice laryngeal mucosa to solutions that simulated human gastric juice and to assess the topical protective effect of cashew gum on mice laryngeal mucosal integrity in vitro.