Association of Rhizophora mangle and ascorbic acid in hydrogels: Evaluation of cytotoxic and immunomodulatory effects

Abstract Polyphenolics from Rhizophora mangle (R. mangle) have shown wound healing and anti- inflammatory effects that may be potentiated by being associated with ascorbic acid, an important substance for collagen and elastin synthesis that plays a role in tissue repair. In our study, we aimed to formulate an association of R. mangle and ascorbic acid in hydrogels and evaluate the association's cytotoxic and immunomodulatory effects. In a pre-formulation study, three gelling polymers (i.e.xanthan gum, poloxamer and hydroxyethyl cellulose) were tested. The selected polymer (i.e. xanthan gum) was used to evaluate cytotoxic and immunomodulatory effects using flow cytometry. Xanthan gum (1.5%) had a homogeneous appearance, an orange colour, a smooth surface, intense brightness and the typical odour, as well as non-Newtonian pseudoplastic behaviour. With a pH of 5.0-5.3 and a non-cytotoxic profile, xanthan gum induced the proliferation and activation of CD4 +, CD8+ and NK T lymphocytes and the production of IL- 2, IL-4, IL-10, IL-17 and TNF-α cytokines in stimulated splenocytes. The results suggest that the association of R. mangle and ascorbic acid in 1.5% xanthan gum hydrogel may be promising in preparations for wound-healing processes.

Biocompatibility and immunostimulatory properties of fish collagen and shrimp chitosan towards peripheral blood mononuclear cells (PBMCs).

Several naturally occurring biopolymers are commercially produced from livestock and farmed animals processing wastes, including aquatic organisms. These wastes are considered valuable coproducts of fishery processing industry, from which biopolymers may be recovered and exploited for their bioactive potential. The aim of this work was to prepare polymeric films from collagen and chitosan solutions, extracted from fishery discards, and investigate the cytotoxicity and immunomodulatory activity towards human peripheral blood mononuclear cells (PBMCs). PBMCs were isolated from healthy donors and treated with Chitosan, Collagen, Chitosan+Collagen solutions and Chitosan+Collagen film in order to measure the changes in cell viability, cytosolic calcium concentration ([Ca2+]cyt), mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS) levels, differentiation and activation of T CD8+ and CD4+ lymphocytes, and cytokine production. Results showed that collagen and chitosan preparations did not show cytotoxic effect, while cellular IL-6, IL-10, and TNF-α release was observed. Chitosan and collagen were able to promote non-cytotoxic PBMCs activation through cytosolic and mitochondrial ROS production. There was a noteworthy phenotyping of lymphocytes T CD8+ and CD4+ counting and an increase of [Ca2+] cyt and ΔΨm levels. These results suggest that chitosan/collagen-based biomaterials produce immunostimulatory effects on PBMC with potential to biomedical approaches.

Pectin-like Polysaccharide Extracted from the Leaves Caesalpinia pulcherrima is a Promising Antioxidant and Immunomodulator Agent

Abstract Studies have shown that Caesalpinia pulcherrima extracts promote antioxidant, healing, immunomodulating and antiparasitic activities and its polysaccharides can be used as functional food. In this sense, this work had as objective the isolation and characterization of a polysaccharide-like pectin, extracted from the C. pulcherrima leaves and its possible applications as an antioxidant and immunomodulator agent. The molecule was characterized by high performance liquid chromatography, fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Its antioxidant potential was evaluated through the methods of phosphomolybdenum, ABTS radical scavenging [2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid], DPPH (1,1-diphenyl-2-picrylhydrazyl) and nitric oxide radical. The immunostimulating effects of pectin were tested in splenocytes to evaluate its toxic, proliferative and cell activator and immunomodulatory potential. The polysaccharide obtained has structural characteristics similar to pectins. Pectin showed high in vitro antioxidant activity for ABTS radical scavenging, moderate activity for phosphomolybdenum and low activity for DPPH and nitric oxide. In vitro immunomodulation assays showed that pectin obtained did not promote a cytotoxic effect (viability > 90%). The increase in cytosolic ROS levels indicates a possible mechanism of cell activation without causing damage. Immunophenotyping showed that pectin increased a subpopulation of CD8+ T lymphocytes and monocytes. In addition, it promoted a mostly pro-inflammatory response confirmed by the production of cytokines IL-2, -4, -6, IFN-γ and TNF-α. These results reinforce the ethnopharmacological use of C. pulcherrima leaves and expand the use of this plant for future applications as herbal medicines.

Evaluation of cytotoxic, immunomodulatory effects, antimicrobial activities and phytochemical constituents from various extracts of Passiflora edulis F. flavicarpa (Passifloraceae).

The leaves of P. edulis were subjected to physicochemical analysis, such as ion content, extractives, and structural molecules. The hexanic, ethanolic and ethyl acetate extracts were submitted to phytochemical analyzes by GC-MS, HPLC-MS, and spectrophotometry. In addition, antioxidant (DPPH, ABTS and TAA methods) potential, antimicrobial (MIC method) action, cytotoxicity and immunostimulant activity (flow cytometry analysis) were performed. The extracts showed a moderate antioxidant capacity and revealed the presence of several metabolites, mainly phenols, such as caffeic acid, p-coumaric acid and luteolin. The ethyl acetate and ethanolic extracts showed antifungal activity. In addition, the extracts did not affect splenocytes viability at 12.5 µg/mL and promoted the production of IL-6, IL-10, IL-17 and TNF-α cytokines. P. edulis extracts showed antifungal and antioxidant activity and were able to induce immunostimulatory action in splenocyte cultures in vitro.

Evaluation of cytotoxic, immunomodulatory and antibacterial activities of aqueous extract from leaves of Conocarpus erectus Linnaeus (Combretaceae).

OBJECTIVES: This work evaluated the antibacterial activity, cytotoxicity and immunomodulatory effect on human peripheral blood mononuclear cells (PBMCs) promoted by aqueous extract from Conocarpus erectus leaves (AELCe). METHODS: The extract was characterized by thin layer chromatography and ultraperformance liquid chromatography coupled to mass spectrometry (UPLC-MS). Cytotoxicity of AELCe (6.25-50 µg/ml) was investigated using annexin V and propidium iodide. Cytokine and nitric oxide levels in PBMCs culture supernatants exposed or not to AELCe (12.5 µg/ml) were determined, and antibacterial activity was evaluated by disc diffusion and broth microdilution methods. KEY FINDINGS: AELCe contained 3',4'-OH flavonoids, phenylpropanoglycosides, saponins, polymeric proanthocyanidins and hydrolysable tannins. Moreover, 10 other compounds were identified through UPLC-MS technique. AELCe did not affect lymphocyte viability at 6.25 and 12.5 µg/ml. IL-2, IL-10, TNF-α, IFN-γ and nitric oxide was produced in higher levels by cells treated with AELCe. Proliferation and activation of CD8+ T lymphocytes were also stimulated. AELCe showed bacteriostatic activity against clinical and antibiotic-resistant strains of Staphylococcus aureus (MIC between 250 and 1000 µg/ml). CONCLUSIONS: AELCe showed a moderate bacteriostatic activity and promoted an immunomodulatory status through higher production of Th1 cytokines, nitric oxide release and T CD8+ lymphocytes stimulation.