In vitro antibacterial and anti-inflammatory effects of Anacardium occidentale L. extracts and their toxicity on PBMCs and zebrafish embryos

Nobiletin derivative, 5-acetoxy-6,7,8,3',4'-pentamethoxyflavone, inhibits neuroinflammation through the inhibition of TLR4/MyD88/MAPK signaling pathways and STAT3 in microglia

OBJECTIVE

Microglia in the central nervous system regulate neuroinflammation that leads to a wide range of neuropathological alterations. The present study investigated the anti-neuroinflammatory properties of nobiletin (Nob) derivative, 5-acetoxy-6,7,8,3',4'-pentamethoxyflavone (5-Ac-Nob), in lipopolysaccharide (LPS)-activated BV2 microglia.

MATERIALS AND METHODS

By using the MTT assay, Griess method, flow cytometry, and enzyme-linked immunosorbent assay (ELISA), we determined the cell viability, the levels of nitric oxide (NO), reactive oxygen species (ROS), and pro-inflammatory factors (interleukin 1 beta; IL-1β, interleukin 6; IL-6, tumor necrosis factor alpha; TNF-α and prostaglandin E2; PGE2) in LPS-stimulated BV2 microglia. Toll-like receptor 4 (TLR4)-mediated myeloid differentiation primary response gene 88 (MyD88)/nuclear factor-kappa B (NF-κB), mitogen-activated protein kinase (MAPK) signaling pathway and signal transducer and activator of transcription 3 (STAT3) were measured by western blotting. Analysis of NO generation and mRNA of pro-inflammatory cytokines was confirmed in the zebrafish model.

RESULTS

5-Ac-Nob reduced cell death, the levels of NO, ROS, inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX-2), and pro-inflammatory factors in LPS-activated BV-2 microglial cells. TLR4-mediated MyD88/NF-κB and MAPK pathway (p38, ERK and JNK) after exposure to 5-Ac-Nob was also suppressed. Moreover, 5-Ac-Nob inhibited phosphorylated STAT3 proteins expression in LPS-induced BV-2 microglial cells. Furthermore, we confirmed that 5-Ac-Nob decreased LPS-induced NO generation and mRNA of pro-inflammatory cytokines in the zebrafish model.

CONCLUSIONS

Our findings suggest that 5-Ac-Nob represses neuroinflammatory responses by inhibiting TLR4-mediated signaling pathway and STAT3. As a result of these findings, 5-Ac-Nob has potential as an anti-inflammatory agent against microglia-mediated neuroinflammatory disorders.

Sustainable multifunctional phenolic lipids as potential therapeutics in Dentistry

Phenolic lipids components of the cashew nutshell liquid (CNSL) have molecular structures capable of chemical signalling that regulate gene expression, metabolism and inflammation. This study sets out to assess how CNSL derivatives impact oral bacteria, from an antibacterial and anti-collagenolytic perspective, as well as its biocompatibility with dental pulp stem cells. Two hemi-synthetic saturated CNSL derivative compounds were selected (LDT11-Anacardic Acids-derivative and LDT409-cardanol-derivative). Bacteriostatic activity was tested against Streptococcus mutans and Veillonella parvula. Antimicrobial capacity against preformed S. mutans biofilms was investigated using a collagen-coated Calgary Biofilm Device and confocal microscopy. Clostridium histolyticum, P. gingivalis and S. mutans biofilms were used to assess anti-collagenolytic activity. Biocompatibility with human dental pulp stromal cells (HDPSCs) was investigated (MTT for viability proportion, LDH assays for cell death rate). LDTs inhibited the bacterial growth, as well as partially inhibited bacterial collagenases in concentrations higher than 5 μg/mL. Dose–response rates of biofilm cell death was observed (LDT11 at 20, 50, 100 μg/mL = 1.0 ± 0.4, 0.7 ± 0.3, 0.6 ± 0.03, respectively). Maximum cytotoxicity was 30%. After 1 week, LDT409 had no HDPSCs death. HDPSCs viability was decreased after 24 h of treatment with LDT11 and LDT409, but recovered at 72 h and showed a massive increase in viability and proliferation after 1 week. LDTs treatment was associated with odontoblast-like morphology. In conclusion, LDT11 multifunctionality and biocompatibility, stimulating dental pulp stem cells proliferation and differentiation, indicates a potential as a bio-based dental material for regenerative Dentistry. Its potential as a bacterial collagenases inhibitor to reduce collagen degradation in root/dentinal caries can be further explored.