Pterostilbene Complexed With Cyclodextrin Exerts Anti-biofilm And Anti-inflammatory Effects

Objectives: Resveratrol (RES) is a natural polyphenol with potential as an adjunctive therapeutic modality for periodontitis. However, inferior pharmacokinetics and toxicity concerns about its solvent dimethyl sulfoxide (DMSO) pose challenges in translating benefits to clinical applicability. Research on RES analogs has provided evidence of their superior pharmacokinetic properties; but changing the solvent may cause different drug-solvent interactions potentially affecting drug activity. Our study aimed to investigate the comparative antimicrobial and anti-inflammatory properties of RES and its analogs (pterostilbene [PTS], oxyresveratrol [OXY] and piceatannol [PIC]), utilizing 2-hydroxypropyl-β-cyclodextrin (HPβCD) as the solvent, which has a well-documented safety profile and FDA approval. These properties were investigated against Fusobacterium nucleatum, a key periodontal pathogen.
Methods: Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by broth microdilution assay and culture methods respectively. Biofilm inhibition was determined using crystal violet assay. To determine if PTS induced leakage of cellular contents, extracellular DNA and protein were quantified. Anti-inflammatory effects of PTS were evaluated in RAW 264.7 macrophages. Cellular NF-κβ activity and expression of pro-inflammatory cytokines were determined by reporter assay and RT-qPCR respectively.
Results: PTS in HPβCD had an MIC (0.02 mg/mL) 1000-fold lower than that of RES, OXY and PIC (20 mg/mL). Interestingly, MIC was 125-fold higher when PTS was dissolved in DMSO (2.5 mg/mL). In addition, PTS inhibited F. nucleatum biofilm formation at 24, 36 and 48-hour timepoints. Elevated extracellular DNA and proteins suggest that PTS exerted antimicrobial effects via eliciting leakage of cellular contents. PTS conferred dose-dependent inhibition of F. nucleatum-induced NF-κβ activation, with corresponding down-regulation of IL-1β, IL-6 and TNF-α expression.
Conclusions: Compared to RES and other analogs, PTS has superior antimicrobial potency against F. nucleatum. Coupled with its anti-inflammatory properties, these data provide the basis for future research on PTS and HPβCD as candidate nutraceuticals for adjunctive treatment of periodontitis.