Evaluating hop extract concentrations found in commercial beer to inhibit Streptococcus mutans biofilm formation

Nanofibrous ε-Polycaprolactone Matrices Containing Nano-Hydroxyapatite and Humulus lupulus L. Extract: Physicochemical and Biological Characterization for Oral Applications

Oral bone defects occur as a result of trauma, cancer, infections, periodontal diseases, and caries. Autogenic and allogenic grafts are the gold standard used to treat and regenerate damaged or defective bone segments. However, these materials do not possess the antimicrobial properties necessary to inhibit the invasion of the numerous deleterious pathogens present in the oral microbiota. In the present study, poly(ε-caprolactone) (PCL), nano-hydroxyapatite (nHAp), and a commercial extract of Humulus lupulus L. (hops) were electrospun into polymeric matrices to assess their potential for drug delivery and bone regeneration. The fabricated matrices were analyzed using scanning electron microscopy (SEM), tensile analysis, thermogravimetric analysis (TGA), FTIR assay, and in vitro hydrolytic degradation. The antimicrobial properties were evaluated against the oral pathogens Streptococcus mutans, Porphyromonas gingivalis, and Aggregatibacter actinomycetemcomitans. The cytocompatibility was proved using the MTT assay. SEM analysis established the nanostructured matrices present in the three-dimensional interconnected network. The present research provides new information about the interaction of natural compounds with ceramic and polymeric biomaterials. The hop extract and other natural or synthetic medicinal agents can be effectively loaded into PCL fibers and have the potential to be used in oral applications.

The Antibacterial Effect of Humulus lupulus (Hops) against Mycobacterium bovis BCG: A Promising Alternative in the Fight against Bovine Tuberculosis?

The female flowers of the Humulus lupulus plant or Hops have been used extensively within the brewing industry for their aroma and bitterness properties. It was also found that beer that contained hops was less likely to spoil, thus revealing the antimicrobial potential of these plants. One species of bacteria, Mycobacterium spp., is of particular interest as it is the causative agent of both human and animal forms of tuberculosis (TB). In this study an aqueous extraction process was employed to analyse the antibacterial properties of 50 hop extracts (45 individual variants); against M. bovis BCG. Using an agar well diffusion assay we found that all hops exhibited a level of inhibitory activity which ranged from 1.2 mm (+/− 0.08 mm) in the case of hop variant; Target, to 15.7 mm (+/− 0.45 mm) in the case of hop variant Citra. The Citra variant had a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 16% v/v. This is the first study to analyse a wide range of hops for their antimicrobial potential against M. bovis BCG and recommends that further research focuses on other Mycobacteria spp., the potential for antimicrobial synergy and the antibacterial effect of individual components.