Showing papers by "Enzo A. Palombo published in 2011"

Traditional Medicinal Plant Extracts and Natural Products with Activity against Oral Bacteria: Potential Application in the Prevention and Treatment of Oral Diseases.

Abstract: Oral diseases are major health problems with dental caries and periodontal diseases among the most important preventable global infectious diseases. Oral health influences the general quality of life and poor oral health is linked to chronic conditions and systemic diseases. The association between oral diseases and the oral microbiota is well established. Of the more than 750 species of bacteria that inhabit the oral cavity, a number are implicated in oral diseases. The development of dental caries involves acidogenic and aciduric Gram-positive bacteria (mutans streptococci, lactobacilli and actinomycetes). Periodontal diseases have been linked to anaerobic Gram-negative bacteria (Porphyromonas gingivalis, Actinobacillus, Prevotella and Fusobacterium). Given the incidence of oral disease, increased resistance by bacteria to antibiotics, adverse affects of some antibacterial agents currently used in dentistry and financial considerations in developing countries, there is a need for alternative prevention and treatment options that are safe, effective and economical. While several agents are commercially available, these chemicals can alter oral microbiota and have undesirable side-effects such as vomiting, diarrhea and tooth staining. Hence, the search for alternative products continues and natural phytochemicals isolated from plants used as traditional medicines are considered as good alternatives. In this review, plant extracts or phytochemicals that inhibit the growth of oral pathogens, reduce the development of biofilms and dental plaque, influence the adhesion of bacteria to surfaces and reduce the symptoms of oral diseases will be discussed further. Clinical studies that have investigated the safety and efficacy of such plant-derived medicines will also be described.

Extracts of Eremophila longifolia inhibit the cariogenic activities of streptococcus mutans and streptococcus sobrinus

Abstract: Plants belonging to the Eremophila genus are an integral part of the traditional medicine of indigenous Australian populations. Extracts of a number of Eremophilia species have demonstrated the presence of bioactivity, including inhibitory effects against Gram positive bacteria. The aim of the present study was to determine the activity of solvent and aqueous extracts of Eremophilia longifoliastem and leaves against Streptococcus mutans and Streptococcus sobrinus. A stem ethanol extract (SEE) demonstrated growth inhibition of the two cariogenic bacteria with a minimum inhibitory concentration (MIC) of 0.5% (w/v). Time-kill experiments indicated bactericidal activity by SEE within a 2 h period. Furthermore, this study assessed the anticariogenic activity of SEE in terms of its effect on glycolytic pH drop, viability of cells within an artificial biofilm and cell attachment to a membrane. In all experiments, SEE demonstrated significant anticariogenic activity compared with controls (p<0.05, Students t-test). SEE also compared favourably with commercial oral healthcare products. Preliminary phytochemical investigations suggested that the active components within SEE were phenolic compounds but unlikely to be flavonoids. Our study advocates SEE as a worthy candidate for further research into alternative chemotherapeutic approaches to dental caries. Key words: Eremophila longifolia, dental caries, biofilm, antibacterial.

Polylactic Acid Composites Utilising Sequential Surface Treatments of Lignocellulose: Chemistry, Morphology and Properties

Abstract: Polylactic acid (PLA)—maple fibre composites have been synthesised using a series of sequentially modified cellulose fibres (namely alkylation followed by either acetylation or silanation) Confirmations of the sequential modifications were made using Fourier Transform Infrared Spectroscopy and Inductively Coupled Plasma—Atomic Emission Spectroscopy and the new surface morphologies analysed using Scanning Electron Microscopy The key advantage of the use of sequential treatments (with initial alkali treatment) was the allowance for direct grafting of suitable chemical groups onto the cellulose in the fibre due to the removal of lignin, hemicellulose and other surface impurities However, a balance was found to exist between alkali exposure time, concentration and resulting fibre integrity The conditions used resulted in a loss in fibre weight, fibre moisture content and tensile strength Sequential treatments with acetylation or silane resulted in a 15–21% strength recovery from that of the alkali treated composite Factors that influenced this recovery in strength were the improved fibre-polymer interface, namely the hydrophilic balancing of the fibres and this further affected the thermal-hydrolysis of the PLA during composite fabrication

Bacteriophage biocontrol has the potential to reduce enterococci on hospital fabrics, plastic and glass

Abstract: Enterococci, particularly vancomycin resistant enterococci (VRE), are a cause of continuing concern in hospitals due to their intrinsic resistance to many antibiotics and the increasing prevalence of acquired resistance to vancomycin. Furthermore, enterococci are able to survive for prolonged periods on surfaces making disinfection more difficult. This study investigated bacteriophage biocontrol as a novel means of disinfecting hard and porous surfaces contaminated with enterococci. Four enterococcal bacteriophages, designated ΦSUT1, ΦSUT2, ΦSUT3 and ΦSUT4, were isolated from sewage and landfill leachate, characterised and used as biocontrol agents in studies investigating the efficacy of phage in the disinfection of vancomycin susceptible enterococci (VSE) and VRE on glass and fabrics commonly found in hospitals. Sterile glass slides and swatches of fabrics were inoculated with 105 cfu enterococci and 109 pfu/ml phage. Inoculated surfaces were incubated at ambient temperature for 2 h and bacterial populations were recovered by plating onto KF streptococcus agar. ΦSUT1 produced significant reductions in growth of Enterococcus faecalis on all surfaces tested, while ΦSUT4 produced significant reductions in growth of VRE (M168600) on all surfaces except for polyester. Phage cocktails containing ΦSUT1 and ΦSUT6 produced greater reductions in growth of VRE (M252807) on all surfaces compared to treatments using either phage alone. Although the results from this study varied considerably, the promising findings from ΦSUT1 studies indicated that phage biocontrol of enterococci should be further explored using broader host range phages.