Inverted amino acids reduce the adhesion and biofilm biomass of early oral colonizers.

BACKGROUND: Early colonizers adhere to the dental surface and facilitate the initial adhesion of secondary colonizers to form oral biofilms, which may cause oral infections. OBJECTIVES: This study aimed to determine the antimicrobial, anti-adhesion and antibiofilm potency of inverted amino acids on early colonizer streptococci and their mixed species. MATERIAL AND METHODS: The following test strains were used: Streptococcus gordonii (American Type Culture Collection (ATCC) 35105); Streptococcus mitis (ATCC 49456); Streptococcus oralis (ATCC 10557); Streptococcus salivarius (ATCC 7073); and Streptococcus sanguinis (ATCC BAA-1455). The concentration-dependent antimicrobial potency of d-alanine (d-ala), d-arginine (d-arg), d-leucine (d-leu), d-methionine (d-met), and d-tryptophan (d-try) was determined using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method with AlamarBlue modification. The adhesion of primary colonizers in the presence of 25-mM d-amino acids (dAAs) was assessed using the colony forming unit (CFU) assay. The CFU assay was conducted on 24-h flow cell bacterial biofilm models after exposure to 25-mM inverted dAAs. RESULTS: No minimum inhibitory concentration (MIC) point was detected at any concentration tested. The minimum bactericidal concentration (MBC) point was not observed. The adhesion of S. mitis, S. oralis and mixed species was reduced by all tested dAAs. No adverse effects were observed on S. gordonii with any of the tested dAAs. The biofilm biomass of test strains under flow conditions was significantly reduced after a 5-min exposure to all tested dAAs at 25-mM concentration. CONCLUSIONS: D-amino acids did not inhibit bacterial growth and did not show bactericidal or bacteriostatic effects on test strains at any concentration tested (ranging from 6.25 mM to 100 mM). However, dAAs effectively inhibit the adhesion of early colonizers, thereby preventing the formation of oral biofilm.

Phytomedicinal properties of Hygrophila schulli (Neeramulliya).

Hygrophila schulli which is known as "Neermulli'' in the vernacular is an herbaceous plant native to Sri Lanka. Ancient medicinal literature suggests the use of H. schulli whole plant or its parts for the treatment of different communicable and non-communicable diseases including diabetes mellitus and tuberculosis. Active constituents and secondary metabolites including alkaloids, tannins, steroids, proteins, flavonoids, and glycosides are identified to possess antimicrobial, antitumor, antioxidant, hepatoprotective, anthelmintic, nephroprotective, antidiabetic, anticataract, anti-inflammatory, anti-nociceptive, hematopoietic, diuretic, antiurolithiatic, antipyretic, neuroprotection, and anti-endotoxin activities. In this review, we reviewed clinical studies, patents, and analytical studies from the earliest found examples from 1886 to the end of 2021. We critically analyzed and attempt to summarize the information based on bioactivities and chemical composition of H. schulli plant extracts which will be of future use for researchers in this field.