Delmopinol interactions with cell walls of gram-negative and gram-positive oral bacteria

A clinical and microbiological study on the enantiomers of delmopinol

Objective The clinical part of this study aimed to investigate whether the racemate of delmopinol [(±)-delmopinol] is equivalent to its two enantiomers [(+)-delmopinol and (-)-delmopinol] with respect to efficiency and to determine and compare their pharmacokinetic properties. The purpose of the pre-clinical part was to elucidate possible differences in antimicrobial efficiency. Materials and methods The compounds were tested clinically in a double-blind, randomized, cross-over study comprising three treatment periods of 4 days each. The antimicrobial efficacy of the enantiomers was compared in vitro with respect to planktonic and biofilm bacteria of different species. Results No statistically significant differences in prevention of plaque formation were observed. Except for a somewhat higher systemic exposure in terms of AUC and Cmax indicated for (-)-delmopinol compared to (+)-delmopinol, the pharmacokinetic properties were similar. The most common adverse event was a transient anaesthetic feeling in the mouth. This event was reported with the same frequency for all three test solutions. The enantiomers showed similar antimicrobial effects on planktonic bacteria and their biofilms. Conclusions The enantiomers were found to be equally effective with respect to inhibition of plaque development and only minor differences were observed with respect to their pharmacokinetic properties. No differences could be observed in the adverse events reports. There is, therefore, no reason to use one of the enantiomers of delmopinol instead of the racemate. This was further supported by the antimicrobial tests. It is suggested that the combined action of cationic and neutral delmopinol is important for its effect on biofilms.

Effects of Copaifera duckei Dwyer oleoresin on the cell wall and cell division of Bacillus cereus

The aim of this work was to evaluate the antibacterial activity of Copaifera duckei oleoresin and to determine its possible mechanism of action against bacteria of clinical and food interest. The antibacterial activity was determined by agar diffusion and dilution methods; the mechanism of action by transmission electron microscopy and by SDS-PAGE; the bioactive compounds by bioautography; and the chemical analysis by GC/MS. Oleoresin showed activity against nine of the 11 strains of bacteria tested. Bacillus cereus was the most sensitive, with a MIC corresponding to 0.03125 mg ml−1 and with a bactericidal action. Oleoresin acted on the bacterial cell wall, removing proteins and the S-layer, and interfering with the cell-division process. This activity probably can be attributed to the action of terpenic compounds, among them the bisabolene compound. Gram-negative bacteria tested were not inhibited. C. duckei oleoresin is a potential antibacterial, suggesting that this oil could be used as a therapeutic alternative, mainly against B. cereus.

Study on antibacterial effect of 45S5 Bioglass

Previous studies have shown that bioactive glasses possessed antibacterial effect on common bacteria due to the high aqueous pH value caused by the bioactive glass dissolution. In the present study, the efficiency of the antibacterial effect of 45S5 Bioglass (45S5 BAG) against S. aureus, S. epidermidis and E. coli and its mechanism were investigated. The results showed that 45S5 BAG exhibited a strong antibacterial effect against the bacteria, and the sensitivity of gram-negative and gram-positive bacteria to Bioglass was different. Furthermore, a dose-dependent bacterial adhesion on 45S5 BAG particles and the formation of needle-like Bioglass debris were observed, which resulted in the damage of cell walls and inactivation of bacteria. The results suggested that both the high pH and bioglass debris on the surface of bacteria may be the possible mechanisms of the antibacterial effect of 45S5 BAG particulates.

6-month use of 0.2% delmopinol hydrochloride in comparison with 0.2% chlorhexidine digluconate and placebo. (I). Effect on plaque formation and gingivitis

A double-blind, randomised, 6-month clinical trial with parallel group design in 149 patients with gingivitis was conducted to study the efficacy and safety of delmopinol hydrochloride 2 mg/ml (0.2% w/v, Decapinol Mouthwash) used for partly supervised mouthrinsing in comparison with chlorhexidine digluconate 2 mg/ml (0.2% w/v, Hibitane Dental, ICI Pharmaceuticals, UK) and placebo as an addition to normal oral hygiene. Assessments of efficacy were performed using the plaque index and bleeding on probing (BOP). Delmopinol showed 22% lower plaque index scores than placebo after 3 months (p<0.01) and 13% lower scores after 6 months. The corresponding figures for chlorhexidine were 38% (p<0.001) and 38% (p<0.001) after 3 and 6 months, respectively. Bleeding on probing was reduced for delmopinol in comparison with placebo by 11% after 3 months and by 18% (p<0.05) after 6 months. For chlorhexidine the corresponding figures were 18% (p<0.01) and 22% (p<0.01) after 3 and 6 months, respectively. While chlorhexidine showed greater plaque reduction than delmopinol (p<0.01 at 6 months), no statistically significant difference was reached between these two solutions regarding BOP. Both active solutions showed an increased amount of dental calculus in comparison with placebo. A transient anaesthetic sensation in the oral mucosa and taste affection were commonly reported adverse events in both the delmopinol and the chlorhexidine groups. The number of patients withdrawn from treatment due to adverse events or lack of cooperation was 7 in the chlorhexidine group, 4 in the placebo group and 1 in the delmopinol group. The results showed that rinsing with either 0.2% delmopinol hydrochloride or 0.2% chlorhexidine digluconate twice daily for 60 secs for 6 months results in less plaque formation and gingivitis than rinsing with placebo. Mouthrinsing with the 0.2% delmopinol hydrochloride solution was well accepted in this study.

Development of plaque and gingivitis after mouthrinsing with 0.2% delmopinol hydrochloride

A double-blind, randomized, 2-wk experimental gingivitis clinical trial with cross-over design in 14 dental students was conducted in order to study the efficacy and safety of delmopinol hydrochloride solution (2 mg/ml), used with no other oral hygiene procedures, in comparison with placebo. Plaque formation was measured by the Quigley & Hein Plaque Index and gingivitis was assessed by bleeding on probing according to Mühlemann & Son. Rinsing with delmopinol resulted in lower plaque scores compared to placebo. The development of gingivitis was weak during the 2-wk test periods, and thus no conclusive results were obtained. As in previous studies, the most frequent adverse event when rinsing with delmopinol was a transient anaesthetic sensation in the oral mucosa. The results showed that rinsing with delmopinol hydrochloride solution (2 mg/ml) for 60 s twice daily with no other oral hygiene procedures led to less plaque formation than rinsing with placebo. This study also showed good tolerance and acceptability of mouthrinsing with delmopinol.

Antimicrobial properties of delmopinol against oral bacteria

Antimicrobial properties of the morpholine derivative delmopinol hydrochloride were investigated in vitro. Minimum inhibitory concentrations were measured for a range of oral bacteria by broth and agar dilution techniques and minimum bactericidal concentrations were measured in broth. The rate of kill was investigated by determination and analysis of kill curves. The results indicated that delmopinol is a relatively weak antimicrobial in comparison with chlorhexidine. However, it may selectively affect certain species of oral bacteria which are of importance in plaque formation.