Inhibition of dextransucrase activity in Streptococcus mutans by plant phenolics.

Streptococcus mutans is responsible for causing dental caries in humans and utilizes sucrose for its growth. The dextransucrase (EC 2.4.1.5) is responsible for sucrose metabolism, which exhibits both hydrolytic and glucosyltransferase activities. In this study, we examined the effects of the plant phenols, namely gallic, tannic and syringic acids and aqueous extracts of certain traditionally used chewing sticks (Acacia arabica, Azadirachta indica, Pongamia pinnata and Salvadora persica) for prevention of dental caries on hydrolytic activity of dextransucrsae in S. mutans. Gallic acid (4-5 mM) produced 80-90% inhibition of the enzyme, while tannic acid (0.2 mM) and syringic acid (5 mM) inhibited the enzyme activity 80% and 48%, respectively in vitro. The aqueous extracts of chewing sticks produced 35-40% inhibition of dextransucrase activity at 5 mg phenol concentration. Kinetic analysis revealed mixed-type of enzyme inhibition by polyphenols, where both Km and Vmax were altered. The value of Ki for tannic, gallic and syringic acids were 0.35, 1.6 and 1.94 mM, respectively. The enzyme inhibition by polyphenols was optimum at pH 7-7.5, while by plant extract was maximum at pH 5-6. These results suggest that plant polyphenols may find potential applications in the prevention and control of dental caries by inhibiting dextransucrase activity in S. mutans.

Comparative evaluation of the antimicrobial efficacy of four chewing sticks commonly used in South India: An in vitro study.

Background and Aim: The use of chewing sticks has been well documented since ancient times in India. Chewing sticks are a good alternative to the toothbrush for maintaining oral hygiene. The present study was designed and conducted to compare and evaluate the antimicrobial effects of the aqueous extracts of neem, miswak, mango, and banyan chewing sticks against two bacterial species considered the most important in the initiation and progression of dental caries, namely Streptococcus mutans and Lactobacillus acidophilus, respectively. Materials and Methods: Twigs of the above mentioned chewing sticks were sun dried and powdered, and sterile aqueous solutions of 10%, 25% and 50% concentrations were prepared. Culture plates for S mutans and L acidophilus were prepared and the growth was transferred to nutrient agar and Mueller-Hinton agar; antimicrobial activity of the extracts was tested after 72 h, using the disc diffusion method. Normal saline was used as control. Results: The antimicrobial activity of neem, miswak, and mango extracts increased as their concentrations increased. Both banyan extract and saline showed no antimicrobial activity against the organisms tested. Conclusion and Recommendations: Based on the zones of inhibition, aqueous extracts of neem showed the most antimicrobial activity against S mutans, while miswak extracts showed superior antimicrobial activity against L acidophilus. We recommend further phytochemical and pharmacological studies to discover newer nonsynthetic tooth pastes and mouthwashes.

Antimicrobial properties of Ethiopian chewing sticks against Candida albicans.

Ethnobotanical survey was done in Jimma, Ethiopia, to identify the plants used for oral hygiene and evaluate the same against a selected oral pathogen. The survey revealed the use of chewing sticks to manage oral hygiene/infection. In spite of their wide use, very little has been done to evaluate their antimicrobial activity. Hence 11 chewing stick plants were chosen for antimicrobial study against an oral pathogen – Candida albicans the causative organism for oral candidiasis by agar well diffusion (Perez, 1991). The results revealed that Olea europaea extract showed maximum inhibition on its own. The activity of Justicia schimperiana was increased to three fold when combined with cinnamon and brown honey. The research documents the use of chewing sticks to manage oral infection caused by Candida albicans, which will be of immense assistance to developing countries with financial constraints and limited health care facilities.

Cytotoxicity evaluation of Persica mouthwash on cultured human and mouse cell lines in the presence and absence of fetal calf serum.

Background and Aims: The effectiveness of an ideal antimicrobial agent depends on its ability to kill microbes while causing minimal toxicity to host cells. Several studies have been reported on the antimicrobial effects of chewing sticks (Salvadora persica) on oral bacteria. The purpose of this study was to evaluate the cytotoxic effects of Persica™ and chlorhexidine (CHX) mouthwashes on cultured human and mouse cell lines. Materials and Methods: This was an experimental study. The toxic effects of four dilutions of Persica™ and CHX mouthwashes on KB, Saos-2, J744 A1, and gingival fibroblast cells were evaluated by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay. The effect of fetal calf serum (FCS) components on the cytotoxicity of these mouthwashes was also investigated. Statistical Analysis: Analysis of variance and the Kruskal-Wallis test were used to evaluate the results. Results: The results indicated that Persica™, at concentrations higher than 0.1%, exerted a very significant cytotoxic effect on all the cell lines (P < 0.01). CHX, at a concentration of 0.001%, exerted toxic effects only on gingival fibroblasts; concentrations higher than 0.001% were required to produce significant cell death in the other cell lines. At all the concentrations under study, both Persica™ and CHX exerted significantly greater cytotoxic effects in the absence of FCS than in its presence (i.e., in control culture medium). The toxicities of both mouthwashes were attenuated in the presence of FCS (10%). Conclusion: Our results indicate that both Persica™ and CHX mouthwashes are toxic to macrophage, epithelial, fibroblast, and osteoblast cells in a concentration-dependent manner.