In vitro antimicrobial activity of Spinacia Oleracea against Streptococcus mutans and Lactobacillus acidophilus

Abstract

Introduction: The use of traditional medicine is well known in India. The high number of bacterial resistance to antibiotics drives much of the current interest in natural antimicrobial molecules. Spinacia oleracea (spinach) possesses medicinal properties. Dental caries is prevalent in about 89% of the Indian population. Streptococcus mutans is the primary causative organism for dental caries and Lactobacillus for further development of caries. Aim: The aim of this study is to determine minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of aqueous and ethanolic extracts of spinach against S. mutans and Lactobacillus. Materials and Methods: About 10 g of freshly harvested spinach was extracted with 95% ethanol and distilled water. The extract was converted into dried powder in desiccator and was dissolved to get 20 mg/ml concentration. The MIC was determined by nine dilutions of each aqueous and ethanolic extracts made with brain–heart infusion. To determine the MBC, the MIC dilution tubes, with no visible growth, and the control tube were subcultured onto the broth media and incubated for 24 h anaerobically and the colonies were counted on the next day. Results: The ethanolic extract exhibited MIC at 12.5 μg/ml against S. mutans and at 25 μg/ml against Lactobacillus. In MBC, the ethanolic extract showed greater bacteriostatic activity against S. mutans compared to Lactobacillus acidophilus. Conclusion: There is preliminary evidence for the antimicrobial activity of spinach extracts against S. mutans and this raises the possibility that spinach may have preventive effect on dental caries.