Evaluation Of the Antimicrobial Efficacy of Nymphaea nouchali var. caerulea (Blue Water Lily) Extract Against Streptococcus Mutans (MTCC 10449): An In-Vitro Study

Abstract

Introduction: Dental plaque in initially begins pellicle formation and with Streptococcus mutans colonization and biofilm maturation, driving gingivitis and periodontitis. Plant derived agents targeting plaque are promising; Nymphaea nouchali is phenolic and flavonoid rich with documented antimicrobial, antioxidant, and antibiofilm effects, but its activity against oral primary colonizers remains underexplored.
Aim: To evaluate the antimicrobial efficacy of Nymphaea nouchali var. caerulea flower extract against S. mutans using agar well diffusion technique, in comparison with 0.2% chlorhexidine.
Materials and Method: Dried Nymphaea nouchali var caerulea (blue water lily) petals are macerated with 70% ethanol, kept in orbital shaker at 30°C for 24 h and filtered and reduced on a magnetic stirrer to obtain crude extract. S.mutans inoculum (0.5 McFarland) is lawn cultured on blood agar. Wells received the extract, saline (negative control) and 0.2% chlorhexidine (positive control). Plates are incubated anaerobically at 37°C for 24 h. Zones of inhibition are measured and analyzed as mean ± SD in triplicates.
Results: One-way ANOVA revealed highly significant differences in antimicrobial activity across the groups (p<0.001). The Nymphaea nouchali var. caerulea petal extract exhibited a robust mean zone of inhibition (ZOI) of 4.200±0.237mm, which post hoc Bonferroni analysis confirmed was significantly superior to the saline negative control (0.000mm, p<0.001). While the Chlorhexidine positive control yielded the largest overall ZOI (6.167±0.153mm), the extract demonstrated definitive and reproducible antimicrobial potential.
Conclusion: The hydroalcoholic extract of Nymphaea nouchali var. caerulea exhibits a statistically highly significant in vitro antimicrobial effect against Streptococcus mutans. These findings establish its definitive potential as a natural phytotherapeutic candidate in inhibitory plaque formation, justifying further quantitative validation and formulation development.