Screening of Selected Plant-Derived Extracts for Their Antimicrobial Activity against Oral Pathogens

Abstract

Background: Dental caries is a major public health concern that affects the populations of many countries worldwide. In this paper, we screened twenty-four plant-derived extracts for their antimicrobial activity against a representative panel of cariogenic bacteria. Methods:The leaves of each species were dried, powdered and sequentially extracted with n-hexane, dichloromethane and methanol under Sonication for 5 min. The minimum inhibitory concentration (MIC) values of the resulting extracts were determined by using the broth micro dilution method in 96-well micro plates. Chlorhexidine was used as positive control. The chemical composition of the most active extract was determined by gas chromatography -mass spectrometry (GC-MS). Results:The n-hexane extract of P. neochilus (PN-Hex) afforded the lowest MIC values against S. mitis (MIC = 31.2μg/mL), S. mutans (MIC = 31.2μg/mL), S. sanguinis (MIC = 31.2μg/mL), S. salivarus (MIC = 62.5μg/mL), S. sobrinus (MIC = 62.5μg/mL), E. faecalis (MIC = 62.5μg/mL) and L. casei (MIC = 250μg/mL). GC-MS analysis of this extract revealed that spathulenol (46.1 %), trans-caryophyllene (19.0 %), caryophyllene oxide (10.7 %) and germacrene D (7.8 %) were the major constituents in PN-Hex. Conclusion:The n-hexane extract of P. neochilus (PN-Hex) displays promising antimicrobial activity against some cariogenic bacteria. Our results suggest that this extract might be promising for the development of new oral care products.