The antibacterial effect of Plectranthus scutellarioides (L.) R.Br. leaves extract against bacteria associated with peri-implantitis

Highlights

• The quercetin derivatives reported in this study were the first been identified for this plant species.

• The optimize method used for the mass-based identification can be reproducible and applied for the future isolation, identification and characterizations of the plant chemical compounds.

• The plant extract was effective against all the bacteria tested and note that, there were no studies have been carried out on the effects of this plant on oral bacteria especially the obligate anaerobes.

• The plant extract also was not toxic towards HnGF.

• The SEM image showed the plant extract have exert its antibacterial activity through cell wall destruction.

Abstract

Background and aim

The present study investigates Plectranthus scutellarioides (L.) R.Br. as potential antibacterial oral rinse against bacteria associated with peri-implantitis to prevent the initial infection as well as disease progression.

Experimental procedure

Phytochemical screening was done on P. scutellarioides lyophilized extract to identify the presence of chemical constituent by using mass-based identification. The extract was screened for its antibacterial activity against 4 Gram-positive aerobes (early colonizer) and 5 Gram-negative facultative anaerobes as well as obligate anaerobes (late colonizer) using disc diffusion method. The extract was tested for minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), its cytotoxicity effects on human gingival fibroblast cell (HnGF) as well as bacteria morphological changes by scanning electron microscopy (SEM).

Results and conclusion

Four flavonoid compounds were identified namely quercetin-3-glucoside, quercitrin, quercetin 3-(6″-acetylglucoside) and quercetin 3-O-acetyl-rhamnoside. The sensitivity test revealed that P. scutellarioides extract was effective against all the bacteria tested. MIC concentrations for the Gram-positive aerobes were in the range of 1.56–12.50 mg/mL, and the MBC concentrations were within 3.13–12.50 mg/mL. For Gram-negative obligate anaerobes, the MIC concentration were within 3.13–12.50 mg/mL and MBC within 6.25–200.00 mg/mL. The ethanolic extract did not have any cytotoxic effect on HnGF cells at the tested concentrations. SEM images showed bacterial cell wall disruption for all the bacteria tested. The results showed that P. scutellarioides extract exerts its antibacterial property by disrupting the cell wall of all the bacteria tested. Hence, P. scutellarioides may benefit from further investigations on its safety for oral use as an adjunctive treatment for peri-implantitis.