In vitro investigation of antibacterial activity of Gum Arabic prepared by two different processing methods against Enterococcus faecalis

Abstract

Abstract Introduction: Entrococcus faecalis is a known cause of endodontic treatment failure. Synthetic drugs have been preferred for decades, but recently, many plants have been reported for their antibacterial activity. The study was carried out to investigate the antibacterial effect of Gum Arabic (GA) processed with two different processing methods against Enterococcus faecalis. Method: Antibacterial susceptibility tests against Enterococcus faecalis (ATCC 29212) were performed for 200mg/ml ethanolic extracts of spray-dried and mechanically ground GA using Agar disc diffusion. Sodium Hypochlorite (1%), Chlorhexidine (0.2%), and Antibiotic multi-disc were used as positive controls, and ethanol (20%) as a negative. The inhibition zones diameters were measured. Serial dilutions of both types of Gum Arabic (100, 50, 25, 12.5 mg/ml) were tested for their antibacterial activity. Results: In Concentration 200 mg/ml, spray-dried GA displayed a significantly greater inhibition zone against E. faecalis than mechanically ground (P=0.02). Both types of Gum Arabic exhibited lower antibacterial activity than chlorhexidine (0.2%). However, only mechanically ground GA showed significant result (P=0.005). Spray-dried GA showed significantly higher antibacterial activity against than Tetracycline 300mcg (P=0.005). The antibacterial activity of spray-dried GA exceeded that of mechanically ground in all concentrations of serial dilutions, except for 12.5mg/ml, both are similar. Conclusion: processing method of Gum Arabic affects its antibacterial potency against E. faecalis. In high concentrations, spray-dried GA is active antibacterial, while mechanically ground is non-active. Decreasing the concentration of mechanically ground GA increases its inhibitory effect, but the opposite effect was observed with spray-dried GA.