Antimicrobial and Antioxidant Activities of Volatile Oils from Four Citrus Species on Selected Oral Pathogens and GC-MS Identification of Associated Compounds

Abstract

This study evaluated the in-vitro antioxidant and antimicrobial activities of peel volatile oils of Citrus aurantifolia, Citrus limon, Citrus paradisi and Citrus sinensis on clinical isolates of Methicillinresistant Staphylococcus aureus, Methicillin-sensitive Staphylococcus aureus, Ciprofloxacin resistant Escherichia coli, Ciprofloxacin sensitive Escherichia coli and Candida albicans obtained from the oral cavity. Gas chromatography-Mass spectrometric (GC-MS) analysis of the oils was also carried out. The agar well diffusion method was used to determine the antimicrobial activity of the oils while the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method was used to evaluate the antioxidant activity. Total flavonoid and phenol contents of oils were equally determined. The composition of the oils was determined by GC-MS analysis. The volatile oil of C. aurantifolia exhibited the most activity against the test pathogens with a minimum inhibitory concentration (MIC) range of 2 – 4 mg/ml, while C. limon had the least antimicrobial activity as its MIC could not be determined against Methicillin-resistant Staphylococcus aureus, Ciprofloxacin resistant and sensitive Escherichia coli. C. limon and C. paradisi had MICs in the range of 4-16 mg/ml and 4-32 mg/ml respectively.C. sinensis peel oil had the highest DPPH radical scavenging activity of 47.86±2.22% and C. aurantifolia the least with a value of 25.27±1.23%. Methylisobutyl ketone was identified in C. paradisi, C. aurantifolia and C.sinensis. This study revealed that the peel volatile oils of the investigated citrus species possess antioxidant and antimicrobial activities against oral pathogens and have the potential to be used in the management of oral diseases caused by the selected pathogens