Phytochemistry, antioxidant and antibacterial activities of two Moroccan Teucrium polium L. subspecies: Preventive approach against nosocomial infections

Abstract

The aim of the present study was to determine the chemical composition and antioxidant activity of essential oils (EOs) from two Teucrium polium subspecies, to evaluate, also their antibacterial activities, against some nosocomial-bacteria. The phytochemical screening of essential oils was analyzed using gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry analysis (GC-MS). The antibacterial activities were assessed by disc diffusion method and minimal inhibitory concentration (MIC), against Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Citrobacter koseri and Acinetobacter baumannii) and Gram-positive bacteria Staphylococcus aureus. The antioxidant potential was evaluated in vitro by three assays, namely free radical scavenging activity against 1,1-diphenyl-2-picrylhydrzyl (DPPH), ferric reducing activity power (FRAP) and total antioxidant capacity. Twenty-six components were identified in the EO of Teucrium polium subsp. aurum representing. Its major component was Caryophyllene (19.13%) followed by γ-Muurolene (13.02%), τ-cadinol, (11.01%), α-Gurjunene (9.2%), Rosifoliol (8.79%), 3-Carene (7.04%). However, twenty two components were identified in the EO of T. polium subsp. polium. Its major components are 3-carene (16.49%), γ-Muurolene (14.03%), α-pinene (9.94%), α-phellandrene (6.93%) and Caryophyllene (7.51%). The antibacterial activity of both essential oils showed a higher activity against tested nosocomial bacteria especially against S. aureus and A. baumannii. The EO of T. polium subsp. aureum showed better antioxidant activity as measured by DPPH and FRAP assays with IC50 values of 3.7 ± 0.2 mg/ml and 2.31 ± 0.11 mg/ml, respectively. The total antioxidant capacity assay showed that T. polium subsp. aureum had a significant activity with value to 3308.27 mg equivalent to ascorbic acid/g of EO. The Moroccan T. polium essential oils could be exploited as an antimicrobial agent for the treatment of several infectious diseases caused by bacteria, especially, those who have developed resistance to conventional antibiotics. Keywords: Teucrium polium, GC-MS, Nosocomial infections, Antibacterial, Antioxidant