Abstract:
The indiscriminate use of antibacterial agents has led to one of the largest recent global health problems which is the emergence of bacterial resistance. The present study was aimed to investigate the antimicrobial and antioxidant activity of ethanolic extracts of the two medicinal plants; Rosmarinus officinalis L. and Thymus vulgaris L.on Escherichia coli (E.coli).
Antibiotic susceptibility test was applied against E.coli urinary isolates using Chloramphenicol, Gentamycin, Amoxicillin , Ceftriaxone and Ciprofloxacin. According to the result, 88.7% of isolates were sensitive to Chloramphenicol, 39.6% were sensitive to Ceftriaxone, 87% were sensitive to Gentamycin , 0% were sensitive to Amoxycillin and 71.7% were sensitive to Ciprofloxacin and there was 7(13%) E.coli isolates which were multi drug resistant (MDR).
Plant extraction and E.coli suspension were prepared. The ethanolic extracts of R. officinalis and T. vulgaris were examined with concentrations of 100, 50, 25and 12.5 mg/ml against 53 isolates of Escherichia coli. The antioxidant activity through the 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) method and chemical analysis of both extracts by Gas Chromatography Mass Spectrometry (GC/MS) was identified.
The inhibitory zone of R. officinalis was found between 8-23mm and for T. vulgaris was between (8-20mm), For R. officinalis extract 100mg/ml the inhibition zone was between 9-23mm for 91% of E.coli with mean (16±7 mm), 50mg/ml inhibition zone was between (8-19mm) for 64% of E.coli with mean (13.5±6 mm), 25mg/ml inhibition zone was between (8-12mm) for 34% of E.coli with mean (10± 2 mm) and 12.5mg/ml inhibition zone was between (0-8mm) for 2% with mean (4±4 mm).
T. vulgaris extract 100mg/ml showed inhibition zone between (8-20mm) for 94% of E.coli with mean (14±6 mm), 50mg/ml inhibition zone was between (8-15mm) for 77% of E.coli with mean (11.5±3.5 mm), 25mg/ml inhibition zone was between (8-12mm) for 54% of E.coli with mean (10± 2 mm) and 12.5mg/ml inhibition zone was between (8-12mm) for 28% of E.coli with mean (10±2 mm). The MIC of of R. officinalis and T. vulgaris against (MDR) isolates between 12.5 to 50 mg/ml and the MBC between 25to 100 mg/ml.
Also both extracts showed high antioxidant activity, the DPPH radical scavenging potential of T. vulgaris was 83.09% followed by R. officinalis (81.26 %).
The GC/MS analysis of both plants revealed presence of different chemical constituents which have different biological activities. The chemical analysis of R. officinalis showed the most abundant compounds were, Eeucalyptol, Bicycloheptan and Octahydrodibenz anthracene, for T. vulgaris the most abundant compounds were Thymol, phytol and Hexadecanoic acid.
In conclusion, Rosmarinus officinalis and Thymus vulgaris ethanolic extracts have antimicrobial properties and antioxidant activity ( T. vulgaris showed higher antioxidant activity than R. officinalis) which might justify the use of those herbs in traditional medicine.
