Evaluation of Antibacterial and Antioxidant Activities of Methanolic Extracts of Some Medicinal Plants in Northern Part of Jordan

Abstract: The objective of this study was to assess the antibacterial and antioxidant activities of methanolic extracts obtained from aerial parts of four medicinal plants: Achillea fragrantissima, Teucrium polium L., Rosmarinus officinalis and Alhgi graecorum. Both broth dilution and disc diffusion methods were used to assess the antibacterial activity of these extracts against several numbers of bacterial isolates. Antioxidant activity of these extracts was measured for the first time in vitro by 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid (ABTS) method and expressed as trolox equivalent antioxidant capacity (TEAC). All extracts exhibit antibacterial activity in dose-dependent manner against Gram negative and Gram positive bacteria. MIC were found between 1.2-2.9 mg/ml for Achillea fragrantissima, 1.2 - 2.7 mg/ml for Teucrium polium, 1.1-1.8 mg/ml for Alhgi graecorum, and 0.9 - 1.7 mg/ml for Rosmarinus officinalis against the tested bacteria. On other hand, the Rosmarinus officinalis exhibited the best ABTS scavenging capacity (424 mmol/g dry matter), followed by Achillea fragrantissima (192 mmol/g dry matter). The lowest ABTS scavenging capacities were obtained from Teucrium polium and Alhgi graecorum, 174 and 172 mmol/g dry matter, respectively. Similarly, Rosmarinus officinalis exhibited the highest antioxidant activity when IC50 (21 ?g/ml extract) was measured, followed by Achillea fragrantissima (69 ?g/ml extract), Teucrium polium (80 ?g/ml extract) and finally Alhgi Graecorum (103 ?g/ml extract). In conclusion, our plant extracts exhibited both antibacterial and antioxidant activities with Rosmarinus officinalis showing the most antibacterial and antioxidant activities. Thus, our results may, in part, support the traditional use of these plant species for medicinal purposes.