Xanthine Oxidase Inhibition, In Vitro Antioxidant Activity And Antibacterial Effect Of The Aerial Part Extracts Of Thymus Pallidus Coss

Background: The Algerian medicinal plant Thymus pallidus Coss. is traditionally known to be used as an anti-infective, expectorant, healer of wounds and against inflammatory and gastrointestinal diseases.Objective: The aim of the present study is to investigate the antioxidants and the antibacterial activities of the aerial part extracts of this plant.Methods: Polyphenols extraction was performed with methanol 85%, followed by preliminary fractionation based on the polarity of the solvent. The extraction and fractionation process gave the crude extract (CrE), chloroform extract (ChE), ethyl acetate extract (EtAE) and aqueous extract (AqE). The antioxidant activity of extracts was evaluated using in vitro assays. While the antimicrobial activity was determined using disk diffusion method.Results: Quantitative analysis of polyphenol and flavonoids showed that EtAE includes the highest amount (P <= 0.001) with 495.12 +/- 1.91 mu g GAE/mg of extract and 97.25 +/- 2.84 mu g QE/mg of extract, for both polyphenols and flavonoids respectively. The results of the antioxidant activity of extracts showed that the EtAE exhibited the highest inhibition activity on XO (IC50 =51.6 +/- 0.2 mu g/ml) compared to other extracts (P <= 0.001). Moreover, the EtAE was the most effective fraction in free radical scavenging assay against ABTS radical and hydrogen peroxide (EC50= 3.21 +/- 0.03 mu g/ml and EC50 = 1 2.12 +/- 0.05 mu g/ml, respectively) compared to other extracts (P <= 0.01). Using beta-carotene/ linoleic acid bleaching assay, the AqE and ChE recorded a considerable inhibition effect on linoleic acid oxidation with a ratio of 81.81% and 80.86%, respectively. In the antimicrobial activity evaluation, the extracts exhibited moderate antibacterial activity against bacterial strain, with inhibition zone ranging from 07 to 14 mm. In addition, the EtAE showed a good action spectrum against six bacterial strains. In conclusion, the EtAE of Thymus pallidus showed good antioxidant activity and antibacterial effect.Conclusion: The obtained results revealed the presence of a strong correlation between the antioxidant and antibacterial activities of the extract and its total phenolic content. Furthermore, they reported that the EtAE has a considerable antioxidant capacity. This can be considered as an alternative natural source of antioxidants used generally as additives in food and pharmaceutical preparation.