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Objective: Evaluation of the polyphenols, flavonoids and tannins contents of different aqueous extracts of the aerial part of Alkanna tinctoria and their antioxidant activities.  Methodology: Three extracts;  decoction, macerate and infusion of the aerial part of Alkanna tinctoria were prepared. The content of total polyphenols, flavonoids and tannins of the extracts was carried out and antioxidant activity was assessed using DPPH (2,2’-diphenyl-1-picryl hydrazyl), β-carotene bleaching and iron chelation tests. Results : The results showed that Infusion (Inf) was the richest in total polyphenols (189.66 ± 30.77 mg EGA / g of dried extract) and flavonoids (26.80 ± 8.37 mg EQ / g of dried extract). While the content of tannins is almost the same for Dec and Inf (40.27 ± 15.00, 40.25 ± 18.27 mg ETA / g of dried extract). Moreover, the two extracts Inf (IC50 of 0.09 ± 0.0015 mg / ml) and Dec (IC50 of 0.17 ± 0. 031 mg / ml) showed a very strong anti-radical activity towards the radical DPPH. In the β-carotene bleaching test, Inf and Dec showed a significant inhibitory activity of peroxidation with values ​​of 100% and 99.8% and are more effective compared to BHT (98.15%). Dec and Mac showed strong chelating activity with IC50s of 0.003 ± 0.0002 mg / ml and 0.005 ± 0.00008 mg / ml respectively. These chelating activities remain higher than EDTA. Conclusion: It may be concluded that the extracts of the aerial part of Alkanna tinctoria exhibit significant both content of polyphenols and antioxidant activity. Keywords: Alkanna tinctoria, polyphenols, flavonoids, antioxidant activity.

In the course of our phytochemical studies of plant Tamus communis L., methanol soluble extract (EMeOH) (138 g) was chromatographed on a silica gel column. The column was eluted with chloroform and then with chloroform /methanol mixtures of increasing polarity. A total of 52 fractions (400 ml each) were collected and grouped according to their TLC behaviour into 6 main fractions (I-VI).  Total phenolic and flavonoid contents in these extracts were determined by a colorimetric method. Values varied between 73.143±0.009 and 29.214±0.003 equivalent Gallic acid/g lyophilisate. All the extracts showed inhibitory properties on xanthine oxidase, the IC50 ranges from 0.029±0.017 mg/ml to 0.237±0.026 mg/ml. The extracts exhibited an additional superoxide scavenging capacity by using both enzymatic methods and IC50 values ​​range from 0.039±0.023 mg/ml to 0.141±0.086 mg/ml. These results show that Tamus communis L. extracts have strong anti-oxidant effects and may have some clinical benefits. Keywords: Xanthine oxidase, Antioxidant, Superoxide scavenger, Tamus communis L.

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 μg GAE/mg of extract and 97.25±2.84 μg 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 μg/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 μg/ml and EC50 =12.12±0.05 μg/ml, respectively) compared to other extracts (P≤0.01). Using β-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.