Total Phenolic Contents and Antioxidant Properties of Algerian Alkanna tinctoria aerial part Extracts

Abstract

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.