Comparison of phenolic content and antioxidant activity of methanolic and ethanolic extracts of Limoniastrum guyonianum

摘要

Limoniastrum guyonianum Durieu ex Boiss. (Plumbaginaceae) popularly known as ”Zeta” is mainly mentioned to cure constipation, diabetes, leprosy, hypertension and other ailments. Its efficacy is widely acclaimed among communities in Southeastern Algeria. The present study is designed to determine the phenolic composition and the antioxidant activities of hydro alcoholic extracts of this raw material. The phenolic extracts of the dried and powdered aerial parts of Limoniastrum guyonianum were obtained by conventional maceration using 70% methanol and ethanol in water as solvent. The hydro alcoholic extracts were evaluated for their phenolic contents via colorimetric methods and were investigated for their antioxidant capacities using phosphomolybdate, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) tests. The highest amounts of total phenolic (121.51 mg GAE/g DW), flavonoids (8.65 mg RE/g DW), condensed tannins (44.57 mg EPE/g DW) and overall antioxidant activity (55.57 mg AAE/g DW) were found in the methanolic extracts. The IC50 values of methanolic and ethanolic extracts for DPPH radical scavenging activity were 31.10 and 23.25 μg/ml, respectively. As for ABTS (successively, 22.71 and 21.25 μg/ml), the top 26.97 and 08.60 % scavenging activity were observed in plant extracts. The trend observed for bioactive compounds was confirmed by antioxidant activity assays and high correlation values were obtained with all studied antioxidant compounds. Collectively, the findings suggested that Limoniastrum guyonianum is a natural source of antioxidant substances, which may be useful for curing diseases arising from oxidative deterioration.