Scientific African (Nov 2020)
Polyphenol composition and antioxidant activity of Searsia tripartita and Limoniastrum guyonianum growing in Southeastern Algeria
Abstract
Due to the notable medicinal value of Searsia tripartita and Limoniastrum guyonianum, it was of great interest to conduct phytochemical and antioxidant investigations. Polyphenol extracts of the dried powder of plants were prepared by maceration in 70% of methanol. The concentrated extracts were successively fractioned with distilled water, ethyl acetate and n-butanol. Obtained extracts were analysed for their phenol compositions by colorimetric processes and were evaluated for their total antiradical capacity by ABTS, DPPH and ORAC assays. Additionally, the phytochemical components were characterized in the methanolic extracts by HPLC–DAD–ESI-MS/MS in the negative ionisation mode. S. tripartita exhibited the higher quantity of phenolic compounds. The ethyl acetate extract of S. tripartita had the greatest quantities of polyphenols (55.5 ± 4.9 mg gallic acid equivalent per gram of dry residue (GAE/g DR)), flavonoids (44.2 ± 0.8 mg rutin equivalent per gram of dry residue (RE/g DR)), and tannins (12.5 ± 2.5 mg GAE/g DR). In L. guyonianum, the aqueous fraction had the highest quantity of polyphenols and tannins (10.2 ± 1.4 and 3.2 ± 1.9 mg GAE/g DR, respectively), whereas flavonoids (1.8 ± 0.2 mg RE/g DR) were higher in the ethyl acetate portion. The antioxidant capacity of the hydromethanolic extract of S. tripartita was found to be 3–16 times more effective than that of L. guyonianum using ORAC, DPPH, ABTS tests. HPLC analysis of hydromethanolic extracts provided tentative identification of four flavonoid glycosides in S. tripartita (myricetin-3-O-glucoside, myricetin-3-O-rhamnoside, quercetin-3-O-glucoside, and quercetin-3-O-rhamnoside) and five phenolic metabolites of the flavonoid class in L. guyonianum (myricetin-3-O-rhamnosylglucoside, myricetin-3-O-glucuronide, myricetin-3-O-pentoside, quercetin-3-O-glucuronide, and eriodictyol-7-O-rutinoside). Our findings revealed that these plants could be used as a potent source of health molecules.
