Assesment of antioxidant potential of phenolic compounds fractions of Algerian Ceratonia siliqua L. pods during ripening stages
The consecutive extraction via different solvents of increasing/decreasing polarity, which allowed a pre-fractionation of the extracted compounds, is widely used as major method for extraction of polyphenols. Thus, the phenolic compounds of Ceratonia siliqua L., at unripe and ripe stages, were extracted by four solvents of increasing polarity (hexane, chloroform, ethyl acetate, and acetone/water (70:30, v/v), consecutively. The extracts were evaluated for their total phenolic and flavonoid contents, while the antioxidant capacity was assessed in vitro using DPPH radical and hydrogen peroxide (H2O2) scavenging assays. The phenolic profile has been carried out by HPLC-MS/MS. The results showed that the phenolic contents and antioxidant capacity varied with the nature of extracts and the ripening stage. The 70% aqueous acetone and the ethyl acetate extracts contained the highest phenolic and flavonoid contents, and subsequently showed a pronounced scavenging activity on DPPH and hydrogen peroxide at unripe and ripe stages. The HPLC-MS/MS allowed the identification of five free phenolic acids (gallic, syringic, cinnamic, p-coumaric and ellagic acid for the first time) and five flavonoids (apigenin, naringenin, kaempferol, quercetin rhamnoside and myricetin rhamnoside) at both ripening stages.