PRELIMINARY PHYTOCHEMICAL INVESTIGATION AND ANTIOXIDANT POTENTIAL OF VARIOUS EXTRACTS OF DIETARY TURNIP (Brassica Rapa L.)

Abstract

In the present work, the aqueous and methanolic extract of the underground part (comestible part) of Brassica Rapa (Brassicaceae) was subjected to phytochemical and biological evaluation. The results show that the methanolic extract of B. rapa (MEBr) presents a higher yield than the aqueous extract of B. rapa (AqEBr) (24% vs 17%) respectively. The qualitative and quantitative phytochemical analysis revealed the presence of some chemical families. However, MEBr showed higher contents of polyphenols, total flavonoids and condensed tannins compared to AqEBr. The total antioxidant activity (TAC) of MEBr (5.32 ± 0.56 mg AAE/gr DE) was more powerful than that of AqEBr (2.68 ± 0.33 mg AAE/gr DE). According to the DPPH test, the IC50 values are (0.14±0.12 mg/ml vs 1.9±0.45 mg/ml) for MEBr and AqEBr respectively. On the other hand, the FRAP test confirmed that AqEBr has antioxidant activity with a maximum of 1.41mg/ml, which is still higher than that of MEBr 0.83 mg/ml. We conclude, that methanol was a more efficient extractor than water for B. rapa species, which allows a good yield, a high rate of secondary metabolites and a powerful antioxidant activity. B. rapa is a rich source of antioxidants that can eliminate free radicals and reduce the risk of chronic diseases. Abbreviations: MEBr: Methanolic Extract of Brassica rapa, AqEBr: Aqueous Extract of Brassica rapa, TAC: Total Antioxydant Capacity, DPPH: 2.2'-diphenyl-1-pycrilhydrazyl, FRAP: Ferric-Reducing Antioxidant Power Assay, IC50: Inhibitory Concentration 50.