Glucosinolate profiles by HPLC-DAD, phenolic compositions and antioxidant activity of Eruca vesicaria longirostris: Impact of plant part and origin
The glucosinolate profiles, phenol and flavonoid contents and the antioxidant activity of Eruca vesicaria longirostris were studied for different organs and origins. Eleven desulpho-glucosinolates (DS-GLSs) were isolated and quantified by lipid chromatography- DAD. Similarity between profiles was obtained. Total DS-GLS content, expressed as sinigrin equivalents (SE) revealed a certain variabilily ranging between (76.07-45.61), (27.01-13.53), (4.52 -18.01), (9.39-3.37) and (1.16-13.99) µmol /g DW for seeds, flowers, leaves, roots and stems, respectively. Results showed that seeds are rich in phenolics as they contain highest amounts of phenolics ranging from 27.6±0.5 to 33.47±0.5 mg GAE/g extract as compared to all other parts. Leaves and flowers had a significantly higher total phenolic content than stems and roots in all samples (p < 0.05). According to statistical analysis, the investigated seed extracts with values between (16.20±0.10-18.50±0.10 mg QE/g) exhibited the highest total flavonoids content, followed by leaves (13.00±0.40-15.80±0.30mg QE/g), flowers (10.40±0.40-12.90±0.90 mg QE/g) and stems (7.80±0.20- 9.80±0.70 mg QE/g). Antioxidant activity tested by DPPH, ABTS and FRAP assays, was higher for seeds, leaves and flowers than the other studied organs. These organs were characterized by a significantly high content in glucoerucin, nasturtin and epiprogroitrin, respectively.