ASSESSMENT OF HEAVY METAL CONTENT AND ANTIOXIDANT ACTIVITY OF SOME SELECTED VEGETABLES

A. N. Ukom, V. O. USMAN, P. C. Ojimelukwe

Abstract


Abstract: Selected vegetables from Agbara market and Iyana-Iba market were evaluated for heavy metal content and antioxidant activities. Data showed significant (p<0.05) variations in their results. For heavy metals, Cu content ranged from 0.29 to 4.92 mg/kg, with cucumber having the highest value (4.92 mg/kg), while the least was from fluted pumpkin (0.29 mg/kg).Zn content ranged from 6.18 to 21.48 mg/kg with highest value of 21.48 mg/kg from Lagos spinach, and the least from tomato (6.18 mg/kg). Pb and Co were not detected. The antioxidants showed that TPC ranged from 3.94 (Lagos spinach) to 20 mgGAE/gfw (cucumber), TFC ranged from 2.18 to 22.51 mgQE/gfw, while TAA ranged from 40.34 (cucumber) to 78.33 mg/mL (tomatoes). The vegetables (especially tomatoes) that possessed high content of TAA exhibited strongest antioxidant activity.  Correlation analysis revealed that only TAA was positively correlated with antioxidant activity assays: ABTS (R2 = 0.999), DPPH (R2= 0.925), FRAP (R2= 0.996) and RP (R2= 0.754), respectively. The result indicates that TAA is the main contributor to antioxidant activities in the vegetable extracts. This study revealed that vegetables with higher heavy metal content (cucumber and Lagos spinach) had lower antioxidant activity and that higher antioxidant vegetables are resilient to heavy metal contamination.


Key words: Vegetables, Agbara market, Iyana-Iba market, heavy metals, antioxidant activity


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Chemical Society of Nigeria