Investigation of Antioxidant Activities in Relation to the Phytochemical Constituents and Selected Metals in Fresh Fruits and their Health Risk Assessment

Abstract

The present study is based on the measurement of concentrations of selected metals (Na, K, Ca, Mg, Fe, Zn, Cu, Mn, Cr, Co, Sr, Li, Ni, Pb and Cd) as well as quantification of some phytochemical constituents (phenolics, flavonoids, flavonols and ascorbic acid) and various antioxidant activity assays (DPPH radical scavenging assay, hydroxyl radical scavenging activity, Fe2+ chelating activity, ferric reducing antioxidant potential assay and phosphormolybdenum assay) in the available commercial fresh fruits. For metal analysis, dried fruit samples were digested in nitric acid, followed by perchloric acid and quantification of selected metals was performed by flame atomic absorption spectrophotometer. For phytochemical and antioxidant analysis, dried samples were extracted in water and acetone for separation of their hydrophilic and lipophilic contents and measurements were performed employing UV-Visible spectrophotometer. Data obtained from the metal analysis, phytochemical constituents and antioxidant assays were subjected to descriptive statistical and correlation study in order to evaluate both the intra and inter-relationships among the selected metals, phytochemicals and antioxidant activities. A number of significant correlations among the phytochemicals in the fruits manifested their mutual distribution in the fruits. Among the metals, Zn showed strong positive association with various phytochemicals and total antioxidant activity assays. Multivariate cluster analysis was used to identify the plausible pollution sources and to find out the multiple relationships among the selected metals in the fruits. Significant anthropogenic intrusions of the metals were noted in the fruits mainly associated with the fertilizers, agriculture sprays, biomass burning and ferrous industries. Individual metal contents, phytochemical constituents and antioxidant activities were also compared in all fruit samples. Among the selected metals, concentrations of Ca, Mg, Na and K were found at the elevated levels in the fruits. Highest antioxidant potential was shown by dates. Other fruits with significant antioxidant potential include round jujube berries, black chaunsa mango, grapes, apple and black mulberry fruit. Risk assessment in terms of health risk index (HRI), target hazard quotient (THQ) and target cancer risk (TCR) was found to be safe and showed non-significant adverse health effect related to the metal contents through lifetime consumption of the fruits