The Impact of Mining on Antioxidant Activity and Nutritional Composition of Zea mays in Edo North, Edo State, Nigeria

Mining operations can significantly alter soil conditions, leading to compaction and contamination. These changes can negatively affect plant growth and agricultural output. This research examined the effects of mining activities on the antioxidant properties and nutritional content of maize (Zea mays) cultivated in areas influenced by mining compared to areas unaffected by mining in Edo North, Nigeria. Maize was grown using soil samples collected from mining sites (Okpella, Ikpeshi) and a non-mining control site (Afuze). The methanolic extracts of the maize were analyzed for phytochemicals, proximate composition and antioxidant activity. Phytochemical screening revealed the presence of tannins, alkaloids, flavonoids, terpenoids, saponins, steroids, and phenols in both mining and non-mining sites. Maize from non-mining sites exhibited significantly higher concentrations of these phytochemicals. Non-mining site (Afuze site A) had the highest total phenolic content (28.31 ± 0.02 µg/mg), and the highest value of total flavonoid was obtained in the extracts from Afuze site A (10.35±0.13µg/mg). Ikpeshi and Okpella showed higher radical scavenging activity compared to non-mining site. The highest DPPH radical scavenging activity was recorded for extract from Ikpeshi site B (0.93±0.04µg/mg). Extracts from Ikpeshi site B were recorded to have the highest ABTS radical scavenging activities (0.93±0.05µg/mg). The highest hydroxyl scavenging activity was recorded for extract from Ikpeshi site A (0.94±0.05µg/mg). Reducing Antioxidant Power revealed that extracts from Ikpeshi site A had the highest scavenging activity (0.98±0.05µg/mg). Proximate analysis revealed that mining significantly reduced moisture content, ash, acid-insoluble ash, and water-soluble ash in maize. The results suggest that mining activities may negatively impact the overall nutritional value of maize.