Phytochemical profiling and evaluation of antioxidant, antibacterial activities, and heavy metal levels in Ocimum basilicum L. seed extracts

Abstract

This study evaluated the bioactivity and safety of Ocimum basilicum seed extracts in methanol (ME) and hexane (HE). ME exhibited superior antioxidant activity (DPPH IC₅₀: 130.64 ppm; FRAP: 83.2% at 400 ppm Fe³⁺), correlating with its higher phenolic content (78 ± 0.61 mg GAE/g). In contrast, HE showed moderate efficacy (DPPH IC₅₀: 213.54 ppm; FRAP: 81.0%) due to its non-polar constituents. Antibacterial assays revealed dose-dependent inhibition, with ME outperforming HE against both Gram-positive (S. aureus: 20.4 ± 0.40 mm at 400 ppm) and Gramnegative (E. coli: 15.9 ± 0.32 mm) bacteria, though gentamicin remained more potent. Heavy metal analysis detected essential metals (Fe: 272.67 ± 0.069 ppm; Zn: 113.01 ± 0.290 ppm; Cu: 32.23 ± 0.081 ppm) within safe limits, while toxic metals (Pb, Cd) were undetected (<0.023 ppm). Method validation confirmed precision (recovery rates: 91–105%) and sensitivity (LODs: 0.01–0.84 ppm). Results highlight ME’s potential for nutraceutical applications, supported by its bioactive richness and safety profile, while HE’s utility may lie in lipid-centric formulations. This work highlights the role of solvent polarity in phytochemical recovery, positioning O. basilicum seeds as a safe and antioxidant-rich resource. [African Journal of Chemical Education—AJCE 16(1), January 2026]