Comparative phytochemical profiling and bioactivity of ginger (Zingiber officinale) rhizomes from Jaba and Kachia, Southern Kaduna

Abstract

The growing incidences of antibacterial chemotherapeutic resistance and oxidative stress-associated diseases has intensified the search for plant-based bioactive compounds. This study evaluated the antibacterial, antioxidant, toxicological, and phytochemical properties of Z. officinale rhizomes sourced from Jaba and Kachia in Southern Kaduna, Nigeria. Extracts were prepared using n-hexane, ethyl acetate, and methanol, and antibacterial activity was assessed against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Enterococcus faecalis using the agar well diffusion method. Antioxidant activity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, while total phenolic and flavonoid contents were quantified spectrophotometrically. Acute toxicity was evaluated in Wistar rats, and phytochemical profiling was conducted using Gas Chromatography-Mass Spectrometry (GC-MS). The methanol extract exhibited the highest antibacterial activity, with inhibition zones up to 21.67 mm and a minimum inhibitory concentration of 12.5 mg/mL against S. aureus. It also showed the strongest antioxidant activity, with 92.56% radical scavenging and the lowest half-maximum inhibitory concentration (IC₅₀) value (19.4 mg/mL), correlating with its high phenolic content (2226.33 mg GAE/100 g). Ethyl acetate extracts showed moderate activity, while n-hexane extracts were largely inactive. No mortality or toxicity was observed at doses up to 5000 mg/kg. GC-MS analysis identified major bioactive compounds including [6]-gingerol, guaiacol, capsaicin, and [6]-shogaol. These findings indicate that Z. officinale, particularly methanol extracts, is a potent and safe source of bioactive compounds with promising antimicrobial and antioxidant applications.