In-vitro antioxidants, antimicrobial and toxicological evaluation of Nigerian Zingiber officinale

Abstract Background Zingiber officinale is a rhizome commonly consumed as a delicacy, medicine or spice. It is considered as a safe spice with several medicinal properties. The aim of this study was to evaluate in-vitro antioxidants, antimicrobial and safety of Nigerian Z. Officinale. Methods Methanol extract of Nigerian Z. Officinale (MEZO) was evaluated for phytochemical composition, total flavonoids and phenol contents using standard procedures. Antibacterial study was carried out via the agar well diffusion method. Antioxidant activities were carried out using 2, 2′- diphenyl-1- picrylhydrazyl (DPPH), and ferric reducing antioxidant properties (FRAP) assay. Twenty five (25) wister rats were randomly grouped into five (A-E) of five animals each. Animals in Groups A-D were orally administered 75,150, 300 and 600 mg/kg bwt of the extract on daily basis for 4 weeks while those in Group A (control) received distilled water. Results Total phenolic and flavonoids contents of the extract were 15.24 ± 0.02 mg GAE/g and 19.84 ± 0.32 mg/g CE respectively. The extract promoted an inhibition of free radicals with IC50 values of 47.05 ± 2.03 μg/mL and 89.15 ± 0.29 μg/mL in DPPH and FRAP assay. At extract concentration of 100 μg/mL, K. pneumoniae showed the highest susceptibility of 29.04 ± 0.35 mm, followed by P. aeuruginisa (26.03 ± 0.41 mm), while S. aureus (15.08 ± 0.20 mm) was least susceptible. The serum concentrations of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), sodium, albumin, total proteins and the computed organs/body weight ratios compared favorably (p > 0.05) with control at all extract doses tested. The bilirubin, urea and creatinine levels significantly (p < 0.05) increase while chloride decreases in rats dosed 600 mg/kg bwt. However, potassium level increases significantly (p < 0.05) in rats dose 300 mg/kg of the extract when compare with the control. Conclusion This study revealed the strong antioxidant and antimicrobial potentials of methanol extract of Nigerian Zingiber officinale. It was also found to be relatively safe for consumption and thus could serve as a source of candidate for the development of new antioxidants and antimicrobial drugs