Chromatographic analysis, antioxidant, anti-inflammatory, and xanthine oxidase inhibitory activities of ginger extracts and its reference compounds

Ginger, Zingiber officinale Roscoe, is a spice used as a medicinal plant in many countries. We are the first to report the HPTLC analysis of ginger extract and analysis of their active principles with comparative antioxidant, anti-inflammatory, and xanthine oxidase inhibitory activities. The five fractions were obtained by using different polarity solvents with selective extraction procedure from ginger rhizomes and found that they revealed the difference in bioactivity against studied parameters. The ethyl acetate extract (EAE) showed significant antioxidant activity studied by DPPH, FRAP, and H2O2 assay (IC50 ± SEM [μg/mL]: 6.8 ± 0.6, 12 ± 0.2, and 20 ± 2.5, respectively). In the xanthine/xanthine oxidase system, the antioxidant potentials of EAE and the water extract (WE) (% inhibition: 76% and 74%, respectively) were higher than those of the ethanol extract (EE), diethyl ether extract (DEE), and n-butanol extract (NBE). Regarding anti-inflammatory activity, EAE exhibited greater inhibition of lipoxidase (80%), and β-glucuronidase (78%) compared to hyaluronidase (46%) and diene-conjugates (37%). Chromatographic analysis revealed that several principal substances including 6-gingerol, 6-shogaol, and 6-paradol were responsible for the biological activities for ginger. Compound 6-gingerol revealed high FRAP-reducing activity (IC50 ± SEM [μM]: 5 ± 0.4). 6-Gingerol also significantly inhibited the activities of xanthine oxidase (85%), lipoxidase (87%), β-glucuronidase (85%), and hyaluronidase (56%), respectively. These results indicated that ginger rhizome fractions and its active constituents having promising antioxidant, anti-inflammatory, and anti-gout properties and might be used as potential natural drug against oxidative stress and inflammatory related diseases after successful in vivo study and clinical trials.