The quality of botanicals has been reported to be influenced by their places of cultivation. Although, ginger remains a common health remedy both in Ghana and China, no comparative study exists to the best of the authors’ knowledge, on the anti-inflammatory properties of ginger from these two countries. The aim of this study was to comparatively assess the anti-inflammatory effect of the methanolic extracts of fresh ginger samples from Ghana and China and identify biomarker(s) that is/are diagnostic of acute inflammation via untargeted metabolomics. A phytochemical assessment of the ginger extracts was initially performed with high performance liquid chromatography- quadrupole time-of-flight mass spectrometry (HPLC-Q/TOF-MS). Low (200 mg/kg) and maximum (400 mg/kg) doses the ginger extracts from each country were assessed using Sprague-Dawley (SD) rats against groups for positive (indomethacin, 10 mg/kg) and negative controls (no drug). Blood samples were taken from the retro orbital vein at four time points: 1, 4, 8 and 24 h after induction of inflammation. The levels of tumor necrosis factor-α (TNF-α) and prostaglandin E2 (PGE2) were determined in the plasma samples. The metabolomics study was also performed with HPLC-QTOF/MS and the data analyzed with MetaboAnalyst 3.0 and SIMCA 14.1. Phytochemical evaluation revealed marked differences in terms of the compounds deemed to have anti-inflammatory activities in the ginger samples from the two countries. Ginger extract from Ghana showed superior anti-inflammatory effects over that from China. In the metabolomics study, L-valine was identified as the diagnostic biomarker of acute inflammation from 8 differential metabolites identified.
Key words: Anti-inflammatory effects, biomarker, ginger, China, Ghana, L-valine, metabolomics.
SD, Sprague-Dawley; TNF-α, tumor necrosis factor-α; PGE2, prostaglandin E2; HPLC/QTOF-MS, high performance liquid chromatography-quadrupole time-of-flight mass spectrometry; ELISA, enzyme-linked immunosorbent assay; OPLS-DA, orthogonal partial least-squares discrimination analysis; VIP, variable importance in projection; ANOVA, analysis of variance; ACN, acetonitrile; NR, normal rats; NC, negative control; SIMCA, soft independent modelling by class analolgy.