METHODS: A structured electronic search on worldwide accepted scientific databases (Web of Science, PubMed, Google Scholar, Science Direct, SciFinder, Wiley Online Library) was carried out to compile the relevant information. Some information was obtained from books and database on medicinal plants used in various countries.
RESULTS: About 60 metabolites, mainly polyphenols, and terpenoids have been isolated and identified. However, most of the reported pharmacological studies were based on crude extracts, and only a few of those isolated metabolites, particularly zerumbone have been investigated for biological and pharmacological activities. Many of the mechanistic studies to understand the pharmacological effects of the plant are limited by many considerations with regard to design, experimentation and interpretation.
CONCLUSION: The bioactive metabolites should be further investigated on their safety and more elaborate preclinical studies before clinical trials can be undertaken.
METHODS: High-performance liquid chromatography (HPLC) with photodiode array detection and mass spectrometry was employed to identify and quantify the flavonoids and anthocyanins in the ginger extracts. The antioxidant activity of the leaf extracts was determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and thiobarbituric acid (TBA) assays. The substrate specificity of chalcone synthase, the key enzyme for flavonoid biosynthesis, was investigated using the chalcone synthase (CHS) assay.
RESULTS: CO(2) levels of 800 μmol·mol-1 significantly increased anthocyanin, rutin, naringenin, myricetin, apigenin, fisetin and morin contents in ginger leaves. Meanwhile, the combined effect of SA and CO(2) enrichment enhanced anthocyanin and flavonoid production compared with single treatment effects. High anthocyanin content was observed in H Bara leaves treated with elevated CO(2) and SA. The highest chalcone synthase (CHS) activity was observed in plants treated with SA and CO(2) enrichment. Plants not treated with SA and kept under ambient CO(2) conditions showed the lowest CHS activity. The highest free radical scavenging activity corresponded to H Bara treated with SA under high CO(2) conditions, while the lowest activity corresponded to H Bentong without SA treatment and under atmospheric CO(2) levels. As the level of CO(2) increased, the DPPH activity increased. Higher TBA activity was also recorded in the extracts of H Bara treated with SA and grown under high CO(2) conditions.
CONCLUSIONS: The biological activities of both ginger varieties were enhanced when the plants were treated with SA and grown under elevated CO(2) concentration. The increase in the production of anthocyanin and flavonoids in plants treated with SA could be attributed to the increase in CHS activity under high CO(2) levels.
METHODS: We performed a systematic search using PubMed, Scopus, Cochrane Library, Web of Science for randomised controlled trials (RCTs), published until March 17, 2021. The quality assessment was carried out using the Cochrane Collaboration risk of bias tool. The Q-test and I 2 tests were used for the determination of heterogeneity of the included studies. Data were pooled using a random-effects model, and weighted mean difference (WMD) was used for the overall effect size.
RESULTS: Pooled findings of the five RCTs demonstrated that ginger supplementations had significantly reduced hs-CRP (WMD -0.42 mg/L; 95% CI, -0.78, -0.05, P = 0.03), TNF-α (-2.13 pg/mL; 95% CI: -3.41, -0.86, P = 0.001), and IL-6 (WMD: -0.61 pg/mL; 95% CI: -0.92, -0.30, P = 0.001) levels in patients with T2DM. The quality assessment of the studies showed that all of the included studies were at high risk of bias.
CONCLUSIONS: The meta-analysis shows that ginger supplementations reduced inflammatory parameters in patients with T2DM. Nonetheless, the reduction is relatively small, and its meaningful clinical effects are unknown. Future high-quality RCTs are needed to confirm the beneficial effects of ginger supplementation in patients with T2DM.