Ginger

Zingiber officinale Roscoe belongs to the Zingiberaceae plant family. Ginger is a plant native to Southeast Asia and West Africa, and is also cultivated in India and China, as well as in almost all tropical countries. Ginger grows as a perennial, the rhizomes (rootstock) reproduce vegetatively, i.e. purely by cell division. The bulbous rhizome (ginger rhizome - Ziningiberis rhizoma) is used phytotherapeutically.

Ginger is used as a phytotherapeutic agent in many countries. Scientific findings confirm the pharmacological properties of ginger, such as antioxidant and anti-inflammatory properties. In contrast, a more specific and less studied bioactivity is the possible neuroprotective effect of ginger. Zingiber officinale is one of the phytotherapeutics with health-promoting properties that are widely used in pharmaceutical products and foods. Its crude extract is known for its pharmacological effects (Fakhri S et al. 2021). Ginger rhizome is often added to food as a spice or taken as a dietary supplement and has been widely used in traditional medicine since time immemorial (Mohd Yusof YA et al. 2016).

Ginger consists of several bioactive compounds that contribute to its recognized biological activities. Ginger contains a variety of bioactive compounds, including phenolic compounds, terpenes, lipids and carbohydrates. Therefore, its pharmacological effects are mainly attributed to phenolic compounds and terpenes (Jafarzadeh A et al. 2021). Of the 400 types of compounds in ginger, four phenolic compounds are mainly responsible for its biological effects:

• Gingerol (see gingerols below)
• shogaol
• paradol
• zingerone

In fresh ginger, gingerols such as 6-gingerol, 8-gingerol and 10-gingerol are the most important polyphenols. Gingerols can be converted into corresponding shogaols by heat treatment or long-term storage. After hydrogenation, shogaols can be converted into paradols. Other phenolic compounds in ginger are quercetin, zingerone, gingerone-A and numerous polyphenols; all have shown high antioxidant activity (Arcusa R et al. 2022).

Ginger-derived terpenes (alpha-zingiberene, camphene, alpha-curcumene, beta-sesquiphellandrene, alpha-farnesene, beta-bisabolene, alpha-pinene) are known to prevent inflammatory processes and bacterial growth, have an antioxidant effect, prevent high blood sugar levels, have an anti-inflammatory effect, have neuroprotective and anti-carcinogenic properties (Kiyama R 2020).

The effect of ginger is similar to that of non-steroidal anti-inflammatory drugs ( NSAIDs ), but has no negative effects on the gastric mucosa (Ballester P et al. 2022). Ginger has been shown to potentially prevent cardiovascular diseases associated with pathologies that are considered risk factors for cardiovascular diseases (e.g. diabetes, obesity and metabolic syndrome).

Furthermore, ginger extract showed antioxidant effects in human chondrocyte cells, where oxidative stress was mediated by interleukin-1beta (IL-1β). It stimulated the expression of several antioxidant enzymes. Furthermore, ginger extracts can reduce the production of ROS in human fibrosarcoma cells with H2O2-induced oxidative stress (Mao Q-Q et al. 2019).

Antioxidant and anti-inflammatory properties: Ginger extracts have antioxidant and anti-inflammatory abilities, as well as possible neuroprotective effects. Ginger inhibits lipid peroxidation through its antioxidant effect. For example, 6-gingerol increases Beclin1 expression to promote autophagy in endothelial cells and inhibits signaling of the PI3K/AKT/mTOR pathway without affecting the cell cycle (Santos Braga S 2019).

Ginger has a beneficial effect in diseases where increased ROS production is described, along with lipid peroxidation and tissue damage mediated by pro-inflammatory cytokines, particularly TNF-alpha (Raja DA 2004). The antioxidant effect of ginger extract is due to several bioactive ginger compounds, such as 6-gingerol, 8-gingerol, 10-gingerol and 6-shogaol. The highest antioxidant effect in vitro is exhibited by 6-gingerol, followed by 6-shogaol.

6-gingerol has been shown to inhibit xanthine oxidase, an enzyme that catalyzes the oxidation of hypoxanthine to xanthine and of xanthine to uric acid in the final phase of purine metabolic degradation with the formation of reactive oxygen species (Ali A MA et al.(2018). In addition, this compound has been shown to be able to increase superoxide dismutase and catalase activity. In animal experiments, 6-gingerol regulates lipogenesis, fatty acid oxidation, mitochondrial dysfunction and oxidative stress. It also increases the activity of the antioxidant enzyme superoxide dismutase dismutase (SOD) and lowers the concentration of malondialdehyde (MDA), a marker for lipid peroxidation, in a concentration-dependent manner (Zhang F et al. 2017).

Ginger compounds such as 6-gingerol and 6-shogaol have an anti-inflammatory effect by inhibiting the production of inflammatory mediators such as prostaglandin E2, nitric oxide (NO), inflammatory cytokines (TNF-alpha), interleukin-1beta (IL-1β) and the proinflammatory transcription factor (NF-kappaB). They also inhibit COX-1 and COX-2 (Jiang TA 2019). Apparently, 6-shogaol reduces nitric oxide (NO) synthesis as well as the release of arachidonic acid more than 6-gingerol.

One of the main areas of application of ginger is the treatment of inflammatory diseases of the urinary tract (Ballester P et al. 2022).

Rheumatoid arthritis (RA): Ginger is able to modulate the immune response through its anti-inflammatory properties. Specifically, it inhibits the COX-2 and LOX signaling pathway (Funk JL et al. 2016). Clinical evidence shows that ginger extracts, especially 6-shogaol and zingerone, have anti-arthritic effects (Funk JL et al. 2016). 8-Shogaol is effective against synovitis by inhibiting TNF-alpha, IL-1beta and IL-17-mediated inflammation (Jo S et al. 2022). Supplementation with 1.5 g ginger per day caused a significant reduction in IL-1beta and hs-CRP and a significant decrease in TNF-alpha in patients with RA (n=63) (Aryaeian N et al. 2019).

Psoriasis: Ginger inhibits inflammatory reactions by reducing NF-kappaB, which leads to a reduction in cytokine gene expression. Administration of ginger and metformin in liposomes over a period of 21 days lowers TNF-alpha and IL-22 levels. Lipid-based nanoparticles can be introduced as a new strategy to improve the efficacy of psoriasis treatment by enhancing the localization of the drug. These results show that the bioactive compounds of ginger represent an alternative treatment method for psoriasis treatment (Jenabikordi K et al. 2021).

Inflammatory bowel disease(IBD): Turmeric (Curcuma longa) improves the altered intestinal barrier function in IBD by reducing the expression of myosin light chain kinase (MLCK). It also reduces the production of TNF-alpha, IL-4, IL-6 and IL-13 by macrophages in response to allergens. Ginger extracts have antioxidant, antitumor, anti-inflammatory and anti-ulcer effects. They have been used worldwide for many years to treat vomiting, diarrhea and infections (Nikkhah Bodagh M et al. 2019).

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