Curcumin

Curcumin, an orange-yellow natural dye (flavonoid) that is almost insoluble in water and easily soluble in ethanol and ether.

Curcumin is obtained as the most effective ingredient from Curcumae longae rhizoma and Calamus (Soleimani V et al. 2018). A number of in vitro and in vivo experiments have shown that curcumin has various pharmacological effects, such as regulation of immunity, antioxidation, inhibition of inflammation, antitumor, antiangiogenesis, anticoagulation and free radical scavenging (Sharifi-Rad J et al. 2020). Numerous randomized controlled trials (RCTs) have shown that curcumin has anti-inflammatory effects in various autoimmune diseases. ADRs are rare, making this phytotherapeutic a potential alternative to NSAIDs (Abd El-Hack ME et al.2021; Razavi BM et al. 2021).

Curcumin has a strong antioxidant, anti-inflammatory and antibacterial effect (Panahi Y et al. (2019).

Furthermore, in various. A cardioprotective effect has also been demonstrated in various experiments. Curcumin lowers the total cholesterol level, promotes wound healing by activating growth factors and has a neuroprotective effect in animal experiments. In the intestinal epithelium, curcumin can significantly reduce the increased expression of the CXCL1 and CXCL2 genes caused by 5-fluorouracil (5-FU).

Several studies have been conducted in which extracts of Curcuma species were tested in patients with osteoarthritis. These patients showed an improvement in pain, physical function and quality of life after taking curcumin. They also reported reduced concomitant use of analgesics and side effects during treatment.

In vitro studies showed that curcumin can prevent apoptosis of chondrocytes, suppress the release of proteoglycans and metal metalloproteases as well as the expression of cyclooxygenase, prostaglandin E-2 and inflammatory cytokines in chondrocytes (Chin KY 2016).

The anti-inflammatory mechanism of curcumin has not yet been fully elucidated. There is evidence of inhibition of interleukin-1β. The inhibitory effect of curcumin on inflammatory activation is apparently specific for the NLRP3 inflammasome, but not for the NLRC4 or AIM2 inflammasome (Yin H et al. 2018).

Curcumin in psoriasis: Several recent studies have reported that curcumin can reduce oxidative stress in psoriasis lesions (Barygina V et al. (2013). In addition, the therapeutic efficacy of curcumin may also be related to its ability to inhibit phosphorylase kinase. Curcumin is able to downregulate proinflammatory cell factors (such as IL-17, TNF-α, INF-gamma and IL-6 (Reddy S et al. 1994). In addition, curcumin is able to improve the barrier function of the skin by upregulating involucrin (iNV) and filaggrin (FLG) (Varma SR et al.2017). The side effects are apparently negligible. The US Food and Drug Administration (FDA) has defined curcumin as "generally regarded as safe" (GRAS).

Curcumin for AS (ankylosing spondylitis): Ahmadi M et al (2019) investigated the effects and safety of curcumin and Curcuma longa extract in the treatment of AS. They found that Treg cells increased significantly, IL-10 and TGF-β levels increased and IL-6 levels decreased after curcumin intervention. Recent studies have shown that curcumin can promote the differentiation of Treg by increasing FoxP3 expression (Wang L et al. (2015) Human Autoimmune Diseases: A Comprehensive Update. J Intern Med 278:369-395).

Colouring agent for filter papers (curcuma paper)

Antioxidant food additive (E 100 ).

As an antioxidant, curcumin inhibits leukotriene synthesis (see leukotrienes; IL-1 /Yin H et al. 2018) and prostate glandin synthesis.

Curcumin appears to improve osteoarthritis pain (Chin KY 2016)

Curcumin has protective effects on UV-induced skin damage (Panahi Y eet al. 2019).

Curcumin has poor bioavailability and solubility. Most of the absorbed curcumin is excreted unmetabolized in the stool. The smaller absorbed portion is conjugated to glucuronides and sulphates in the intestine via the enzymes UDP-glucuronosyltransferase (UGT) and sulphotransferase (SULT) (Prasad S et al. 2014). These water-soluble metabolites can enter the tissue. It can be assumed that curcuminoids are deposited in the intercellular lipids of the horny layer in a similar way to carotenoids, which explains the preferred yellow coloration of more keratinized skin areas.

The topical application of curcumin is considered helpful for several skin diseases. However, it is associated with a bright orange-yellow discoloration of the affected skin areas (Nguyen TA et al. 2013)

Other side effects:

• Dry mouth
• Xerostomia (dry mouth): Some people report dry mouth after taking curcumin supplements. This may be due to the effect of curcumin on saliva production.
• Skin rashes and itching: In rare cases, curcumin can cause allergic skin reactions. These reactions can range from mild rashes to severe itching.
• Blood clotting disorders: Increased risk of bleeding: Curcumin may affect blood clotting. People taking anticoagulants (blood thinners) or suffering from blood clotting disorders should only take curcumin under medical supervision to minimize the risk of bleeding.

Interactions with medications

• Interaction with anticoagulants and antithrombotics: Curcumin may increase the effect of anticoagulants such as warfarin and aspirin, which may increase the risk of bleeding.
• Impairment of blood sugar control: In diabetics, curcumin may increase the effect of blood sugar lowering drugs, which may lead to hypoglycemia. Careful monitoring of blood sugar levels is therefore necessary.

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2. Barygina V et al. (2013) Altered Redox Status in the Blood of Psoriatic Patients:Involvement of NADPH Oxidase and Role of Anti-TNF-αtherapy. Redox Rep 18:100-106.
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11. Reddy S et al. (1994) Curcumin Is a Non - Ompetitive and Selective Inhibitor of Phosphorylase Kinase. FEBS Lett 341:19-22.
12. Sahebkar A (2014) A systematic review and meta-analysis of randomized controlled trials investigating the effects of curcumin on blood lipid levels. Clin Nutr 33:406-414.
13. Tejada S et al.(2016) Wound Healing Effects of Curcumin: A Short Review. Curr Pharm Biotechnol 17:1002-1007.
14. Varma SR et al.(2017) Imiquimod-Induced Psoriasis-Like Inflammation in Differentiated Human Keratinocytes:Its Evaluation Using Curcumin. Eyr J Pharmacol 813: 33-41.
15. Wang L et al. (2015) Human Autoimmune Diseases: A Comprehensive Update. J Intern Med 278:369-395.
16. Yao M et al. (2015) Neurological recovery and antioxidant effects of curcumin for spinal cord injury in the rat: a network meta-analysis and systematic review. J Neurotrauma 32:381-391.
17. Yin H et al. (2018) Curcumin Suppresses IL-1β Secretion and Prevents Inflammation through Inhibition of the NLRP3 Inflammasome. J Immunol 200:2835-2846.
18. Soleimani V et al. (2018) Turmeric (Curcuma Longa) and its Major Constituent (Curcumin) as Nontoxic and Safe Substances: Review. Phytother Res 32:985-995.
19. Abd El-Hack ME et al.(2021) Curcumin, the Active Substance of Turmeric: Its Effects on Health and Ways to Improve its Bioavailability. J Sci Food Agric 101:5747-5462.
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