World Health Organization (WHO) latest report on 29 June 2021: Despite the downward trend in the number of new deaths from COVID-19, the incidence rate remains high, with an average of more than 370,000 cases reported per day over the past week, with the cumulative number of reported cases worldwide now exceeding 180 million, and the number of deaths worldwide approaching 4 million [1].
(Global Weekly COVID-19 Incidence and Death Report, Published by the World Health Organization, 2021.1.13-6.27)
As the treatment of COVID-19 and its complications becomes more and more intensive, many specific clinical drugs or medicinal and food homologous raw materials show different degrees of positive effects on the treatment or adjuvant treatment of COVID-19, curcumin is one of them.
The known pathophysiology of COVID-19 is primarily concerned with inflammatory responses, cytokine storms, and coagulation diseases. Hemo concentration and difficulty exchanging oxygen and carbon dioxide due to viral infections and inflammation can be an important cause of hypoxia. Curcumin has anti-inflammatory activity and inhibits thrombin to exert antithrombotic effects[2]. This may be the reason why curcumin has some role in adjuvant treatment of COVID-19. In 2020, a review reviewed the inhibitory effects of curcumin on the virus and noted that curcumin could be a potential treatment for COVID-19 infection, laying the groundwork for more research [3]. Recently, a clinical study further explored the potential role of curcumin in the adjuvant treatment of COVID-19.
What is Curcumin?
Curcumin is mainly derived from the rhizome of turmeric (the content of the rhizome is about 2% to 5%[4]). Studies have shown that curcumin has antioxidant, anticancer, antithrombotic, and cardioprotective effects[5],[6],[7] Curcumin is approved by the FDA as a generally recognized as safe substance. Clinical trials have shown that human intake of curcumin up to 12 g/day is safe [5].
*Turmeric is two completely different ingredients from the ginger we are familiar with. Although they belong to the same ginger family, they are under different genera. They have a similar appearance, but with their skin removed, turmeric is a little darker in color.
Why compound piperine?
Piperine is the main active ingredient in black pepper, which contains 2.7%-4% piperine. Piperine has shown a variety of pharmacological effects in vitro and in vivo experiments, such as antioxidant, antibacterial, immunomodulatory and cardiovascular protection. Piperine can also inhibit a variety of metabolic enzymes, thereby improving the oral bioavailability of multiple drugs and nutrients [8]. Piperine has been shown to significantly increase the bioavailability of curcumin by a factor of 20 [9].
Research progress
The latest study, published in the journal Frontiers in Pharmacology in May 2021, was the first to study the effect of curcumin combined with piperine on the adjunctive treatment of COVID-19 in a double-blind randomized controlled trial, showing that oral curcumin plus piperine significantly improved symptoms and reduced hospital stays in moderately to severe patients [10].
The study ultimately included a total of 140 symptomatic adult, non-critically ill patients who tested positive for COVID-19 antigen between July and September 2020. Subjects were randomly assigned to the trial and control groups of 70 patients each (30, 25, and 15 mild, moderate, and severe patients, respectively). Both groups of patients received conventional drug treatment for COVID-19 in the region, on the basis of which supplements were taken: the trial group took capsules of curcumin (525 mg) and piperine (2.5 mg) twice a day, and the control group took lactic acid bacteria and B vitamins for 14 days.
The results showed that compared with the control group, patients with mild, moderate and severe oral curcumin and piperine recovered from multiple symptoms (fever, cough, sore throat, dyspnea) earlier, worsened during hospitalization, had a better ability to maintain oxygen saturation greater than 94% in indoor air during hospitalization, deteriorated health conditions and required further medical measures, and significantly shortened hospital stays in moderate and severe patients.
In addition, the turmeric + piperine group had fewer cases of patients requiring ventilator support and developed thromboembolism, and fewer deaths. There were no deaths in the mild and moderate trial groups, compared with 1 and 5 patients in the control group, respectively; the deaths of severe patients in the experimental group (2/15) were lower than those in the control group (5/15).
In addition to the coronavirus, studies have shown that curcumin has inhibitory effects on a variety of viral infections, such as parainfluenza virus type 3 (PIV-3) and respiratory syncytial virus (RSV) [11]. The main mechanisms are 1) direct interference with viral replication, including viral attachment, dehulling, genomic replication, gene expression, assembly, and release; and 2) cellular signaling pathways necessary to inhibit viral replication, such as the PI3K/Akt signaling pathway (an important intracellular signal transduction pathway) and the NF-κB (a class of nuclear protein factors with multidirectional transcriptional regulation) signaling pathways [12].
Antiviral mechanism of curcumin in host cells[7]
At present, the new crown still threatens the health of human beings around the world, and finding safe, efficient and inexpensive treatments will be the research hotspots of the future.
bibliography
[1] World Health Organization. COVID-19 weekly epidemiological update, edition 29 June 2021
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[8] Haq I U, Imran M, Nadeem M, et al. Piperine: a review of its biological effects[J]. Phytotherapy Research, 2021, 35(2): 680-700.
[9] Han HK. The effects of black pepper on the intestinal absorption and hepatic metabolism of drugs. Expert Opin Drug Metab Toxicol. 2011;7(6):721-729. doi:10.1517/17425255.2011.570332
[10] Pawar KS, Mastud RN, Pawar SK, et al. Oral Curcumin With Piperine as Adjuvant Therapy for the Treatment of COVID-19: A Randomized Clinical Trial. Front Pharmacol. 2021;12:669362. Published 2021 May 28. doi:10.3389/fphar.2021.669362
[11] Moghadamtousi S Z, Kadir H A, Hassandarvish P, et al. A review on antibacterial, antiviral, and antifungal activity of curcumin. BioMed Research International. 2014; 2014: 186864[J].
[12] Mathew D, Hsu W L. Antiviral potential of curcumin[J]. Journal of functional foods, 2018, 40: 692-699.