Curcumin as a Potential Treatment for COVID-19

Abstract

Coronavirus disease 2019 (COVID-19) is an infectious disease that rapidly spread throughout the world leading to high mortality rates. Despite the knowledge of previous diseases caused by viruses of the same family, such as MERS and SARS-CoV, management and treatment of patients with COVID-19 is a challenge. One of the best strategies around the world to help combat the COVID-19 has been directed to drug repositioning; however, these drugs are not specific to this new virus. Additionally, the pathophysiology of COVID-19 is highly heterogeneous, and the way of SARS-CoV-2 modulates the different systems in the host remains unidentified, despite recent discoveries. This complex and multifactorial response requires a comprehensive therapeutic approach, enabling the integration and refinement of therapeutic responses of a given single compound that has several action potentials. In this context, natural compounds, such as Curcumin, have shown beneficial effects on the progression of inflammatory diseases due to its numerous action mechanisms: antiviral, anti-inflammatory, anticoagulant, antiplatelet, and cytoprotective. These and many other effects of curcumin make it a promising target in the adjuvant treatment of COVID-19. Hence, the purpose of this review is to specifically point out how curcumin could interfere at different times/points during the infection caused by SARS-CoV-2, providing a substantial contribution of curcumin as a new adjuvant therapy for the treatment of COVID-19.

Keywords: ACE2; COVID-19; SARS-CoV-2; curcumin; new therapies.

FIGURE 1

Antiviral effects of curcumin. Curcumin prevents cell infection and viral replication in the SARS-CoV, influenza A virus (IAV), zika virus, chikungunya virus, hepatitis C virus (HCV), human norovirus (HuNoV), viral hemorrhagic septicemia virus in fish (VHSV), bovine herpesvirus 1 (BHV-1), respiratory syncytial virus (RSV), Japanese encephalitis virus (JEV), Epstein-Barr virus (EBV), human cytomegalovirus (HCMV), and human immunodeficiency virus (HIV).

FIGURE 2

Potential curcumin targets as antiviral and anti-inflammatory in SARS-CoV-2 infection. The first antiviral effect of curcumin against SARS-CoV-2 is its potential for preventing the binding of viral S protein to the ACE2 receptor and initiate the host cell infection process (1). After penetrating the host cell via endosomes, the virus begins the replication process that requires an acid endosomal environment to initiate the proteolytic process of viral proteins and subsequent release to the external environment. Curcumin acts by inhibiting the Endosomal acidification (2) and processing of the viral proteins (Mpro), necessary for viral release (3,4). Further, the inhibition of ACE mediated by curcumin (5) prevents the increase of Ang II levels. Curcumin inhibits NF-κB (6) through the inhibition of different pathways. The binding of PAMPs, DAMPs, and cytokines that leads to IkB phosphorylation and proteasomal degradation is one of those pathways that cause NF-κB activation. Curcumin prevents both IkB phosphorylation and p65 subunit from the NF-κB (8), which consequently prevents NF-κB activation. The activation of ADAM17 by the AngII-ATR1 axis promotes the interaction between EGF and EGFR receptor, which promotes the activation of the PI3K/AKT/mTOR axis resulting in NF-κB activation. Curcumin acts as a potential inhibitor for mTOR (9), preventing the NF-κB pathway activation. ADAM17-mediated signaling also triggers the release of soluble interleukin 6-receptor, forming a complex with IL-6 (sIL-6R-IL-6) that binds to glycoprotein gp130. This complex binding (sIL-6R-IL-6+gp130) activates the signal transduction pathways responsible to induce the activators of transcription 3 (STAT3). Activation of STAT3 results in activation of NF-κB, which can be prevented by the curcumin (10). The NF-κB activation induces a protein complex formation, knowns as inflammasome, which can lead to cell death through pyroptosis, a pathway to cell death mediated by the activation of caspase-1. However, curcumin can cause the inhibition of inflammasome formation (11) by the inhibition of NF-κB. Abbreviations: TMPRSS2, transmembrane protease, serine 2; ACE1, angiotensin-converting enzyme 1; ACE2, angiotensin-converting enzyme 2; Mpro, main protease; PAMPs, pathogen-associated molecular pattern; DAMPs, damage-associated molecular patterns; ANG I, angiotensin I; Ang II, angiotensin II; ATR1, angiotensin II (AII) receptor 1; ADAM17, a disintegrin and metalloproteinase 17; EGF, epidermal growth factor; EGFR, epidermal growth factor receptor; IL-6R, interleukin 6 receptor; sIL-6R, soluble Interleukin 6 receptor; gp130, glycoprotein 130; PI3K, phosphoinositide 3-kinase; AKT, protein kinase B; mTOR, mammalian target of rapamycin; STAT3, signal transducers and activators of transcription; NF-κB, factor nuclear kappa B.

FIGURE 3

Curcumin as a Potential antithrombotic in hemostatic disorders induced by SARS-CoV-2. Pro-inflammatory cytokines and Ang II elevated levels can induce the production of tissue factor (TF) by the endothelial cells, initiating the coagulation cascade. Curcumin decreases pro-inflammatory cytokines (1) and inhibits TF expression (2) in the vascular endothelium, avoiding the activation of the coagulation cascade. The affinity of curcumin by the SARS-CoV-2 protein S and ACE2 binding can prevent the infection and activation of endothelial cells (3). During the activation of the coagulation cascade, fibrinolysis can occur, generating D-dimers. Curcumin treatment decreases fibrin deposition and D-dimer levels formation (4). Lesions of the endothelial cells can expose the subendothelial collagen, which can be recognized by the platelet’s receptor (GP-VI), leading to platelet cell activation. Curcumin can inhibit the GP-VI receptor, reducing and/or abolishing the platelet activation by binding to collagen (5). The interaction of platelets with monocytes through binding the P-selectin-PSGL-1 receptor promotes monocyte activation, causing an increase of TF expression. Curcumin inhibits this interaction by inhibiting P-selectin in platelets (6). The mobilization of intracellular calcium mediates platelet aggregation. Curcumin prevents calcium-mediated platelet aggregation (7). Besides, curcumin inhibits the thromboxane A2 (TXA2) generation (9) released by activated platelets to stimulate other platelet activation. Thus, curcumin inhibits platelet aggregation (10). Abbreviations: TNF-α, tumor necrosis factor alpha; IL-1β, interleukin 1 beta; Ang II, angiotensin II; GPVI, glycoprotein VI; vWF, Von Willebrand factor; GPIb-IX-V, glycoprotein (GP) Ib-IX-V; PSGL-1, P-selectin glycoprotein ligand-1; AA, arachidonic acid; TXA2, thromboxane A2; TP, thromboxane receptor.

FIGURE 4

Potential curcumin in cell damage caused by SARS-CoV-2 in the lung and heart. Curcumin promotes differentiation from naïve CD4+T-cell to Tregs through the modulation of IL-10 (1). The cytoprotective role of curcumin decreases the death of type II alveolar cells (ATII) with a consequent decrease in the release of DAMPs (2). Curcumin also mediates macrophages' polarization, decreasing the population of inflammatory macrophages M1 to macrophages M2 that participate in the resolving and reparative process (3). The presence of Th17 cells promotes the activation of ATII cells through IL-17. In turn, activated ATII cells release a chemoattractant for neutrophils that causes neutrophil aggregation. Curcumin decreases IL-17 levels with a consequent decrease in neutrophil aggregates. The anticoagulant and antithrombotic effects of curcumin can have protective effects on the heart, decreasing the heart attack risk (5). The anti-inflammatory action of curcumin can prevent damage to cardiomyocytes caused by an excess of inflammatory mediators, known as a cytokine storm (6). Its affinity for protein S and ACE2 can prevent the direct infection of cardiomyocytes by SARS-CoV-2 (7). Abbreviations: ATII, alveolar type II cells; Tregs, regulatory T cells; Th17, T helper 17 cells; CXCL-1, chemokine ligand 1; NET, neutrophil extracellular traps.