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1.
J Tradit Complement Med ; 12(1): 69-72, 2022 Jan.
Article in English | MEDLINE | ID: covidwho-1814845

ABSTRACT

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has emerged as a pandemic and has caused damage to the lives of the people and economy of countries. However, the therapeutic reagents against SARS-CoV-2 remain unclear. The spike (S) protein of SARS-CoV-2 contains a cleavage motif at the S1/S2 boundary, known to be cleaved by furin. As cleavage is essential for S protein activation and viral entry, furin was selected as the target compound. In this study, we examined the inhibitory effects of two lignans (honokiol and magnolol) on furin-like enzymatic activity using a fluorogenic substrate with whole-cell lysates. Of two compounds tested, honokiol partially inhibited furin-like enzymatic activity. We further examined the anti-SARS-CoV-2 activity of honokiol using VeroE6 cell line, which is stably expressing a transmembrane protease serine 2 (TMPRSS2). It was shown that honokiol exhibited remarkable inhibition of SARS-CoV-2 infection. Therefore, honokiol and crude drugs which contain honokiol such as Magnolia species have a potential therapeutic reagents for SARS-CoV-2.

2.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-312156

ABSTRACT

The coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), persists worldwide with limited therapeutic options. Since membrane fusion between SARS-CoV-2 and host cells is essential for the early step of the infection, the membrane compositions, including sphingolipids, in host cells are considered to affect the viral infection. However, the role of sphingolipids in the life cycle of SARS-CoV-2 remains unclear. Here, we assessed several inhibitors of sphingolipid metabolism enzymes against SARS-CoV-2 spike protein-mediated cell-cell fusion and viral infection in vitro . Among the compounds tested, only N -(4-hydroxyphenyl)retinamide (4-HPR, also known as fenretinide), an inhibitor of dihydroceramide Δ4-desaturase 1 (DES1) and well known for having antitumour activity, suppressed cell-cell fusion (50% effective concentration [EC 50 ] = 4.1 µM) and viral infection ([EC 50 ] = 4.4 µM), wherein the EC 50 values are below its plasma concentration in previous clinical trials on tumours. DES1 catalyses the introduction of a double bond in dihydroceramide, and the inhibition efficiencies observed were consistent with an increased ratio of saturated sphinganine-based lipids to total sphingolipids and the decreased cellular membrane fluidity. These findings, together with the accumulated clinical data regarding the safety of 4-HPR, make it a likely candidate drug to treat COVID-19.

3.
J Virol ; 95(17): e0080721, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1486516

ABSTRACT

The membrane fusion between the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and host cells is essential for the initial step of infection; therefore, the host cell membrane components, including sphingolipids, influence the viral infection. We assessed several inhibitors of the enzymes pertaining to sphingolipid metabolism, against SARS-CoV-2 spike protein (S)-mediated cell-cell fusion and viral infection. N-(4-Hydroxyphenyl) retinamide (4-HPR), an inhibitor of dihydroceramide Δ4-desaturase 1 (DES1), suppressed cell-cell fusion and viral infection. The analysis of sphingolipid levels revealed that the inhibition efficiencies of cell-cell fusion and viral infection in 4-HPR-treated cells were consistent with an increased ratio of saturated sphinganine-based lipids to total sphingolipids. We investigated the relationship of DES1 with the inhibition efficiencies of cell-cell fusion. The changes in the sphingolipid profile induced by 4-HPR were mitigated by the supplementation with exogenous cell-permeative ceramide; however, the reduced cell-cell fusion could not be reversed. The efficiency of cell-cell fusion in DES1 knockout (KO) cells was at a level comparable to that in wild-type (WT) cells; however, the ratio of saturated sphinganine-based lipids to the total sphingolipids was higher in DES1 KO cells than in WT cells. 4-HPR reduced cell membrane fluidity without any significant effects on the expression or localization of angiotensin-converting enzyme 2, the SARS-CoV-2 receptor. Therefore, 4-HPR suppresses SARS-CoV-2 S-mediated membrane fusion through a DES1-independent mechanism, and this decrease in membrane fluidity induced by 4-HPR could be the major cause for the inhibition of SARS-CoV-2 infection. IMPORTANCE Sphingolipids could play an important role in SARS-CoV-2 S-mediated membrane fusion with host cells. We studied the cell-cell fusion using SARS-CoV-2 S-expressing cells and sphingolipid-manipulated target cells, with an inhibitor of the sphingolipid metabolism. 4-HPR (also known as fenretinide) is an inhibitor of DES1, and it exhibits antitumor activity and suppresses cell-cell fusion and viral infection. 4-HPR suppresses membrane fusion through a decrease in membrane fluidity, which could possibly be the cause for the inhibition of SARS-CoV-2 infection. There is accumulating clinical data on the safety of 4-HPR. Therefore, it could be a potential candidate drug against COVID-19.


Subject(s)
Cell Membrane/metabolism , Fenretinide/pharmacology , Membrane Fluidity/drug effects , Oxidoreductases/metabolism , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Cell Fusion , Cell Membrane/genetics , Gene Knockout Techniques , HEK293 Cells , Humans , Membrane Fluidity/genetics , Oxidoreductases/deficiency , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
4.
J Virol ; 95(17): e0080721, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1381151

ABSTRACT

The membrane fusion between the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and host cells is essential for the initial step of infection; therefore, the host cell membrane components, including sphingolipids, influence the viral infection. We assessed several inhibitors of the enzymes pertaining to sphingolipid metabolism, against SARS-CoV-2 spike protein (S)-mediated cell-cell fusion and viral infection. N-(4-Hydroxyphenyl) retinamide (4-HPR), an inhibitor of dihydroceramide Δ4-desaturase 1 (DES1), suppressed cell-cell fusion and viral infection. The analysis of sphingolipid levels revealed that the inhibition efficiencies of cell-cell fusion and viral infection in 4-HPR-treated cells were consistent with an increased ratio of saturated sphinganine-based lipids to total sphingolipids. We investigated the relationship of DES1 with the inhibition efficiencies of cell-cell fusion. The changes in the sphingolipid profile induced by 4-HPR were mitigated by the supplementation with exogenous cell-permeative ceramide; however, the reduced cell-cell fusion could not be reversed. The efficiency of cell-cell fusion in DES1 knockout (KO) cells was at a level comparable to that in wild-type (WT) cells; however, the ratio of saturated sphinganine-based lipids to the total sphingolipids was higher in DES1 KO cells than in WT cells. 4-HPR reduced cell membrane fluidity without any significant effects on the expression or localization of angiotensin-converting enzyme 2, the SARS-CoV-2 receptor. Therefore, 4-HPR suppresses SARS-CoV-2 S-mediated membrane fusion through a DES1-independent mechanism, and this decrease in membrane fluidity induced by 4-HPR could be the major cause for the inhibition of SARS-CoV-2 infection. IMPORTANCE Sphingolipids could play an important role in SARS-CoV-2 S-mediated membrane fusion with host cells. We studied the cell-cell fusion using SARS-CoV-2 S-expressing cells and sphingolipid-manipulated target cells, with an inhibitor of the sphingolipid metabolism. 4-HPR (also known as fenretinide) is an inhibitor of DES1, and it exhibits antitumor activity and suppresses cell-cell fusion and viral infection. 4-HPR suppresses membrane fusion through a decrease in membrane fluidity, which could possibly be the cause for the inhibition of SARS-CoV-2 infection. There is accumulating clinical data on the safety of 4-HPR. Therefore, it could be a potential candidate drug against COVID-19.


Subject(s)
Cell Membrane/metabolism , Fenretinide/pharmacology , Membrane Fluidity/drug effects , Oxidoreductases/metabolism , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Cell Fusion , Cell Membrane/genetics , Gene Knockout Techniques , HEK293 Cells , Humans , Membrane Fluidity/genetics , Oxidoreductases/deficiency , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
5.
J Nat Med ; 75(4): 1080-1085, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1375679

ABSTRACT

The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) contains a cleavage motif R-X-X-R for furin-like enzymes at the boundary of the S1/S2 subunits. The cleavage of the site by cellular proteases is essential for S protein activation and virus entry. We screened the inhibitory effects of crude drugs on in vitro furin-like enzymatic activities using a fluorogenic substrate with whole-cell lysates. Of the 124 crude drugs listed in the Japanese Pharmacopeia, aqueous ethanolic extract of Cnidii Monnieris Fructus, which is the dried fruit of Cnidium monnieri Cussion, significantly inhibited the furin-like enzymatic activities. We further fractionated the plant extract and isolated the two active compounds with the inhibitory activity, namely, imperatorin and osthole, whose IC50 values were 1.45 mM and 9.45 µM, respectively. Our results indicated that Cnidii Monnieris Fructus might exert inhibitory effects on furin-like enzymatic activities, and that imperatorin and osthole of the crude drug could be potential inhibitors of the motif cleavage.


Subject(s)
Cnidium/chemistry , Drug Evaluation, Preclinical , Enzyme Assays , Furin/antagonists & inhibitors , Furin/metabolism , Plant Extracts/pharmacology , A549 Cells , COVID-19/drug therapy , COVID-19/virology , Humans , Inhibitory Concentration 50 , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism
6.
J Virol ; 95(17): e0080721, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1350004

ABSTRACT

The membrane fusion between the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and host cells is essential for the initial step of infection; therefore, the host cell membrane components, including sphingolipids, influence the viral infection. We assessed several inhibitors of the enzymes pertaining to sphingolipid metabolism, against SARS-CoV-2 spike protein (S)-mediated cell-cell fusion and viral infection. N-(4-Hydroxyphenyl) retinamide (4-HPR), an inhibitor of dihydroceramide Δ4-desaturase 1 (DES1), suppressed cell-cell fusion and viral infection. The analysis of sphingolipid levels revealed that the inhibition efficiencies of cell-cell fusion and viral infection in 4-HPR-treated cells were consistent with an increased ratio of saturated sphinganine-based lipids to total sphingolipids. We investigated the relationship of DES1 with the inhibition efficiencies of cell-cell fusion. The changes in the sphingolipid profile induced by 4-HPR were mitigated by the supplementation with exogenous cell-permeative ceramide; however, the reduced cell-cell fusion could not be reversed. The efficiency of cell-cell fusion in DES1 knockout (KO) cells was at a level comparable to that in wild-type (WT) cells; however, the ratio of saturated sphinganine-based lipids to the total sphingolipids was higher in DES1 KO cells than in WT cells. 4-HPR reduced cell membrane fluidity without any significant effects on the expression or localization of angiotensin-converting enzyme 2, the SARS-CoV-2 receptor. Therefore, 4-HPR suppresses SARS-CoV-2 S-mediated membrane fusion through a DES1-independent mechanism, and this decrease in membrane fluidity induced by 4-HPR could be the major cause for the inhibition of SARS-CoV-2 infection. IMPORTANCE Sphingolipids could play an important role in SARS-CoV-2 S-mediated membrane fusion with host cells. We studied the cell-cell fusion using SARS-CoV-2 S-expressing cells and sphingolipid-manipulated target cells, with an inhibitor of the sphingolipid metabolism. 4-HPR (also known as fenretinide) is an inhibitor of DES1, and it exhibits antitumor activity and suppresses cell-cell fusion and viral infection. 4-HPR suppresses membrane fusion through a decrease in membrane fluidity, which could possibly be the cause for the inhibition of SARS-CoV-2 infection. There is accumulating clinical data on the safety of 4-HPR. Therefore, it could be a potential candidate drug against COVID-19.


Subject(s)
Cell Membrane/metabolism , Fenretinide/pharmacology , Membrane Fluidity/drug effects , Oxidoreductases/metabolism , SARS-CoV-2/metabolism , Spike Glycoprotein, Coronavirus/metabolism , Cell Fusion , Cell Membrane/genetics , Gene Knockout Techniques , HEK293 Cells , Humans , Membrane Fluidity/genetics , Oxidoreductases/deficiency , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
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