Inhibition of Dengue Virus Protease by Eugeniin, Isobiflorin, and Biflorin Isolated from the Flower Buds of Syzygium aromaticum (Cloves)

Abstract

Dengue virus (DENV) infections are rampant in tropical and subtropical regions of the world with millions of people at risk. There is still no specific antiviral treatment available against these infections. Amongst the different potential therapeutic targets, DENV protease is considered an important target because of its crucial role in the viral replication cycle. We are reporting here a potent DENV protease inhibitor, eugeniin (3), which has been isolated from cloves, along with two other weaker inhibitors, isobiflorin (1) and biflorin (2). In this study, the IC 50 values of 3 against the proteases of DENV serotype-2 and -3 were found to be 94.7 nM and 7.5 μM, respectively. Mechanistically, the compounds 1−3 exhibited a competitive type of inhibition, which were further substantiated by computational docking and saturation transfer difference (STD) NMR spectroscopy. Atomic-level details of the binding of these molecules at the active site of the protease suggested extensive interactions mediated by a network of hydrogen bonds and hydrophobic contacts. With further evaluation, these inhibitors are highly promising in the context of antiviral therapeutics development against DENV.

Facile Synthesis and In Vitro Activity of N-Substituted 1,2-Benzisothiazol-3(2H)-ones against Dengue Virus NS2BNS3 Protease

“…The synthesised BITs were tested for their inhibitory activity against the DENV2 NS2B/NS3 protease assay using the previously reported 96-well plate method [ 16 , 17 , 18 , 19 , 20 ]. Briefly, the reaction mixtures (200 μL) containing 50 μM test compound were incubated with 100 nM protease and 5 μM tetrapeptide substrate Bz-Ile-Lys-Arg-Arg-AMC.…”

“…Previous efforts to discover DENV NS2BNS3 protease inhibitors have resulted in the identification of several peptides [ 8 , 9 ], peptidomimetics with electrophilic warheads [ 10 , 11 ] and cyclopeptides [ 12 , 13 ], as well as small organic molecules, such as synthetic compounds [ 14 , 15 , 16 , 17 , 18 ] and natural products [ 19 , 20 , 21 ], as promising leads. However, none of them has reached clinical application due to unfavourable pharmacokinetics and/or pharmacodynamics.…”

Molecular Basis of the Therapeutical Potential of Clove (Syzygium aromaticum L.) and Clues to Its Anti-COVID-19 Utility

“…Eugeniin was also found to act as a potent inhibitor of the protease of Dengue virus (DENV), which causes infections in tropical and subtropical regions of the world for which there are still no specific antiviral treatments available [ 107 ]. The IC 50 values of eugeniin against the proteases of DENV serotype-2 and -3 were 94.7 nM and 7.5 μM, respectively.…”

“…The IC 50 values of eugeniin against the proteases of DENV serotype-2 and -3 were 94.7 nM and 7.5 μM, respectively. Thus, in consideration of the importance of DENV protease for the viral replication cycle, eugeniin was proposed as a promising drug in the context of anti-DENV therapeutics development [ 107 ]. The other investigated DENV protease inhibitors were isobiflorin and biflorin ( Figure 2 ), even though their inhibitory activity was weaker than eugeniin [ 107 ].…”

“…Thus, in consideration of the importance of DENV protease for the viral replication cycle, eugeniin was proposed as a promising drug in the context of anti-DENV therapeutics development [ 107 ]. The other investigated DENV protease inhibitors were isobiflorin and biflorin ( Figure 2 ), even though their inhibitory activity was weaker than eugeniin [ 107 ]. The atomic-level details of the binding of these three clove phytochemicals to the viral protease were obtained by computational docking and saturation transfer difference (STD) NMR spectroscopy, which showed that the molecular recognition at the active site of the DENV protease involved networks of hydrophobic contacts and hydrogen bonds [ 107 ].…”