Abstract:
BACKGROUND : Influenza A virus (IAV) is still a major health threat. The clinical manifestations of this infection are
related to immune dysregulation, which causes morbidity and mortality. The usage of traditional medication with
immunomodulatory properties against influenza infection has been increased recently. Our previous study showed
antiviral activity of quercetin-3-O-α-L-rhamnopyranoside (Q3R) isolated from Rapanea melanophloeos (RM) (L.) Mez
(family Myrsinaceae) against H1N1 (A/PR/8/34) infection. This study aimed to confirm the wider range of
immunomodulatory effect of Q3R on selective pro- and anti-inflammatory cytokines against IAV in vitro, to evaluate
the effect of Q3R on apoptosis pathway in combination with H1N1, also to assess the physical interaction of Q3R
with virus glycoproteins and RhoA protein using computational docking.
METHODS : MDCK cells were exposed to Q3R and 100CCID50/100 μl of H1N1 in combined treatments (co-, pre- and
post-penetration treatments). The treatments were tested for the cytokines evaluation at RNA and protein levels by
qPCR and ELISA, respectively. In another set of treatment, apoptosis was examined by detecting RhoA GTPase
protein and caspase-3 activity. Molecular docking was used as a tool for evaluation of the potential anti-influenza
activity of Q3R.
RESULTS : The expressions of cytokines in both genome and protein levels were significantly affected by Q3R
treatment. It was shown that Q3R was much more effective against influenza when it was applied in co-penetration
treatment. Q3R in combination with H1N1 increased caspase-3 activity while decreasing RhoA activation. The
molecular docking results showed strong binding ability of Q3R with M2 transmembrane, Neuraminidase of 2009 pandemic H1N1, N1 and H1 of PR/8/1934 and Human RhoA proteins, with docking energy of − 10.81, − 10.47, − 9.52,
− 9.24 and − 8.78 Kcal/mol, respectively.
CONCLUSIONS : Quercetin-3-O-α-L-rhamnopyranoside from RM was significantly effective against influenza infection by
immunomodulatory properties, affecting the apoptosis pathway and binding ability to viral receptors M2
transmembrane and Neuraminidase of 2009 pandemic H1N1 and human RhoA cellular protein. Further research
will focus on detecting the detailed specific mechanism of Q3R in virus-host interactions.
