Abstract

Background:
Dengue virus serotype-3 (DENV-3) infection remains a clinical problem for which no specific antiviral agent has yet been found. The rhizome of the Alpinia purpurata (red 50 galangal) is rich in natural glycosides that have antioxidant and anti-inflammatory properties. However, studies related to antidengue from A. purpurata using in vitro and in silico methods have not been widely conducted.

Aim:
This study aims to describe the anti-dengue mechanism of natural glycosides from A. purpurata rhizomes through antiviral ability in vitro againts Vero E6 cell cultures induced by DENV-3, and molecular docking approach to the DC-SIGN (CD209), CD300a, IL-1β, and SOD receptors.

Methods:
In vitro quantification of the viral replication inhibition value was performed using dengue virus antibodies (4G2) through Enzyme-linked Immunosorbent Assay (ELISA). Meanwhile, molecular docking was performed to assess the binding affinities and complexes interaction. Molecular dynamics simulations confirmed the stability of docking complexes within root mean square fluctuation value. Further screening was conducted using pkCSM webserver to obtain ADMET property values and the ProTox 3.0 webserver to obtain toxicity prediction values.

Results:
In vitro using Vero E6 cell cultures induced with DENV-3 showed a viral replication inhibition value of 105.8107 µg/mL. Molecular docking experiment found that quercetin-3-O-rutinoside has the best potential to inhibit virus binding to DC-SIGN receptors (-7.8 kcal/mol), balance immune signals through CD300a regulation (-7.1 kcal/mol), suppressing the production of IL-1β during cytokine storm (-7.2 kcal/mol), and activating endogenous antioxidant superoxide dismutase (-7.0 kcal/mol) rather than quercetin control. Validation of docking results through molecular dynamics proves that quercetin-3-O-rutinoside complex has RMSF value < 3 Å, which means that complex tends to be stable. ADMET characteristics and toxicity also indicate that quercetin-3-O-rutinoside is safe for cells.

Conclusion:
This study reports the first evidence of the potential of natural glycosides from A. purpurata as antidengue agent in vitro and in silico through the mechanisms of viral entry inhibition, cytokine storm modulation, and endogenous antioxidant activation to reduce free radicals in cells during infection. These findings contribute to the potential of A. purpurata as antiviral, anti-inflammatory, and antioxidant agent.

Key words: Alpinia purpurata; Antidengue; Glycosides; Multiprotein Target.