1.Antiviral activity of a standardized root water extract of Eurycoma longifolia (Physta®) against dengue virus
George, A. ; Zandi, K. ; Biggins, J. ; Chinnappan, S. ; Hassandarvish, P. ; Yusof, A.
Tropical Biomedicine 2019;36(2):412-421
The aim of this study was to investigate the antiviral property of Eurycoma
longifolia Jack (EL) against dengue virus. A propriety standardized extract of Eurycoma
longifolia Jack (Physta®) was tested for anti-viral activity after viral adsorption in Vero
cell line. Viral yield was measured by qRT-PCR in four serotypes of dengue virus. The
antiviral activity was further investigated in an in vivo AG129 mouse model for dengue
inhibitory candidates. 100 mg/kg EL extract was fed twice daily and challenged with a
lethal dose of (~1x105 PFU per mouse) of DENV-2 over a period of six days. Antiviral
activity with IC50 of 33.84, 33.55, 58.35 and 119 μg/ml for DENV-1, DENV-2, DENV-3 and
DENV-4 serotypes respectively was observed. The selectivity index (SI) values determined
as the ratio of cytotoxic concentration (CC50) to inhibitory concentration (IC50) was the
lowest for DENV-2 at 28.9. The dengue virus (DENV) replication measured by qRT-PCR
showed a reduction of 100% for DENV-1, DENV-2, DENV-3 and 80% for DENV-4 at day 2 of
exposure. In the in vivo AG129 mouse model, a lower weight reduction, 30% lower viral
load and 12% higher platelet in the extract group compared to the control was observed at
day 6. The extract of E. longifolia has potential anti-dengue properties with improving
trends in platelet counts. E. longifolia supplementation is potentially a two-pronged
approach in treating dengue fever.