Hepatitis C virus (HCV) causes various liver complications,
including
fibrosis, cirrhosis, and steatosis, and finally progresses toward
hepatocellular carcinoma (HCC). The current study aimed to explore
the antiviral activity of the traditional Pakistani medicinal plant Salix nigra (S. nigra) known as
black willow against the hepatitis C virus (HCV). The anti-HCV activity
of S. nigra was established against
stable Hep G2 cell lines expressing the HCV NS3 gene. Various plant-derived
compounds with anti-HCV activity were identified, making phytotherapy
a promising alternative to conventional treatments due to their cost-effectiveness
and milder side effects. The two extraction methods (Maceration and
Soxhlet) and four solvents (n-hexane, methanol, ethyl
acetate, and water) were used to obtain crude extracts from S. nigra. Cytotoxicity testing showed that methanol
(CC50 25 μg/mL) and water (CC50 30 μg/mL)
extracts were highly toxic, while ethyl acetate and n-hexane (CC50 > 200 μg/mL) extracts were nontoxic
at low concentrations (10–50 μg/mL), making them suitable
for further anti-HCV investigations. Stable transfection of the NS3
gene was successfully performed in Hep G2 cells, creating a cellular
expression system for studying virus–host interaction. The
ethyl acetate extract of S. nigra exhibited
significant inhibition of NS3 gene expression (mRNA and protein levels).
The phytochemical analysis of S. nigra was also performed using the high-performance liquid chromatography
(HPLC) technique. The phytochemical analysis identified several polyphenolic
substances in the extracts of S. nigra. Our results concluded that the extracts of S. nigra have significantly reduced the expression of the NS3 gene at mRNA
and protein levels. These findings contribute to the global efforts
to combat hepatitis C by offering plant-based treatment options for
HCV management.