In Vitro anti-inflammatory and antiviral activities of Pluchea indica (L.) Less. extracts on human monocytes

Pluchea indica (L.) Less., a halophyte from the Asteraceae family, thrives in saline soils and has traditional medicinal uses. This study aimed to investigate the in vitro antioxidant activity, as well as the anti-inflammatory and antiviral potential of ethanol extracts from P. indica.  The crude extract was obtained by refluxing P. indica with 70% ethanol. Phytochemical analysis was conducted, and antioxidant properties were assessed. Toxicity was evaluated in white blood cells, red blood cells, and the THP-1 cell line. The anti-inflammatory effects were analyzed by measuring TNF-α and TGF-β mRNA expression, while antiviral properties were assessed via IFN-β, TLR3, TLR7, TLR8, and TLR9 mRNA expression in THP-1 cells using quantitative RT-PCR.  All ethanol extracts contained alkaloids, phenolics, flavonoids, coumarins, tannins, and terpenoids; however, steroids were only present in the flower extract. Higher levels of phenolic and flavonoid compounds were found in the leaf and flower extracts, correlating with antioxidant activity. None of the extracts exhibited cytotoxicity to immune cells. The leaf extract demonstrated anti-inflammatory properties by decreasing TNF-α mRNA expression while stimulating TGF-β mRNA expression. The root extract showed antiviral effects by inducing IFN-β mRNA expression. Additionally, the stem extract exhibited both anti-inflammatory and antiviral properties by reducing TNF-α mRNA expression and enhancing the expression of TGF-β, IFN-β, TLR3, TLR8, and TLR9 mRNA. This study indicates that ethanol extracts of P. indica, prepared via reflux extraction, possess in vitro antioxidant, anti-inflammatory, and antiviral properties in human immune cells, suggesting their potential as therapeutic agents for inflammatory and viral diseases.