Abstract
Background:
Phragmites australis, a grass species of the Poaceae family, was studied here for the first time in Libya, marking its initial documented phytochemical and biological evaluation. In traditional folk medicine, Phragmites australis has promising therapeutic potential.

Aim:
This study analyzed and identified phytochemical compounds and the antioxidant, cytotoxic, antimicrobial, and antiviral activities of Phragmites australis ethanolic extract (PAEE).

Methods:
Phytochemical profiling was conducted via liquid chromatography–mass spectrometry (LC‒MS). Antioxidant properties were evaluated via the FRAP, DPPH, NO, TAC and TEAC assays. The cytotoxic effects of the extracts on breast (MCF-7), hepatocellular (Hep-G2), and colon (Caco-2) cancer cell lines were assessed via the MTT assay. Antimicrobial effects were tested against four bacterial strains and three fungi, and the antiviral activities of the extracts against HSV-1 and HAV were assessed.

Results:
The ethanolic extract of Phragmites australis (PAEE) contained 65.94 mg/GAE g of total phenolics and 22.7 mg/RE g of total flavonoids. Phytochemical analysis revealed the presence of key bioactive compounds, including flavonoids such as rutin, quercetin, luteolin-7-O-glucoside, caffeic acid, and apigenin-6-C-glucoside, as well as phenolic acids such as protocatechuic acid, coumaric acid, and feruloyl-quinic acid derivatives.
The extract demonstrated significant antioxidant activity. Additionally, the extract exhibited potent antimicrobial efficacy, particularly in counteracting Bacillus subtilis and Klebsiella pneumoniae.

Conclusion:
This study is the first to investigate Phragmites australis from Benghazi, Libya, revealing its rich diversity of polyphenols and flavonoids, along with its strong antioxidant, antibacterial, and antiviral activities.Notably, this is the first report evaluating Libyan-sourced Phragmites australis ethanolic extract for antiviral activity against HSV-1 and HAV, alongside its cytotoxic effects on colorectal adenocarcinoma (Caco-2) cells.

Key words: Phragmites australis, LC‒MS analysis, Phenolics, Antioxidant activity, Antiviral activity