Comprehensive bioactivity of Phragmites australis aqueous extract: Phytochemical analysis, antioxidant, antimicrobial, cytotoxic, and antiviral properties

Background Phragmites australis, a grass species of the Poaceae family, has promising therapeutic potential in traditional medicine. Its phytochemical composition varies depending on its geographical origin, genetic differences, and extraction methods. Aim This study assessed the phytochemical profile and biological activities of Phragmites australis aqueous extract (PAAE). Methods The phenolic profile of the extract was determined using liquid chromatography/electrospray ionization mass spectrometry (LC-ESI-MS). The cytotoxic effects of PAAE on breast (MCF-7), hepatocellular (HepG2), and colon (Caco-2) cancer cell lines were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The antioxidant capacity was assessed by DPPH and FRAP assays. Furthermore, the antimicrobial activity was tested against four bacterial and two fungal species, and the antiviral activity was evaluated against HSV-1 and HAV. Results The polyphenolic and flavonoid contents of the PAAE were 65.94 mg GAE/g and 22.7 mg AAE/g, respectively.LC‒MS analysis revealed high levels of various phenolic compounds, including rutin, quercetin, luteolin-7-O-glucoside, caffeic acid, apigenin-6-C-glucoside, protocatechuic acid, coumaric acid, and feruloyl-quinic acid derivatives. The MTT cell viability assay indicated concentration-dependent inhibition of cell lines, with IC₅₀ values of 20.67 ± 0.09 µg/mL for MCF-7 cells, 10.4 ± 0.08 µg/mL for Caco-2 cells, and 20.67 ± 0.09 µg/mL for HepG2 cells. Furthermore, PAAE exhibited significant antibacterial activity against Bacillus subtilis and Klebsiella pneumoniae , as well as significant antiviral activity, reducing HAV and HSV-1 replication by 99.45% and 79.76%, respectively, at nontoxic concentrations. Conclusion This study is the first to investigate Phragmites australis from Benghazi, Libya, revealing its rich diversity of polyphenols and flavonoids, along with notable antioxidant, antibacterial, and antiviral activities.