Phytochemical Analysis and in Vitro Assessment of Himalayan Polystichum squarrosum Extract for Its Antioxidant and Antimicrobial Activities

ABSTRACT Aerial parts of Polystichum squarrosum (Dryopteridaceae) collected from Kumaun Himalaya, India were assessed for antioxidant potential using the methanolic extract in vitro for DPPH free radical scavenging and ferric-reducing antioxidant assays. The DPPH assay exhibited potent free radical scavenging capacity (IC50, 6.03 ± 1.41 µg mL−1), as well as ferric-reducing antioxidant activity (886.2 mg AAE gm−1 dry extract). In the antibacterial activity tests, the methanolic extract inhibited the growth of Klebsiella pneumoniae (MIC 14 ± 0.57 mm) and Agrobacterium tumefaciens (MIC 12 ± 0.7 mm). Totally, 65 phytochemical compounds were identified using gas chromatography mass spectrometry (GC-MS). Total phenolics (913.33 ± 39.23 mg GAE g−1 dry extract) and total flavonoid contents (30.0 ± 2.64 mg QE g−1 dry extract) were estimated qualitatively. These results demonstrated antioxidant and antimicrobial activities due to the presence of bioactive phytochemicals.