Partial characterization and evaluation of antioxidant and antibacterial activities of a water soluble polysaccharide isolated from Euphorbia hebecarpa roots

Euphorbia hebecarpa has been valued in traditional Iranian medicine; however, its carbohydrate composition has remained largely unexplored. The present study aimed to isolate, identify, and investigate selected biological properties of a carbohydrate fraction (EHC-1) from E. hebecarpa . EHC-1 was extracted using hot water extraction, followed by a two-step chromatographic procedure utilizing DEAE-52 cellulose and Sephadex G-200 columns. Partial structural characterization was performed using gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography- refractive index (HPLC-RID), Fourier transform infrared spectroscopy (FT-IR), and gas chromatography-flame ionization detection (GC-FID). In addition, X-ray diffraction (XRD) confirmed the semi-crystalline nature of the polysaccharide, and thermogravimetric analysis (TGA) was employed to evaluate its thermal stability. Compositional analyses identified EHC-1 as a polysaccharide with an average molecular weight of approximately 148 kDa. The relative monosaccharide composition comprised glucose (51.50%), fructose (35.70%), galactose (5.79%), arabinose (5.86%), and galacturonic acid (1.13%), as determined by the corrected peak area method incorporating relative response factors (RRFs). In vitro assays revealed that EHC-1 demonstrated concentration-dependent antioxidant activity in DPPH, ABTS, and hydroxyl radical scavenging assays, with relatively higher efficacy against hydroxyl radicals (IC 50 = 2.43 ± 0.066 mg/mL). Furthermore, EHC-1 showed moderate antibacterial effects against both Escherichia coli and Staphylococcus aureus strains, with stronger effects against the latter.