Phytochemical study and biological activities of crude polysaccharides extracted from seeds of (Larta) Calligonum polygonoides subsp. comosum (L'Hér.) Soskov. collected from Oued Souf region

Abstract

The present study investigated the phytochemical composition, antioxidant potential, biological activities, acute toxicity, and gastroprotective effects of polysaccharide-rich extracts obtained from Calligonum comosum seeds. Quantitative phytochemical analyses revealed a total phenolic content (TPC) of 61.37 mg GAE/g extract, a total flavonoid content (TFC) of 16.09 ± 0.22 mg QE/g extract, and a condensed tannin content (CTC) of 194.27 mg CE/g extract, indicating that the extract is particularly rich in polyphenolic constituents associated with antioxidant and protective biological activities. Evaluation of antioxidant activity using the DPPH radical scavenging assay demonstrated a concentration-dependent response, with inhibition percentages increasing from 2.71% at 0.1 mg/mL to 11.65% at 0.6 mg/mL. The calculated IC₅₀ value was 3.79 mg/mL, confirming moderate but biologically significant antioxidant activity of the polysaccharide fraction. In vitro photoprotective analysis revealed exceptionally high sun protection factor (SPF) values of 94.76 ± 10.34 and 113.85 ± 48.30, suggesting strong UVB-absorbing capacity attributable to phenolic– polysaccharide conjugates. Biological investigations further demonstrated marked antitussive and gastroprotective activities. In the HCl-induced gastric ulcer model, the untreated ulcerated group exhibited an ulcer area of 125 mm², whereas treatment with the extract significantly reduced lesion severity. The most effective treatment group (A2) produced an ulcer area of only 22 mm² with an inhibition rate of approximately 82.4%, surpassing the positive control treatment. Acute toxicity assessment showed no evidence of severe organ toxicity, indicating a favorable short-term safety profile of the extract. Overall, the findings demonstrate that Calligonum comosum seed polysaccharides possess promising antioxidant, photoprotective, antitussive, and gastroprotective properties with potential pharmaceutical applications.