Аннотация
Abstract Arnebia decumbens (Vent.) Coss. & Kralik is a poorly studied member of the Boraginaceae family with potential medicinal value. This study aimed to investigate the phytochemical composition and biological activities of the aerial and root parts of A.decumbens collected in Kazakhstan. Phytochemical screening revealed the presence of phenolics, flavonoids, anthraquinones, tannins, alkaloids, saponins, amino acids, carbohydrates, and essential mineral elements, with roots containing higher levels of anthraquinones (3.8%) and several bioactive metabolites than aerial parts. The root extract exhibited significantly higher total phenolic content (58.31 ± 2.82 mg GAE/g extract) than the aerial part (32.67 ± 1.26 mg GAE/g extract), which was accompanied by stronger antioxidant activity in both DPPH (175.47 ± 1.96 mg TE/g) and ABTS (104.52 ± 1.06 mg TE/g) assays. In antidiabetic assays, the root extract demonstrated superior inhibition of α-glucosidase and α-amylase, with IC50 values of 627.18 and 548.52 μg/mL, respectively. The strongest antimicrobial activity was observed for the root extract against Pseudomonas aeruginosa (MIC = 78 μg/mL), followed by Enterococcus faecalis (MIC = 156 μg/mL). Cytotoxicity assessment revealed selective activity of the root extract against K562 and Saos-2 cancer cell lines, with IC50 values of 235 and 290 μg/mL, respectively, while no toxicity was detected toward normal NIH-3T3 fibroblasts (IC50 > 2500 μg/mL). The higher biological activity of the roots was closely associated with their elevated phenolic and anthraquinone contents. These findings identify A.decumbens roots as a promising source of natural antioxidant, antidiabetic, antimicrobial, and anticancer agents and provide the first comprehensive evidence supporting the pharmacological potential of this species.