Oligosaccharides from Scorzonera yildirimlii and S. zorkunensis, and their potential antimicrobial, enzyme inhibition, cytotoxic effect, and in silico study

Abstract

In this study, the phytochemical investigation of Scorzonera yildirimlii and S. zorkunensis led to the isolation and identification of eight new oligosaccharide constituents (1–8). Their structures were elucidated through comprehensive spectroscopic analysis (NMR, FT-IR, and mass spectrometry) and comparison with literature data. The structure of isolated compounds were O-α-D-Glcp-(1 → 2)-O-β-D-Fruf-(3 → 1)-O-myo-inositol (1), O-α-D-Glcp-(1 → 2)-O-β-D-Fruf-(3 → 1)-O-epi-inositol (2), O-β-D-Fruf-(2 → 6)-O-α-D-Glcp-(1 → 1)-O-β-D-Glcp (3), O-β-D-Fruf-(2 → 6)-O-α-D-Glcp-(1 → 1)-O-β-D-Galp (4), O-β-D-Fruf-(2 → 6)-O-β-D-Fruf-(2 → 6)-O-α-D-Glcp-(1 → 1)-O-β-D-Glcp (5), O-β-D-Fruf-(2 → 6)-[O-β-D-Glcp-(1 → 4)]-O-α-D-Glcp-(1 → 1)-O-β-D-Glcp (6), O-β-D-Fruf-(2 → 6)-[O-β-D-Glcp-(1 → 4)]-3-OCH3-O-α-D-Glcp-(1 → 1)-O-β-D-Glcp (7), and O-β-D-Fruf-(2 → 6)-[O-β-D-Glcp-(1 → 4)]-O-α-D-Glcp-(1 → 4)-O-α-D-Glcp-(1 → 2)-O-β-D-Fruf (8). The antimicrobial activities of all the isolated compounds (1–8) were investigated against six microorganisms. Compounds 2 and 3 were effective against Mycobacterium smegmatis at minimum inhibitory concentrations (MICs) of 3.13 μg/mL and 3.44 μg/mL, respectively, compared with streptomycin (MIC = 4.0 μg/mL). The enzyme-inhibitory properties of the isolated compounds (1–8) were evaluated against tyrosinase and α-glucosidase. Among the tested compounds, 4 (39.78 ± 10.29 %) exhibited inhibitory activity against tyrosinase, while compound 2 (68.04 ± 4.68 %) exhibited inhibitory activity against α-glucosidase. In silico studies of 1–8 showed the best predicted binding affinities for the Trehalose-LpqY complex in the range of −11.088 kcal/mol to −14.297 kcal/mol, compared to streptomycin (−6.638 kcal/mol). Compounds 1–8 exhibited almost no cytotoxic activity against L-929 cells, further supporting their potential for therapeutic use.