Network analysis, chemical characterization, antioxidant and enzyme inhibitory effects of foxglove (Digitalis cariensis Boiss. ex Jaub. & Spach): A novel raw material for pharmaceutical applications

The present study outlines the phenolic composition and pharmacological properties of different extracts of Digitalis cariensis Boiss. ex Jaub. & Spach root and aerial parts. The metabolic profiles of the studied extracts were characterized by UHPLC-MS. The in vitro antioxidant and enzyme (acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-amylase, and α-glucosidase) inhibitory potential of the extracts were determined. Bioinformatics and docking investigations were also conducted to support the enzyme inhibition test and predict putative targets for potential pharmacological applications. Overall, the methanolic extract followed by the water extract of the D. cariensis root were found to be superior source of antioxidant compounds except for metal chelating ability, in which the water extract of the root (26.34 ± 1.54 mg EDTAE/g) and aerial parts (16.47 ± 0.88 mg EDTAE/g) have showed the highest activity. The tested extracts were potent against AChE (9.11 ± 0.27-9.79 ± 0.28 mg GEs/g extract), α-amylase (0.12 ± 0.01- 0.50 ± 0.01 mmol ACEs/g extract) and α-glucosidase (0.28 ± 0.01-17.29 ± 0.24 mmol ACEs/ g extract). Notable activity against tyrosinase was displayed by the methanolic extracts (Root-MeOH: 123.71 ± 2.70 and aerial parts - MeOH: 137.96 ± 1.07 mg KAE/g extract), while none of the extracts were potent against BChE. According to docking investigations, the observed anti-tyrosinase effect could be related, at least partially, to the presence of luteolin, rosmarinic acid and kaempferol in the extracts. Results amassed herein is the first report on the biological attributes of D. cariensis, which validate the pharmacological uses of this plant.

Keywords: Antioxidants; Chemical fingerprints; Enzyme inhibitors; Foxglove; Network analysis.