In-vitro and In-silico α-amylase Inhibition Activity of Carlina Oxide and Aplotaxene Isolated From the Roots of Carthamus caeruleus and Rhaponticum acaule

Background:Numerous natural products have been successfully developed for clinical use in the treatment of human diseases in almost every therapeutic area.

Objectives:This work aimed to assess the in-vitro and in-silico α-amylase inhibition activities of carlina oxide and aplotaxene, isolated from the roots of Carthamus caeruleus and Rhaponticum acaule respectively.

Methods:The essential oil from C. caeruleus roots was obtained using a Clevenger-type apparatus, and the hexanoic extract from the roots of R. acaule was obtained through maceration. Major components of each plant were separated via column chromatography. The in-vitro α-amylase inhibition activity was evaluated using porcine pancreatic α-amylase, while the molecular docking study was conducted using the Molecular Operating Environment (MOE) with three types of α-amylase: human salivary, pancreatic α-amylase and Aspergillus oryzae α-amylase (PDB: 1Q4N, 5EMY, 7P4W respectively).

Results:The in-vitro α-amylase inhibition results for the essential oil, the hexanoic extract, carlina oxide and aplotaxene showed that carlina oxide exhibited significant activity with IC50 of 0.42 mg/mL. However, the in-silico study showed no interaction between aplotaxene and the three α-amylase enzymes, whereas carlina oxide demonstrated one pi-cation interaction with 5EMY with the amino acid TYR 62 at a distance of 4.70 Å and two pi-H interactions with 7P4W with the amino acid LYS 383 at distances of 4.31 and 4 .03 Å.

Conclusion:In conclusion, carlina oxide has the potential to serve as an alternative agent for α- amylase inhibition, contributing to the reduction of postprandial hyperglycemia.