Phytochemical profile, antioxidant, α-amylase inhibition, binding interaction and docking studies of Justicia carnea bioactive compounds with α-amylase

The present study investigated the antioxidant and in vitro antidiabetic capacities of Justicia carnea aqueous leaf extract (JCAE) using alpha-amylase inhibition model. alpha-Amylase binding-interaction with JCAE was also investigated using fluorescence spectroscopy and molecular docking. Phytochemical screening and Gas Chromatography-Mass Spectrometry (GC-MS) analysis indicated presence of bioactive compounds. Phenolic (132 mg GAE/g) and flavonoid contents (31.08 mg CE/g) were high. JCAE exhibited high antioxidant capacity and effectively inhibited alpha-amylase activity (IC50, 671.43 +/- 1.88 ng/mL), though lesser than acarbose effect (IC50, 108.91 +/- 0.61 ng/mL). alpha-Amylase intrinsic fluorescence was quenched in the presence of JCAE. Ultraviolet-visible and FT-IR spectroscopies affirmed mild changes in a-amylase conformation. Synchronous fluorescence analysis indicated alterations in the microenvironments of tryptophan residues near a-amylase active site. Molecular docking affirmed non-polar interactions of compounds 6 and 7 in JCAE with Asp-197 and Trp-58 residues of a-amylase, respectively. Overall, JCAE indicated potential to prevent postprandial hyperglycemia by slowing down carbohydrate hydrolysis.

Automated summary

The study found that Justicia carnea aqueous leaf extract has high antioxidant and antidiabetic capacities, potentially preventing postprandial hyperglycemia by slowing down carbohydrate hydrolysis.