Extracts of Leaves of Six Locally Available Plants from Bagmati Province of Nepal as Potent Inhibitors of Alpha-amylase, Lipase, Tyrosinase, Elastase, and Cholinesterases

Medicinal plants and their products are gaining global popularity due to their several health benefits. However, the biological activities of the vast majority of medicinal plant species have not been explored yet. In this study, we evaluated the enzyme inhibitory potential of six medicinal plant species involved in digestion, skin-related problems, and neurological problems. The 80% methanol extracts of leaves of six locally available plants from the Bagmati province of Nepal were analyzed for their flavonoids content, phenolics content, antioxidant activity, and enzymes inhibitory potential. Antioxidant activity was analyzed by the DPPH assay. Alpha-amylase inhibition was carried out by the DNSA method. Lipase, tyrosinase, elastase, acetylcholinesterase, and butyrylcholinesterase inhibitions were analyzed by using p-NPB, L-DOPA, AAAPVN, acetylthiocholine, and butyrylthiocholine as a respective substrate. Among the analyzed plants species, Artocarpus heterophyllus displayed highest α-amylase (IC50=6.28 ± 0.01 μg/mL), lipase (IC50= 475.14 ± 3.17 μg/mL), elastase (IC50= 72.75 ± 3.41 μg/mL) and acetylcholinesterase (IC50= 68.66 ± 1.71 μg/mL) inhibition, whereas, Actinidia deliciosa displayed highest tyrosinase inhibition (IC50=139.87 ± 0.72 μg/mL) and butyrylcholinesterase inhibition (IC50= 18.32 ± 0.44 μg/mL). Furthermore, Jasminum humile showed no inhibitory tendencies against elastase and Lygodium japonicum showed no inhibition towards lipase and elastase at the given concentration range. Our study revealed that A. deliciosa and A. heterophyllus are the potential source of α- amylase, lipase, elastase, acetylcholinesterase, and butyrylcholinesterase inhibitors. Based on our findings, we concluded that the analyzed plant species are of great scientific interest to the pharmaceutical, cosmetics, and food industries.