Alpha-amylase inhibitory activity and in silico studies of in vitro sweet basil plantlets treated with chitosan and ZnO NPs

In this study, an efficient protocol was developed to obtain multiplicated, healthy sweet basil plantlets with larger leaves and a greener color by culturing them on MS medium containing 1.0 mg/l 2iP. Chitosan and zinc oxide nanoparticles (ZnO NPs) were used as abiotic elicitors to maximize the main secondary metabolites (phenolic and flavonoid compounds and essential oil) in in vitro plantlets of sweet basil. Chitosan with a concentration of 4.0 mg/l recorded the maximum value of caffeic acid (1.189 mg/g DW), and 10 mg/l of ZnO NPs recorded the maximum content of rutin (0.936 mg/g DW). The plantlets cultured with 2.0 mg/l chitosan recorded the maximum percentage of essential oil (90.63%). 8,9-Dihydro-9-formyl cycloisolongifolene was the major compound (72.44%) and was detected in the plantlets treated with 2.0 mg/l chitosan. The inhibitory activity evaluation of α-amylase revealed that the maximum inhibitory activity was found in the plantlet control and those treated with 4.0 mg/l chitosan of the phenolic and flavonoid fractions. The maximum IC 50 (7.36 ± 0.85) was found in the plantlet extract treated with 4.0 mg/l chitosan, followed by the plantlet control, which recorded 11.53 ± 0.86. Using AutoDuck 4.2 and PyMol software, it was revealed that rutin and caffeic acid compounds (the main active components) own hydrogen binding interactions and hydrophobic binding interactions with the active site of alpha-amylase from the porcine pancreas (PPA) enzyme with good binding energy (5.74 and 5.71 kcal/mol, respectively).