Chemical composition, enzyme inhibitory activities, and molecular docking studies of essential oil of Knema globularia leaves from Vietnam

In the present work, chemical composition, enzyme inhibitory activities, and molecular docking studies of essential oil (EO) of Knema globularia leaves collected from Vinh Phuc Province, Vietnam, were investigated. The EO from the leaves of K. globularia was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS) analysis. The leaf EO yield was 0.14 ± 0.01% (w/w), comprising 39 identified components, constituting 96.77% of the EO content. Notable constituents included β-caryophyllene (54.11%), α-humulene (12.67%), and (E)-β-ocimene (8.82%). Enzyme inhibitions were assessed via the α-amylase inhibitory assay (IC50 = 282.71 ± 10.06 μg/mL) and tyrosinase inhibitory assay (IC50 = 993.92 ± 37.40 μg/mL). The molecular docking method has been employed to observe valuable binding interactions and binding energy with the main compounds on the target enzymes α-amylase and tyrosinase. Caryophyllene oxide exhibits the strongest affinity with α-amylase among the other major compounds. Meanwhile, viridiflorene shows the best binding energy with the tyrosinase enzyme. This is the first study providing valuable scientific data on the in vitro inhibitory activities of α-amylase and tyrosinase enzymes of the leaf EO of K. globularia and evaluating its main compounds through a molecular docking approach on these enzyme targets.