Ocotea daphnifolia: phytochemical investigation, in vitro dual cholinesterase inhibition, and molecular docking studies

This study aimed to evaluate the anticholinesterase activities of extracts and fractions of Ocotea daphnifolia in vitro and characterize its constituents. The effects of hexane, ethyl acetate, and ethanolic extracts on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activity were determined with a spectrophotometry assay. All extracts inhibited cholinesterase activity, and the ethanolic extract (2 mg/mL) exhibited the highest inhibition of both enzymes (99.7% for BuChE and 82.4% for AChE). The ethanolic extract was fractionated by column chromatography resulting in 14 fractions that were also screened for their anticholinesterase effects. Fraction 9 (2 mg/mL) showed the highest activity, inhibiting AChE and BuChE by 71.8% and 90.2%, respectively. This fraction was analyzed by high-performance liquid chromatography high-resolution mass spectrometry which allowed the characterization of seven glycosylated flavonoids (containing kaempferol and quercetin nucleus) and one alkaloid (reticuline). In order to better understand the enzyme-inhibitor interaction of the reticuline toward cholinesterase, molecular modeling studies were performed. Reticuline targeted the catalytic activity site of the enzymes. Ocotea daphnifolia exhibits a dual cholinesterase inhibitory activity and displays the same pattern of intermolecular interactions as described in the literature. The alkaloid reticuline can be considered as an important bioactive constituent of this plant.

Chemical composition, antioxidant and biological activity of Ocotea bicolor Vattimo-Gil (LAURACEAE) essential oil

ABSTRACT The essential oil composition of the Ocotea bicolor, native plant of Brazil, was studied for the first time. The essential oil of the leaf was obtained by hydrodistillation and analyzed by GC/MS. The analytical procedure revealed a predominance of sesquiterpenes, δ-cadinene (7.39%), ß-sesquiphellandrene (6.67%), ß-elemene (5.41%) and α-cadinol (5,23%). The essential oil was submitted to brine shrimp toxicity evaluation, antioxidant and antibacterial tests. The antioxidant activity by the formation of phosphomolybdenum complex method presented positive results. The minimum inhibitory concentration (MIC) values were higher than 1000 µg/mL for the microorganisms tested. Toxicity activity revealed LC50 results of 40.10 (µg/mL), being toxic to the organisms in this study