The Effect of Extraction Solvent on the Phytochemical Contents and Antioxidant and Acetylcholinesterase Inhibitory Activities of Extracts from the Leaves, Bark and Twig of Dipterocarpus alatus

Abstract

The leaves, bark, and twigs of Dipterocarpus alatus have been used to treat many diseases because they contain large amounts of bioactive compounds that can protect against free radical damage. The extraction process is a key step in the utilization of bioactive compounds from plants. Therefore, the aim of this study was to determine the phytochemical compounds, antioxidant capacity and acetylcholinesterase (AChE) inhibitory activity of extracts of D. alatus leaves, bark and twig prepared using three extraction solvents with different polarities; methanol (MeOH), ethanol (EtOH) and isopropyl alcohol (IPA). The results revealed that the bark and twig extracts had a strong antioxidant activity, while the leaves had a potential AChE inhibitory activity. The strong antioxidant activity found in MeOH and EtOH extracts was related to their phenolic acid contents. A class of triterpenoid compounds, dipterocarpol and betulonic acid, which were abundant in the IPA extract, and their presence correlated with AChE inhibitory activity. Solvent polarity was therefore a critical extraction parameter affecting phytochemical content and biological activity.