Anti-acetylcholinesterase activity and antioxidant properties of extracts and fractions of <i>Carpolobia lutea</i>

<p><b>Context:</b> There is an unmet need to discover new treatments for Alzheimer’s disease. This study determined the anti-acetylcholinesterase (AChE) activity, DPPH free radical scavenging and antioxidant properties of <i>Carpolobia lutea</i> G. Don (Polygalaceae).</p> <p><b>Objective:</b> The objective of this study is to quantify <i>C. lutea</i> anti-AChE, DPPH free radical scavenging, and antioxidant activities and cell cytotoxicity.</p> <p><b>Materials and methods:</b> Plant stem, leaves and roots were subjected to sequential solvent extractions, and screened for anti-AChE activity across a concentration range of 0.02–200 μg/mL. Plant DPPH radical scavenging activity, reducing power, and total phenolic and flavonoid contents were determined, and cytotoxicity evaluated using human hepatocytes.</p> <p><b>Results:</b><i>Carpolobia lutea</i> exhibited concentration-dependent anti-AChE activity. The most potent inhibitory activity for the stem was the crude ethanol extract and hexane stem fraction oil (IC<sub>50</sub> = 140 μg/mL); for the leaves, the chloroform leaf fraction (IC<sub>50</sub> = 60 μg/mL); and for roots, the methanol, ethyl acetate and aqueous root fractions (IC<sub>50</sub> = 0.3–3 μg/mL). Dose-dependent free radical scavenging activity and reducing power were observed with increasing stem, leaf or root concentration. Total phenolic contents were the highest in the stem: ∼632 mg gallic acid equivalents/g for a hexane stem fraction oil. Total flavonoid content was the highest in the leaves: ∼297 mg quercetin equivalents/g for a chloroform leaf fraction. At 1 μg/mL, only the crude ethanol extract oil was significantly cytotoxic to hepatocytes.</p> <p><b>Discussion and conclusions:</b><i>Carpolobia lutea</i> possesses anti-AChE activity and beneficial antioxidant capacity indicative of its potential development as a treatment of Alzheimer’s and other diseases characterized by a cholinergic deficit.</p>