Chemical Composition of the Bark of <i>Tetrapterys mucronata</i> and Identification of Acetylcholinesterase Inhibitory Constituents

The secondary metabolite content of <i>Tetrapterys mucronata</i>, a poorly studied plant that is used occasionally in Brazil for the preparation of a psychotropic plant decoction called “Ayahuasca”, was determined to establish its chemical composition and to search for acetylcholinesterase (AChE) inhibitors. The ethanolic extract of the bark of <i>T. mucronata</i> exhibited in vitro AChE inhibition in a TLC bioautography assay. To localize the active compounds, biological profiling for AChE inhibition was performed using at-line HPLC-microfractionation in 96-well plates and subsequent AChE inhibition bioautography. The analytical HPLC-PDA conditions were transferred geometrically to a preparative medium-pressure liquid chromatography column using chromatographic calculations for the efficient isolation of the active compounds at the milligram scale. Twenty-two compounds were isolated, of which six are new natural products. The structures of the new compounds (<b>9</b>, <b>10</b>, <b>16</b>–<b>18</b>, and <b>20</b>) were elucidated by spectroscopic data interpretation. Compounds <b>1</b>, <b>5</b>, <b>6</b>, <b>9</b>, and <b>10</b> inhibited AChE with IC₅₀ values below 15 μM