<p>The phytochemical investigation and evaluation of the phytotoxic effect of the extract and fractions obtained from the leaves of <italic>Annona nutans</italic>(R. E. Fr.) R. E. Fr. were performed. Phytotoxic activity was assessed on radicle and hypocotyl of <italic>Allium cepa</italic> and <italic>Lactuca sativa</italic>, where chloroform and ethyl acetate fractions proved active. Phytochemical investigation of the chloroform fraction was allowed identification of polyketides derivatives: triacontanal, 16-hentriacontane, octacosanol and triacontanol, using the ¹H NMR technique associated with data from GC/MS. Using ethyl acetate fraction, with low activity, flavonoids 3-<italic>O</italic>-β-D-galactopyranosyl-isorhamnetin, 3-<italic>O</italic>-β-D-galactopyranosyl-quercetin and 3-<italic>O</italic>-β-D-apiofuranosyl-(1→2)-galactopyranosyl-quercetin were identified, determined by spectrometric techniques one and two-dimensional NMR, combined with mass spectral data. All substances are being reported for the first time in <italic>Annona nutans</italic>. The phytotoxic activity of chloroform fraction may be related to the presence of triacontanol and similar substances. Triacontanol stimulates growth at very low concentrations, but can have an inhibitory effect at higher concentrations, such as those reported for auxin analogs. The toxicity assay using <italic>Artemia salina</italic> (BST) was also performed, with the chloroform fraction showing a negligible lethal dose, LD₅₀ = 500 mg mL^-1, while the other fractions and extracts showed no activity. Thus, the presence of acetogenins was ruled out.</p>