Fractionation of the CHCl3 extract of the stem bark of Malmea depressa, guided by phytogrowthinhibitory bioassays, led to the isolation of four known phenylpropanoids: 1,2,3,4-tetramethoxy-5-(2-propenyl)benzene (1), 2,3,4,5-tetramethoxycinnamaldehyde (3), trans-isomyristicin (4), and 2,3,4,5-tetramethoxycinnamyl alcohol (5), and a new C6-C1 derivative that was characterized by spectral means as 2,3,4,5-tetramethoxybenzaldehyde (2). Compound 1 exhibited significant phytogrowth-inhibitory activity on seedlings of Amaranthus hypochondriacus (IC50 = 43 µg/ mL) and Echinochloa crusgalli (IC50 = 810 µg/mL) and moderate antifungal activity against Trichophyton mentagrophytes (MIC 500 µg/mL) and Fusarium oxysporum (MIC = 250 µg/mL).