The chemical constituents of the aerial parts of <i>Larrea divaricata</i> and <i>Larrea cuneifolia</i> and their <i>in vitro</i> antimicrobial and cytotoxic activities

Seventeen molecules, including hydroxycinnamate esters, lignans and flavonoids, were isolated from <i>Larrea divaricata</i> and <i>Larrea cuneifolia</i>. The hydroxycinnamate ester divaricatoate (<b>3</b>) and its 4-deoxy form (<b>4</b>) are reported for the first time, whereas the flavonoid 3-methoxyherbacetin (<b>14</b>) is redescribed here, as it had been previously mischaracterised in the literature. Extracts and most of the 17 compounds were tested against <i>Fusarium graminearum</i> and <i>Salmonella enterica</i>. Nordihydroguaiaretic acid (<b>5</b>) and ent <i>(R-R)</i>-parakmerin A (<b>8</b>) showed the lowest MIC values on <i>S. enterica</i> (1.6 and 12.5 µg, respectively) and <i>F. graminearum</i> (25 µg and 3.1 µg, respectively). Both compounds synergized the antimicrobial activity of chloramphenicol and tebuconazole. Tested on human cell lines, <i>Larrea</i> extracts showed higher EC₅₀ values than tebuconazole, whereas compound <b>5</b> exhibited similar values and compound <b>8</b> showed similar or lower values. These compounds are promising antimicrobial agents and chemosensitizers, but their cytotoxicities require further investigation for therapeutic or pesticidal use.