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

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