Phytotoxic phenylpropanoids isolated from Ophryosporus charua (Griseb.) Hieron

Bioguided isolation of the EtOH extract from the medicinal native plant, Ophryosporus charua, against Raphanus sativus, yielded three phenylpropanoids, charuol A [(Z)-4-((1S,2R)-3-acetoxy-1,2-dihydroxypropyl)phenyl) 2-methylbut-2-enoate], charuepoxide [(Z)-4-((2S,3R)-3-(acetoxymethyl oxiran-2-yl)phenyl) 2-methylbut-2-enoate] and charuol B [(Z)-4-((1R,2R)-3-acetoxy-1,2-dihydroxypropyl)phenyl) 2-methylbut-2-enoate]. Their structures and absolute configuration were established by extensive spectroscopic analyses. The effective concentrations for 50% inhibition of germination (ECg50) and root (ECr50) and shoot (ECs50) elongations were determined for these compounds against P. miliaceum (monocot) and Raphanus sativus (dicot). Charuol A was the most active in the inhibition of germination of P. miliaceum (ECg50 = 0.97 mM), followed by charuol B and charuepoxide, although charuol B was the most effective in regulating the root growth of P. miliaceum seedlings, with an ECr50 of 1.0 mM. Charuol A inhibited the germination of R. sativus, while its seedling development was also affected by all three compounds with different effectiveness. Charuol A was also highly effective in the 0.09–0.30 mM range against other test species such as Lactuca sativa, Eruca sativa, Allium ampeloprasum and Secale cereale. Fil: Bravetti, Margarita María del Milagro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Católica de Córdoba; Argentina Fil: Vico, Raquel Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina