Phenyl cinnamate derivatives from Oxalis pes-caprae.

During the screening of Mediterranean invasive plants, Oxalis pes-caprae was identified as promising species. The fresh leaves and twigs of the plant were crumbled and extracted with AcOEt. The solution was concentrated, and separated into acidic and neutral fractions. The crude neutral residue was fractionated by chromatographic procedures, followed by structure elucidation on the basis of 1H- and 13C-NMR, and MS data analysis, and six new phenyl cinnamate derivatives were identified. The phytotoxic effects of the isolated compounds on the germination and growth of the dicotyledon Lactuca sativa L. (lettuce) were studied in the concentration range from 10(-4) to 10(-7) M.