Parasitic weeds cause high damage on crops production each year and their seed bank is almost indestructible. The strategy of suicidal germination is based on the principle of applying germination stimulants in the soil to make the parasites germinate before sowing a crop to which they can attach. This process leads the parasitic seedlings to an inevitable death due to nutrient starvation. [1] Synthetic analogues of germination- inducing factors constitute a cheap and feasible strategy to control seed bank of weeds, although, the stimulant should be easily synthesized and economical to afford mass production. We synthesized a family of N-substituted phthalimides with a lactone ring and containing different substituents in the aromatic ring. The synthetic procedure is simple and starts with commercially available phthalimides. We called this compounds phthalimide-lactones. Recently, we have also synthetized new amide derivatives with different chain sizes in positions 3 and 4. The complete collection (PL00-18) was purified and assayed against parasitic weeds O. minor, O. cumana and P. ramosa. In summary, our structure-activity relationship analysis demonstrated high selectivity according with the structural modification and parasitic species tested. Some of our structural modifications induced levels of germination comparable with the positive control GR- 24, a synthetic analogue of strigolactones, natural and most active host- derived germination-inducing factors. The use of these compounds as new leads for weed control is discussed.

This research was supported by the Ministerio de Economía y Competitividad, Project AGL2013-42238-R and Marie-Curie FP7 COFUND People Programme, AgreenSkills’ fellowship (PCOFUND-GA-2010-267196).

Trabajo presentado en la XXXV Reunión Bienal de la Real Sociedad Española de Química (RSEQ), celebrado en A Coruña del 19 al 23 de julio de 2015.

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