Ginger Phytotoxicity: Potential Efficacy of Extracts, Metabolites and Derivatives for Weed Control

The negative implications for weeds encourage the finding of novel sources of phytotoxic agents for sustainable management. While traditional herbicides are effective, especially at large scales, the environmental impact and proliferation of resistant biotypes present major challenges that natural sources could mitigate. In this study, the potential of ginger metabolites as phytotoxic agents has been investigated for the first time. Root extracts, prepared via various extraction techniques, showed phytotoxicity in wheat (Triticum aestivum L. cv. Burgos) coleoptile bioassays at 800–100 ppm, and the most active extract (prepared by sonication with ethyl acetate) was purified by chromatographic methods, yielding seven compounds: five phenolic metabolites with gingerol and shogaol structures, β-sitosterol, and linoleic acid. Some of the major phenolic metabolites, especially [6]-shogaol and [6]-gingerol, exerted phytotoxicity on wheat coleoptiles, Plantago lanceolata and Portulaca oleracea (broadleaf dicotyledon weeds). This promoted the study of a collection of derivatives, revealing that the 5-methoxy, oxime, and acetylated derivatives of [6]-shogaol and [6]-gingerol had interesting phytotoxicities, providing clues for improving the stability of the isolated structures. Ginger roots have been demonstrated to be a promising source of bioactive metabolites for weed control, offering novel materials with potential for the development of agrochemicals based on natural products.