Sarmentine, a natural herbicide from Piper species with multiple herbicide mechanisms of action

Abstract

Sarmentine, 1-(1-pyrrolidinyl)-(2E,4E)-2,4-decadien-1-one, is a natural amide isolated from the fruits of Piper species. The compound has a number of interesting biological properties, including its broad-spectrum activity on weeds as a contact herbicide. Initial studies highlighted a similarity in response between plants treated with sarmentine and herbicidal soaps such as pelargonic acid (nonanoic acid). However, little was known about the mechanism of action leading to the rapid desiccation of foliage treated by sarmentine. In cucumber cotyledon disc-assays, sarmentine induced rapid light-independent loss of membrane integrity at 100 μM or higher concentration, whereas 3 mM pelargonic acid was required for a similar effect. Sarmentine was between 10 and 30 times more active than pelargonic acid on wild mustard, velvetleaf, redroot pigweed and crabgrass. Additionally, the potency of 30 μM sarmentine was greatly stimulated by light, suggesting that this natural product may also interfere with photosynthetic processes. This was confirmed by observing a complete inhibition of photosynthetic electron transport at that concentration. Sarmentine also acted as an inhibitor of photosystem II (PSII) on isolated thylakoid membranes by competing for the binding site of plastoquinone. This can be attributed in part to structural similarities between herbicides like sarmentine and diuron. While this mechanism of action accounts for the light stimulation of the activity of sarmentine, it does not account for its ability to destabilize membranes in darkness. In this respect, sarmentine has some structural similarity to crotonoyl-CoA, the substrate of enoyl-ACP reductase, a key enzyme in the early steps of fatty acid synthesis. Inhibitors of this enzyme, such as triclosan, cause rapid loss of membrane integrity in the dark. Sarmentine inhibited the activity of enoyl-ACP reductase, with an I50app of 18.3 μM. Therefore, the herbicidal activity of sarmentine appears to be a complex process associated with multiple mechanisms of action.

Recent advances in allelopathy for weed control: from knowledge to applications

“…Other compounds, such as sarmentine, interfere with photosynthetic processes by complete inhibition of photosystem II. Electron transport is inhibited because sarmentine competes for the binding site of plastoquinones …”

“…156,160 Sarmentine, a nitrogen-containing natural product isolated from the fruit of Piper species, was discovered by bioassay-guided isolation with lettuce seeds. 161 It inhibits growth of pigweed (Amaranthus retroflexus L.), barnyard grass (Echinochloa crus-galli L.), bindweed (Convolvulus arvensis L.), crabgrass (Digitaria sanguinalis L.), dandelion (Taraxacum officinale F.), lambsquarter (Chenopodium album L.), annual bluegrass (Poa annua L.), wild mustard (Brassica kaber L.), black nightshade (Solanum nigrum L.), curly dock (Rumex crispus L.) and horseweed (Conyza canadensis L.). Some of the symptoms observed in these weeds included bent stems, closed leaves and tiny black spots.…”

“…Electron transport is inhibited because sarmentine competes for the binding site of plastoquinones. 161 Nevertheless, the main targets of cytotoxic alkaloids include DNA, RNA and associated enzymes such as telomerases, polymerases or topoisomerases. In the case of topoisomerases, inhibition induced by recently isolated alkaloids reduces the stability of the uncoiled DNA chain.…”

Herbicidal Ionic Liquids Containing the Acetylcholine Cation

“…Moreover, ionic liquids are characterized by very low vapour pressure and relatively low flammability, which minimize the risk of fire or explosion ,. Introduction of the organic cation of natural origin into the structure of HIL may result in lowering the toxicity of the anion ,. Moreover, herbicidal ionic liquids may be applied at lower dose in comparison to the commercial substances ,,,,,.…”

“…Moreover, herbicidal ionic liquids may be applied at lower dose in comparison to the commercial substances ,,,,,. Natural‐derived compounds characterized by common accessibility, renewability and biodegradability are in scope of research by scientists around the world ,. Choline‐derivative‐based ionic liquids are known in the literature .…”