Khellin and Visnagin, Furanochromones from Ammi visnaga (L.) Lam., as Potential Bioherbicides

Abstract

Plants constitute a source of novel phytotoxic compounds to be explored in searching for effective and environmentally safe herbicides. From a previous screening of plant extracts for their phytotoxicity, a dichloromethane extract of Ammi visnaga (L.) Lam. was selected for further study. Phytotoxicity-guided fractionation of this extract yielded two furanochromones, khellin and visnagin, for which herbicidal activity had not been described before. Khellin and visnagin were phytotoxic to model species lettuce (Lactuca sativa) and duckweed (Lemna paucicostata), with IC values ranging from 110 to 175 μM. These compounds also inhibited the growth and germination of a diverse group of weeds at 0.5 and 1 mM. These weeds included five grasses [ryegrass (Lolium multiflorum), barnyardgrass (Echinocloa crus-galli), crabgrass (Digitaria sanguinalis), foxtail (Setaria italica), and millet (Panicum sp.)] and two broadleaf species [morningglory (Ipomea sp.) and velvetleaf (Abutilon theophrasti)]. During greenhouse studies visnagin was the most active and showed significant contact postemergence herbicidal activity on velvetleaf and crabgrass at 2 kg active ingredient (ai) ha. Moreover, its effect at 4 kg ai ha was comparable to the bioherbicide pelargonic acid at the same rate. The mode of action of khellin and visnagin was not a light-dependent process. Both compounds caused membrane destabilization, photosynthetic efficiency reduction, inhibition of cell division, and cell death. These results support the potential of visnagin and, possibly, khellin as bioherbicides or lead molecules for the development of new herbicides.

Ammi Visnaga L., a Potential Medicinal Plant: A Review

“…For this purpose, the larvicidal and insecticidal properties of A. visnaga were studied, and the toxicity of khellin was investigated against nymphs Oncopeltus fasciatus (Hemiptera) and the larvae of Aedes aegypti (Diptera), where it showed great activity [88]. Studying the acaricidal and ovicidal activity of khellin and visnagin against Tetranychus urticae showed that both khellin and visnagin were highly promising, and could be used for the development of new botanical acaricides from A. visnaga [89], as well as that they were both phytotoxic to model species lettuce (Lactuca sativa) and duckweed (Lemna paucicostata) [90]. The fruit extract was found to possess an inhibitory action on the lipid content in haemolymph of nymphs and adults [91], while the n-butanolic extract of A.visnaga was also shown to prevent the activity of Glutamic oxaloacetic transaminase (GOT) and Glutamic pyruvic transaminase (GPT) in haemolymph and fat bodies of last instar nymphs and newly-emerged adult females of the dangerous desert locust, Schistocerca gregaria [92].…”

“…A study done in Argentina found that the dichloromethane extract of A. visnaga had a significant herbicidal effect. Phytotoxicity fractionation was done, and the fraction that contained khellin and visnagin was found to be responsible for its significant herbicidal activity [90].…”

Chemical and biological potential of Ammi visnaga (L.) Lam. and Apium graveolens L.: A review (1963-2020)

“…visnaga dichloromethane extract exhibited herbicidal activity. Khellin and visnagin were responsible for their herbicidal effect [22,52].…”

Acute and subacute toxicity of Ammi visnaga on rats

“…This herbicidal activity of khellin and visnagin was not a light-dependent effect. Both khellin and visnagin induced photosynthetic efficiency decrease, membrane destabilization, decline in cell division and death (Travaini et al, 2016). Khellin showed very fast mortality effect for the larvae of Culex quinquefasciatus in various development stages so 18 minutes of khellin action induced a 54.3% mortality rate of the larvae within 24 hours (Pavela et al, 2016).…”