Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition

Abstract

Decalesides are a new class of natural insecticides which are toxic to insects by contact via the tarsal gustatory chemosensilla. The symptoms of their toxicity to insects and the rapid knockdown effect suggest neurotoxic action, but the precise mode of action and the molecular targets for decaleside action are not known. We have presented experimental evidence for the involvement of sodium pump inhibition in the insecticidal action of decaleside in the cockroach and housefly. The knockdown effect of decaleside is concomitant with the in vivo inhibition of Na+, K+ -ATPase in the head and thorax. The lack of insecticidal action by experimental ablation of tarsi or blocking the tarsal sites with paraffin correlated with lack of inhibition of Na+- K+ ATPase in vivo. Maltotriose, a trisaccharide, partially rescued the toxic action of decaleside as well as inhibition of the enzyme, suggesting the possible involvement of gustatory sugar receptors. In vitro studies with crude insect enzyme preparation and purified porcine Na+, K+ -ATPase showed that decaleside competitively inhibited the enzyme involving the ATP binding site. Our study shows that the insecticidal action of decaleside via the tarsal gustatory sites is causally linked to the inhibition of sodium pump which represents a unique mode of action. The precise target(s) for decaleside in the tarsal chemosensilla and the pathway linked to inhibition of sodium pump and the insecticidal action remain to be understood.

Plant‐Derived Substances Used Against Beetles–Pests of Stored Crops and Food–and Their Mode of Action: A Review

“…In 2012, (Rajashekar, Rao & Shivanandappa) described a new class of insecticide, namely, decalesides. These trisaccharides isolated from edible roots of Dendrocalamus hamiltonii turned out to have insecticidal activity targeting insects gustatory sites probably by sodium pump inhibition (Rajashekar & Shivanandappa, ). At the same time, as natural trisaccharides, they undergo rapid hydrolization in mammalian organisms, which makes these compounds safe for humans.…”

The beneficial effect of clove essential oil and its major component, eugenol, on erectile function in diabetic rats

“…CEO includes many components such as flavonoids, alkaloids and monoterpenes, and has broad pharmacological efficacy (Osanloo, Sedaghat, Esmaeili, & Amani, 2018; Salim, 2017). Furthermore, the pharmacological effects of mentioned constituents are different, for example, the main site action of flavonoids is acetylcholinesterase (Perumalsamy, Jang, Kim, Kadarkarai, & Ahn, 2015), as well as alkaloids and monoterpenes target Na‐K‐ATPase or Na + and K + channels (Lucia, Zerba, & Masuh, 2013; Rajashekar & Shivanandappa, 2017). The differences between the pharmacological activities of CEO and its isolated compound, E may result from the synergistic or additive effects of the secondary compounds.…”

Toxicity of the spiny thick‐foot Pachypodium

“…In addition, novel compounds are emerging that inhibit the Na + /K + -ATPase, including sanguinarine, an isoquinoline alkaloid from poppies (Mackraj et al, 2008), and palytoxin, a fatty alchohol from marine organisms (Rossini and Bigiani, 2011). Perhaps most relevant to the present study, trisaccharides (containing lactones) have been found in roots of Decalepis hamiltonii (Apocynaceae), which have strong insecticidal activity derived from inhibiting the Na + /K + -ATPase (Rajashekar and Shivanandappa, 2017).…”

“…The sodium-potassium pump is a critical cellular enzyme occurring in all animal cells and is responsible for several primary functions, including the maintenance of cell resting potential. Recent work has found novel compounds in the Apocynaceae (e.g., trisaccharides), not traditionally included as cardiac glycosides, that nonetheless gain their toxicity from binding to Na + /K + -ATPase (Rajashekar and Shivanandappa, 2017). Despite the ubiquitous target site of cardiac glycosides in animal cells, hundreds of adapted insect species specialize on cardenolide-containing plants (Petschenka et al, 2013b;Bramer et al, 2015;Agrawal, 2017;Petschenka et al, 2017).…”