8.C.8. The Celangulin V (CV) Family
The botanical insecticide celangulin V (CA-V) is a polycyclic insect digestive poison acting on midgut tissues of the target insect larvae. It is the main insecticidal constituent of Celastrus angulatus and is associated with the midgut epithelia of the target insects (Qi et al. 2006). The V-ATPase H subunit of the midgut cells of lepidopteran larvae is the putative target protein of celangulin V (Wang et al. 2017).
compared the effects of CV on the midgut membrane potentials of Mythimna separata and Agrotis ipsilon larvae with those of the Cry1Ab toxin from Bacillus thuringiensis and with those of inactive CV-MIA, a synthetic derivative of CV. They investigated the changes in the apical membrane potentials (Vam) and basolateral membrane potentials (Vbm) of the midguts of sixth-instar larvae force-fed with the test toxins. Similar to the effect of Cry1Ab, the Vam of CV-treated midguts rapidly decayed over time in a dose-dependent manner while CV-MIA did not influence Vam. the Vam of A. ipsilon larval midguts directly incubated with CV decayed less than that of M. separata larval midguts. Similar to Cry1Ab, CV did not affect the Vbm of isolated midguts. CV initially inhibits V-ATPase in the apical membrane, affecting intracellular pH, homeostasis, and nutrient transport mechanisms in lepidopteran midgut cells (Wang et al. 2017). The AB subunits of the V-ATPase are the probable targets of CV (Ding et al. 2019).