Effects of a Chitin-Binding Vicilin fromEnterolobium contortisiliquumSeeds on Bean Bruchid Pests (Callosobruchus maculatusandZabrotes subfasciatus) and Phytopathogenic Fungi (Fusarium solaniandColletrichum lindemuntianum)

Abstract

Chitin-binding vicilin from Enterolobium contortisiliquum seeds was purified by ammonium sulfate followed by gel filtration on Sephacryl 300-SH and on Sephacryl 200-SH. The vicilin, called EcV, is a dimeric glycoprotein composed of 1.03% carbohydrates and a Mr of 151 kDa, consisting of two subunits of Mr of 66.2 and 63.8 kDa. The EcV homogeneity was confirmed in a PAGE where it was observed to be a unique acid protein band with slow mobility in this native gel. E. contortisiliquum vicilin (EcV) was tested for anti-insect activity against C. maculatus and Zabrotes subfasciatus larvae and for phytopathogenic fungi, F. solani and C. lindemuntianum. EcV was very effective against both bruchids, producing 50% mortality for Z. subfasciatus at an LD50 of 0.43% and affected 50% of the larvae mass with an ED50 of 0.65%. In artificial diets given to C. maculatus, 50% of the larvae mass was affected with an ED50 of 1.03%, and larva mortality was 50% at LD50 of 1.11%. EcV was not digested by midgut homogenates of C. maculatus and Z. Subfasciatus until 12 h of incubation, and at 24 h EcV was more resistant to Z. subfasciatus larval proteases. The binding to chitin present in larvae gut associated to low EcV digestibility could explain its lethal effects. EcV also exerted an inhibitory effect on the germination of F. solani at concentrations of 10 and 20 microg mL-1. The effect of EcV on fungi is possibly due to binding to chitin-containing structures of the fungal cell wall.

Identification of Albizia lebbeck seed coat chitin-binding vicilins (7S globulins) with high toxicity to the larvae of the bruchid Callosobruchus maculatus

“…It has been hypothesized that particular plant chitin-binding proteins can adhere to insect PMs, interfering with their normal functions and affecting nutrient absorption (12). In addition, chitin-binding vicilins from several plants have been demonstrated to be toxic to several species of insects and fungi (5,8,13,14,34). However, it has also been reported that intact vicilin and vicilin-derived peptides are absorbed by the insect's intestinal tract and incorporated into internal organs and eggs (7,35).…”

Safety aspects of the production of foods and food ingredients from insects

“…This has been demonstrated in murine sensitization studies, for example in mice allergic to Aspergillus fumigatus and with the chitin‐binding allergen Blo t 12 from mites ( Blomia tropicalis ) . Furthermore, chitin‐binding vicilins, leguminous storage proteins, have been described in Enterolobium contortisiliquum and Erythrina velutina . Vicilins have been described as important allergens in other edible legumes such as peanuts and soybeans .…”

Genus Enterolobium : traditional uses, chemistry and biological activities

“…Some tentative hypotheses are considered in order to explain the toxic mechanism of action of enterolobin towards C. maculatus. Moura et al, 2007, purified Chitinbinding vicilin from E.contortisiliquum seeds by ammonium sulfate followed by gel filtration on Sephacryl 300-SH and on Sephacryl 200-SH. The vicilin, called E.contortisiliquum vicilin (EcV), is a dimeric glycoprotein.…”