Comparison between the Mechanisms of Action of Plant Toxins Ricin and Viscumin on the Stage of Intracellular Dissociation

Abstract

Pharmacological effects of mistletoe extracts are determined by the concentration of three toxic lectins: mistletoe lectin I (MLI, or viscumin), MLII, MLIII. These proteins, as well as ricin, belong to ribosome-inactivating proteins type 2 (RIP2). However, the extracts from the plant Ricinus communis, containing ricin, are highly toxic. Ricin is about 30 times more effective in cell culture than viscumin. The dissociation of subunits and the transmembrane transport of catalytic subunit into the cytoplasm are needed to obtain the cytotoxic effect of RIP2. In this paper, hybridomas producing monoclonal antibodies against catalytic subunits of ricin and viscumin are described. Monoclonal antibodies against different epitopes, including one localized in intra-subunit area of catalytic subunits of ricin and viscumin, do not inhibit the enzymatic activity of these proteins in cell-free system. These hybridomas are resistant to the cytotoxic action of native toxins. Protective effect of antibodies are about the same for both toxins, though the dissociation of the subunits of ricin is more effective. The causes of the differences in activity of plant toxins as pharmacological agents, and the importance of above mentioned epitopes for neutralizing antibodies at the clinical applications of mistletoe extracts are discussed.

Bioinformatics Analysis of Linear B-cell Viscumin Toxin Epitope With Potential Use in Molecularly Imprinted Polymer Biosensors

“…As it can be inferred, the MIP nanoparticles showed excellent capabilities for the detection of the epitope, such as the HSA protein [27]. Also, another group worked on B-cell epitope prediction and investigated its probability in detail.…”

Cryo scanning probe nanotomography study of the structure of alginate microcarriers

“…In agreement with previous studies, our results indicated that microspheres produced of natural materials could be used as biodegradable and biocompatible cell carriers for tissue regeneration, and injected into the body for effective delivery of cells within affected areas. 25,[44][45][46][47][48] The inuence of macro-and microstructure on mechanical properties and biocompatibility of 3D structures for tissue engineering and regenerative medicine has been conrmed in numerous publications, 4,19,[49][50][51] but the inuence of nanostructure on these properties is not as clear. For example, in one earlier study, 47 hollow nanober polylactide microspheres were used as carriers of injected chondrocytes to regenerate cartilaginous tissue.…”