Toxicological studies on plant proteins: a review

Abstract

Nowadays, toxicological studies are contributing to human health more than ever. Reports on the toxicological studies of plant proteins, which are continuously growing in number in the literature, have been reviewed. Two important aspects are discussed: dietary safety evaluation, including toxicity tests and the maximum daily intake allowance, and the appropriate proportion in our daily diets of proteins from traditional foods and of new proteins from plant sources not traditionally employed as foods. Water hyacinth leaf proteins, sweet lupin proteins and canola proteins have not been shown to be toxic, although they are not traditionally employed as food proteins. These findings are very important for exploiting valuable new protein sources that are suitable for human or animal consumption and applicable to the food industry. Acutely toxic proteins, including lectins, ribosome-inactivating proteins, inhibitors of proteolytic enzymes and glycohydro-lases, have been isolated from plant materials and identified. Their toxicities and molecular characteristics have been described. The toxicity of proteins depends upon their specific native structures. Once they are denatured by appropriate treatment, such as heating, their toxicity can be reduced or even eliminated. These findings indicate that raw materials that contain this kind of toxic protein are not edible. However, after proper processing, they may be suitable for human or animal consumption. Although the toxicities of type 2 ribosome-inactivating proteins reported by different authors vary, the maximum dosages are still trace amounts.

A Glyco-chip for the Detection of Ricin by an Automated Chemiluminescence Read-out System

“…The RIP2 homologues of ricin bind to galactose. 1 Moreover, several bacterial toxins bind to N-acetylgalactosamine, N-acetylneuraminic acid or galactose. 21,34,35 All of them would bind to the same carbohydrates on the chip.…”

“…1 The oral lethal dose for humans is estimated to be 1 -20 mg/kg bodyweight. 2 It occurs worldwide, because it is an industrial side product of castor oil production from seeds of the castor oil plant.…”

Possible mechanisms of Leukoagglutinin induced apoptosis in human cells in vitro

“…Thus, they may be involved in the cell cycle regulation as well as mechanisms of cell differentiation, proliferation, and death. Many lectins are known to induce cell proliferation (Shanmugham et al, ) and some of them are toxic (Wu and Sun, ).…”

Toxin Content of Commercial Castor Cultivars

“…Ricin is a heterodimer that targets cell surfaces and when taken up by the cell, causes loss of ribosomal function leading to cell death. As little as 1 lg/kg body weight may cause death in humans [3,6]. The presence of this toxin adds expense in handling the seed meal remaining after oil processing.…”