Ricin: An Ancient Story for a Timeless Plant Toxin

Abstract

The castor plant (Ricinus communis L.) has been known since time immemorial in traditional medicine in the pharmacopeia of Mediterranean and eastern ancient cultures. Moreover, it is still used in folk medicine worldwide. Castor bean has been mainly recommended as anti-inflammatory, anthelmintic, anti-bacterial, laxative, abortifacient, for wounds, ulcers, and many other indications. Many cases of human intoxication occurred accidentally or voluntarily with the ingestion of castor seeds or derivatives. Ricinus toxicity depends on several molecules, among them the most important is ricin, a protein belonging to the family of ribosome-inactivating proteins. Ricin is the most studied of this category of proteins and it is also known to the general public, having been used for biocrimes in several cases. Here, the main steps of ricin research are reported with particular regards to its enzymatic activity, structure and cytotoxicity. Moreover, we discuss ricin toxicity for animals and humans, as well as the relation amongst bioterrorism and ricin and its impact on environmental toxicity. Ricin has also been of great utility to develop a number of immunotoxins specific for the elimination of unwanted cells, mainly cancer cells; some of these immunotoxins gave promising results also in clinical trials.

130 years of Plant Lectin Research

“…Therefore Kocourek and Horejsi [23] extended the concept: "Lectins are proteins of non-immunoglobulin nature capable of specific recognition and reversible binding to carbohydrate moieties of complex carbohydrates without altering the covalent structure of any of the recognized glycosyl ligands". In 1988 Barondes [24] described lectins as "carbohydrate-binding proteins other than antibodies or enzymes" which is somewhat contradictory to the first findings on lectins, since ricin is composed of a ribosome-inactivating domain with enzymatic activity linked to a carbohydrate-binding domain [25]. The definition which is accepted widely in the scientific world nowadays was published in 1995 by Peumans and Van Damme, and defines lectins as "all proteins possessing at least one non-catalytic domain, which binds reversibly to a specific mono-or oligosaccharide" [26].…”

Early Response to the Plant Toxin Stenodactylin in Acute Myeloid Leukemia Cells Involves Inflammatory and Apoptotic Signaling

“…Among type 2 RIPs, the most known being ricin (Polito et al, 2019), stenodactylin is a highly toxic lectin purified from the caudex of Adenia stenodactyla Harms (Pelosi et al, 2005;Stirpe et al, 2007). Due to its elevated cytotoxicity, especially toward nervous cells, it is considered to be among the most cytotoxic RIPs discovered so far, and an attractive molecule for the production of ITs (Monti et al, 2007;Polito et al, 2016c).…”

Insecticidal potential of some plant extracts in nano and normal form on immatures stages of red palm weevil Rhynchophorus ferrugineus

“…These findings are in agreement with previous studies where castor have been proved to have insecticidal activities against, peach fruit flies (Ali, 2018), RPW, (Ali et al, 2019) Maconellicoccus hirsutus (Holtz et al, 2019), The toxic activity of castor is probably due to the presence of its major active components such as :the alkaloid ricinine, Nmethyl ricinine and the ricin protein, which are toxic substances in the leaves. (Worbs et al, 2011;Fallström, 2014;Polito et al, 2019), these active components cause reduction in all types of hemocytes and plasmocytes, it decreased carbohydrate content, (Ali and Ibrahim, 2018).…”