Current trends in the treatment and therapeutic strategies against Ribosome-inactivating proteins

Ribosome-inactivating proteins (RIPs) are cytotoxic RNA N-glycosidases from plants, bacteria, and fungi that depurinate a conserved adenine residue in the sarcin-ricin loop (SRL) of 28S rRNA, halting protein synthesis by blocking the recruitment of translation elongation factors. Ricin, a Type II RIP from Ricinus communis , features an enzymatic A-chain (RTA) linked by disulfide bond to lectin B-chain (RTB). RTB binds cell-surface galactose for retrograde entry and release RTA in the cytosol that interacts with the SRL and causes apoptosis. Inhalation of ricin leads to pulmonary edema; ingestion to gastrointestinal hemorrhage and multi-organ failure. Shiga toxin (AB 5 ) from Shigella and Shiga toxin producing E. coli (STEC) targets Gb3 on renal/endothelial cells, inducing hemolytic uremic syndrome (HUS) with anemia, thrombocytopenia, and renal failure. Mucoricin from Mucorale fungi inactivates ribosomes while disrupting endothelial barriers, promoting angioinvasion and necrosis in mucormycosis following similar mode of action. Real-world threats persist: 1992/2024 STEC outbreaks (Jack in the Box, McDonald’s) drove HUS and food safety reforms; ricin featured in the 1978 Markov assassination and a 2025 ISIS plot in India; India’s 2021 COVID-mucormycosis surge exceeded 47,000 cases amid hyperglycemia. Therapeutics include anti-RTA/RTB monoclonal antibodies, DNA-encoded platforms, RiVax/RVEc vaccines, small-molecule inhibitors of RTA, Gb3 decoys, and antimicrobials like trans-cinnamaldehyde/allicin. Yet, no approved antidotes exist, highlighting urgent needs in research and biodefense. This review examines three clinically significant RIPs—ricin, Shiga toxin, and mucoricin—detailing their mechanisms, real-world incidents, and therapeutic strategies.