Lectins are especially-powerful compounds in the broad class of RIPs (Ribosome-Inactivating Proteins), which various plants generate in many formats, in almost any organ, from leaves and roots to seed. The compounds are dangerous because they can grind cell function to a halt by interfering with the manufacture of proteins, which takes place at special sites called ribosomes. A limited number, the most truly potent, are dangerous to humans. Even very small amounts can be deadly.
Concern about dangerous lectins is core to the recently popular dietary plan promoted by Steven Gundry in his well-known book The Plant Paradox, as well as his other publications and programs. Gundry’s diet shuns the bean family (peas, beans, peanuts), the grains (wheat, rice, corn), cucurbits (cucumber, squash, pumpkin, etc.), solanums (tomatoes, eggplant, chili peppers), and a host of other foods, such as cheese from anyplace but Southern Europe. Though he doesn’t include Castor Beans in the dietary list, Gundry does remind us that ricin (from Castor Bean, i.e. Ricinus) is the King of Lectins. As the first lectin isolated, this compound is occasionally in the news due to particularly prominent cases of poisoning. For more background on Ricinus, read the Gazette report titled Castor Oyl.
Many plants of historically-noted herbal value produce RIPs. One of the least obvious was uncovered in 1983, when researchers isolated Saporin from Saponaria officianalis, otherwise called Soapwort, or more ebulliently Bouncing Bet. The good thing is that though Saporin is an RIP, it is not a lectin, which makes it safer to handle. But it is still powerful, and we learn researchers are studying the molecule for its possible use as a targeted, very selective poison that could, perhaps, treat illnesses through denaturing proteins in viruses or cancerous cells. Medical practitioners use many toxic substances to good effect, an ancient tactic. Apothecaries ascribe the summary of that method to Paracelsus, who is said to have taught “the dose makes the poison.”
Do not confuse Saporin with Saponin, which we also associate with Saponaria. The soapiness of Saponin is the reason for the generic name, as well as the common name Soapwort. The association relates to historical use as a soap substitute. Extracts from the root raise enough lather to have been useful for cleansing.
Saporin (the RIP) was introduced in a 1983 article by Fiorenzo Stirpe, Anna Gasperi-Campani, Luigi Barbieri, A Falasca, Anna Abbondanza, and William A. Stevens https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1152554/
Also of note: “Ribosome-Inactivating Proteins from Plants: Present Status and Future Prospects” (ReadCube)