Edulitin 2, a Ribotoxin-Like Protein From Boletus edulis That Triggers Apoptosis in Colon Cancer Cells While Preserving the Integrity of the Intestinal Microbiota

Porcini (Boletus edulis Bull.) are a reservoir of pharmacological biomolecules with health‐promoting properties. Here, we investigated the cytotoxic activity of edulitin 2, a ribotoxin‐like protein purified from B. edulis fruiting bodies, against two human colon cancer cell lines (Caco‐2 and HT29), and assessed its potential impact on gut microbiota. Edulitin 2 exhibited marked cytotoxicity toward both cell lines in a dose‐ and time‐dependent manner. The effect was particularly evident after 72‐h, with EC50 values in the 10−7 M range for both cell lines. Moreover, edulitin 2 significantly affected barrier integrity in Caco‐2 monolayer models. Edulitin 2 kills cells mainly by triggering apoptotic mechanisms, with limited involvement of necroptosis and absence of necrosis. These results support edulitin 2 as a potential therapeutic agent due to the reduced risk of inducing inflammation‐related damage. Furthermore, this toxin proved to be harmless to microbial consortia simulating the gut microbiota. Overall, these findings make edulitin 2 a promising bioactive compound that combines cytotoxicity toward colorectal tumor cells with microbiota compatibility. This dual profile supports its further exploration in preclinical models (for loco‐regional treatment and as payload of immunotoxins) and highlights the potential of edible mushrooms as a source of novel ribotoxin‐like proteins with biomedical relevance.