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.