Tomatidine is a steroidal alkaloid that has been found in the skins and leaves of tomatoes. It suppresses NF-κB signaling in LPS-stimulated macrophages, blocking induced expression of inducible nitric oxide synthase (iNOS) and COX-2. Tomatidine inhibits acid sphingomyelinase activity by 84.2% when used at a concentration of 10 mM. It also has antibacterial properties, preferentially blocking the replication of S. aureus variants that are pathogenic in cystic fibrosis over normal strains (MICs = 0.12 and >16 µg/ml, respectively). It prevents skeletal muscle atrophy associated with fasting or spinal cord injury in mice. Tomatidine has also been used as a negative control for cyclopamine in studies involving signaling mediated by the hedgehog pathway.