citrinin 

A mycotoxin secondary metabolite produced by fungi. It was first isolated from Penicillium citrinum, and produced by other fungi in genus of Aspergillaceae (family), such as the Monascus and Aspergillus.
It is often found in long-stored food (mainly grains, sometimes fruits and other plant products).
It can cause nephrotoxic, hepatotoxic, and cytotoxic effects, by reduced cytokine production, inhibition of RNA and DNA synthesis, induction of oxidative stress, inhibition of nitride oxide gene expression, increase in reactive oxygen species (ROS) production, and activation of apoptosis.
It often occurs together with other mycotoxins like ochratoxin A or aflatoxin B1, because they are produced by the same fungi species.
Together with ochratoxin A, it has increased synergistic nephrotoxic effects including Balkan endemic nephropathy (a form of interstitial nephritis causing kidney failure), as well as influencing apoptosis and necrosis in hepatocytes.
Cf. aristolochic acid