You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Chemical"].

Please return the output as a JSON object of the format: {"Chemical": ["Arsenic", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

Pterostilbene inhibits dimethylnitrosamine-induced liver fibrosis in rats. Pterostilbene, found in grapes and berries, exhibits pleiotropic effects, including anti-inflammatory, antioxidant, and anti-proliferative activities. This study was conducted to investigate the effect of pterostilbene on liver fibrosis and the potential underlying mechanism for such effect. Sprague-Dawley rats were intraperitoneally given dimethyl n-nitrosamine (DMN) (10mg/kg) 3 days per week for 4 weeks. Pterostilbene (10 or 20mg/kg) was administered by oral gavage daily. Liver function, morphology, histochemistry, and fibrotic parameters were examined. Pterostilbene supplementation alleviated the DMN-induced changes in the serum levels of alanine transaminase and aspartate transaminase (p<0.05). Fibrotic status and the activation of hepatic stellate cells were improved upon pterostilbene supplementation as evidenced by histopathological examination as well as the expression of α-smooth muscle actin (α-SMA), transforming growth factor-β1 (TGF-β1), and matrix metalloproteinase 2 (MMP2). These data demonstrated that pterostilbene exhibited hepatoprotective effects on experimental fibrosis, potentially by inhibiting the TGF-β1/Smad signaling.
{"Chemical": ["Pterostilbene", "dimethyl n-nitrosamine", "dimethylnitrosamine", "DMN", "pterostilbene"]}