Hepatoprotective Ability of Tetramethylpyrazine Produced by Bacillus Amyloliquefaciens

Tetramethylpyrazine (TTMP), an important aroma compound, was produced by Bacillus amyloliquefaciens XJB-104 with distillers’ grains as raw material. The yield of TTMP under optimized fermentation procedure was 3176.52 mg/L. TTMP in the fermentation broth was purified and the purity (> 99%) was measured by gas chromatography–mass spectrometry. Furthermore, the hepatoprotective activity of TTMP in ethanol–water system was evaluated by biochemical indicators of liver injury, parameters of antioxidant defense system and inflammatory response, and liver histopathological assessment in mice. Ethanol treatment increased serum levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase, suggesting liver damage. Both high and low dose of TTMP significantly decreased levels of these indicators. Furthermore, the reduction in the activities or concentrations of superoxide dismutase, catalase, reduced glutathione and malondialdehyde in liver tissue caused by ethanol was significantly alleviated by TTMP. Increased inflammatory cytokines including transcription factor, tumor necrosis factor, interleukin-1beta, interleukin, macrophage chemoattractant protein, inducible nitric oxide synthase and cyclooxygenase were also suppressed by TTMP treatment. It is concluded that TTMP in ethanol–water system has potential liver-protective activity, especially when ethanol is consumed at low doses for short periods of time.