Intestinal flora performs a crucial role in human health and its imbalance may cause numerous pathological changes. The liver can also affect the intestinal function through bile secretion via the enterohepatic cycle. The pathophysiological association between the gut and the liver is described as the gut-liver axis. The present study investigated the role of intestinal flora in alcohol-induced liver fibrosis. A total of 36 C57 mice were randomly and equally divided into 3 different dietary regimes: Group I (alcohol injury; received alcohol); group II (alcohol injury with flora imbalance; received alcohol plus lincomycin hydrochloride) and group III (alcohol injury with corrected flora imbalance; received alcohol, lincomycin hydrochloride and extra probiotics). The present study then investigated several indicators of liver damage. Alkaline phosphatase (ALP) levels, aspartate aminotransferase (AST) levels and alanine aminotransferase (ALT) levels in mice serum were studied. Masson staining and Annexin V-fluorescein isothiocyanate/propidium iodide double staining was also performed, and the expression of mothers against decapentaplegic homolog (smad) 3 and smad4 proteins in hepatic stellate cells (HSCs) of the mice was examined using western blot analysis. The levels of serum ALP, AST and ALT were the highest in group II mice, and all 3 levels decreased in group III mice compared with those from group II. The degree of liver fibrosis was aggravated in group II mice compared with group I mice. The apoptosis of HSCs was significantly inhibited in group II mice, but was increased in group III mice. The HSCs in group II mice exhibited higher expression of smad3 and smad4, whilst group III mice (with corrected intestinal flora imbalance) exhibited downregulated expression of smad3 and smad4. The present data indicates that the intestinal flora perform a significant role in maintaining liver homeostasis. Furthermore, an imbalance of intestinal flora can exacerbate alcohol-induced liver fibrosis in mice through the transforming growth factor β/SMA/MAD homology signaling pathway, which subsequently leads to more serious liver damage.

H3B‐6545 is a selective ERα covalent antagonist, which has been demonstrated to be effective in anti‐tumor. To fully understand its mechanism of action, it is necessary to investigate the in vitro and in vivo metabolic profiles. For in vitro metabolism, H3B‐6545 (50 μM) was incubated with the hepatocytes of rat and human for 2 h. For in vivo metabolism H3B‐6545 was orally administered to rats at a single dose of 10 mg/kg, and plasma, urine and fecal samples were then collected. All samples were analyzed by using ultra‐high performance liquid chromatography combined with linear ion trap‐orbitrap tandem mass spectrometry (UHPLC‐LTQ‐Orbitrap‐MS) operated in positive ion mode. The structures of the metabolites were elucidated by comparing their MS and MS2 spectra with those of parent drug. A total of 11 metabolites, including a GSH adduct, were detected and structurally identified. M2, M7 and M8 were further unambiguously identified by using reference standards. Among these metabolites, M1, M5, M7 and M10 were newly found and reported for the first time. The metabolic pathways of H3B‐6545 included deamination (M8 and M9), dealkylation (M2, M3 and M10), N‐hydroxylation (M6), hydroxylation (M1 and M4), formation of amide derivatives (M5 and M7) and GSH conjugation (G1).