Clinical studies demonstrated that nonalcoholic steatohepatitis is associated with liver-related outcomes in chronic hepatitis B. Furthermore, primary biliary fibrosis and biliary atresia occurred in patients with HBV infection. Interestingly, hepatitis B virus surface protein (HBs) transgenic mice spontaneously develop hepatic steatosis. Our aim is to investigate the effect of Abcb4 knockout-induced cholestasis on liver steatosis in HBs transgenic mice. Hybrids of HBs transgenic and Abcb4−/− mice were bred on the BALB/c genetic background. Lipid synthesis, storage, and catabolism as well as proteins and genes that control lipid metabolism were analyzed using HPTLC, qPCR, western blot, electrophoretic mobility shift assay (EMSA), lipid staining, and immunohistochemistry. Hepatic neutral lipid depots were increased in HBs transgenic mice and remarkably reduced in Abcb4−/− and HBs/Abcb4−/− mice. Similarly, HPTLC-based quantification analyses of total hepatic lipid extracts revealed a significant reduction in the amount of triacylglycerols (TAG), while the amount of free fatty acids (FFA) was increased in Abcb4−/− and HBs/Abcb4−/− in comparison to wild-type and HBs mice. PLIN2, a lipid droplet-associated protein, was less expressed in Abcb4−/− and HBs/Abcb4−/−. The expression of genes-encoding proteins involved in TAG synthesis and de novo lipogenesis (Agpat1, Gpat1, Mgat1, Dgat1, Dgat2, Fasn, Hmgcs1, Acc1, Srebp1-c, and Pparγ) was suppressed, and AMPK and CREB were activated in Abcb4−/− and HBs/Abcb4−/− compared to wild-type and HBs mice. Simulating cholestatic conditions in cell culture resulted in AMPK and CREB activation while FASN and PLIN2 were reduced. A concurrent inhibition of AMPK signaling revealed normal expression level of FASN and PLIN2, suggesting that activation of AMPK–CREB signaling regulates hepatic lipid metabolism, i.e. synthesis and storage, under cholestatic condition. In conclusions, in vivo and mechanistic in vitro data suggest that cholestasis reduces hepatic lipid storage via AMPK and CREB signaling. The results of the current study could be the basis for novel therapeutic strategies as NASH is a crucial factor that can aggravate chronic liver diseases.

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The photoinduced dynamics of two DTE-BODIPY conjugates A, B with carboxylic acid anchoring groups coupled to the surface of TiO2 were studied by ultrafast transient absorption spectroscopy. For compound A, with an orthogonal orientation of the BODIPY chromophore and the photoswitchable DTE unit, a charge separated state could not be reliably detected. Nevertheless, besides the energy transfer from the BODIPY to the closed DTE, indications for an electron transfer reaction were found by analyzing fluorescence quenching on TiO2 in steady state fluorescence measurements. For compound B with a parallel orientation of chromophore and photoswitch, a charge separated state was conclusively identified via the observation of a positive absorption signal (at λpr > 610 nm) at later delay times. An electron transfer rate of 7 x 1010 s-1 can be extracted, indicating slower processes in the dyads in comparison to previously published electron transfer reactions of DTE compounds coupled to TiO2.

The active principle of most traditional medicines is not known, as for Sarcocephalus pobeguinii Hua ex Pellegr. bark extract. It is used as an antidiabetic drug in Gabonese folk medicine. Diabetes mellitus is increasing globally, and products from natural sources are gaining interest as a remedy. As the active antidiabetic compounds have not been characterized so far, a mobile phase for high-performance thin-layer chromatography (HPTLC) was newly developed to target single active compounds in the unpolar ground bark extract of S. pobeguinii by effect-directed analysis (EDA). One natural compound zone showed multipotent activities by effect-directed detection, that is, antidiabetic, cholinesterase inhibiting, and antioxidative activities. Its characterization was performed via online elution of the active substance zone from the HPTLC layer into the high-resolution mass spectrometry (HRMS) system. Important parts of the structure were assigned by MS/MS experiments and led to the preliminary assignment of strictosamide, an indole alkaloid. The saccharide moiety of the active molecule was characterized with a selective derivatization reagent (diphenylamine aniline phosphoric acid reagent). Strictosamide was already reported as a constituent of the extract, and its cholinesterase inhibiting property was confirmed. However, it was newly found to be active as a free-radical scavenger and α-glucosidase inhibitor, which might partially explain the successful use as antidiabetic and antioxidative folk medicine. The fast bioprofiling by HPTLC-UV/vis/FLD-EDA-HRMS was proven to be suited as an analytical tool for the discovery of multipotent active compounds.