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Artemisia annua is the main natural source of artemisinin production. In A. annua , extended drought stress severely reduces its biomass and artemisinin production while short-term water-withholding or abscisic acid (ABA) treatment can increase artemisinin biosynthesis. ABA-responsive transcription factor AabZIP1 and JA signaling AaMYC2 have been shown in separate studies to promote artemisinin production by targeting several artemisinin biosynthesis genes. Here, we found AabZIP1 promote the expression of multiple artemisinin biosynthesis genes including AaDBR2 and AaALDH1 , which AabZIP1 does not directly activate. Subsequently, it was found that AabZIP1 up-regulates AaMYC2 expression through direct binding to its promoter, and that AaMYC2 binds to the promoter of AaALDH1 to activate its transcription. In addition, AabZIP1 directly transactivates wax biosynthesis genes AaCER1 and AaCYP86A1. The biosynthesis of artemisinin and cuticular wax and the tolerance of drought stress were significantly increased by AabZIP1 overexpression, whereas they were significantly decreased in RNAi- AabZIP1 plants. Collectively, we have uncovered the AabZIP1-AaMYC2 transcriptional module as a point of cross-talk between ABA and JA signaling in artemisinin biosynthesis, which may have general implications. We have also identified AabZIP1 as a promising candidate gene for the development of A. annua plants with high artemisinin content and drought tolerance in metabolic engineering breeding. AabZIP1 regulates artemisinin biosynthesis via directly transactivating AaADS and AaCYP71AV1 , and indirectly up-regulating AaDBR2 and AaALDH1 via AaMYC2. Moreover, AabZIP1 improves drought tolerance by promoting wax biosynthesis in Artemisia annua. [Display omitted] [ABSTRACT FROM AUTHOR]

Background: Pterocephalus hookeri (C. B. Clarke) Höeck, a Tibetan medicine widely used for treatment of rheumatoid arthritis, was recorded in Chinese Pharmacopoeia (2020 version) with slight toxicity. The liver injury was observed in mice with administration of n-butanol extract (BUE) in our previously study. However, the toxic components and the mechanism were still unrevealed.Purpose: The present study was aimed to isolate and structural elucidate of the toxic compound pterocephin A (PA), as well as evaluate its liver toxicity and investigate its mechanism.Methods: PA was isolated from the BUE of P. hookeri. Its structure was determined by analysis of HRMS, NMR and ECD data. L-02 cellular viability, LDH, ALT, AST, ROS, intracellular Ca2+ and the fluidity of cell membrane were assessed by multifunctional microplate reader. The PI staining, cell membrane permeability assessment, and mitochondrial fluorescence staining analysis were determined through the fluorescence microscope. Liver samples for mice were assessed by pathological and immunohistochemistry analysis. Expression levels of indicated proteins were measured by western blotting assays.Results: PA was determined as a previously undescribed oleanolane-type triterpenoid saponin. In vitro study revealed PA significantly induced hepatotoxicity by inhibition of L-02 cell growth, abnormally elevation of ALT and AST. Mechanically, PA induced the damage of cell membrane, fragmentation of mitochondria, and subsequently increase of intracellular Ca2+ and ROS levels, which trigged by necroptosis with the activation of RIP1 and NF-κB signaling pathways. In vivo study confirmed PA could induce liver injury in mice with observation of the body weight loss, increasing of serum ALT and AST, and the histopathological changes in liver tissues.Conclusion: Our present study indicated that PA was an undescribed toxic constituent in P. hookeri to induce liver injury in mice by activation of necroptosis and inflammation. And the findings are of great significance for the clinical use safely of this herb. [ABSTRACT FROM AUTHOR]

Background: In our previous study, we demonstrated the hepatoprotective effect of Herpetospermum pedunculosum in cholestatic rats. A bioassay-guided study also led to the identification and isolation of a lignan, dihydrodiconiferyl alcohol (DA) from the seeds of H. pedunculosum.Purpose: To investigate whether DA could alleviate cholestasis and determine the mechanisms underlying such action.Methods: Male Sprague-Dawley (SD) rats were administered with DA (10, 20 or 40 mg/kg) intragastrically once daily for 7 days prior to treatment with α-naphthylisothiocyanate (ANIT) (60 mg/kg). We then evaluated the levels of a range of serum indicators, determined bile flow, and carried out histopathological analyses. Western blotting was then used to investigate the levels of inflammatory mediators and the Farnesoid X Receptor (FXR), proteins involved in the downstream biosynthesis of bile acids, and a range of transport proteins. Molecular docking was used to simulate the interaction between DA and FXR. Cell viability of human hepatocytes (L-02) cells was determined by MTT. Then, we treated guggulsterone-inhibited L-02 cells, Si-FXR L-02 cells, and FXR-overexpression cells with the FXR agonist GW4064 (6 μM) or DA (25, 50 and 100 μM) for 24 h before detecting gene and protein expression by RT-PCR and western blotting, respectively.Results: DA significantly attenuated ANIT-induced cholestasis in SD rats by reducing liver function indicators in the serum, increasing bile flow, improving the recovery of histopathological injuries in the liver, and by alleviating pro-inflammatory cytokines in the liver. DA also increased the expression levels of FXR and altered the levels of downstream proteins in the liver tissues, thus indicating that DA might alleviate cholestasis by regulating the FXR. Molecular docking simulations predicted that DA was as an agonist of FXR. In vitro mechanical studies further showed that DA increased the mRNA and protein expression levels of FXR, Small Heterodimer Partner 1/2, Bile Salt Export Pump, Multidrug Resistance-associated Protein 2, and Na+/taurocholate Co-transporting Polypeptide, in both guggulsterone-inhibited and Si-FXR L-02 cells. Moreover, DA enhanced the mRNA and protein expression of FXR, and its downstream genes and proteins, in L-02 cells containing an FXR-overexpression plasmid.Conclusion: DA may represent an effective agonist for FXR has significant therapeutic potential for the treatment of cholestatic liver injury. [ABSTRACT FROM AUTHOR]

Background: Traditionally, seeds of Herpetospermum pedunculosum were used to treat liver disease or cholepathy. Up to date, their protecting effect against cholestasis was remain unclarified.Purpose: To investigate the efficacy, possible mechanisms, and active constituents of the ethyl acetate extract from the seeds of Herpetospermum pedunculosum (HPEAE), studies were carried out using cholestasis rat model induced by α-naphthylisothiocyanate (ANIT).Methods: Male rats were intragastrically treated with HPEAE (100, 200 or 400 mg/kg) once a day for 7 days and were modeled with ANIT (60 mg/kg). The levels of serum indicators, bile flow, and histopathology were evaluated. Indices of oxidative stress and inflammatory mediators were detected using the enzyme-linked immunosorbent assay. Western blotting method was employed for analyzing the protein levels in the signal pathways of farnesoid X receptor (FXR), kelch ech associating protein 1/nuclear factor erythroid 2-related factor 2 (Keap1/Nrf2) and nuclear factor κB (NF-κB). The chemical compositions of HPEAE was analyzed by HPLC, and partially chemical components of HPEAE were identified by comparisons of their retention times with the standards. The FXR agonistic activity of the identified compounds was evaluated in l-02 cells induced by guggulsterone using a high-content screening system.Results: The cholestasis caused by ANIT can be significantly ameliorated by restoring the liver function indexes of alanine transaminase, aspartate transaminase, alkaline phosphatase, gamma-glutamyltransferase, total bilirubin, direct bilirubin and total bile acid, which are dose-dependent, as well as pathological liver injury and bile flow. Mechanical studies suggested that HPEAE can activate the expression of FXR and then up regulate its downstream proteins (multidrug resistance-associated protein 2, bile salt export pump and Na+/taurocholate cotransporting polypeptide). Moreover, the levels of the active oxygen index glutathione, superoxide dismutase, glutathione peroxidase, catalase and malondialdehyde were markedly restored by treatment with HPEAE. Western blotting further confirmed that HPEAE up regulated the expression of quinone oxidoreductase 1, heme oxygenase 1 and Keap1, lowered the expression of Nrf2 and reduced oxidative stress. HPEAE also up regulated P-glycoprotein 65, phosphorylated P-glycoprotein 65 and inhibitor of NF-κB kinase α expression, down regulated inhibitor of NF-κB (IκB), restored inflammatory mediator tumor necrosis factor-α, interleukin-1β (IL-1β), IL-6 and IL-10, and reduced inflammatory response. Fifteen compounds were identified (12 lignans and 3 coumarins). Among them, five lignans exhibited the significant FXR agonistic activity in vitro.Conclusion: HPEAE may alleviate the cholestasis and liver injury caused by ANIT in rats by activating FXR, as well as suppressing the Keap1/Nrf2 and NF-κB signaling pathways and lignans may be its main active components. [ABSTRACT FROM AUTHOR]