Bitter taste receptors (TAS2Rs) have attracted a great deal of interest because of their recently described bronchodilator and anti-inflammatory properties. The aim of this study was to identify natural direct TAS2R14 agonists from Radix Bupleuri that can inhibit mast cell degranulation. A ligand-based virtual screening was conducted on a library of chemicals contained in compositions of Radix Bupleuri, and these analyses were followed by cell-based functional validation through a HEK293-TAS2R14-G16gust44 cell line and IgE-induced mast cell degranulation assays, respectively. Saikosaponin b (SSb) was confirmed for the first time to be a specific agonist of TAS2R14 and had an EC50 value of 4.9 μM. A molecular docking study showed that SSb could directly bind to a TAS2R14 model through H-bond interactions with Arg160, Ser170 and Glu259. Moreover, SSb showed the ability to inhibit IgE-induced mast cell degranulation, as measured with a β-hexosaminidase release model and real-time cell analysis (RTCA). In a cytotoxicity bioassay, SSb showed no significant cytotoxicity to HEK293 cells within 24 hours. This study demonstrated that SSb is a direct TAS2R14 agonist that inhibit IgE-induced mast cell degranulation. Although the target and in vitro bioactivity of SSb were revealed in this study, it still need in vivo study to further verify the anti-asthma activity of SSb.

Oxidative stress is the main pathogenesis of diabetic microangiopathy, which can cause microvascular endothelial cell damage and destroy vascular barrier. In this study, it is found that carnosol protects human microvascular endothelial cells (HMVEC) through antioxidative mechanisms. First, we measured the antioxidant activity of carnosol. We showed that carnosol pretreatment suppressed tert-butyl hydroperoxide (t-BHP)-induced cell viability, affected the production of lactate dehydrogenase (LDH) as well as reactive oxygen species (ROS), and increased the produce of nitric oxide (NO). Additionally, carnosol promotes the protein expression of vascular endothelial cadherin (VE-cadherin) to keep the integrity of intercellular junctions, which indicated that it protected microvascular barrier in oxidative stress. Meanwhile, we investigated that carnosol can interrupt Nrf2-Keap1 protein−protein interaction and stimulated antioxidant-responsive element (ARE)-driven luciferase activity in vitro. Mechanistically, we showed that carnosol promotes the expression of heme oxygenase 1(HO-1) and nuclear factor-erythroid 2 related factor 2(Nrf2). It can also promote the expression of endothelial nitric oxide synthase (eNOS). Collectively, our data support the notion that carnosol is a protective agent in HMVECs and has the potential for therapeutic use in the treatments of microvascular endothelial cell injury.

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Advances in cancer treatment have led to significant improvements in long-term survival in many types of cancer, but heart dysfunction and heart failure, associated with cancer treatment, have also increased. Anthracyclines are the main cause of this type of cardiotoxicity. In this study, we describe a combined experimental and cell morphology analysis approach for the high-throughput measurement and analysis of a cardiomyocyte cell profile, using partial least square linear discriminant analysis (PLS-LDA) as the pattern recognition algorithm. When screening a small-scale natural compound library, rosmarinic acid (RosA), as a candidate drug, showed the same cardioprotective effect as the positive control. We investigated the protective mechanism of RosA on a human cardiomyocyte cell line (AC16) and human induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs). We showed that RosA pretreatment suppressed doxorubicin (Dox)-induced cell apoptosis and decreased the activity of caspase-9. RosA promotes the expression of Heme oxygenase-1 (HO-1) and reduces the production of reactive oxygen species (Ros), which is induced by Dox. Meanwhile, it can also promote the expression of cardiac-development-related protein, including histone deacetylase 1 (HDAC1), GATA binding protein 4 (GATA4) and troponin I3, cardiac type (CTnI). Collectively, our data support the notion that RosA is a protective agent in hiPSC-CMs and has the potential for therapeutic use in the treatment of cancer therapy-related cardiac dysfunction and heart failure.