Designed P-glycoprotein inhibitors with triazol-tetrahydroisoquinoline-core increase doxorubicin-induced mortality in multidrug resistant K562/A02 cells.

Multidrug resistance (MDR) refers to the cross-resistance of cancer cells to one drug, accompanied by other drugs with different mechanisms and structures, which is one of the main obstacles of clinical chemotherapy. Overexpression of P-glycoprotein (P-gp) was an extensively studied cause of MDR. Therefore, inhibiting P-gp have become an important strategy to reverse MDR. In this study, two series of triazole-tetrahydroisoquinoline-core P-gp inhibitors were designed and synthesized. Among them, compound I-5 had a remarkable reversal activity of MDR activity and the preliminary mechanism study was also carried out. All the results proved that compound I-5 was considered as a promising P-gp-mediated MDR reversal candidate.

Design, synthesis, and biological evaluation of novel nitric oxide releasing dehydroandrographolide derivatives.

A series of new hybrids of dehydroandrographolide (TAD), a biologically active natural product, bearing nitric oxide (NO)-releasing moieties were synthesized and designated as NO-donor dehydroandrographolide. The biological activities of target compounds were studied in human erythroleukemia K562 cells and breast cancer MCF-7 cells. Biological evaluation indicated that the most active compound I-5 produced high levels of NO and inhibited the proliferation of K562 (IC50 1.55 µmol·L-1) and MCF-7 (IC50 2.91 µmol·L-1) cells, which were more potent than the lead compound TAD and attenuated by an NO scavenger. In conclusion, I-5 is a novel hybrid with potent antitumor activity and may become a promising candidate for future intensive study.

Injectable self-assembled peptide hydrogels for glucose-mediated insulin delivery.

Closed-loop glucose-responsive insulin delivery with excellent biocompatibility has the potential to improve the health and quality of life of diabetic patients. Herein, we developed an excellent glucose-responsive insulin delivery system using a pH-sensitive peptide hydrogel loaded with insulin and a glucose-specific enzyme. The designed peptide can be used as a carrier that is loaded with insulin and enzyme via a self-assembly process under physiological conditions. When hyperglycemia is encountered, the enzymatic conversion of glucose into gluconic acid leads to a decrease in the local pH, and the hydrogel is disassembled because of the strong inter- and intramolecular electrostatic repulsions between ornithine (Orn) residues; this is followed by the release of insulin. The glucose-responsive hydrogel system was characterized by studying its structure, conformation, rheology, morphology, acid sensitivity and the amounts of consistent release of insulin in vitro and in vivo. In vivo experiments indicated that the closed-loop insulin glucose-responsive system could efficiently regulate blood glucose in streptozocin-induced (STZ-induced) type 1 diabetic rats for 8 days.

Pro-apoptotic cationic host defense peptides rich in lysine or arginine to reverse drug resistance by disrupting tumor cell membrane.

Host defense peptides have been demonstrated to exhibit prominent advantages in cancer therapy with selective binding ability toward tumor cells via electrostatic attractions, which can overcome the limitations of traditional chemotherapy drugs, such as toxicity on non-malignant cells and the emergence of drug resistance. In this work, we redesigned and constructed a series of cationic peptides by inserting hydrophobic residues into hydrophilic surface or replacing lysine (K) with arginine (R), based on the experience from the preliminary work of host defense peptide B1. In-depth studies demonstrated that the engineered peptides exhibited more potent anti-cancer activity against various cancer cell lines and much lower toxicity to normal cells compared with B1. Further investigation revealed that compounds I-3 and I-7 could act on cancer cell membranes and subsequently alter the permeability, which facilitated obvious pro-apoptotic activity in paclitaxel-resistant cell line (MCF-7/Taxol). The result of mitochondrial membrane potential assay (ΔΨm) demonstrated that the peptides induced ΔΨm dissipation and mitochondrial depolarization. The caspase-3 cellular activity assay showed that the anti-cancer activity of peptides functioned via caspase-3-dependent apoptosis. The study yielded compound I-7 with superior properties for antineoplastic activity in comparison to B1, which makes it a promising potential candidate for cancer therapy.

Synthesis and biological evaluation of JL-A7 derivatives as potent ABCB1 inhibitors.

Cancer chemotherapy failure is often due to the overexpression of ATP-binding cassette (ABC) transporters (particularly ABCB1), resulting in a variety of structurally and pharmacologically unrelated drugs efflux. The multidrug resistance (MDR) phenomenon could be reversed by ABCB1 inhibitors. Now, JL-A7 as the lead compound based on a triazol-N-ethyl-tetrahydroisoquinoline scaffold, 18 compounds were designed and synthesized. Substitution in para positions yielded high activities toward ABCB1. Moreover, compound 5 could effectively block the drug efflux function of ABCB1 and increase the accumulation of anti-cancer drugs to achieve effective treatment concentration in MDR cells.

Exploration of 2-((Pyridin-4-ylmethyl)amino)nicotinamide Derivatives as Potent Reversal Agents against P-Glycoprotein-Mediated Multidrug Resistance.

Overexpression of the ATP-binding cassette (ABC) transport proteins, like ABCB1, commonly referred to as P-glycoprotein (P-gp), initiates active efflux of a broad spectrum of unrelated chemotherapeutic drugs in structure and function, leading to chemotherapy failure. A series of 2-((pyridin-4-ylmethyl)amino)nicotinamide derivatives as potent reversal agents against P-glycoprotein-mediated multidrug resistance (MDR) were designed and synthesized. The majority of target compounds displayed great reversal potency, especially 9n. In-depth studies demonstrated 9n has high potency (EC50 = 119.6 ± 6.9 nM), low cytotoxicity, and long duration (>24 h) in reversing adriamycin (ADM) resistance in K562/A02 cells. 9n also improved the effects of other cytotoxic agents related to MDR, increased accumulation of ADM, interrupted P-gp-mediated Rh123 efflux function, and suppressed P-gp ATPase activity in K562/A02 MDR cells. The Western blot analysis indicated that the MDR reversal by 9n was not due to a decrease in protein expression. Besides, the effect of CYP3A4 was not influenced by 9n, avoiding the toxicity caused by drug interactions. The study yielded 9n with superior properties compared to the classical inhibitor verapamil (VRP) and leading compound apatinib.

Design, Synthesis, and Pharmacological Characterization of N-(4-(2 (6,7-Dimethoxy-3,4-dihydroisoquinolin-2(1H)yl)ethyl)phenyl)quinazolin-4-amine Derivatives: Novel Inhibitors Reversing P-Glycoprotein-Mediated Multidrug Resistance.

P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) is a principal obstacle for successful cancer chemotherapy. A novel P-gp inhibitor with a quinazoline scaffold, 12k, was considered to be the most promising for in-depth study. 12k possessed high potency (EC50 = 57.9 ± 3.5 nM), low cytotoxicity, and long duration of activity in reversing doxorubicin (DOX) resistance in K562/A02 cells. 12k also boosted the potency of other MDR-related cytotoxic agents with different structures, increased accumulation of DOX, blocked P-gp-mediated Rh123 efflux, and suppressed P-gp ATPase activity in K562/A02 MDR cells. However, 12k did not have any effects on CYP3A4 activity or P-gp expression. In particular, 12k had a good half-life and oral bioavailability and displayed no influence on DOX metabolism to obviate the side effects closely related to increased plasma concentrations of cytotoxic agents in vivo.

A novel mitochondria-targeting fluorescent probe for hydrogen sulfide in living cells.

A novel mitochondria-targeting fluorescent probe compound S-N3 for hydrogen sulfide (H2 S) in living cells has been designed and synthesized in this study. This article contained the chemosynthesis and some studies on bioactivity of the target compound in living cells. Compound S-N3 is easy to synthesize and can remain stable under the effect of pH, system and photostability. In addition, it shows low cytotoxicity in cell imaging. And it can react with H2 S highly selective in PBS or FBS solution, which would cause the obvious increase in fluorescence intensity. Therefore, the low-cost detection method for H2 S is allowed for monitoring the quantity of H2 S existed in the mitochondria.

Design, synthesis and biological evaluation of LBM-A5 derivatives as potent P-glycoprotein-mediated multidrug resistance inhibitors.

A novel series of P-glycoprotein (P-gp)-mediated multidrug resistance (MDR) inhibitors with triazol-N-phenethyl-tetrahydroisoquinoline or triazol-N-ethyl-tetrahydroisoquinoline scaffold were designed and synthesized via click chemistry. Most of the synthesized compounds showed higher reversal activity than verapamil (VRP). Among them, the most potent compound 4 showed a comparable activity with the known potent P-gp inhibitor WK-X-34 with lower cytotoxicity toward K562 cells (IC50>100µM). Compared with VRP, compound 4 exhibited more potency in increasing drug accumulation in K562/A02 MDR cells. Moreover, compound 4 could significantly reverse MDR in a dose-dependent manner and also persist longer chemo-sensitizing effect than VRP with reversibility. Further mechanism studies revealed that compound 4 could remarkably increase the intracellular accumulation of Adriamycin (ADM) in K562/A02 cells as well as inhibit rhodamine-123 (Rh123) efflux from the cells. These results suggested that compound 4 may represent a promising candidate for developing P-gp-mediated MDR inhibitors.