Xin Deng

pH-sensitive peptide hydrogel for glucose-responsive insulin delivery

Glucose-responsive system is one of important options for self-regulated insulin delivery to treat diabetes, which has become an issue of great public health concern in the world. In this study, we developed a novel and biocompatible glucose-responsive insulin delivery system using a pH-sensitive peptide hydrogel as a carrier loaded with glucose oxidase, catalase and insulin. The peptide could self-assemble into hydrogel under physiological conditions. When hypoglycemia is encountered, neighboring alkaline amino acid side chains are significantly repulsed due to reduced local pH by the enzymatic conversion of glucose into gluconic acid. This is followed by unfolding of individual hairpins, disassembly and release of insulin. The glucose-responsive hydrogel system was characterized on the basis of structure, conformation, rheology, morphology, acid-sensitivity and the amount of consistent release of insulin in vitro and vivo. The results illustrated that our system can not only regulate the blood glucose levels in vitro but also in mice models having STZ-induced diabetes. STATEMENT OF SIGNIFICANCE In this report, we have shown the following significance supported by the experimental results. 1. We successfully developed, characterized and screened a novel pH-responsive peptide. 2. We successfully developed a novel and biocompatible pH-sensitive peptide hydrogel as glucose-responsive insulin delivery system loaded with glucose oxidase, catalase and insulin. 3. We successfully confirmed that the hydrogel platform could regulate the blood glucose level in vitro and in vivo. Overall, we have shown enough significance and novelty with this smart hydrogel platform in terms of biomaterials, peptide chemistry, self-assembly, hydrogel and drug delivery. So we believe this manuscript is suitable for Acta Biomaterialia.

Design, Synthesis, and Biological Evaluation of Andrographolide Derivatives as Potent Hepatoprotective Agents

Poor water solubility limits the clinical use of andrographolide and its derivatives. In an attempt to develop potent hepatoprotective drugs, a strategy was proposed to improve the aqueous solubility of andrographolide. Ten andrographolide derivatives were designed, synthesized, evaluated for aqueous solubility and in vivo hepatoprotective activity against CCl4‐induced liver injury in mice. As expected, the aqueous solubility of synthetic derivatives was effectively improved. All compounds demonstrated the effect of different degrees in improving the liver enzyme (ALT and AST) activity, especially the most promising compound 9d significantly improved liver enzyme activity, with high potency to be a new lead.

Evaluation of hypoglycemic and antioxidative effects of synthesized peptide MC62.

Diabetes mellitus has been considered as a major health problem in the world today. This study aimed to investigate the hypoglycemic and antioxidative effects of peptide MC62 which was synthesized by solid‐phase peptide synthesis method against diabetes induced by streptozotocin. MC62 was administered daily and injected intraperitoneally to the diabetic mice at a dose of 1 μmol/kg body weight for 20 days. The levels of fasting blood glucose and HbA1C, pancreatic islet damage, and associated changes in antioxidative activities were evaluated in streptozotocin‐induced diabetic mice used the exenatide as positive control. After the administration of MC62 together with exenatide for 20 days, the elevated fasting blood glucose and HbA1C levels were reduced, and antioxidative activities were restored. It was confirmed with the histological finding that MC62 prevented the islet from damage in diabetic mice. This indicated that MC62 can prevent mice from hyperglycemia which may be associated with oxidative stress. It also suggested that MC62 could be used as a safe alternative hypoglycemic candidate for treatment of diabetes.

Design, synthesis and biological evaluation of novel peptides with anti-cancer and drug resistance-reversing activities.

Chemotherapy is an important approach used to treat cancer, but severe side effects and emerging drug resistance restrict its clinical application. In this present study, we found that peptide B1 showed specific cytotoxicity to tumor cells. Moreover, a helix-wheel plot predicted that the Ser14 in this peptide is located at the interface of the hydrophobic and hydrophilic faces of B1. Subsequently, we wondered whether replacing Ser14 would alter the activity of B1, and so a series of B1 analogs were synthesized where the Ser14 was replaced by amino acids with distinct physicochemical properties. Amongst them, peptides where Ser14 was substituted by a nonpolar and basic amino acid had improved anti-cancer activity. Further investigations revealed that B1 and its analogs were capable of penetrating into cytoplasm and triggering cytochrome C release from mitochondria, which ultimately resulted in apoptosis. Meanwhile, B1 and its analogs inhibited the migration of cancer cells. The peptides also acted against drug-resistant cells and had drug resistance-reversing effects. In conclusion, these peptides might be promising candidates for oncotherapy.

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 rapid and sensitive UPLC-MS/MS method for determination of HZ08 in rat plasma and tissues: application to a pharmacokinetic study of liposome injections.

Overexpression of P-glycoprotein leads to tumor multidrug resistance (MDR). HZ08, a novel tetrahydro-isoquinoline derivate, was discovered to inhibit the MDR in the cancer cell lines of MCF-7/ADM, K562/ADM and KBV in our previous studies. A rapid and sensitive ultra-performance liquid chromatography-tandem mass spectrometric method (UPLC-MS/MS) was developed and validated for determination of HZ08 in rat plasma and tissues after intravenous administration of HZ08 liposome injection at different doses. The analytes were extracted from plasma and tissues using protein precipitation by acetonitrile with clotrimazole as internal standard. The chromatographic separation was performed on a Thermo BDS HYPERSIL C18 column (100 mm × 4.6mm, 2.4 μm) at a flow rate of 0.7 ml/min using 0.2% ammonium acetate solution (containing 0.1% formic acid) and methanol as mobile phase. The total run time was 4 min. The tandem mass detection was applied with electrospray ionization in positive ion selected reaction monitoring mode. The ion transitions monitored were m/z 523.5 to 342.3 for HZ08 and 277.1 to 165.1 for the internal standard, respectively. The calibration curves obtained were linear in different matrices, and the lower limit of quantification (LLOQ) achieved was 1 ng/ml for rat plasma and 0.25 ng/ml for rat tissues, respectively. The RSDs for intra- and inter-day precision were less than 15%. Extraction recovery, matrix effect and stability were satisfactory in rat plasma and tissues. The developed method was successfully applied to a pharmacokinetic study of HZ08 liposome injection following intravenous administration of 1, 3, 10mg/kg to Sprague-Dawley rats. The data profiles revealed that HZ08 had linear pharmacokinetic properties at the tested doses, and was rapidly distributed into the systemic circulation with wide distribution throughout the body followed by a rapid elimination phase. The major distribution tissues of HZ08 in rats were lung, spleen and liver. These results provided constructive contribution to support the clinical evaluation.

Design, Synthesis, and Biological Evaluation of Novel Cholesteryl Peptides with Anticancer and Multidrug Resistance‐Reversing Activities

Antimicrobial peptides have been suggested as promising chemotherapeutics for cancer therapy due to their efficient antitumor activity and lower toxicity to benign cells. In previous study, we find the peptide B1 presents specific cytotoxicity to cancer cells. As hydrophobicity plays a pivotal role in the anticancer activity of peptide, we introduce cholesterol‐like moiety (3β‐amino‐5‐cholestene) to the N‐terminus of B1 expect to ameliorate the anticancer activity of B1. Biological evaluations revealed that target peptides show improved anticancer activity. The peptides can also penetrate into the cytoplasm and activating mitochondria–cytochrome c apoptosis pathway. Besides, the peptides acted on multidrug‐resistant cells and had multidrug resistance‐reversing activity. It is therefore suggested these peptides might be promising candidates for oncotherapy.

A High-Sensitivity Coumarin-Based Fluorescent Probe for Monitoring Hydrogen Sulfide in Living Cells

A novel coumarin‐based fluorescence probe has been constructed for the selective and sensitive detection of hydrogen sulfide (H2S). This probe displays high sensitivity and linearity to H2S in degassed PBS buffers and fetal bovine serum. It reacts with H2S with high selectivity over Cys, GSH, and other anions. Meanwhile, successful detection of H2S in living cells was also demonstrated.

Evaluation of Anti‐inflammatory and Analgesic Effects of Synthesized Derivatives of Ibuprofen

Inflammatory and pain are major areas for drug discovery. Current analgesic drugs often cause a number of side‐effects. In the present study, we modified carboxylic acid group of ibuprofen, one of non‐steroidal anti‐inflammatory drugs, based on the common structure of transient receptor potential vanilloid type 1 antagonists which are considered as new candidates for analgesic drugs, and synthesized several derivatives of ibuprofen. Comprehensive evaluations of the pharmacological properties of these compounds were investigated. Compound 17 showed weak cyclooxygenase inhibition and exhibited strong transient receptor potential vanilloid type 1 antagonistic activity. It was found to be capable of blocking noxious thermal nociception and capsaicin‐induced nociception in mice. Besides, 17 showed less ulcerogenic action than ibuprofen did and had no hyperthermia side‐effect compared with common transient receptor potential vanilloid type 1 antagonists. Therefore, it suggested that 17 could be used as a safe alternative analgesic candidate for pain treatment.

Synthesis and in vitro anti-cancer evaluation of luteinizing hormone-releasing hormone-conjugated peptide

Luteinizing hormone-releasing hormone (LHRH) is a decapeptide hormone released from the hypothalamus and shows high affinity binding to the LHRH receptors. It is reported that several cancer cells also express LHRH receptors such as breast, ovarian, prostatic, bladder and others. In this study, we linked B1, an anti-cancer peptide, to LHRH and its analogs to improve the activity against cancer cells with LHRH receptor. Biological evaluation revealed that TB1, the peptide contains triptorelin sequence, present favorable anti-cancer activity as well as plasma stability. Further investigations disclosed that TB1 trigger apoptosis by activating the mitochondria–cytochrome c–caspase apoptotic pathway, it also exhibited the anti-migratory effect on cancer cells.