Multifunctional Protein Hybrid Nanoplatform for Synergetic Photodynamic-Chemotherapy of Malignant Carcinoma by Homologous Targeting Combined with Oxygen Transport.

Photodynamic therapy (PDT) under hypoxic conditions and drug resistance in chemotherapy are perplexing problems in anti-tumor treatment. In addition, central nervous system neoplasm-targeted nanoplatforms are urgently required. To address these issues, a new multi-functional protein hybrid nanoplatform is designed, consisting of transferrin (TFR) as the multicategory solid tumor recognizer and hemoglobin for oxygen supply (ODP-TH). This protein hybrid framework encapsulates the photosensitizer protoporphyrin IX (PpIX) and chemotherapeutic agent doxorubicin (Dox), which are attached by a glutathione-responsive disulfide bond. Mechanistically, ODP-TH crosses the blood-brain barrier (BBB) and specifically aggregated in hypoxic tumors via protein homology recognition. Oxygen and encapsulated drugs ultimately promote a therapeutic effect by down-regulating the abundance of multidrug resistance gene 1 (MDR1) and hypoxia-inducible factor-1-α (HIF-1α). The results reveal that ODP-TH achieves oxygen transport and protein homology recognition in the hypoxic tumor occupation. Indeed, compared with traditional photodynamic chemotherapy, ODP-TH achieves a more efficient tumor-inhibiting effect. This study not only overcomes the hypoxia-related inhibition in combination therapy by targeted oxygen transport but also achieves an effective treatment of multiple tumors, such as breast cancer and glioma, providing a new concept for the construction of a promising multi-functional targeted and intensive anti-tumor nanoplatform.

A new mitochondria-targeted fluorescent probe for exogenous and endogenous superoxide anion imaging in living cells and pneumonia tissue.

As a precursor of all reactive oxygen species (ROS), superoxide anions play an important role in organisms. However, excessive superoxide anions can cause various diseases. Thus, it is highly urgent to develop efficient tools for in situ superoxide anion detection. In this work, a novel boric acid-based, mitochondria-targeted fluorescent probe Mito-YX for superoxide anion detection was designed by regulating its intramolecular charge transfer (ICT) effect. The probe exhibited turn-on fluorescence enhancement within 4 min of reaction with the superoxide anion. In addition, Mito-YX also exhibited high selectivity and a low detection limit down to 0.24 µM with good mitochondrial targeting characteristics, which provided a necessary basis for in vivo detection of superoxide anions. What is more, Mito-YX was successfully applied for the in situ monitoring of superoxide anions in living MCF-7 cells, RAW 264.7 cells and a mouse model of lung inflammation stimulated by LPS. This work provided an important and promising tool for rapid in situ diagnosis and research of the progression of pneumonia.

Synthesis and Biological Evaluation of Dithiobisacetamides as Novel Urease Inhibitors.

Thirty-eight disulfides containing N-arylacetamide were designed and synthesized in an effort to develop novel urease inhibitors. Biological evaluation revealed that some of the synthetic compounds exhibited strong inhibitory potency against both cell-free urease and urease in intact cell with low cytotoxicity to mammalian cells even at concentration up to 250 µM. Of note, 2,2'-dithiobis(N-(2-fluorophenyl)acetamide) (d7), 2,2'-dithiobis(N-(3,5-difluorophenyl)acetamide) (d24), and 2,2'-dithiobis(N-(3-fluorophenyl)acetamide) (d8) were here identified as the most active inhibitors with IC50 of 0.074, 0.44, and 0.81 µM, showing 32- to 355-fold higher potency than the positive control acetohydroxamic acid. These disulfides were confirmed to bind urease without covalent modification of the cysteine residue and to inhibit urease reversibly with a mixed inhibition mechanism. They also showed very good anti-Helicobacter pylori activities with d8 showing a comparable potency to the clinical used drug amoxicillin. The impressive in vitro biological profile indicated their immense potential as therapeutic agents to tackle H. pylori caused infections.

A new fluorescently labeled bisphosphonate for theranostics in tumor bone metastasis.

Bone metastasis of malignant solid tumors has become one of the most serious complications, especially in breast cancer, which was particularly challenging for early detection and treatment in clinical practice. In this work, we reported a new fluorescently labeled bisphosphonate for bone metastasis detection of breast cancer. The designed probes were based on Rhodamine B and bisphosphonate as recognition group, which can specifically target hydroxyapatite (HA) existed in bone tissue. After the osteoclasts were adsorbed on the bone surface, the surrounding microenvironment was acidified, causing the HA to locally dissolve. The probe bound to the HA was then released, and realized the fluorescence turn on under acidic conditions. In vitro experiments showed that G0 was more excellent than G2 owing to shorter connecting arm. Subsequently, we proved that G0 could combine with HA rapidly and exhibit excellent response in solid state. More importantly, we established a model of bone metastasis with MDA-MB-231 cells which was similar to the clinical cases and evaluated the theranostics value of G0 prospectively, which provide the potential application prospect in clinical.

A novel fast-response and highly selective AIEgen fluorescent probe for visualizing peroxynitrite in living cells, C. elegans and inflammatory mice.

Most of the ONOO- fluorescent probes have restricted applications because of their aggregation-caused quenching (ACQ) effect, long response time and low fluorescence enhancement. Herein, we developed a novel AIEgen fluorescent probe (PE-XY) based on a benzothiazole and quinolin scaffold with high sensitivity and selectivity for imaging of ONOO-. The results indicated that probe PE-XY exhibited fast response towards ONOO- with 2000-fold enhancement of fluorescence intensity ratio in vitro. Moreover, PE-XY exhibited a relatively high sensitivity (limit of detection: 8.58 nM), rapid response (<50 s), high fluorescence quantum yield (δ = 0.81) and excellent selectivity over other analytes towards ONOO-in vitro. Furthermore, PE-XY was successfully applied to detect endogenous ONOO- levels in living HeLa cells, C. elegans and inflammatory mice with low cytotoxicity. Overall, this work provided a novel fast-response and highly selective AIEgen fluorescent probe for real-time monitoring ONOO- fluctuations in living systems.

Glutathione-responsive prodrug conjugates for image-guided combination in cancer therapy.

Theranostic prodrug was highly desirable for precise diagnosis and anti-cancer therapy to decrease side effects. However, it is difficult to conjugate chemo-drug and molecular probe for combined therapy due to the complex pharmacokinetics of different molecules. Here, a novel anticancer theranostic prodrug (BTMP-SS-PTX) had been designed and synthesized by conjugating paclitaxel (PTX) with 2-(benzo[d]thiazol-2-yl)-4-methoxyphenol (BTMP) through a disulphide (-S-S-) linkage, which was redox-sensitive to the high concentration of glutathione in tumors. Upon activation with glutathione in weakly acid media, the BTMP-SS-PTX can be dissociated to release free PTX and visible BTMP, which realized the visual tracking of free drug. The cytotoxicity study demonstrated that soluble prodrug BTMP-SS-PTX displayed more outstanding anticancer activity in HepG2, MCF-7 and HeLa cells, lower toxicity to non-cancer cells (293 T) than free drugs. Furthermore, BTMP-SS-PTX was still able to induce apoptosis of HeLa cells and significantly inhibited tumor growth in HeLa-xenograft mouse model. On the basis of these findings, BTMP-SS-PTX could play a potential role in cancer diagnosis and therapy.

Synthesis and Structure-Activity Relationship Studies of N-monosubstituted Aroylthioureas as Urease Inhibitors.

BACKGROUND: Thiourea is a classical urease inhibitor which is usually used as a positive control, and many N,N'-disubstituted thioureas have been determined as urease inhibitors. However, due to steric hindrance, N,N'-disubstituted thiourea motif could not bind urease as thiourea. On the contrary, N-monosubstituted thiourea with a tiny thiourea motif could theoretically bind into the active pocket as thiourea. OBJECTIVE: A series of N-monosubstituted aroylthioureas were designed and synthesized for evaluation as urease inhibitors. METHODS: Urease inhibition was determined by the indophenol method and IC50 values were calculated using computerized linear regression analysis of quantal log dose-probit functions. The kinetic parameters were estimated via surface plasmon resonance (SPR) and by nonlinear regression analysis based on the mixed type inhibition model derived from Michaelis-Menten kinetics. RESULTS: Compounds b2, b11, and b19 reversibly inhibited urease with a mixed mechanism, and showed excellent potency against both cell-free urease and urease in the intact cell, with IC50 values being 90- to 450-fold and 5- to 50-fold lower than the positive control acetohydroxamic acid, respectively. The most potent compound b11 showed an IC50 value of 0.060 ± 0.004µM against cell-free urease, which bound to urea binding site with a very low KD value (0.420±0.003nM) and a very long residence time (6.7 min). Compound b11 was also demonstrated to have very low cytotoxicity to mammalian cells. CONCLUSION: The results revealed that N-monosubstituted aroylthioureas bound to the active site of urease as expected, and represent a new class of urease inhibitors for the development of potential therapeutics against infections caused by urease-containing pathogens.

N-monosubstituted thiosemicarbazide as novel Ure inhibitors: synthesis, biological evaluation and molecular docking.

Background: Identification of novel Ure inhibitors with high potency has received considerable attention. Methodology & results: Ure inhibition was determined using the indophenol method, the affinities to Ure were estimated via surface plasmon resonance. Seventeen new plus ten known N-monosubstituted thiosemicarbazides were synthesized and identified as novel Ure inhibitors. Out of these compounds, compound b5 shows excellent activity against both crude Ure from Helicobacter pylori (IC50 = 0.04 µM) and Ure in living cell (IC50 = 0.27 µM), with the potency being over 600-fold higher than clinical used drug acetohyroxamic acid, respectively. Surface plasmon resonance demonstrated the high affinity (Kd.#x00A0;= 6.32 nM) of b5 to Ure. Conclusion: This work provides a class of novel and promising Ure inhibitors.

N-monoarylacetothioureas as potent urease inhibitors: synthesis, SAR, and biological evaluation.

A urease inhibitor with good in vivo profile is considered as an alternative agent for treating infections caused by urease-producing bacteria such as Helicobacter pylori. Here, we report a series of N-monosubstituted thioureas, which act as effective urease inhibitors with very low cytotoxicity. One compound (b19) was evaluated in detail and shows promising features for further development as an agent to treat H. pylori caused diseases. Excellent values for the inhibition of b19 against both extracted urease and urease in intact cell were observed, which shows IC50 values of 0.16 ± 0.05 and 3.86 ± 0.10 µM, being 170- and 44-fold more potent than the clinically used drug AHA, respectively. Docking simulations suggested that the monosubstituted thiourea moiety penetrates urea binding site. In addition, b19 is a rapid and reversible urease inhibitor, and displays nM affinity to urease with very slow dissociation (koff=1.60 × 10-3 s-1) from the catalytic domain.