Qingyong Li

Organic anion-transporting polypeptides: a novel approach for cancer therapy

Abstract Organic anion-transporting polypeptides (OATPs) encoded by the SLCO genes constitute an important transporter superfamily that mediates transmembrane transport of various clinical drugs and endogenous nutrients. Eleven human OATPs with different transport functions are expressed in various tissues. Bile acids, steroid hormone conjugates, prostaglandins, testosterone and thyroid hormones that promote cell proliferation are typical substrates of OATPs. Many important clinical drugs have been identified as substrates of OATP1B1, OATP1B3, OATP2B1 and OATP1A2. Liver-specific OATP1B1 and OATP1B3 as well as testis-specific OATP6A1 are expressed in malignancies and can act as biomarkers for many tumours. Various studies have shown the associations of genetic polymorphisms in OATP genes with the uptake pharmacokinetics of their substrates. Because of their abundant expression in tumours and their high transport activity for many cancer drugs, OATPs should be considered as important therapeutic targets in anti-cancer drug design.

Ionic liquid-aqueous solution ultrasonic-assisted extraction of three kinds of alkaloids from Phellodendron amurense Rupr and optimize conditions use response surface

In this paper, we chose diffident kinds of ionic liquids to optimal selection an optimal one to extract alkaloids from Phellodendron amurense Rupr. Four ionic liquids with diffident carbon chains or anions have been investigated and 1-butyl-3-methylimidazolium bromide with best productivity. Then, selections have been optimized in different conditions, including concentration of ionic liquid, time for ultrasonic treatment, ultrasonic power and solid-liquid ratio. Moreover, three conditions have been comprehensively assessment by response surface methodology, the optimal conditions were determined as follows ultrasonic power 100 W, extraction time 75 min and ratio of solvent to raw material 1:14. Under these conditions, the yield% (MIX) was 106.7% (extracted by heat reflux being defined 100%). Comparing with other methods, the advantages are saving conserving, time saving, high yield% and especially pollution-free.

Total synthesis of six 3,4-unsubstituted coumarins.

In this article we describe a new methodology for the total synthesis of 3,4-unsubstituted coumarins from commercially available starting materials. Six examples were prepared, including five naturally occurring coumarins—7-hydroxy-6,8-dimethoxy-coumarin (isofraxidin), 7-hydroxy-6-methoxycoumarin (scopoletin), 6,7,8-trimethoxy-coumarin, 6,7-dimethoxycoumarin (scoparone), and 7,8-dihydroxycoumarin (daphnetin) and one synthetic coumarin, 7-hydroxy-6-ethoxycoumarin. Moreover, five important o-hydroxybenzaldehyde intermediates were also obtained, namely 2,4-dihydroxy-3,5-dimethoxybenzaldehyde, 2,4-dihydroxy-5-methoxybenzaldehyde, 5-ethoxy-2,4-dihydroxy-benzaldehyde, 2-hydroxy-3,4,5-trimethoxybenzaldehyde, and 2-hydroxy-4,5-dimethoxy-benzaldehyde. The method developed herein involves just three or four steps and allows for the rapid synthesis of these important molecules in excellent yields. This is the first synthesis of 6,7,8-trimethoxycoumarin and 7-hydroxy-6-ethoxycoumarin.

The biological characteristics of a novel camptothecin–artesunate conjugate

A novel conjugate of camptothecin and artesunate (C-Q) was prepared and its cytotoxicity was evaluated using the MTT assay. In addition, the antitumour activity and toxicity of C-Q were investigated in mice, and interaction between transferrin (TF) and C-Q was investigated to evaluate its interaction with biological macromolecules. In the MTT assay, C-Q showed better inhibitory activity against MCF7 breast cancer cells and SMMC-7721 liver cancer cells than camptothecin or artesunate. In vivo, C-Q showed lower toxicity and better antitumour activity compared with camptothecin. Fluorescence spectroscopy showed static quenching of TF in the presence of C-Q, and thermodynamic parameters (ΔH>0 and ΔG<0) indicated that the reaction was spontaneous and endothermic. The main binding force between C-Q and TF was hydrophobic, as indicated by thermodynamic parameters (ΔH>0 and ΔS>0). Thus, synchronous fluorescence spectra showed that C-Q had no influence on the conformation of TF. Our results indicated that C-Q represents a novel potential anticancer therapeutic vector with advantages over current methods of CPT and ART administration. This novel drug delivery system allows the use of these drugs in a manner associated with few side effects for normal tissue, and which facilitates synergistic effects of anti-tumour drugs.

Preparation, formula optimization and antitumor actions of mannitol coupling camptothecin nanoparticles.

The purpose of this work is to prepare a formulation using mannitol coupling Camptothecin (CPT) nanoparticles (CPT-NPs) to circumvent the difficult solubilization practice based on central composite experimental statistical design. CPT-NPs were prepared with a high-pressure homogenization technique method. The independent variables considered for the optimization of CPT-NPs were percentage of CPT in raw material (CPT and mannitol), concentration of CPT in working liquid, cycles numbers and homogenizer pressure for drug loading efficiency, particle size and polydispersity index. Analysis of variance (ANOVA) statistical test was used to assess the optimization. The optimized CPT-NPs showed an appropriate drug loading efficiency (18.09 ± 2.13%), a homogeneous particle size (165.33 ± 37.23 nm) and a low polydispersity index (0.29 ± 0.01). The CPT-NPs group show higher inhibition ratio (79.95%) of H22 tumor growth in vivo compared with TPT and CPT at the same dose. Changes in mice body weight demonstrate CPT-NPs have the lower toxicity. The results of biodistribution studies indicated the obviously superiority of CPT-NPs in increasing the accumulation of CPT within tumor. Overall, CPT-NPs under optimum conditions are considered to be potentially feasible to overcome formulation challenges for drug delivery.

Two Novel Curcumin Analogues Induced Reactive Oxygen Species Generation and Mitochondrial-Related Apoptosis in Human Breast Cancer MCF - 7 Cells

Objective: Curcumin has been shown to have significant protective effects against cancer and induction of apoptosis is a crucial strategy for cancer therapy, so we have now evaluated the mechanisms involved in two novel asymmetric curcumin analogues induced cell death in MCF - 7 cells. Methods: The cytotoxicity of two curcumin analogues towards tumor cells was investigated by MTT assays. The morphological analysis using a laser scanning confocal microscope. Futher cell cycle analysis, reactive oxygen species (ROS), mitochondrial transmembrane potentials (Δφm), intracellular Ca2+ levels analysis and apoptosis assays via a flow cytometry (FCM). We used western blot assays to determine the expressions of apoptosis-related factors and p38MAPK at protein level. Results: MCF - 7 cells showed a significant loss of viability, reduced mitochondrial membrane potential (Δφm), increased intracellular Ca2+ levels, and increased production of ROS, which activated the pro-apoptotic p38 mitogen-activated protein kinase. Pretreatment with the antioxidant, N-acetylcysteine, inhibited both two curcumin analogues mediated ROS production and cytotoxicity. Western blotting revealed that the loss of Δφm inhibited Bcl-2, and induced Bax and Bak expression; this promoted release of cytochrome c and apoptosis inducing factor from the mitochondria to the cytosol, activation of caspase-9 and caspase-3 in the cytosol, and induction of apoptosis. Conclusion: The two curcumin analogues displays strong antitumor effect through ROS-dependent mitochondria apoptosis pathway in MCF - 7 cells, and has promising potential to be developed as antitumor compounds.

A liquid chromatography-tandem mass spectrometry method for pharmacokinetics and tissue distribution of a camptothecin quaternary derivative in rats.

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to identify and quantify the camptothecin quaternary derivative CPT8 for application in pharmacokinetics and tissue distribution studies. Rat plasma and tissue samples were extracted with methanol by using camptothecin as the internal standard (IS). Chromatographic separation of CPT8 and the IS was achieved using a Hypersil GOLD C18 column, with a flow rate of 1.0 mL/min followed by quantification with tandem mass spectrometry, operating with electrospray ionization in the positive ion mode and by applying multiple reaction monitoring. The MS/MS ion transitions were monitored at m/z 484.3-361.2 for CPT8 and m/z 349.0-305.2 for the IS (CPT). A calibration curve was constructed using CPT8 concentrations ranging from 2.5 ng/mL to 2500 ng/mL (r>0.993). The efficiency of CPT8 extraction from plasma and tissue samples ranged from 91.23% to 105.4%. Intra- and inter-day precision (relative standard deviation) values were 0.21% and 7.25%, respectively. No matrix effects were observed. The freeze-thaw stability, post-extraction stability, and stability following short- and long-term storage at low temperatures ranged from 84.12% to 108.2%. The preclinical data obtained using this method is expected to facilitate future clinical investigations of CPT8.

Pharmacokinetic studies of novel berberine derivatives with ultra-performance liquid chromatography–tandem mass spectrometry

An ultra-performance liquid chromatography with tandem mass spectrometric detection method was developed for the detection of berberine and its derivatives (A4, B4) in rat plasma and other organs. This validated method was successfully applied to our pharmacokinetic study of BBR derivatives in rats. At the same dose of administration, the Cmax of B4 was about eight times higher than BBR, and its half-life was approximately two times longer than BBR, according to the bigger areas under plasma concentration curves. Inversely, the pharmacokinetic parameter levels of A4 were all inferior to BBR, suggesting a tight structure-activity relationship of these compounds. Small dose of parenteral administration was used for the study of absolute oral bioavailability of A4, B4, and BBR, and the results calculated were 0.12%, 3.4% and 0.7%, respectively. The accumulations of B4 among all organs were intestine>liver>heart>kidney>lung>spleen>plasma, proving a deeply targeting property of B4, which met our experimental assumption. Together, the experimental results proved that compared with BBR and A4, the derivative B4 had higher absolute oral bioavailability and the ability of deeply targeting so that can be likely used in some organ-targeted diseases.

Transport and killing mechanism of a novel camptothecin-deoxycholic acid derivate on hepatocellular carcinoma cells

Abstract Camptothecin-20(s)-O-glycine ester-[N-(3′α, 12′α-dihydroxy-24′-carbonyl-5′β-cholan)] (A2), 10-(3′α,12′α-dihydroxy-5′β-cholan-24′-carboxyl)-(20 s)-camptothecin (C2), and 10-O-(3-O-(3′α, 12′α-dihydroxy-24′-carbonyl-5′β-cholan)-propyl)-(20S)-camptothecin (D2) are novel camptothecin-deoxycholic acid analogues. MTT assays were performed to assess the anticancer activity of these compounds against hepatocellular carcinoma SMMC-7721, breast carcinoma MCF-7, and colorectal carcinoma HCT-116 cells. A2 had a high killing ability on SMMC-7721 cells selectively, but C2 and D2 did not exhibit selectivity with regard to SMMC-7721 killing. Uptake assays were performed in an effort to elucidate the transport mechanisms of A2 into SMMC-7721 cells. A2 increased the mRNA expression of OATP1B3 (an organic anion-transporting polypeptide) and uptake of A2 was inhibited by rifampin (inhibitor of OATP1B3), which indicated that the transporter-mediated transport of A2 was mediated by OATP1B3. In addition, according to the western blot and apoptosis assays, we found that A2 killed SMMC-7721 cells by inducing cell apoptosis mainly via an AIF (apoptosis-inducing factor) pathway and a caspase-dependent mitochondria apoptosis pathway.

Optimization of hydrogel containing toluidine blue O for photodynamic therapy by response surface methodology

Photodynamic therapy with toluidine blue O (TBO) hydrogel exhibits antibacterial activity against Staphylococcus aureus and Escherichia coli in this paper. The response surface methodology is employed to optimize formulations for antibacterial activity. The optimal formulations are carbomer concentration of 3% (w/v), TBO concentration of 0.1mg/mL and the quality ratio of NaOH and carbomer of 0.4 (w/w). Under the optimized formulations, the log-transformed of CFUmL-1 on the Staphylococcus aureus and Escherichia coli are 0.84 and 1.26 (the log-transformed of CFUmL-1 of negative control groups on the Staphylococcus aureus and Escherichia coli are 8.21 and 8.47), respectively. In comparison with photodynamic therapy with TBO aqueous solution, the proposed formulations provide a much stronger antibacterial activity against Staphylococcus aureus and Escherichia coli. TBO hydrogels are stable during 6weeks at three different temperatures (4, 25 and 40°C) with respect to no change of color, transparency, pH and viscosity. 50% and 68.26% of TBO are released from carbomer hydrogel after 4h and 24h, respectively. TBO hydrogel alone or light alone (630nm) treatment is incapable of showing antibacterial activity against Staphylococcus aureus and Escherichia coli. Therefore, photodynamic therapy with the novel optimized TBO hydrogel formulations is a promising treatment strategy for periodontitis.