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Featured researches published by Rugang Zhong.


Ultrasonics Sonochemistry | 2010

Improved synthesis of diethyl 2,6-dimethyl-4-aryl-4H-pyran-3,5-dicarboxylate under ultrasound irradiation.

Chengliang Ni; Xiaohui Song; Hong Yan; Xiu-Qing Song; Rugang Zhong

Diethyl 2,6-dimethyl-4-aryl-4H-pyran-3,5-dicarboxylates (1) have been synthesized by the reaction of aryl aldehyde and 1,3-diketone catalyzed by ZnCl(2) under ultrasound irradiation. The effects of changes in the ultrasonic power, temperature, and reaction time are discussed. With the optimized reaction conditions, various aryl aldehydes were used to synthesize 4H-pyrans (1) under the influence of ultrasound irradiation. Compared with the conventional thermal methods, the remarkable advantages of this method are the simple experimental procedure, shorter reaction time and high yield of product.


Molecules | 2009

Design, synthesis and anti-HIV integrase evaluation of 4-oxo-4H-quinolizine-3-carboxylic acid derivatives.

Yi‐Sheng Xu; Cheng-Chu Zeng; Zi-Guo Jiao; Liming Hu; Rugang Zhong

4-Oxo-4H-quinolizine-3-carboxylic acid derivatives bearing sulfamido, carboxylamido, benzimidazole and benzothiazole substituents have been designed and synthesized. The structures of these new compounds were confirmed by 1H-NMR, 13C- NMR, IR and ESI (or HRMS) spectra. Compounds were screened for possible HIV integrase inhibitory activity.


Analytical Letters | 2012

Determination of Lead in Human Hair by High Resolution Continuum Source Graphite Furnace Atomic Absorption Spectrometry with Microwave Digestion and Solid Sampling

Lijiao Zhao; Ting Ren; Rugang Zhong

The content of lead in human hair was measured by high resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GFAAS) combined with microwave-assisted digestion (MAD) and direct solid sampling (DSS). Hair strands were washed, dried, and then cut into three parts (root, middle portion, and tip). For MAD-GFAAS assays, approximately 0.25 g of hair was completely digested using a mixture of concentrated nitric acid and hydrogen peroxide in a closed system. In the DSS-GFAAS assays, 0.1–0.2 mg of dried hair was directly introduced into a graphite furnace using a solid autosampler. The temperature programs were optimized and the effects of various added modifiers were compared. The results indicated that NH4H2PO4 was the optimal modifier for analysis of Pb using GFAAS. Use of the optimal modifier and temperature program gave similar limits of detection for MAD-GFAAS and DSS-GFAAS of 1.16 ng/g and 0.82 ng/g, respectively. Both methods also produced satisfactory recoveries ranging from 98.69% to 103.14%. There was no significant difference observed between the Pb contents of hair strands determined by the MAD-GFAAS and DSS-GFAAS assays, which both indicated that the Pb levels increased along the hair strands. Comparison of the two methods revealed that DSS-GFAAS had several advantageous characteristics over MAD-GFAAS, including the need for much less sample material and having a less time-consuming procedure, lower sample blank absorbance, lower memory effect, and no risk of environmental pollution by digesting chemicals. The direct solid sampling technique can be employed as a good alternative to conventional wet digestion in AAS assays.


Rapid Communications in Mass Spectrometry | 2011

Quantification of meCCNU-induced dG-dC crosslinks in oligonucleotide duplexes by liquid chromatography/electrospray ionization tandem mass spectrometry.

Bao-Qing Bai; Lijiao Zhao; Rugang Zhong

Chloroethynitrosoureas (CENUs) are important alkylating agents widely used in the treatment of cancers. Decomposition of CENUs generates active electrophilic ions that damage DNA, including the formation of dG-dC crosslinks which represents the most important cytotoxic mechanism of CENUs. In this work, a high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS) method was employed to analyze the dG-dC crosslinks induced by 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (meCCNU, Semustine). The direct quantitation of dG-dC crosslinks in oligonucleotide duplexes was achieved by the selected reaction monitoring (SRM) mode using synthesized (15) N(3) -labeled dG-dC as an internal standard. Methods of enzymatic digestion and HPLC separation were developed for obtaining separation and reproducibility of the dG-dC peak in chromatograms. The limit-of-detection (LOD) was determined to be 0.08 nM and the limit-of-quantification (LOQ) was determined to be 0.16 nM. The linearity of the calibration curve was 0.9997 over the range of 0.08 to 32 nM. The precision and accuracy of the method ranged from 1.1 to 6.6% and 96 to 109%, respectively. The recovery of the dG-dC crosslink in the enzymatic hydrolysates from the oligonucleotide duplex was determined to be from 91 to 106%. The results of the validation study indicate that the method is suitable for quantifying dG-dC crosslinks in DNA. Consequently, this method was used to determine meCCNU-induced dG-dC crosslinks in four duplexes with different GC contents. The results showed that the crosslinking fraction (CF) increased as the GC content in the duplex increased, and a relatively low CF was observed in the early period of the reaction.


Chemical Research in Toxicology | 2014

Investigations on the Effect of O6-Benzylguanine on the Formation of dG-dC Interstrand Cross-Links Induced by Chloroethylnitrosoureas in Human Glioma Cells Using Stable Isotope Dilution High-Performance Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry

Guohui Sun; Lijiao Zhao; Tengjiao Fan; Sisi Li; Rugang Zhong

Chloroethylnitrosoureas (CENUs) are bifunctional alkylating agents widely used for the clinical treatment of cancer. They exert anticancer activity by inducing DNA interstrand cross-links (ICLs) within GC base pairs to form dG-dC cross-links. This lesion inhibits DNA double strand separation during replication and transcription and results in the apoptosis of cancer cells. However, O(6)-alkylguanine DNA alkyltransferase (AGT) repairs the DNA ICLs by removing the alkyl group at the O(6) position of either O(6)-(2-chloroethyl)deoxyguanosine (O(6)-ClEtdGuo) or N1,O(6)-ethanodeoxyguanosine (N1,O(6)-EtdGuo), which are intermediates in the formation of dG-dC cross-links. The action of AGT leads to drug resistance against CENUs. O(6)-Benzylguanine (O(6)-BG) was identified as an effective AGT inhibitor that enhances the antitumor effects of CENUs. In this study, the effect of O(6)-BG on the formation of dG-dC cross-links was investigated by treating human brain glioma SF767 cells with 1-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-3-(2-chloroethyl)-3-nitrosourea (ACNU). The levels of dG-dC cross-link were determined using stable isotope dilution high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The results indicated that ACNU induced higher levels of dG-dC cross-link in SF767 cells pretreated with O(6)-BG compared to cells without O(6)-BG pretreatment. The highest dG-dC cross-linking levels were generally observed at 12 h for all drug concentration groups, a result which was consistent with cytotoxicity assay. These results provided direct evidence for the enhancement of dG-dC cross-linking levels caused by the inhibition of AGT by O(6)-BG. These data indicate that dG-dC cross-links may be developed as a biomarker for evaluating the activity of novel O(6)-BG analogues as AGT inhibitors for combination therapy with CENUs.


International Journal of Toxicology | 2011

Photocytotoxicity of Hypocrellin B (HB) was Enhanced by Liposomalization in Vitro

Zhixiang Zhou; Lina Zhang; Huimin Liu; Qi Zhang; Boya Liu; Ping Ai; Hongtao Ma; Wei Liu; Zelin Li; Wang Sheng; Yi Zeng; Rugang Zhong

Hypocrellin B (HB) was encapsulated into a phosphatidylcholine liposome. Encapsulation of HB into liposomes not only improved the delivery of this photosensitizer but also increased its photodynamic efficacy compared to free HB molecules. Liposomal HB showed a higher cellular uptake than free HB as measured by confocal microscopy and was internalized into cultured HeLa cells by caveolar endocytosis, which was lipid-raft-dependent. Cell viability measurements demonstrated that liposomal HB was more phototoxic to HeLa cells than free HB as a result of the higher concentration of intracellular HB delivered by the liposomal formulation. The encapsulation of HB influenced the cell death pathway by an increased rate of necrotic cells after irradiation versus free HB, and a Type II (singlet oxygen) mechanism was responsible for the photocytotoxicity.


Rapid Communications in Mass Spectrometry | 2014

Quantification of DNA interstrand crosslinks induced by ACNU in NIH/3T3 and L1210 cells using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.

Lili Li; Lijiao Zhao; Rugang Zhong

RATIONALE Chloroethylnitrosoureas (CENUs) are important alkylating agents employed for the clinical treatment of cancer. The cellular toxicity of CENUs is primarily due to induction of DNA interstrand crosslinks (ICLs), which has been characterized as l-(3-deoxycytidyl), 2-(l-deoxyguanosinyl)ethane (dG-dC). However, the formation of dG-dC crosslinks can be prevented by O(6) -alkylguanine-DNA alkyltransferase (AGT), which removes the O(6) -chloroethyl group from O(6) -chloroethylguanine (O(6) -ClEt-Gua), and ultimately its increased expression can result in drug resistance. Differing levels of AGT expression can lead to varying amounts of dG-dC crosslinking, which influences the sensitivity of cells to CENUs. METHODS In this work, a sensitive method for the quantitation of dG-dC crosslinks in cellular DNA has been established using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC/ESI-MS/MS). RESULTS The limit of detection (LOD) and limit of quantitation (LOQ) of the method were determined to be 2 fmol and 8 fmol on-column, respectively, and the recovery ranged from 96% to 105% with the relative standard deviation (RSD) below 5%. Using this method, the levels of dG-dC crosslink induced by 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) were determined in NIH/3T3 fibroblasts cells (high level of expression of AGT) and L1210 leukemia cells (low level of expression of AGT). The time-course profile indicated that the levels of dG-dC crosslink uniformly increased in the early incubation period and reached the maximum at 12 h. Subsequently, the amount of dG-dC crosslinking decreased to very low levels presumably owing to the repair of O(6) -ClEt-Gua by AGT. The crosslinking levels in L1210 cells were significantly higher than those in NIH/3T3 cells at each time point. This provides strong evidence that high express of AGT in CENU-resistant cells inhibits the formation of dG-dC crosslinks. CONCLUSIONS This work will contribute to the further understanding of the drug resistance of CENUs, and will provide a means to evaluate the anticancer activity of new bifunctional anticancer agents.


Journal of Environmental Quality | 2013

Determination of lead, cadmium, copper, and nickel in the tonghui river of beijing, china, by cloud point extraction-high resolution continuum source graphite furnace atomic absorption spectrometry.

Ting Ren; Lijiao Zhao; Bo-Si Sun; Rugang Zhong

Heavy metal contamination of water has become an important problem in recent years. Most hazardous heavy metals exist in environmental water in trace or ultra-trace amounts, which requires establishing highly sensitive analytical methods. In this research, quantitative analyses were performed using high-resolution continuum source graphite furnace atomic absorption spectrometry combined with cloud point extraction (CPE) to determine Pb, Cd, Cu, and Ni levels in environmental surface water. By optimizing the CPE conditions, the enrichment factors were 29 for Pb, Cd, and Cu and 25 for Ni. The limits of detection (LOD) were 0.080, 0.010, 0.035, and 0.014 μg L for Pb, Cd, Cu, and Ni, respectively. The sensitivity of the method is comparable with those reported in previous investigations using various methods and improves outcome by 2 to 3 orders of magnitude compared with the LODs of the current national standard methods of China. Our method was used to determine Pb, Cd, Cu, and Ni in 55 water samples collected from the Tonghui River, which is the principal river in the urban area of Beijing, China. The results indicated that the distributions of the four heavy metals in the Tonghui River were related with the environments. The levels of Pb and Ni exhibit increasing trends along the river from upstream to downstream possibly due to the existence of some chemical factories in the downstream area. Lead, Cd, Cu, and Ni averaged 13.9, 0.8, 46.8, and 38.5%, respectively, of the total amount of the determined heavy metals. The levels of the four heavy metals conformed to the Environmental Quality Standards for Surface Water (Grade I) of China. This work provides a reliable quantitative method to determine trace-amount heavy metals in water, which lays a foundation for establishing standards and regulations for environmental water protection.


Bioorganic & Medicinal Chemistry | 2016

Synthesis and antitumor activity evaluation of a novel combi-nitrosourea prodrug: Designed to release a DNA cross-linking agent and an inhibitor of O6-alkylguanine-DNA alkyltransferase

Guohui Sun; Na Zhang; Lijiao Zhao; Tengjiao Fan; Shufen Zhang; Rugang Zhong

The drug resistance of CENUs induced by O(6)-alkylguanine-DNA alkyltransferase (AGT), which repairs the O(6)-alkylated guanine and subsequently inhibits the formation of dG-dC cross-links, hinders the application of CENU chemotherapies. Therefore, the discovery of CENU analogs with AGT inhibiting activity is a promising approach leading to novel CENU chemotherapies with high therapeutic index. In this study, a new combi-nitrosourea prodrug 3-(3-(((2-amino-9H-purin-6-yl)oxy)methyl)benzyl)-1-(2-chloroethyl)-1-nitrosourea (6), designed to release a DNA cross-linking agent and an inhibitor of AGT, was synthesized and evaluated for its antitumor activity and ability to induce DNA interstrand cross-links (ICLs). The results indicated that 6 exhibited higher cytotoxicity against mer(+) glioma cells compared with ACNU, BCNU, and their respective combinations with O(6)-benzylguanine (O(6)-BG). Quantifications of dG-dC cross-links induced by 6 were performed using HPLC-ESI-MS/MS. Higher levels of dG-dC cross-link were observed in 6-treated human glioma SF763 cells (mer(+)), whereas lower levels of dG-dC cross-link were observed in 6-treated calf thymus DNA, when compared with the groups treated with BCNU and ACNU. The results suggested that the superiority of 6 might result from the AGT inhibitory moiety, which specifically functions in cells with AGT activity. Molecular docking studies indicated that five hydrogen bonds were formed between the O(6)-BG analogs released from 6 and the five residues in the active pocket of AGT, which provided a reasonable explanation for the higher AGT-inhibitory activity of 6 than O(6)-BG.


Journal of Photochemistry and Photobiology B-biology | 2012

Photo-killing mechanism of 2-demethoxy-2,3-ethylenediamino hypocrellin B (EDAHB) to HeLa cells.

Zhixiang Zhou; Qianqian Li; Wei Liu; Lina Zhang; Hongtao Ma; Wang Sheng; Zelin Li; Yi Zeng; Rugang Zhong

2-Demethoxy-2,3-ethylenediamino hypocrellin B (EDAHB) is a diamino-substituted hypocrellin B (HB) with high absorption of red light and high quantum yield of both singlet oxygen ((1)O(2)) and superoxide anions (O(2)(-)). Here we reported the cellular uptake, subcellular location, and cytotoxicity of EDAHB, as well as EDAHB-mediated photodynamic therapy (PDT) efficiency, and cell apoptosis. Results showed that EDAHB accumulated in HeLa cells rapidly up to 1h, with a subsequent decrease in the rate of uptake. EDAHB distributed with well-defined spots throughout the cytoplasm of the cells. EDAHB showed a much higher photopotentiation factor than HB. The phototoxicity of EDAHB to HeLa cells occurred via a mitochondria/caspase apoptosis pathway. This study showed EDAHB to be a promising candidate of photosensitizer for anti-tumor PDT.

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Lijiao Zhao

Beijing University of Technology

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Hong Yan

Beijing University of Technology

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Yunjing Luo

Beijing University of Technology

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Xiu-Qing Song

Beijing University of Technology

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Guohui Sun

Beijing University of Technology

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Cheng-Chu Zeng

Beijing University of Technology

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Yi Zeng

Beijing University of Technology

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Na Zhang

Beijing University of Technology

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Liming Hu

Beijing University of Technology

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Ting Ren

Beijing University of Technology

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