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Gopinatha Suresh Kumar - One of the best experts on this subject based on the ideXlab platform.

  • natural aristolochia alkaloid Aristololactam β d glucoside interaction with biomacromolecules and correlation to the biological perspectives
    Mini-reviews in Medicinal Chemistry, 2018
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    BACKGROUND Natural aristolochia alkaloids have attracted the attention of both chemists and biologists from the stand point of their structural and pharmacological aspects. Many of the compounds isolated in this group are potent tumor inhibitors. These are divided into nitrophenanthrinic acid, phenanthrene lactams and isoquinoline alkaloids. A number of structure-activity studies have been performed on aristolochia alkaloids. Of particular interest is the molecule with the β-D-glucoside moiety that has similarity to the clinical anticancer agent daunomycin. OBJECTIVE The anticancer activity of Aristololactam-β-D-glucoside has been thought to be due to its DNA and RNA binding activities among other actions. In this article we focus on the physicochemical property of this alkaloid and the structural and functional aspects of its binding to different nucleic acid and protein structures. METHODS This review highlights a large number of biophysical studies employing various analytical techniques like absorbance, fluorescence, circular dichroism, thermal melting, viscosity, IR study, isothermal calorimetry and differential scanning calorimetry. RESULT The detailed binding mechanism in terms of the structural and thermodynamic aspects at the molecular level has been discussed. CONCLUSION This review enables to assess the high potential of developing Aristololactam-β-Dglucoside and related alkaloids as therapeutic agents.

  • targeting human telomeric g quadruplex dna with antitumour natural alkaloid Aristololactam β d glucoside and its comparison with daunomycin
    Journal of Molecular Recognition, 2017
    Co-Authors: Abhi Das, Sabyasachi Chatterjee, Gopinatha Suresh Kumar
    Abstract:

    Study on anticancer agents that act via stabilization of telomeric G-quadruplex DNA has emerged as novel and exciting field for anticancer drug discovery. The interaction of carbohydrate containing anticancer alkaloid Aristololactam-β-D-glucoside (ADG) with human telomeric G-quadruplex DNA sequence was characterized by different biophysical techniques. The binding parameters were compared with daunomycin (DAN), a well-known chemotherapeutic drug. The Scatchard binding isotherms revealed noncooperative binding for both with the binding affinity values of (1.01 ± 0.05) × 106 and (1.78 ± 0.18) × 106 M−1 for ADG and DAN, respectively. Circular dichroism, ferrocyanide quenching study, anisotropy study, thiazole orange displacement, optical melting, differential scanning calorimetry study, and molecular docking study suggest significant stacking and stabilizing efficiency of ADG with comparison to DAN. The energetics of the interaction for ADG and DAN revealed that both reactions were predominantly entropy driven. Negative heat capacity values were obtained from the temperature dependence of the enthalpy change. The standard molar Gibbs energy change exhibited only marginal alterations with temperature suggesting the occurrence of enthalpy-entropy compensation. These findings indicate that ADG can act as a stabilizer of telomeric G-quadruplex DNA and thereby can be considered as a potential telomerase inhibitor.

  • binding of the alkaloid Aristololactam β d glucoside and daunomycin to human hemoglobin spectroscopy and calorimetry studies
    Journal of Biomolecular Structure & Dynamics, 2016
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    The interaction of the plant alkaloid Aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human hemoglobin was studied by different spectroscopic and calorimetric meth...

  • Binding of the alkaloid Aristololactam-β-D-glucoside and daunomycin to human hemoglobin: spectroscopy and calorimetry studies
    2015
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    The interaction of the plant alkaloid Aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human hemoglobin was studied by different spectroscopic and calorimetric methods. The binding affinity values of ADG and DAN, estimated from spectroscopic experiments, were 3.79 × 104 and 6.68 × 104 M−1, respectively. From circular dichroism, 3D fluorescence, and FTIR studies it was observed that, DAN induced stronger conformational changes than ADG in the protein. From synchronous fluorescence spectroscopy results, a pronounced shift in the maximum emission wavelength of tyrosine residues was observed in both cases suggesting that the drugs changed the polarity around tyrosine residues with marginal change around the tryptophan residues. The thermodynamics of the binding interaction analyzed using microcalorimetry presented single binding events that were exothermic in nature in both cases. The binding was driven by large positive standard molar entropy changes with small favorable enthalpy contributions. Negative heat capacity changes in both cases are correlated to the involvement of significant hydrophobic forces in the complexation process. The affinity of DAN to Hb was higher than that of ADG.

  • binding studies of Aristololactam β d glucoside and daunomycin to human serum albumin
    RSC Advances, 2014
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    The interaction of the plant alkaloid Aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human serum albumin (HSA) was investigated. Absorption and steady-state fluorescence spectroscopy, steady state fluorescence anisotropy, circular dichroism and isothermal titration calorimetry techniques have been exploited to characterize the binding phenomena. Absorbance and fluorescence quenching experiments revealed the formation of a strong complex of DAN and HSA, and comparatively weaker complex between ADG and HSA. Spectroscopic analysis suggested the binding affinity of ADG to HSA to be of the order of 104 M−1 and that of DAN–HSA to be of the order of 105 M−1. Fluorescence quenching data suggested a static quenching mechanism in both cases at the ground state. Three dimensional fluorescence and circular dichroism data are consistent with a conformational change in the protein on binding of ADG and DAN. The calorimetric study revealed exothermic binding of both drugs which was favored by negative standard molar enthalpy and standard molar entropy contributions. ADG was found to be a weaker binder to HSA compared to DAN. Detailed comparative biophysical aspects of the binding are presented.

Shao-qing Cai - One of the best experts on this subject based on the ideXlab platform.

  • phenanthrene derivatives from roots and rhizomes of asarum heterotropoides var mandshuricum
    Fitoterapia, 2017
    Co-Authors: Yu Jing, Ming-ying Shang, Xuan Wang, Yifan Zhang, Jiawei Tang, Guangxue Liu, Shao-qing Cai
    Abstract:

    Abstract Five new phenanthrene derivatives: 9-ethoxy-7-methoxy-Aristololactam IV (1), norcepharadione A N-β- d -glucopyranoside (2), Aristololactamoside I (3), Aristololactamoside II (4) and aristothiolactoside (5) together with eleven known phenanthrene derivatives (6–16) were isolated from the ethanol extract of the roots and rhizomes of Asarum heterotropoides var. mandshuricum. The Aristololactams with substitution of ethoxy at C-9 position (1, 9, and 10) and the sulfur-containing phenanthrene derivative (5) were reported in the genus Asarum for the first time. Furthermore, six phenanthrene glucoside derivatives (2–5, 13 and 14) were also found in this genus for the first time and compounds 7 and 9–15 were isolated from the genus Asarum for the first time. Six of them (1, 2, 9, 10, 13 and 14) were submitted to cytotoxicity test against human renal proximal tubular epithelial cell lines (HK-2) using MTT and LDH assays. Compounds 1 and 10 showed significant cytotoxic activity against HK-2 cell lines with IC50 values of 18.18 and 20.44 μmol/L in MTT assay and 84.36 and 35.06 μmol/L in LDH assay, respectively. Compound 9 showed moderate cytotoxicity in MTT assay with IC50 values of 95.60 μmol/L, but no cytotoxicity in LDH assay. Compounds 2, 13 and 14 showed cytotoxic effect in neither MTT assay nor LDH assay. Considering the other nephrotoxic phenanthrene derivatives (6, 8, 12, 15 and 16) previously tested, the results implied the potency of renal toxicity of this herb used as a medicine.

  • Aristololactams and aporphines from the stems of fissistigma oldhamii annonaceae
    Phytochemistry, 2013
    Co-Authors: Shu Zhu, Ming-ying Shang, Xuan Wang, Katsuko Komatsu, Xinyu Zang, Yanjing Bai, Shao-qing Cai
    Abstract:

    Abstract Two Aristololactams, Aristololactam GI ( 1 ) and Aristololactam GII ( 2 ), and three aporphines, fissistigamide A ( 3 ), fissistigamide B ( 4 ) and fissistigmine ( 5 ), together with nineteen known alkaloids, one flavone and one anthraquinone were isolated from the ethanol extracts of the stems of Fissistigma oldhamii (Annonaceae). Their structures were elucidated primarily by analysis of NMR, IR, UV, MS and CD data. Alkaloid 1 is a chiral Aristololactam formed from a phenylpropanoid derivative attached to a 3,4-dihydroxy Aristololactam scaffold. The absolute configuration of 1 was determined by comparing experimental and calculated ECD spectra. The anti-inflammatory activity of the crude extracts and the five alkaloids were tested by measuring the amount of TNF- α and IL-6 released from LPS stimulated RAW264 cell via ELISA. The results demonstrated that the CHCl 3 -soluble part and alkaloid 2 exhibited significant anti-inflammatory activity in vitro in both assays.

  • a new aristolochic acid derivative from asarum himalaicum
    Acta pharmaceutica Sinica, 2011
    Co-Authors: Bai Bo Xie, Ming-ying Shang, Xuan Wang, Shao-qing Cai, Kuo Hsiung Lee
    Abstract:

    To study the chemical constituents of Asarum himalaicum, fifteen compounds were isolated from a 70% ethanol extract by using a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, and semi-preparative HPLC. By spectroscopic techniques including 1H NMR, 13C NMR, and HR-ESI-MS, these compounds were identified as 4-demethoxyaristolochic acid BII (1), aristolochic acid I (2), aristolochic acid Ia (3), 7-hydroxyaristolochic acid I (4), aristolochic acid IV (5), aristolic acid II (6), debilic acid (7), Aristololactam I (8), 9-hydroxyAristololactam I (9), 7-methoxyAristololactam IV (10), (2S)-narigenin-5, 7-di-O-beta-D-pyranosylglucoside (11), 4-hydroxybenzoic acid (12), 3, 4-dihydroxybenzoic acid (13), 4-hydroxycinnamic acid (14), and beta-sitosterol (15). All of these compounds (1-15) were obtained from A. himalaicum for the first time. Among them, 1 was identified as a new compound, and compounds 3-6, 9, 12-14 were isolated from Asarum genus for the first time. Since the kidney toxicity of aristolochic acids and Aristololactams has been reported, the result of this investigation suggests that it should be cautioned to use A. himalaicum as a medicine.

  • 5 methoxyAristololactam i the first natural 5 substituted Aristololactam from asarum ichangense
    Natural Product Communications, 2011
    Co-Authors: Ming-ying Shang, Xuan Wang, Bai Bo Xie, Kuo Hsiung Lee, Katsuko Komatsu, Shao-qing Cai
    Abstract:

    A new Aristololactam, 5-methoxyAristololactam I (1), was isolated from an ethanol extract of the whole plant of Asarum ichangense C. Y. Cheng et C. S. Yang, together with twenty known compounds (2-21). The structure of 1 was elucidated by spectroscopic methods. Compounds 11, 13, 17, and 19 were isolated from Aristolochiaceae for the first time. Compounds 2, 14, and 15 are considered as common constituents of the genus Asarum.

  • chemical constituent from fruit of aristolochia contorta
    China Journal of Chinese Matera Medica, 2010
    Co-Authors: Ming-ying Shang, Xuan Wang, Shao-qing Cai
    Abstract:

    OBJECTIVE To study the chemical constituents of the fruit of Aristolochia contorta. METHOD The compounds were isolated by chromatographic techniques and crystalization, the structures were elucidated by spectrum analysis. RESULT Fifteen compounds were isolated from the dry fruit of A. contorta, which were six aristolochic acids: aristolochic acid I, aristolochic acid III a, aristolochic acid IVa, aristolochic acid II, aristolochic acid III and aristolochic acid VIIa. Three aristolactams: Aristololactam I, Aristololactam II and Aristololactam IIIa. Three phenolic acids syringic acid, vanillic acid and p-coumaric acid. Three other type compounds: pentacosane acid, beta-sitosterol and daucossterol. CONCLUSION Aristolochic acid III, aristolochic acid VIIa, Aristololactam IIIa, and penfacosane acid were isolated from A. contorta for the first time, and compounds 4-13 were isolated from the furit of A. contorta for the first time.

Cai Shao-qing - One of the best experts on this subject based on the ideXlab platform.

  • Phenanthrene derivatives from roots and rhizomes of Asarum heterotropoides var. mandshuricum
    FITOTERAPIA, 2017
    Co-Authors: Yu Jing, Zhang Yi-fan, Shang Ming-ping, Yu Jie, Tang Jia-wei, Liu Guang-xue, Li Yao-li, Li Xiao-mei, Wang Xuan, Cai Shao-qing
    Abstract:

    Five new phenanthrene derivatives: 9-ethoxy-7-methoxy-Aristololactam IV (1), norcepharadione A N-beta-D-glucopyranoside (2), Aristololactamoside I (3), Aristololactamoside II (4) and aristothiolactoside (5) together with eleven known phenanthrene derivatives (6-16) were isolated from the ethanol extract of the roots and rhizomes of Asarum heterotropoides var. mandshuricum. The Aristololactams with substitution of ethoxy at C-9 position (1, 9, and 10) and the sulfur-containing phenanthrene derivative (5) were reported in the genus Asarum for the first time. Furthermore, six phenanthrene glucoside derivatives (2-5, 13 and 14) were also found in this genus for the first time and compounds 7 and 9-15 were isolated from the genus Asarum for the first time. Six of them (1, 2, 9, 10, 13 and 14) were submitted to cytotoxicity test against human renal proximal tubular epithelial cell lines (HK-2) using mu and LDH assays. Compounds 1 and 10 showed significant cytotoxic activity against HK-2 cell lines with IC50 values of 18.18 and 20.44 mu mol/L in MIT assay and 8436 and 35.06 mu mol/L in LDH assay, respectively. Compound 9 showed moderate cytotoxicity in MIT assay with IC50 values of 95.60 mu mol/L, but no cytotoxicity in LDH assay. Compounds 2, 13 and 14 showed cytotoxic effect in neither MIT assay nor LDH assay. Considering the other nephrotoxic phenanthrene derivatives (6, 8, 12, 15 and 16) previously tested, the results implied the potency of renal toxicity of this herb used as a medicine. (C) 2017 Published by Elsevier B.V.National Natural Science Foundation of China [81274073, 81173494]; 985 Project of Peking University; National Eleventh Five-year Key Technologies R&D Program of China [2006BAI14B01]SCI(E)ARTICLE101-10811

  • Aristololactams and aporphines from the stems of Fissistigma oldhamii (Annonaceae)
    phytochemistry, 2013
    Co-Authors: Ge Yue-wei, Wang Xuan, Zhu Shu, Shang Ming-ying, Zang Xin-yu, Bai Yan-jing, Komatsu Katsuko, Cai Shao-qing
    Abstract:

    Two Aristololactams, Aristololactam GI (1) and Aristololactam GII (2), and three aporphines, fissistigamide A (3), fissistigamide B (4) and fissistigmine (5), together with nineteen known alkaloids, one flavone and one anthraquinone were isolated from the ethanol extracts of the stems of Fissistigma oldhamii (Annonaceae). Their structures were elucidated primarily by analysis of NMR, IR, UV, MS and CD data. Alkaloid 1 is a chiral Aristololactam formed from a phenylpropanoid derivative attached to a 3,4-dihydroxy Aristololactam scaffold. The absolute configuration of 1 was determined by comparing experimental and calculated ECD spectra. The anti-inflammatory activity of the crude extracts and the five alkaloids were tested by measuring the amount of TNF-alpha and IL-6 released from LPS stimulated RAW264 cell via ELISA. The results demonstrated that the CHCl3-soluble part and alkaloid 2 exhibited significant anti-inflammatory activity in vitro in both assays. (C) 2012 Elsevier Ltd. All rights reserved.Biochemistry & Molecular BiologyPlant SciencesSCI(E)PubMed2ARTICLE201-2078

  • 5-MethoxyAristololactam I, the First Natural 5-Substituted Aristololactam from Asarum ichangense
    natural product communications, 2011
    Co-Authors: Xie Bai-bo, Wang Xuan, Shang Ming-ying, Komatsu Katsuko, Lee Kuo-hsiung, Cai Shao-qing
    Abstract:

    A new Aristololactam, 5-methoxyAristololactam I (1), was isolated from an ethanol extract of the whole plant of Asarum ichangense C.Y. Cheng et C. S. Yang, together with twenty known compounds (2 - 21). The structure of 1 was elucidated by spectroscopic methods. Compounds 11, 13, 17, and 19 were isolated from Aristolochiaceae for the first time. Compounds 2, 14, and 15 are considered as common constituents of the genus Asarum.Chemistry, MedicinalFood Science & TechnologySCI(E)PubMed2ARTICLE111-14

  • Quality control of traditional chinese medicine by monoclonal antibody method
    2011
    Co-Authors: Shang Ming-ying, Cai Shao-qing, Tian Min, Tanaka Hiroyuki, Li Xiao-wei, Shoyama Yukihiro
    Abstract:

    In a previous study, we reported the preparation, characterization, variation, specificity, and sensitivity of an anti-aristolochic acid-II (AA-II) monoclonal antibody. The preparation procedure was as follows. AA-II conjugated with bovine serum albumin was used as an antigen for immunizing BALB/c mice. Splenocytes isolated from the immunized mice were fused with an aminopterin-sensitive mouse myeloma cell line to produce hybridoma cells secreting a mono-clonal antibody (MAb) against AA-II. The selected MAb was subsequently cloned. Hapten number, isotype, and an esti-mated dissociation constant (KD) of the secreted MAb were determined. This MAb was used to establish an ELISA method. The linear range was 0.19-13 μg/ml. Anti-AA-II MAb showed extremely high specificity for AA-II, low cross-reactivity (CR) against other AAs or Aristololactam-I, and negligible CR (<0.5%) toward other natural compounds with different chemical structures. This study describes the successful application of the ELISA method using anti-AA-II MAb to determine AA-II concentration in several crude drugs derived from Aristolochia species. The highest AA-II concentration (2.82 μg/mg) was observed in the stem of A. manshuriensis, followed by that in the fruit of A. contorta (0.81 μg/mg). In case of A. indica, AA-II concentration in the root was higher than that in the aerial parts. These data indicated that the established ELISA method can be used for the quality control of crude drugs derived from Aristolochia plants.PubMed0160-5

  • Studies on morphology and aristolochic acid analogue constituents of Asarum campaniflorum and a comparison with two official species of Asari Radix et Rhizoma
    journal of natural medicines, 2010
    Co-Authors: Li Yao-li, Yu Jie, Shang Ming-ying, Tian Min, Cai Shao-qing
    Abstract:

    Dried whole herbs or roots and rhizomes of Asarum campaniflorum have been sold under the trade name Xixin and used as folk remedies in its producing areas for a long time. In order to avoid the misuse of A. campaniflorum as official species of Xixin (Asari Radix et Rhizoma), a comparative study based on the morphological and phytochemical analysis of the aerial and underground parts was carried out. The usual morphological methods and a microscopic imaging system were used. The results show that A. campaniflorum could be easily distinguished from two official species (Asarum sieboldii and A. heterotropoides var. mandshuricum) by the diameter of thicker roots (1.3-2.7 mm), distinct large parenchymatous cells in phloem of roots, and the size of oil cells in upper leaf epidermises [(40)80-140(174) A mu m in diameter, where numbers in parentheses are for rare cases], etc. Nine aristolochic acid analogues (AAAs) were identified and estimated by high-performance liquid chromatography-diode array detection (HPLC-DAD). The aerial and underground parts of A. campaniflorum contained 3-4 AAAs, i.e., Aristololactam-II-N-beta-d-glucoside (AL-II-Glc), Aristololactam I (AL-I), Aristololactam II (AL-II), and aristolochic acid I (AA-I), while only AL-I was detected in underground parts of A. sieboldii and no AAAs were detected in underground parts of A. heterotropoides var. mandshuricum. The respective contents (in mg/g) in aerial and underground parts of A. campaniflorum, were as follows: AL-I, 0.06-0.12, 0.05-0.10; AL-II, 0.03-0.04, 0.01-0.03; AA-I, 0.01-0.02, 0.0-0.0. These data suggest A. campaniflorum has a high risk of causing aristolochic acid nephropathy. All these discoveries can contribute to not only the better understanding of this new resource species, but also the safe use of the crude drug Xixin.Chemistry, MedicinalPharmacology & PharmacySCI(E)PubMed6ARTICLE4442-4516

Abhi Das - One of the best experts on this subject based on the ideXlab platform.

  • natural aristolochia alkaloid Aristololactam β d glucoside interaction with biomacromolecules and correlation to the biological perspectives
    Mini-reviews in Medicinal Chemistry, 2018
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    BACKGROUND Natural aristolochia alkaloids have attracted the attention of both chemists and biologists from the stand point of their structural and pharmacological aspects. Many of the compounds isolated in this group are potent tumor inhibitors. These are divided into nitrophenanthrinic acid, phenanthrene lactams and isoquinoline alkaloids. A number of structure-activity studies have been performed on aristolochia alkaloids. Of particular interest is the molecule with the β-D-glucoside moiety that has similarity to the clinical anticancer agent daunomycin. OBJECTIVE The anticancer activity of Aristololactam-β-D-glucoside has been thought to be due to its DNA and RNA binding activities among other actions. In this article we focus on the physicochemical property of this alkaloid and the structural and functional aspects of its binding to different nucleic acid and protein structures. METHODS This review highlights a large number of biophysical studies employing various analytical techniques like absorbance, fluorescence, circular dichroism, thermal melting, viscosity, IR study, isothermal calorimetry and differential scanning calorimetry. RESULT The detailed binding mechanism in terms of the structural and thermodynamic aspects at the molecular level has been discussed. CONCLUSION This review enables to assess the high potential of developing Aristololactam-β-Dglucoside and related alkaloids as therapeutic agents.

  • targeting human telomeric g quadruplex dna with antitumour natural alkaloid Aristololactam β d glucoside and its comparison with daunomycin
    Journal of Molecular Recognition, 2017
    Co-Authors: Abhi Das, Sabyasachi Chatterjee, Gopinatha Suresh Kumar
    Abstract:

    Study on anticancer agents that act via stabilization of telomeric G-quadruplex DNA has emerged as novel and exciting field for anticancer drug discovery. The interaction of carbohydrate containing anticancer alkaloid Aristololactam-β-D-glucoside (ADG) with human telomeric G-quadruplex DNA sequence was characterized by different biophysical techniques. The binding parameters were compared with daunomycin (DAN), a well-known chemotherapeutic drug. The Scatchard binding isotherms revealed noncooperative binding for both with the binding affinity values of (1.01 ± 0.05) × 106 and (1.78 ± 0.18) × 106 M−1 for ADG and DAN, respectively. Circular dichroism, ferrocyanide quenching study, anisotropy study, thiazole orange displacement, optical melting, differential scanning calorimetry study, and molecular docking study suggest significant stacking and stabilizing efficiency of ADG with comparison to DAN. The energetics of the interaction for ADG and DAN revealed that both reactions were predominantly entropy driven. Negative heat capacity values were obtained from the temperature dependence of the enthalpy change. The standard molar Gibbs energy change exhibited only marginal alterations with temperature suggesting the occurrence of enthalpy-entropy compensation. These findings indicate that ADG can act as a stabilizer of telomeric G-quadruplex DNA and thereby can be considered as a potential telomerase inhibitor.

  • binding of the alkaloid Aristololactam β d glucoside and daunomycin to human hemoglobin spectroscopy and calorimetry studies
    Journal of Biomolecular Structure & Dynamics, 2016
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    The interaction of the plant alkaloid Aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human hemoglobin was studied by different spectroscopic and calorimetric meth...

  • Binding of the alkaloid Aristololactam-β-D-glucoside and daunomycin to human hemoglobin: spectroscopy and calorimetry studies
    2015
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    The interaction of the plant alkaloid Aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human hemoglobin was studied by different spectroscopic and calorimetric methods. The binding affinity values of ADG and DAN, estimated from spectroscopic experiments, were 3.79 × 104 and 6.68 × 104 M−1, respectively. From circular dichroism, 3D fluorescence, and FTIR studies it was observed that, DAN induced stronger conformational changes than ADG in the protein. From synchronous fluorescence spectroscopy results, a pronounced shift in the maximum emission wavelength of tyrosine residues was observed in both cases suggesting that the drugs changed the polarity around tyrosine residues with marginal change around the tryptophan residues. The thermodynamics of the binding interaction analyzed using microcalorimetry presented single binding events that were exothermic in nature in both cases. The binding was driven by large positive standard molar entropy changes with small favorable enthalpy contributions. Negative heat capacity changes in both cases are correlated to the involvement of significant hydrophobic forces in the complexation process. The affinity of DAN to Hb was higher than that of ADG.

  • binding studies of Aristololactam β d glucoside and daunomycin to human serum albumin
    RSC Advances, 2014
    Co-Authors: Abhi Das, Gopinatha Suresh Kumar
    Abstract:

    The interaction of the plant alkaloid Aristololactam-β-D-glucoside (ADG) and the anticancer agent daunomycin (DAN) with human serum albumin (HSA) was investigated. Absorption and steady-state fluorescence spectroscopy, steady state fluorescence anisotropy, circular dichroism and isothermal titration calorimetry techniques have been exploited to characterize the binding phenomena. Absorbance and fluorescence quenching experiments revealed the formation of a strong complex of DAN and HSA, and comparatively weaker complex between ADG and HSA. Spectroscopic analysis suggested the binding affinity of ADG to HSA to be of the order of 104 M−1 and that of DAN–HSA to be of the order of 105 M−1. Fluorescence quenching data suggested a static quenching mechanism in both cases at the ground state. Three dimensional fluorescence and circular dichroism data are consistent with a conformational change in the protein on binding of ADG and DAN. The calorimetric study revealed exothermic binding of both drugs which was favored by negative standard molar enthalpy and standard molar entropy contributions. ADG was found to be a weaker binder to HSA compared to DAN. Detailed comparative biophysical aspects of the binding are presented.

Xuan Wang - One of the best experts on this subject based on the ideXlab platform.

  • phenanthrene derivatives from roots and rhizomes of asarum heterotropoides var mandshuricum
    Fitoterapia, 2017
    Co-Authors: Yu Jing, Ming-ying Shang, Xuan Wang, Yifan Zhang, Jiawei Tang, Guangxue Liu, Shao-qing Cai
    Abstract:

    Abstract Five new phenanthrene derivatives: 9-ethoxy-7-methoxy-Aristololactam IV (1), norcepharadione A N-β- d -glucopyranoside (2), Aristololactamoside I (3), Aristololactamoside II (4) and aristothiolactoside (5) together with eleven known phenanthrene derivatives (6–16) were isolated from the ethanol extract of the roots and rhizomes of Asarum heterotropoides var. mandshuricum. The Aristololactams with substitution of ethoxy at C-9 position (1, 9, and 10) and the sulfur-containing phenanthrene derivative (5) were reported in the genus Asarum for the first time. Furthermore, six phenanthrene glucoside derivatives (2–5, 13 and 14) were also found in this genus for the first time and compounds 7 and 9–15 were isolated from the genus Asarum for the first time. Six of them (1, 2, 9, 10, 13 and 14) were submitted to cytotoxicity test against human renal proximal tubular epithelial cell lines (HK-2) using MTT and LDH assays. Compounds 1 and 10 showed significant cytotoxic activity against HK-2 cell lines with IC50 values of 18.18 and 20.44 μmol/L in MTT assay and 84.36 and 35.06 μmol/L in LDH assay, respectively. Compound 9 showed moderate cytotoxicity in MTT assay with IC50 values of 95.60 μmol/L, but no cytotoxicity in LDH assay. Compounds 2, 13 and 14 showed cytotoxic effect in neither MTT assay nor LDH assay. Considering the other nephrotoxic phenanthrene derivatives (6, 8, 12, 15 and 16) previously tested, the results implied the potency of renal toxicity of this herb used as a medicine.

  • Aristololactams and aporphines from the stems of fissistigma oldhamii annonaceae
    Phytochemistry, 2013
    Co-Authors: Shu Zhu, Ming-ying Shang, Xuan Wang, Katsuko Komatsu, Xinyu Zang, Yanjing Bai, Shao-qing Cai
    Abstract:

    Abstract Two Aristololactams, Aristololactam GI ( 1 ) and Aristololactam GII ( 2 ), and three aporphines, fissistigamide A ( 3 ), fissistigamide B ( 4 ) and fissistigmine ( 5 ), together with nineteen known alkaloids, one flavone and one anthraquinone were isolated from the ethanol extracts of the stems of Fissistigma oldhamii (Annonaceae). Their structures were elucidated primarily by analysis of NMR, IR, UV, MS and CD data. Alkaloid 1 is a chiral Aristololactam formed from a phenylpropanoid derivative attached to a 3,4-dihydroxy Aristololactam scaffold. The absolute configuration of 1 was determined by comparing experimental and calculated ECD spectra. The anti-inflammatory activity of the crude extracts and the five alkaloids were tested by measuring the amount of TNF- α and IL-6 released from LPS stimulated RAW264 cell via ELISA. The results demonstrated that the CHCl 3 -soluble part and alkaloid 2 exhibited significant anti-inflammatory activity in vitro in both assays.

  • a new aristolochic acid derivative from asarum himalaicum
    Acta pharmaceutica Sinica, 2011
    Co-Authors: Bai Bo Xie, Ming-ying Shang, Xuan Wang, Shao-qing Cai, Kuo Hsiung Lee
    Abstract:

    To study the chemical constituents of Asarum himalaicum, fifteen compounds were isolated from a 70% ethanol extract by using a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, and semi-preparative HPLC. By spectroscopic techniques including 1H NMR, 13C NMR, and HR-ESI-MS, these compounds were identified as 4-demethoxyaristolochic acid BII (1), aristolochic acid I (2), aristolochic acid Ia (3), 7-hydroxyaristolochic acid I (4), aristolochic acid IV (5), aristolic acid II (6), debilic acid (7), Aristololactam I (8), 9-hydroxyAristololactam I (9), 7-methoxyAristololactam IV (10), (2S)-narigenin-5, 7-di-O-beta-D-pyranosylglucoside (11), 4-hydroxybenzoic acid (12), 3, 4-dihydroxybenzoic acid (13), 4-hydroxycinnamic acid (14), and beta-sitosterol (15). All of these compounds (1-15) were obtained from A. himalaicum for the first time. Among them, 1 was identified as a new compound, and compounds 3-6, 9, 12-14 were isolated from Asarum genus for the first time. Since the kidney toxicity of aristolochic acids and Aristololactams has been reported, the result of this investigation suggests that it should be cautioned to use A. himalaicum as a medicine.

  • 5 methoxyAristololactam i the first natural 5 substituted Aristololactam from asarum ichangense
    Natural Product Communications, 2011
    Co-Authors: Ming-ying Shang, Xuan Wang, Bai Bo Xie, Kuo Hsiung Lee, Katsuko Komatsu, Shao-qing Cai
    Abstract:

    A new Aristololactam, 5-methoxyAristololactam I (1), was isolated from an ethanol extract of the whole plant of Asarum ichangense C. Y. Cheng et C. S. Yang, together with twenty known compounds (2-21). The structure of 1 was elucidated by spectroscopic methods. Compounds 11, 13, 17, and 19 were isolated from Aristolochiaceae for the first time. Compounds 2, 14, and 15 are considered as common constituents of the genus Asarum.

  • chemical constituent from fruit of aristolochia contorta
    China Journal of Chinese Matera Medica, 2010
    Co-Authors: Ming-ying Shang, Xuan Wang, Shao-qing Cai
    Abstract:

    OBJECTIVE To study the chemical constituents of the fruit of Aristolochia contorta. METHOD The compounds were isolated by chromatographic techniques and crystalization, the structures were elucidated by spectrum analysis. RESULT Fifteen compounds were isolated from the dry fruit of A. contorta, which were six aristolochic acids: aristolochic acid I, aristolochic acid III a, aristolochic acid IVa, aristolochic acid II, aristolochic acid III and aristolochic acid VIIa. Three aristolactams: Aristololactam I, Aristololactam II and Aristololactam IIIa. Three phenolic acids syringic acid, vanillic acid and p-coumaric acid. Three other type compounds: pentacosane acid, beta-sitosterol and daucossterol. CONCLUSION Aristolochic acid III, aristolochic acid VIIa, Aristololactam IIIa, and penfacosane acid were isolated from A. contorta for the first time, and compounds 4-13 were isolated from the furit of A. contorta for the first time.