- Chitosan grafted butein: A metal-free transducer for electrochemical genosensing of exosomal CD24
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Metal-free cost-efficient biocompatible molecules are beneficial for opto-electrochemical bioassays. Herein, chitosan (CS) conjugated butein is prepared via graft polymerization. Structural integrity between radical active sites of CS and its probable conjugation routes with reactive OH group of butein during grafting were comprehensively studied using optical absorbance/emission property, NMR, FT-IR and XPS analysis. Fluorescence emission of CS-conjugated butein (CSB) was studied in dried flaky state as well as in drop casted form. Cyclic voltammetric study of CSB modified glassy carbon electrode exhibits 2e?/2H+ transfer reaction in phosphate buffered saline electrolyte following a surface-confined process with a correlation coefficient of 0.99. Unlike pristine butein, CSB modified electrode display a highly reversible redox behavior under various pH ranging from 4 to 9. For the proof-of-concept CSB-modified flexible screen printed electrodes were processed for electrochemical biosensing of exosomal CD24 specific nucleic acid at an ultralow sample concentration, promising for ovarian cancer diagnosis.
- Babu, Kannadasan Anand,Balasubramanian, Subramanian,Krishnan, Vinoth,Kumar, Shanmugam Senthil,Pandey, Gaurav R.,Paramasivam, Selvaraj,Pazhani, Gururaja Perumal,Ravichandiran, Velayutham,Veerapandian, Murugan
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- Synthesis and biological evaluation of isoliquiritigenin derivatives as a neuroprotective agent against glutamate mediated neurotoxicity in HT22 cells
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Glutamate-induced neurotoxicity is characterized by cellular Ca2+ uptake, which is upstream of reactive oxygen species (ROS)-induced apoptosis signaling and MAPKs activation. In the present study, we synthesized isoliquiritigenin analogs with electron-donating and electron-withdrawing functional groups. These analogs were evaluated for neuroprotective effect against glutamate-induced neurotoxicity in HT22 cells. Among these analogs, compound BS11 was selected as a potent neuroprotective agent. Cellular Ca2+ concentration, ROS level, MAPKs activation and AIF translocation to the nucleus were increased upon treatment with 5 mM glutamate. In contrast, we identified that compound BS11 reduced the cellular Ca2+ concentration and ROS level upon glutamate exposure. Western blot analysis showed that MAPK activation was decreased by treatment with compound BS11. We further identified that cotreatment of compound BS11 and glutamate inhibited translocation of AIF to the nucleus.
- Selvaraj, Baskar,Kim, Dae Won,Huh, Gyuwon,Lee, Heesu,Kang, Kyungsu,Lee, Jae Wook
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- Analogues of xanthones——Chalcones and bis-chalcones as α-glucosidase inhibitors and anti-diabetes candidates
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Two series of compounds (chalcones and bis-chalcones) were designed, synthesized, and evaluated as α-glucosidase inhibitors (AGIs) with 1-deoxynojirimycin as positive control in vitro. Most of the compounds with two or four hydroxyl groups showed better inhibitory activities than 1-deoxynojirimycin towards α-glucosidase with noncompetitive mechanism. Moreover, most of the hydroxy bis-chalcones exhibit good α-glucosidase inhibitory activities in enzyme test. Inspiringly, bis-chalcones 2g (at 1 μM concentration) has stronger effect than 1-deoxynojirimycin on reducing the glucose level in HepG-2 cells (human liver cancer cell line).
- Cai, Chao-Yun,Rao, Li,Rao, Yong,Guo, Jin-Xuan,Xiao, Zhi-Zun,Cao, Jing-Yu,Huang, Zhi-Shu,Wang, Bo
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- Preparation of tyrosinase inhibitors and antibrowning agents using green technology
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Chalcones and their derivatives have attracted great interests in recent years for their comprehensive biological activities. In this study, 2,4,2′,4′-tetrahydroxychalcone and its two derivatives, 1,3,5-tris-(2,4-dihydroxy-phenyl)pentane-1,5-dione (new co
- Dong, Xue,Zhang, Yinan,He, Jia-Liang,Zhang, Shuang,Zeng, Mao-Mao,Chen, Jie,Zheng, Zong-Ping
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p. 589 - 596
(2015/11/17)
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- Enantioselective biomimetic total syntheses of kuwanons i and J and brosimones A and B
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The first enantioselective total syntheses of prenylflavonoid Diels-Alder natural products (-)-kuwanonI, (+)-kuwanonJ, (-)-brosimoneA, and (-)-brosimoneB have been accomplished from a common intermediate based on a concise synthetic strategy. Key elements of the synthesis include a biosynthesis-inspired asymmetric Diels-Alder cycloaddition mediated by a chiral ligand/boron Lewis acid, as well as a process involving regioselective Schenck ene reaction, reduction, and dehydration to realize a biomimetic dehydrogenation for generation of the required diene precursor. Furthermore, a remarkable tandem inter-/intramolecular asymmetric Diels-Alder cycloaddition process was applied for the synthesis of (-)-brosimoneA. Four in a row: The first enantioselective total syntheses of the prenylflavonoid natural products (-)-kuwanonI, (+)-kuwanonJ, (-)-brosimoneA, and (-)-brosimoneB have been accomplished based on a concise synthetic strategy. Key elements of the synthesis include a biosynthesis-inspired asymmetric Diels-Alder cycloaddition mediated by a chiral ligand/boron Lewis acid, as well as a process involving regioselective Schenck ene reaction, reduction, and dehydration.
- Han, Jianguang,Li, Xia,Guan, Yong,Zhao, Wenjun,Wulff, William D.,Lei, Xiaoguang
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p. 9257 - 9261,5
(2014/11/07)
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- Aspergillus niger catalyzes the synthesis of flavonoids from chalcones
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Flavonoids, which have many biological activities and have been widely used in nature, can be artificially synthesized. However, regioselective cyclization of chalcones is difficult by chemical methods. In this study, we demonstrated that Aspergillus nige
- Alarcon, Julio,Alderete, Joel,Escobar, Carlos,Araya, Ramiro,Cespedes, Carlos L.
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p. 160 - 167
(2013/09/12)
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- Design, synthesis and SAR study of hydroxychalcone inhibitors of human β-secretase (BACE1)
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According to the structural characteristics of isoliquiritigenin from Glycyrrhiza uralensis, a series of hydroxychalcones has been designed, synthesized and evaluated for their in vitro inhibitory activities of β-secretase (BACE1). Structure-activity relationship study suggested that inhibitory activity against BACE1 was governed to a greater extent by the hydroxyl substituent on A-and B-ring of the chalcone, and the most active compound was substituted with four hydroxyl group (17, IC50=0.27 μM).
- Ma, Lei,Yang, Zhengyi,Li, Chenjing,Zhu, Zhiyuan,Shen, Xu,Hu, Lihong
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p. 643 - 648
(2012/04/10)
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- Electron transfer-initiated Diels-Alder cycloadditions of 2′-hydroxychalcones
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An efficient approach to cyclohexenyl chalcones employing highly electron rich 2′-hydroxychalcone dienophiles via electron transfer-initiated Diels-Alder cycloaddition is described. Using the methodology, the total synthesis of nicolaiodesin C has been accomplished. Copyright
- Cong, Huan,Ledbetter, Dustin,Rowe, Gerard T.,Caradonna, John P.,Porco Jr., John A.
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supporting information; experimental part
p. 9214 - 9215
(2009/02/02)
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- Synthesis and evaluation of 2′,4′,6′-trihydroxychalcones as a new class of tyrosinase inhibitors
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In this study, we synthesized a series of hydroxychalcones and examined their tyrosinase inhibitory activity. The results showed that 2′,4′,6′-trihydroxychalcone (1), 2,2′,3,4′,6′-pentahydroxychalcone (4), 2′,3,4,4′,5,6′-hexahydroxychalcone (5), 2′,4′,6′-trihydroxy- 3,4-dimethoxychalcone (9) and 2,2′,4,4′,6′-pentahydroxychalcone (15) exhibited high inhibitory effects on tyrosinase with respect to l-tyrosine as a substrate. By the structure-activity relationship study, it was suggested that the 2′,4′,6′-trihydroxyl substructure in the chalcone skeleton were efficacious for the inhibition of tyrosinase activity. And also, the catechol structure on B-ring of chalcones was not advantageous for the inhibitory potency. Furthermore, 15 (IC50 = 1 μM) was found to show the highest activity out of a set of 15 hydroxychalcones, even better than both 2,2′,4,4′-tetrahydroxychalcone (13, IC50 = 5 μM) and kojic acid (16, IC50 = 12 μM), which were known as potent tyrosinase inhibitors. Kinetic study revealed that 15 acts as a competitive inhibitor of tyrosinase with Ki value of 3.1 μM.
- Jun, Nishida,Hong, Gao,Jun, Kawabata
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p. 2396 - 2402
(2007/10/03)
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- Synthesis and PPAR-γ ligand-binding activity of the new series of 2′-hydroxychalcone and thiazolidinedione derivatives
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Fifteen chalcones and three thiazolidinedione (TZD) chalcones were prepared to evaluate their peroxisome proliferator-activated receptor-γ (PPAR-γ) ligand-binding activities. Among the three TZDs, one compound possessed PPAR-γ transactivation potential, while the others showed antagonistic activity against PPAR-γ transactivation. Among the chalcones, compound 5 was the most potent, and structure-activity relationship studies indicated that a methoxyl group in position C-4 and hydroxyl group in position C-4′ or 5′ in chalcone plays a key role in determining the potency of PPAR-γ activation.
- Sang, Hoon Jung,Soo, Young Park,Kim-Pak, Youngmi,Hong, Kyu Lee,Kyong, Soo Park,Kuk, Hyun Shin,Ohuchi, Kazuo,Shin, Hyun-Kyung,Sam, Rok Keum,Soon, Sung Lim
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p. 368 - 371
(2007/10/03)
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- Chalcones as potent tyrosinase inhibitors: The importance of a 2,4-substituted resorcinol moiety
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Chalcones with tetra-substituted hydroxyl groups were synthesized and tested as tyrosinase inhibitors towards designing novel whitening agents, resulting with the most potent inhibitor, with IC50 of 0.02 μM concn. Compounds, which inhibit tyrosinase, could be effective as depigmenting agents. We have introduced a group of mono-, di-, tri- and tetra-substituted hydroxychalcones as effective tyrosinase inhibitors, showing that the most important factor determining tyrosinase inhibition efficiency is the position of the hydroxyl group(s) rather their number. The aim of the present study was to investigate the contribution of the different functional groups of the tetrahydroxychalcones to their inhibitory potency, with a view to optimizing the design of whitening agents. Four tetrahydroxychalcones were evaluated, the commercially available Butein and other three were synthesized, and their inhibitory effect on tyrosinase was tested. Results showed that a 2,4-substituted resorcinol subunit on ring B contributed the most to inhibitory potency. Changing the resorcinol substitute to position 3,5- or placing it on ring A significantly diminished the inhibitory effect of the compounds. A catechol subunit on ring A acted as a metal chelator (in the presence of copper ions) and as a competitive inhibitor (in the presence of tyrosinase), while a catechol on ring B oxidized to o-quinone (in the presence of both copper ions and tyrosinase). Three of the compounds also demonstrated antioxidant activity, which may contribute to the prevention of pigmentation. An examination of correlations between inhibitory activity and physical properties of the chalcones tested (such as dissociation energy and molecular planarity) showed positive correlation with the moment dipole value in the Y-axis, which may be used as an indicator of the inhibitory potential of new molecules. The present study revealed two very active tyrosinase inhibitors, 2,4,3′,4′- hydroxychalcone and 2,4,2′,4′-hydroxychalcone (with IC50 of 0.2 and 0.02 μM, respectively). Structure-related activity studies added some understanding of the role and contribution of different functional groups associated with tyrosinase inhibitors.
- Khatib, Soliman,Nerya, Ohad,Musa, Ramadan,Shmuel, Maayan,Tamir, Snait,Vaya, Jacob
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p. 433 - 441
(2007/10/03)
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- Synthesis of flavonoids and their effects on aldose reductase and sorbitol accumulation in streptozotocin-induced diabetic rat tissues
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Aldose reductase, the key enzyme of the polyol pathway, and oxidative stress are known to play important roles in the complications of diabetes. A drug with potent inhibition of aldose reductase and oxidative stress, therefore, would be a most promising drug for the prevention of diabetic complications. The purpose of this study was to develop new compounds with these dual-effects through synthesis of chalcone derivatives and by examining the structure-activity relationships on the inhibition of rat lens aldose reductase as well as on antioxidant effects. A series of 35 flavonoid derivatives were synthesized by Winget's condensation, oxidation, and reduction of appropriate acetophenones with appropriate benzaldehydes. The inhibitory activity of these derivatives on rat lens aldose reductase and their antioxidant effects, measured using Cu2+ chelation and radical scavenging activities on 1,1-diphenyl-picrylhydrazyl in-vitro, were evaluated. Their effect on sorbitol accumulation in the red blood cells, lenses and sciatic nerves of streptozotocin-induced diabetic rats was also estimated. Among the new flavonoid derivatives synthesized, those with the 2′,4′-dihydroxyl groups in the A ring such as 2,4,2′,4′-tetrahydroxychalcone (22), 2,2′,4′-trihydroxychalcone (11), 2′,4′-dihydroxy-2,4-dimethylchalcone (21) and 3,4,2′,4′-tetrahydroxychalcone (18) were found to possess the highest rat lens aldose reductase inhibitory activity in-vitro, their IC50 values (concentration of inhibitors giving 50 % inhibition of enzyme activity) being 1.6 × 10-7, 3.8 × 10-7, 4.0 × 10-7 and 4.6 × 10-7 M, respectively. All of the chalcones tested except 3, 18, 23 with o-dihydroxy or hydroquinone moiety showed a weak free radical scavenging activity. In the in-vivo experiments, however, compound 18 with o-dihydroxy moiety in the B ring showed the strongest inhibitory activity in the accumulation of sorbitol in the tissues. It also showed the strongest activity in transition metal chelation and free radical scavenging activity. Of the 35 4,2′-dihydroxyl and 2′,4′-dihydroxyl derivatives of flavonoid synthesized, including chalcone, flavone, flavanone, flavonol and dihydrochalcone, some chalcone derivatives synthesized were found to possess aldose reductase inhibition and antioxidant activities in-vitro as well as inhibition in the accumulation of sorbitol in the tissues in-vivo. 3,4,2′,4′-Tetrahydroxychalcone (18, butein) was the most promising compound for the prevention or treatment of diabetic complications.
- Lim, Soon Sung,Jung, Sang Hoon,Ji, Jun,Shin, Kuk Hyun,Keum, Sam Rok
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p. 653 - 668
(2007/10/03)
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- COMPARISON BETWEEN METABOLITE PRODUCTIONS IN CELL CULTURE AND IN WHOLE PLANT OF MACLURA POMIFERA
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Plant tissue cultures of Maclura pomifera showed a metabolite accumulation pattern which was both quantitatively and qualitatively different from that of the parent plant.Triterpenes and flavonoids were isolated from callus and cell cultures, however, xanthones and stilbenes, which have been reported in the whole plant, were not found.Among the flavonoids, flavones and flavanones were produced preferentially by the suspended cells, but with the prenyl substituents exclusively on ring A, while the isoflavones did not show 3',4'-dihydroxyl substitution pattern found in the products isolated from fruits.A new prenylated 6'-deoxychalcone was also isolated from the callus and cell cultures. - Key words: Maclura pomifera; Moraceae; cell cultures; flavonoid production; biosynthesis.
- Monache, Giuliano Delle,Rosa, Maria Cristina De,Scurria, Rosalba,Vitali, Alberto,Cuteri, Angela,et al.
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p. 575 - 580
(2007/10/02)
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