- Structure-Activity Relationship Studies of Isomeric 2,4-Diaminoquinazolines on β-Amyloid Aggregation Kinetics
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A library of isomeric 2,4-diaminoquinazoline (DAQ) derivatives were synthesized and evaluated for antiaggregation potential toward Aβ40/42. Structure-activity relationship data identified compound 3k (N4-(4-bromobenzyl)quinazoline-2,4-diamine) with a 4-bromobenzyl substituent as the most potent inhibitor (Aβ40 IC50 = 80 nM) and was almost 18-fold more potent compared to the reference agent curcumin (Aβ40 IC50 = 1.5 μM). The corresponding N2-isomer 4k (N2-(4-bromobenzyl)quinazoline-2,4-diamine) was also able to prevent Aβ aggregation (Aβ40 IC50 = 1.7 μM). However, compound 4k exhibited superior inhibition of Aβ42 aggregation (Aβ42 IC50 = 1.7 μM) compared to compound 3k (Aβ42 IC50 = 14.8 μM) and was ～1.8-fold more potent compared to curcumin (Aβ42 IC50 = 3.1 μM). These results were supported by Aβ aggregation kinetics investigations and transmission electron microscopy studies, which demonstrate the suitability of DAQ ring system to develop antiamyloid agents as pharmacological tools to study Aβ aggregation.
- Mohamed, Tarek,Shakeri, Arash,Tin, Gary,Rao, Praveen P. N.
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- Dual and selective inhibitors of pteridine reductase 1 (PTR1) and dihydrofolate reductase-thymidylate synthase (DHFR-TS) from Leishmania chagasi
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Leishmaniasis is a tropical disease found in more than 90 countries. The drugs available to treat this disease have nonspecific action and high toxicity. In order to develop novel therapeutic alternatives to fight this ailment, pteridine reductase 1 (PTR1) and dihydrofolate reductase-thymidylate synthase (DHF-TS) have been targeted, once Leishmania is auxotrophic for folates. Although PTR1 and DHFR-TS from other protozoan parasites have been studied, their homologs in Leishmania chagasi have been poorly characterized. Hence, this work describes the optimal conditions to express the recombinant LcPTR1 and LcDHFR-TS enzymes, as well as balanced assay conditions for screening. Last but not the least, we show that 2,4 diaminopyrimidine derivatives are low-micromolar competitive inhibitors of both enzymes (LcPTR1 Ki = 1.50–2.30 μM and LcDHFR Ki = 0.28–3.00 μM) with poor selectivity index. On the other hand, compound 5 (2,4-diaminoquinazoline derivative) is a selective LcPTR1 inhibitor (Ki = 0.47 μM, selectivity index = 20).
- Teixeira, Bárbara Velame Ferreira,Teles, André Lacerda Braga,Silva, Suellen Gon?alves da,Brito, Camila Carane Bitencourt,Freitas, Humberto Fonseca de,Pires, Acássia Benjamim Leal,Froes, Thamires Quadros,Castilho, Marcelo Santos
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- SNAr reaction in aqueous medium in the presence of mixed organic and inorganic bases
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N-Arylation of amines with fluorobenzonitriles in aqueous medium is described. A mixture of N,N-diisopropylethyl amine and Na2CO3 (1:1) is found to achieve maximum conversion by refluxing for 3 hours in water. The product can be easily isolated by solvent extraction.
- Shelke, Nilesh B.,Ghorpade, Ramrao,Pratap, Ajay,Tak, Vijay,Acharya
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p. 31226 - 31230
(2015/04/22)
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- Fragment based search for small molecule inhibitors of HIV-1 Tat-TAR
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Basic molecular building blocks such as benzene rings, amidines, guanidines, and amino groups have been combined in a systematic way to generate ligand candidates for HIV-1 TAR RNA. Ranking of the resulting compounds was achieved in a fluorimetric Tat-TAR
- Zeiger, Mirco,Stark, Sebastian,Kalden, Elisabeth,Ackermann, Bettina,Ferner, Jan,Scheffer, Ute,Shoja-Bazargani, Fatemeh,Erdel, Veysel,Schwalbe, Harald,G?bel, Michael W.
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supporting information
p. 5576 - 5580
(2015/01/08)
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- Discovery and optimization of 2,4-diaminoquinazoline derivatives as a new class of potent dengue virus inhibitors
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The results of a high-throughput screening assay using the DENV-2 replicon showed that the 2,4-diaminoquinazoline derivative 4a has a high dengue virus inhibitory activity (EC50 = 0.15 μM). A series of 2,4-diaminoquinazoline derivatives based on 4a as a lead compound were synthesized and subjected to structure-antidengue activity relationship studies. Among the series of 2,4-diaminoquinazoline derivative probed, 4o was observed to display both the highest antiviral potency (EC50 = 2.8 nM, SI > 1000) and an excellent pharmacokinetic profile.
- Chao, Bo,Tong, Xian-Kun,Tang, Wei,Li, De-Wen,He, Pei-Lan,Garcia, Jean-Michel,Zeng, Li-Min,Gao, An-Hui,Yang, Li,Li, Jia,Nan, Fa-Jun,Jacobs, Michael,Altmeyer, Ralf,Zuo, Jian-Ping,Hu, You-Hong
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experimental part
p. 3135 - 3143
(2012/06/01)
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- Synthesis of 2,4-diaminoquinazolines and tricyclic quinazolines by cascade reductive cyclization of methyl N -cyano-2-nitrobenzimidates
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An efficient route to N4-substituted 2,4-diaminoquinazolines has been developed by employing tandem condensation of cyanoimidate-amine and reductive cyclization in iron-HCl system. This method is tolerant of a following intramolecular N-alkylation and produces two fused heterocycles in a one-pot procedure. This protocol is a facile two-step synthesis of tricyclic quinazolines, which is effected by potent cyanoimidation and tandem reductive cyclization from 2-nitrobenzaldehydes. Moreover, the forming process of tricyclic quinazolines has been investigated from the ring-opening/ring-closing cascade point of view. It is found that the preparation of tricyclic quinazolinones in good yields relies on the selective hydrolysis of tricyclic quinazolines in base or acid system.
- Yin, Ping,Liu, Nan,Deng, Yu-Xing,Chen, Yue,Deng, Yong,He, Ling
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p. 2649 - 2658
(2012/06/01)
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- Efficient copper-catalyzed synthesis of 4-aminoquinazoline and 2,4-diaminoquinazoline derivatives
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We have developed an efficient copper-catalyzed method for the synthesis of 4-aminoquinazoline and 2,4-diaminoquinazoline derivatives via reactions of substituted 2-bromobenzonitriles with amidines or guanidine, and the method is of economical and practic
- Yang, Xiaobo,Liu, Hongxia,Futa, Hua,Qiao, Renzhong,Jiang, Yuyang,Zhao, Yufen
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supporting information; experimental part
p. 101 - 106
(2010/08/06)
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- Antifolate and Antibacterial Activities of 5-Substituted 2,4-Diaminoquinazolines
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A series of 5-substituted 2,4-diaminoquinazolines (3) has been synthesized and evaluated as inhibitors of the enzyme dihydrofolate reductase (DHFR) from both bacterial and mammalian sources.The best compounds (e.g. 53) show good activity against Escherichia coli DHFR, but there is no significant selectivity for the bacterial over the mammalian enzyme.The structure-activity relationships for enzyme inhibition appear to be complex and not amenable to simple analysis; a hypotesis to explain the observed qualitative structure-activity relationships is proposed.The inhibitory activities of the compounds against the growth of intact bacterial cells in vitro closely parallel those for the inhibition of the isolated bacterial enzymes, suggesting that their antifolate action is responsible for their antibacterial effects.Five of the compounds were tested for their ability to cure a systemic E. coli infection in the mouse, but they showed no therapeutic effects at their maximum tolerated doses.
- Harris, Neil V.,Smith, Christopher,Bowden, Keith
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p. 434 - 444
(2007/10/02)
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- Direct Synthesis of 2,4-Diaminoquinazolines from 2-Fluorobenzonitriles
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In a search for new methods for preparing 2,4-diaminoquinazolines having a diversity of substituents in the benzenoid ring, it was found that the reaction of 2,6-difluorbenzonitrile with guanidine carbonate gave 2,4-diamino-5-fluoroquinazoline in excellent yield.Extension of this approach to other 2-fluorobenzonitriles, some of which were elaborated for the first time, showed that this reaction possesses considerable generality.The cyclization was sucessful even when electron donating groups were present at position six.Only in two cases where a primary or secondary amino group was also present ortho to the cyano group was this transformation unsucessful.
- Hynes, John B.,Pathak, Alpana,Panos, Constantina H.,Okeke, Claudia C.
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p. 1173 - 1177
(2007/10/02)
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