- Preparation of 3-bromo-l-tyrosine and 3,5-dibromo-l-tyrosine
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l-Tyrosine is converted to 3-bromo-l-tyrosine in good yield by reaction with 1.2 equiv. of DMSO in HBr/AcOH, while reaction with 2.2 equiv. of DMSO under comparable conditions results in formation of 3,5-dibromo-l-tyrosine in good yield. This is the simplest, safest and most efficient method for the preparation of gram quantities of either 3-bromo-l-tyrosine or 3,5-dibromo-l-tyrosine.
- Phillips, Robert S.,Busby, Susan,Edenfield, Leia,Wickware, Kevin
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- Bromotyrosine-derived Metabolites from the Sponge Aiolochoria crassa
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A chemical investigation of secondary metabolites from the sponge Aiolochroia crassa has been performed and five bromotyrosine derivatives (1-5) were identified. Their structures have been assigned on the basis of spectroscopic analysis, of which araplysillin III (2) and hexadellin C (3) possess new structures. The absolute configurations of dibromotyrosine moieties of 2 were determined by HPLC analysis of derivatized constituent amino acids obtained from acid hydrolysis. The stereochemistry of the spirocyclohexadienylisoxazoline moiety of compounds 1-3 was deduced from spectroscopic comparison of the same moiety of aerothionin, of which the absolute configuration was previously assigned by X-ray and CD analysis. - Keywords: antibiotics; marine metabolites; spiro compounds.
- Gao, Hongfeng,Kelly, Michelle,Hamann, Mark T.
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- Convenient access to L-3,4,5-trioxygenated phenylalanine compounds from L-tyrosine
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A convenient and efficient synthesis of L-3,4,5-trioxygenated phenylalanine derivatives from L-tyrosine was developed. Dibromo phenylalanine is converted easily to bis-phenol via copper-catalyzed hydroxylation. The synthetic potential of this methodology has been demonstrated by efficient synthesis of L-3,4,5-trimethoxyphenylalanine methyl ester and one key intermediate of Trabectedin.
- Zhou, Shengfeng,Zhou, Chen,Lu, Qian,Liu, Xintong,Yuan, Jie,Yu, Xinhong
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- A novel class of tyrosine derivatives as dual 5-LOX and COX-2/mPGES1 inhibitors with PGE2 mediated anticancer properties
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Leukotriene and prostaglandin pathways are controlled by the enzymes, LOX and COX/mPGES1 respectively and are responsible for inflammatory responses. PGE2, produced by mPGES1, leads to the progression of inflammation as well as cancer. A series of 19 novel tyrosine derivatives are synthesized, characterized and tested against 5-LOX, in vitro, and production of PGE2, in HeLa cells. 6b-v and 6c-i, are found to possess maximum inhibitory action against 5-LOX and PGE2 production. The compound 6b-v is found to act by disrupting the redox cycle of the 5-LOX enzyme, and its activity is comparable to that of the commercial drug, Zileuton. The activity of the other compound 6c-i is comparable to a drug in clinical trials, Licofelone, and it has been found to inhibit the mRNA expression of mPGES1 predominantly. It also arrests the HeLa cells in the S and G2/M phases of the cell cycle indicating anticancer activity. Also, compounds, 6b-iv and 6b-viii inhibit both the LT & PG pathways in the inflammation cascade. Presence of iodine in the phenyl ring appears to favour the inhibition of 5-LOX whereas chlorine favours the inhibition of PGE2 production. These leads could be further optimized and developed as drugs against inflammation and cancer.
- Puratchikody, Ayarivan,Umamaheswari, Appavoo,Irfan, Navabshan,Sinha, Shweta,Manju,Ramanan, Meera,Ramamoorthy, Gayathri,Doble, Mukesh
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supporting information
p. 834 - 846
(2019/01/09)
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- Synthesis and trypanocide activity of chloro-l-tyrosine and bromo-l-tyrosine derivatives
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Twenty-two halogenated l-tyrosine derivatives were synthesized to examine new substances for the treatment of Chagas disease. The synthesis of these derivatives with different degree of substitution in the amino group with methyl iodide, giving primary, tertiary, and quaternary amino acids. All compounds were tested in vitro against intracellular amastigotes of Trypanosoma cruzi, and the cytotoxicity were evaluated over monocytic cell line U-937. Compound 25 was the most active against T. cruzi with a EC50 of 75.52 μM compared with benznidazole with a EC50 of 58.79 μM. Compounds 3, 4, 7, and 15 were the derivatives with the best selectivity index (SI) with values of 7.5, 8.3,12.1, and 8.6, respectively. Finally, compound 7 was the safer and the more promising derivative against T. cruzi.
- Pastrana Restrepo, Manuel,Galeano Jaramillo, Elkin,Martínez Martínez, Alejandro,Robledo Restrepo, Sara
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p. 2454 - 2465
(2018/10/02)
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- Anti-parasite and cytotoxic activities of chloro and bromo L-tyrosine derivatives
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A series of twenty-one L-tyrosine derivatives with modifications in the halogenation pattern of the aromatic ring and different degree of methylations on the amine and phenolic hydroxyl groups were synthesized. The structures of all the intermediates and target compounds were confirmed unambiguous by spectroscopy analysis. Additionally, all compounds were evaluated against Plasmodium falciparum and Leishmania panamensis parasites between 20-702 μg mL-1. The cytotoxic evaluation was done to determine the selectivity index for each compound. Six compounds had the lower EC50 (effective concentration 50) against L. panamensis. One of these compounds was the most active with an EC50 at 24.13 μg mL-1 (76.07 μM). All derivatives showed no significant activity against P. falciparum and no compound has in vitro antifungal activity at 500 μg mL-1.
- Restrepo, Manuel Pastrana,Jaramillo, Elkin Galeano,Martínez, Alejandro Martínez,Arango, Ana Mesa,Restrepo, Sara Robledo
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p. 2569 - 2579
(2018/11/06)
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- Chemistry of unprotected amino acids in aqueous solution: Direct bromination of aromatic amino acids with bromoisocyanuric acid sodium salt under strong acidic condition
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Brominations of unprotected aromatic amino acids such as phenylalanine, tyrosine, and glycine, with bromoisocyanuric acid mono sodium salt (BICA-Na) were conducted in 60% aq. H2SO4 at 0°C to give a mixture of mono-brominated products in good yield. Unexpectedly, meta-bromophenylglycine was obtained as main product accompanied by ortho- and para-substituted products, while phenylalanine gave only ortho- and para-substituted products. Bromination of 2-phenylethylamine or benzylamine showed a tendency similar to the corresponding amino acids.
- Yokoyama, Yuusaku,Yamaguchi, Tomotsugu,Sato, Masanori,Kobayashi, Eri,Murakami, Yasuoki,Okuno, Hiroaki
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p. 1715 - 1719
(2007/10/03)
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- The synthesis, distribution, and anti-hepatic cancer activity of YSL
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(I) HCl/CH3OH; (II) DCC/HOBt/NMM with corresponding carboxyl component; (III) HCl/CH3CO2C2H5 (6 mol/L); (IV) NaOH/H2O/CH3OH; (V) 3H2 and 10% Pd/C. YSL was prepared stepwise from C terminal to N terminal with the side chain un-protective amino acids, Boc-Leu-OMe, Boc-Ser-OH, and Boc-Tyr-OH, as the starting materials in 39.5% total yield (31.2 g/per batch). With the side chain un-protective Boc-(3,5-dibromo)-Tyr-OH and HClA·Ser-Leu-OMe as the starting materials (3,5-3H-Tyr)-Ser-Leu-OH was obtained in 29% yield. The determination of radioactive quantity in the urine and feces indicated that even after the administration for 130 h only 8.4% (5.35% in urine and 3.05% in feces) of total radioactive quantity from the metabolite of [3,5-3H-Tyr]-Ser-Leu-OH were monitored. The distribution study revealed the relative accumulation level of the individual tissue was arranged in the sequence of spleen > liver > kidney > lung > heart > muscle > brain. Selecting hepatic cancer as the target YSL significantly increased the survival time of H22 tumor cells implanted mice.
- Ding, Wenfeng,Zhang, Jiali,Yao, Zhi,Lu, Rong,Wu, Dezhu,Li, Ginfu,Shen, Zilong,Sun, Yingji,Lin, Gang,Wang, Chao,Zhao, Ming,Peng, Shiqi
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p. 4989 - 4994
(2007/10/03)
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- Formation of Quinol Ethers using (Diacetoxyiodo)benzene
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The use of (diacetoxyiodo)benzene for the oxidative coupling of a hindered phenol with aliphatic alcohols or other phenols has been investigated.
- Lewis, Norman,Wallbank, Philip
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p. 1103 - 1106
(2007/10/02)
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