A modification of the Hammett equation for predicting ionisation constants of p-vinyl phenols

Sipilä, Julius; Nurmi, Harri; Kaukonen, Ann Marie; Hirvonen, Jouni; Taskinen, Jyrki; Yli‐Kauhaluoma, Jari

doi:10.1016/j.ejps.2005.04.002

Cited by 8 publications

(6 citation statements)

References 31 publications

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“…Although the chemical structure of the two substances is quite similar, the interaction with iron is apparently different. The dissociation constants for the carboxyl group in the two substances are quite similar, 4.36-4.41 for caffeic acid (19)(20)(21) and 4.43 for coumaric acid (21), which is natural considering the similarity in chemical structure. It has been shown that the presence of the catechol moiety gives rise to a higher antioxidant activity in lipid systems (22) and, thus, caffeic acid is considered to be a more efficient antioxidant than p-coumaric acid.…”

Section: Discussionmentioning

confidence: 79%

Phenolic Acid Nanoparticle Formation in Iron-Containing Aqueous Solutions

Nilsson

Löf

Bergenståhl

2008

J. Agric. Food Chem.

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This paper presents results which show that the interaction between two phenolic acids, p-coumaric and caffeic acid, with iron results in the formation of meta-stable colloidal nano particles. The particles are characterized with dynamic light scattering and cryo-transmission electron microscopy. The results show that the nanoparticle formation is an important feature of phenolic acids which is likely to have a large impact on the behavior of these substances as well as their functionality as antioxidants.

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Section: Discussionmentioning

confidence: 79%

Phenolic Acid Nanoparticle Formation in Iron-Containing Aqueous Solutions

Nilsson

Löf

Bergenståhl

2008

J. Agric. Food Chem.

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“…While a significant number of recent publications can be found reporting on new and better programs and methods for p K a prediction (see refs − and − for additional approaches using empirical or quantum chemical methods, respectively), albeit mostly for specific classes of compounds, much less prior work exists comparing such approaches. Melun et al used the REGDIA regression diagnostics algorithm in S-Plus to examine the accuracy of p K a predictions of four programs: ACD/p K a , Marvin, PALLAS, and SPARC .…”

Section: Introductionmentioning

confidence: 99%

Comparison of Nine Programs Predicting pK_a Values of Pharmaceutical Substances

Liao

Nicklaus

2009

J. Chem. Inf. Model.

160

135

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Knowledge of the possible ionization states of a pharmaceutical substance, embodied in the pK(a) values (logarithm of the acid dissociation constant), is vital for understanding many properties essential to drug development. We compare nine commercially available or free programs for predicting ionization constants. Eight of these programs are based on empirical methods: ACD/pK(a) DB 12.0, ADME Boxes 4.9, ADMET Predictor 3.0, Epik 1.6, Marvin 5.1.4, Pallas pKalc Net 2.0, Pipeline Pilot 5.0, and SPARC 4.2; one program is based on a quantum chemical method: Jaguar 7.5. We compared their performances by applying them to 197 pharmaceutical substances with 261 carefully determined and highly reliable experimental pK(a) values from a literature source. The programs ADME Boxes 4.9, ACD/pK(a) DB 12.0, and SPARC 4.2 ranked as the top three with mean absolute deviations of 0.389, 0.478, and 0.651 and r(2) values of 0.944, 0.908, and 0.894, respectively. ACD/pK(a) DB 12.0 predicted all sites, whereas ADME Boxes 4.9 and SPARC 4.2 failed to predict 5 and 18 sites, respectively. The performance of the quantum chemical-based program Jaguar 7.5 was not as expected, with a mean absolute deviation of 1.283 and an r(2) value of 0.579, indicating the potential for further development of this type of approach to pK(a) prediction.

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“…Methyl α-cyano-4-hydroxycinnamate (3c)The desired product was isolated by crystallization (twice from methanol) as a pale yellow solid (4.63 g, 76%), mp = 210-212 • C [lit. 208-210 • C][37]…”

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confidence: 99%

β2-Homo-Amino Acid Scan of µ-Selective Opioid Tetrapeptide TAPP

et al. 2020

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TAPP (H-Tyr-d-Ala-Phe-Phe-NH2) is a potent, µ-selective opioid ligand. In order to gain further insights into pharmacophoric features of this tetrapeptide, we have performed a β2-Homo-amino acid (β2hAA) scan of the TAPP sequence. To this aim, 10 novel analogues have been synthesized and evaluated for µ-opioid and δ-opioid receptor affinity as well as for stability in human plasma. The derivatives included compounds in which a (R)- or (S)-β2-Homo-Homologue replaced the amino acids in the TAPP sequence. The derivatives with (R)- or (S)-β2hPhe4 turned out to bind µOR with affinities equal to that of the parent. β2hAAs in position 1 and 3 resulted in rather large affinity decreases, but the change differed depending on the stereochemistry. β2-Homologation in the second position gave derivatives with very poor µOR binding. According to molecular modelling, the presented α/β-peptides adopt a variety of binding poses with their common element being an ionic interaction between a protonable amine of the first residue and Asp147. A feature required for high µOR affinity seems the ability to accommodate the ring in the fourth residue in a manner similar to that found for TAPP. Contrary to what might be expected, several compounds were significantly less stable in human plasma than the parent compound.

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A modification of the Hammett equation for predicting ionisation constants of p-vinyl phenols

Cited by 8 publications

References 31 publications

Phenolic Acid Nanoparticle Formation in Iron-Containing Aqueous Solutions

Phenolic Acid Nanoparticle Formation in Iron-Containing Aqueous Solutions

Comparison of Nine Programs Predicting pK_a Values of Pharmaceutical Substances

β2-Homo-Amino Acid Scan of µ-Selective Opioid Tetrapeptide TAPP

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A modification of the Hammett equation for predicting ionisation constants of p-vinyl phenols

Cited by 8 publications

References 31 publications

Phenolic Acid Nanoparticle Formation in Iron-Containing Aqueous Solutions

Phenolic Acid Nanoparticle Formation in Iron-Containing Aqueous Solutions

Comparison of Nine Programs Predicting pKa Values of Pharmaceutical Substances

β2-Homo-Amino Acid Scan of µ-Selective Opioid Tetrapeptide TAPP

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Product

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Comparison of Nine Programs Predicting pK_a Values of Pharmaceutical Substances