Sterically protected hemins with electronegative substituents: efficient catalysts for hydroxylation and epoxidation

Traylor, Patricia S.; Dolphin, David; Traylor, Teddy G.

doi:10.1039/c39840000279

Cited by 224 publications

(84 citation statements)

References 2 publications

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“…30) Considering that the oxidation of piperine and piplartine occurs at the piperidine ring, the higher reactivity of piplartine must be related to the presence of the double bond, once it can stabilize by resonance the radical formed during the first of the metalloporphyrin-catalyzed oxidation. 31) It is also reported that in metalloporphyrin biomimetic reactions carried out in solvents as dichloroethane and acetonitrile, the oxidation of cyclohexane occur via this mechanism, leading to a predominant alcohol formation, [31][32][33][34][35] such as have occurred in the present work.…”

Section: Discussionmentioning

confidence: 80%

Biomimetic Oxidation of Piperine and Piplartine Catalyzed by Iron(III) and Manganese(III) Porphyrins

Schaab

Crotti

Iamamoto

et al. 2010

Biological & Pharmaceutical Bulletin

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Piperine and piplartine ( Fig. 1) are naturally occurring amides from Piper species (Piperaceae), which have been used in folk medicine of tropical and subtropical countries for treatment of asma, bronchitis, fever, hemorrhoidal afflictions, gastrointestinal diseases, rheumatism, and as food additive.1-3) The amide piperine is the pungent principle of black pepper (P. nigrum) and can be extracted from dried fruits with a yield of 3-7%.4) Several biological activities have been associated to piperine, including inhibition of liver metabolism, antioxidant, central nervous system depressant and antitumoral activities. [4][5][6][7][8][9] Piplartine is one of the major amide isolated from the roots of P. tuberculatum (popularly known as "long pepper"), which has been largely used in the folk medicine as a sedative and antidote for snake bite. Piplartine has shown significant cytotoxicity against cell tumor lines, as well as antifungal, antimitotic and anti-platelet aggregation compound.9-13) Piplartine anticancer potential has been highlighted by the undergoing preclinical evaluation. In vivo studies using murine tumors demonstrated that in spite of a moderate anticancer activity, piplartine has weak toxicological side effects. 3,14) Additionally, it increases 5-fluorouracil anticancer efficacy, while reduces chemotherapeutical side effects, as evidenced by the prevention of 5-FUinduced leucopenia.15) These data suggests that piplartine is a promising anticancer compound to be used in combination of already known antineoplastic agents.The study of the oxidative metabolism on promising natural products is of major importance before they become medicines, since their oxidations can affect the drug's safety and efficacy, due to the formation of therapeutically active or toxic metabolites. 16) Thus, efforts have been addressed to describe the metabolic pathways of drug candidate compounds.The cytochrome P450 (CYP) enzymes are catalytic hemoproteins known for their role in the metabolism of non-polar comounds, present in all forms of life (plants, bacteria, mammals). They have played a key role in the oxidative transformation of endogenous and exogenous molecules. 17,18) The cytochrome P450 enzymes catalyze the hydroxylation of saturated carbon-hydrogen bonds, epoxidation of double bounds, oxidation of heteroatoms, dealkylation reactions, and oxidations of aromatic carbons, etc.17) The oxidative metabolism of drugs by cytochrome P450 monooxygenases has been extensively studied through biological models, such as direct experiments on animals, the use of perfused organs or isolated cells. However, there are several ethical restrictions using animals and also experimental drawnbacks associated with the isolation of some hydrophilic and reactive metabolites that could bind to biological macromolecules, preparation of liver and cells (microsomes, hepatocytes) are of variable quality with low yields. [18][19][20] Thus, alternative model systems of cytocrome P450 have been employed in studies of P450 functions, as well as in syn...

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Section: Discussionmentioning

confidence: 80%

Biomimetic Oxidation of Piperine and Piplartine Catalyzed by Iron(III) and Manganese(III) Porphyrins

Schaab

Crotti

Iamamoto

et al. 2010

Biological & Pharmaceutical Bulletin

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“…Within 1 h of reaction time, the M nmTPP molecule was completely degraded. Even more robust por phyrins [22][23][24][25][26] such as the 'second-generation' ori/io-substituted chloro-porphyrins, and the penta-substituted chloro-and fluoro-porphyrins were either completely degraded during the course of the reaction or, in the case of M nmTpentaFPP, were unreactive. The reason for this fast oxidative degradation of the M nm por phyrin catalysts is most likely due to a rhodium -superoxo species that forms as a result of the interaction between the reduced rhodium bipyridyl complex and molecular oxygen.…”

Section: Discussionmentioning

confidence: 99%

“…We chose M nmTPP complexes that are modified with electron-withdrawing substituents at the ortho positions in the phenyl rings as well as porphyrins with completely substituted phenyl rings. These so-called 'second genera tion' porphyrins [22][23][24][25][26] are less susceptible to attack at the meso-positions due to both steric effects from the substituents and the electronwithdrawing effect which makes the m eso-posi tion less favorable to electrophilic degradation. The results of epoxidation reactions carried out with these catalysts are shown in Table 2.…”

Section: Epoxidationmentioning

confidence: 99%

A manganese(III) porphyrin/rhodium(III) bipyridine/formate catalyst system for the reductive activation of molecular oxygen

Gosling¹,

Nolte²

1996

Journal of Molecular Catalysis A: Chemical

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“…The microcosms were randomly set up in a 2 × 4 experimental block (6 times replicated) with 2 plant treatments (with and without maize plants) and 4 soil treatments: control soil (CT), compost-amended soil at 2 kg m -2 rate (COM), soil added with 1 g m -2 synthetic iron-porphyrin (POR), compostamended and iron-porphyrin-treated soil (COM+POR). The iron-porphyrin [meso-tetra(2,6-dichloro-3-sulfonatophenyl) porphyrinate of Fe(III)chloride], otherwise referred to as biomimetic catalyst, was synthesized according to the procedure of Traylor et al (1984) as modified by Piccolo et al (2005). The iron-porphyrin was surface-sprayed upon POR and POR+COM microcosms as a buffered solution (0.1 M phosphate buffer at pH 7.0) soon after soil filling.…”

Section: Experimental Set-upmentioning

confidence: 99%

Effects of a biomimetic iron‐porphyrin on soil respiration and maize root morphology as by a microcosm experiment

Gelsomino

Tortorella

Cianci

et al. 2010

Z. Pflanzenernähr. Bodenk.

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A synthetic, water-soluble iron-porphyrin [meso-tetra(2,6-dichloro-3-sulfonatophenyl) porphyrinate of Fe(III) chloride] has recently been proposed as a biomimetic catalyst in the process of oxidative polymerization of terrestrial humic acids, to increase their conformational stability and thus contribute to a reduction of soil CO 2 release into the atmosphere. This study was aimed at investigating changes in selected soil chemical properties, CO 2 efflux, and maize root morphotopology after the addition of iron-porphyrin as a microcosm-style experiment, located in a greenhouse. The addition of mature compost was also included as an experimental factor in order to reveal synergistic effects in regard to freshly added organic materials. Iron-porphyrin determined a negligible effect on soil organic budget in both unplanted and planted microcosms. Conversely, the biomimetic catalyst was found to have significant and contrasting effects on soil respiration, apparently reflecting different iron porphyrin-plant-compost interactions. Consequently, iron-porphyrin significantly reduced CO 2 efflux from the bare (unplanted) soil, which was, conversely, stimulated in maize-planted microcosms. Additionally, combined iron-porphyrin and compost addition synergistically acted in increasing soil respiration in planted microcosms. Moreover, root biomass was increased with the addition of iron-porphyrin, and a further effect on maize root morphology was noted when used in combination with compost; notably the length of coarse and fine roots increased. We hypothesized that the efficacy of iron-porphyrin in reducing CO 2 efflux from soil may be mediated by morphological changes in the plant-root system.

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Sterically protected hemins with electronegative substituents: efficient catalysts for hydroxylation and epoxidation

Cited by 224 publications

References 2 publications

Biomimetic Oxidation of Piperine and Piplartine Catalyzed by Iron(III) and Manganese(III) Porphyrins

Biomimetic Oxidation of Piperine and Piplartine Catalyzed by Iron(III) and Manganese(III) Porphyrins

A manganese(III) porphyrin/rhodium(III) bipyridine/formate catalyst system for the reductive activation of molecular oxygen

Effects of a biomimetic iron‐porphyrin on soil respiration and maize root morphology as by a microcosm experiment

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