Fluorinated Mn(III)/(II)-Porphyrin with Redox-Responsive 1 H and 19 F Relaxation Properties.

A new fluorinated manganese porphyrin, (Mn-TPP-p-CF3 ) is reported capable of providing, based on the Mn(III)/Mn(II) equilibrium, dual 1 H relaxivity and 19 F NMR response to redox changes. The physical-chemical characterization of both redox states in DMSO-d6 /H2 O evidenced that the 1 H relaxometric and 19 F NMR properties are appropriate for differential redox MRI detection. The Mn(III)-F distance (dMn-F =9.7-10 Å), as assessed by DFT calculations, is well tailored to allow for adequate paramagnetic effect of Mn(III) on 19 F T1 and T2 relaxation times. Mn-TPP-p-CF3 has a reversible Mn(II)/Mn(III) redox potential of 0.574 V vs. NHE in deoxygenated aqueous HEPES/ THF solution. The reduction of Mn(III)-TPP-p-CF3 in the presence of ascorbic acid is slowly, but fully reversed in the presence of air oxygen, as monitored by UV-Vis spectrometry and 19 F NMR. The broad 1 H and 19 F NMR signals of Mn(III)-TPP-p-CF3 disappear in the presence of 1 equivalent ascorbate replaced by a shifted and broadened 19 F NMR signal from Mn(II)-TPP-p-CF3 . Phantom 19 F MR images in DMSO show a MRI signal intensity decrease upon reduction of Mn(III)-TPP-p-CF3 , retrieved upon complete reoxidation in air within ~24 h. 1 H NMRD curves of the Mn(III)/(II)-TPP-p-CF3 chelates in mixed DMSO/water solvent have the typical shape of Mn(II)/Mn(III) porphyrins.

Antioxidant activity of ethanolic extracts of Pothomorphe umbellata L. Miq. (Pariparoba)

Oxidative stress has been implicated in many pathological conditions such as cancer, aging inflammation and cell death. The Brazilian flora is particularly rich in medicinal plants employed for many purposes. Among them the Piperaceae family and specially the "pariparobas" are widely used in the treatment of liver diseases. In vitro antioxidant activity of Pothomorphe umbellata L. Miq. was evaluated and compared with that of Piper regnellii, another plant from the Piperaceae family commonly used as it were P. umbellata. A purified fraction of the ethanolic extract of P. umbellata, containing 4-nerolidylcatechol was also assayed for antioxidant activity and compared with that of alpha-tocopherol. Rat brain homogenates were incubated with increasing aliquots of crude extracts of different parts of the plants or 4-nerolidylcatechol/alpha-tocopherol for 1 h at 37 degrees Celsius. Both malondialdehyde (MDA) and chemiluminescence (CL) were assayed to evaluate brain tissue autoxidation. The Q1/2 for MDA assay for root, stem and leaves were 4.4, 19.3 and 38.5 mug/mL for P. umbellata and 26.0,64.4 and 13.3 mug/mL for P regnellii, respectively. Calculated MDA and CL Q1/2 values for 4-nerolidylcatechol and alpha-tocopherol were O.75 and O.68 muM for 4-nerolidylcatechol and 14.4 and 1O.9 muM for alpha-tocopherol, respectively. These results indicate high antioxidant activity of P. umbellata root extract as compared to that of vitamin E, which was attributed to the presence of 4-nerolidylcatecho1.