Amino acid, Antioxidant and Ion Profiles of Carpolobia lutea Leaf (Polygalaceae)

Purpose: To evaluate the amino acid, antioxidant and ionic profiles of Carpolobia lutea leaf (Polygalaceae) extract (CLL).Methods: The powdered leaf was macerated and subjected to gradient solvent extraction with nhexane, chloroform, ethyl acetate and ethanol for 72 h to obtain their respective fractions. Amino acid analysis was by cation-exchange chromatography using automated amino acid analyser. Antioxidant potential was obtained by spectrophotometric assay using 2, 2-Diphenyl-1-picrylhydrazyl DPPH while elemental and ionic analyses were carried out by atomic absorption spectrophotometry and potentiometric titration, respectively.Results: Proline, alanine, serine, valine, glycine, glutamate and lysine were found in the ethanol fraction while lysine, phenyl alanine, glycine and serine were present in the ethyl acetate fraction but not in the non-polar fractions, n-hexane and chloroform. The ethyl acetate fraction contained more lysine, phenyl alanine, glycine and serine the other leaf fractions. Minimal radical scavenging activity of all the fractions was recorded. The most abundant cations in the extract were potassium and phosphorus (2.16 ± 0.05 and 1.90 ± 0.06 mg/g, respectively) while the most abundant anion was phosphate with a concentration of 23.23 ± 4.61 mg/g for the aqueous leaf fractionConclusion: The study shows that CLL fractions contain variety of amino acids which could promote wound healing, as well as major and minor elemental ions which, as essential body electrolytes, are required for various metabolic processes in the body.Keywords: Carpolobia leaf, Polygalaceae, Amino acid, Antioxidant, Ionic profile

Magnetic resonance spectroscopy as a non-invasive method to quantify muscle carnosine in humans: a comprehensive validity assessment

Carnosine is a dipeptide abundantly found in human skeletal muscle, cardiac muscle and neuronal cells having numerous properties that confers performance enhancing effects, as well as a wide-range of potential therapeutic applications. A reliable and valid method for tissue carnosine quantification is crucial for advancing the knowledge on biological processes involved with carnosine metabolism. In this regard, proton magnetic resonance spectroscopy (1H-MRS) has been used as a non-invasive alternative to quantify carnosine in human skeletal muscle. However, carnosine quantification by 1H-MRS has some potential limitations that warrant a thorough experimental examination of its validity. The present investigation examined the reliability, accuracy and sensitivity for the determination of muscle carnosine in humans using in vitro and in vivo experiments and comparing it to reference method for carnosine quantification (high-performance liquid chromatography – HPLC). We used in vitro 1H-MRS to verify signal linearity and possible noise sources. Carnosine was determined in the m. gastrocnemius by 1H-MRS and HPLC to compare signal quality and convergent validity. 1H-MRS showed adequate discriminant validity, but limited reliability and poor agreement with a reference method. Low signal amplitude, low signal-to-noise ratio, and voxel repositioning are major sources of error

The spin label amino acid TOAC and its uses in studies of peptides: chemical, physicochemical, spectroscopic, and conformational aspects

We review work on the paramagnetic amino acid 2,2,6,6-tetramethyl-N-oxyl-4-amino-4-carboxylic acid, TOAC, and its applications in studies of peptides and peptide synthesis. TOAC was the first spin label probe incorporated in peptides by means of a peptide bond. In view of the rigid character of this cyclic molecule and its attachment to the peptide backbone via a peptide bond, TOAC incorporation has been very useful to analyze backbone dynamics and peptide secondary structure. Many of these studies were performed making use of EPR spectroscopy, but other physical techniques, such as X-ray crystallography, CD, fluorescence, NMR, and FT-IR, have been employed. The use of double-labeled synthetic peptides has allowed the investigation of their secondary structure. A large number of studies have focused on the interaction of peptides, both synthetic and biologically active, with membranes. In the latter case, work has been reported on ligands and fragments of GPCR, host defense peptides, phospholamban, and β-amyloid. EPR studies of macroscopically aligned samples have provided information on the orientation of peptides in membranes. More recent studies have focused on peptide–protein and peptide–nucleic acid interactions. Moreover, TOAC has been shown to be a valuable probe for paramagnetic relaxation enhancement NMR studies of the interaction of labeled peptides with proteins. The growth of the number of TOAC-related publications suggests that this unnatural amino acid will find increasing applications in the future

Redox capacitive assaying of C-reactive protein at a peptide supported aptamer interface

Electrochemical immunosensors offer much in the potential translation of a lab based sensing capability to a useful "real world" platform. In previous work we have introduced an impedance-derived electrochemical capacitance spectroscopic analysis as supportive of a reagentless means of reporting on analyte target capture at suitably prepared mixed-component redox-active, antibody-modified interfaces. Herein we directly integrate receptive aptamers into a redox charging peptide support in enabling a label-free low picomolar analytical assay for C-reactive protein with a sensitivity that significantly exceeds that attainable with an analogous antibody interface