RESUMO
Gadolinium-based contrast agents (GBCAs) are used in around 40 % of MRI procedures. Despite initial perceptions of minimal risk, their long-term use has emphasized the need to reduce toxicity and develop more efficient GBCAs with extended blood retention. Advancements in nanomaterials have led to improved GBCAs, enhancing MRI diagnostics. This study synthesizes and characterizes nanostructured gadolinium(III) micelles as superior MRI contrast agents. The complexes, [Gd(L)2], where L is a ligand of the N-alkyl-N-methylglucamine surfactant series (L8, L10 or L12, L10), form nanostructured micelles in aqueous solution. Gd(L8)2 and Gd(L10)2 relaxivities remained stable across concentrations. Compared to Gd-DTPA, Gd(III) micelles showed enhanced T1-weighted MRI contrast. Gd(L12)2 micelles exhibited cytotoxicity against B16F10 melanoma cells (IC50 42.5 ± 2.2 µM) and L292L929 fibroblasts (IC50 52.0 ± 2.5 µM), with a selectivity index of 1.2. In vivo application in mice brain T2-weighted images suggests nanostructured Gd(III) micelles are promising MRI contrast agents for targeting healthy organs or tumors.
RESUMO
Cysteine proteinases from the latex of plants of the family Caricaceae are widely used industrially as well as in pharmaceutical preparations. In the present work, a 23 kDa cysteine proteinase from Carica candamarcensis latex (designated CMS1MS2) was purified for crystallization using three chromatography steps. The enzyme shows about fourfold higher activity than papain with BAPNA as substrate. Crystals suitable for X-ray diffraction experiments were obtained by the hanging-drop method in the presence of PEG and ammonium sulfate as precipitants. The crystals are monoclinic (space group P2(1)), with unit-cell parameters a = 53.26, b = 75.71, c = 53.23 A, beta = 96.81 degrees , and diffract X-rays to 1.8 A resolution.