Aspectos estruturais, farmacológicos e toxicológicos de Mo-CBP4, uma proteína ligante à quitina de Moringa oleifera com atividade anti-inflamatória e antinociceptiva via oral

Abstract

Mo-CBP4 is a chitin-binding protein that is associated with the antinociceptive and anti-inflammatory effects of Moringa oleifera seeds, a tree known for its medicinal value. The aim of this study was the structural, pharmacological and toxicological characterization of Mo-CBP4, focusing on its use as a therapeutic agent. Mo-CBP4 is a 11.8 kDa heterodimer, composed by 3.9 kDa and 8.4 kDa chains. Mo-CBP4 sequencing by Edman degradation and mass spectrometry showed the presence of many basic amino acid residues and high similarity with other proteins from M. oleifera seeds. Circular dichroism spectroscopy showed that the Mo-CBP4 contains 36% α-helix, 15% β-sheet, 19% turn and 30% unordered and high structural stability to temperature and pH variations. Mo-CBP4 (0.1, 1.0 and 10 mg/kg) by intravenous administration showed anti-inflammatory activity on the model of carrageenan-induced peritonitis in rats, with inhibition (79%) of neutrophil migration already at the lowest dose. Mo-CBP4 (40 mg/kg), when administered by oral route on mice, using the same mentioned model, also presented anti-inflammatory activity, causing a significant inhibition (48%) of neutrophil migration. Mo-CBP4 retained this activity even after heating at 100 °C or pre-incubation with 0.1 M N-acetyl-D-glucosamine, both for 1 hour. Serum levels of IL-1β and IL-10 after peritonitis induction changed in Mo-CBP4-pretreated mice. In addition, Mo-CBP4 (10 mg/kg), administered intraperitoneally, also showed antinociceptive activity by using the formalin (2.5%) test in mice model, inhibiting just the peripheral pain. In the carrageenan-induced mechanical hypernociception model, animals pretreated with oral Mo-CBP4 (20, 40 and 80 mg/kg), 1 hour prior to inflammatory agent use, proved to be more resistant to sensitization after 1, 3 and 5 hours, with maximal inhibition at a dose of 40 mg/kg, being this activity correlated with the reduction of neutrophil migration. Direct hypernociception caused by epinephrine or PGE2 was not affected with Mo-CBP4 pretreatment. Mo-CBP4 did not impair the locomotor activity of animals in the open field test. In general, no toxic signs or adverse effects were seen after oral administration of Mo-CBP4 at a single dose (2000 mg/kg) or after repeated doses (10, 40 and 100 mg/kg). Similarly, cytotoxicity and genotoxicity tests with Mo-CBP4, using tumour or normal cells, showed no toxicity. The results suggest that due to anti-inflammatory and antinociceptive properties, high stability and apparent lack of toxicity, Mo-CBP4 has great potential as a future biopharmaceutical drug.