Estudo de solubilidade e das atividades antioxidante e anti-Helicobacter pylori da isocumarina paepalantina obtida de Paepalanthus latipes Silv.
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Date
2016-03-24
Authors
Damasceno, João Paulo Loureiro
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Publisher
Universidade Federal do Espírito Santo
Abstract
Helicobacter pylori is a Gram-negative bacteria that infects the gastric mucosa, causing disorders like gastritis, peptic ulcers and stomach cancer, and which eradication is difficult. The standard treatment is not always successful because of its side effects, high costs and poor patient compliance, leading to the search for new drugs. In this context, the isocoumarin paepalantine, 9,10-dihydroxy-5,7-dimethoxy1H-naphtho (2,3c) pyran-1-one, isolated from the capitula of Paepalanthus bromelioides, has demonstrated a broad range of biological activities such as antibacterial, antioxidant, anti-inflammatory and cytotoxic. Among these, the antimicrobial and antioxidant activities stand out and allow the evaluation of the effects of H. pylori infection and the modulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) involved in this process. The molecule is poorly studied and there are few data in the literature on its solubility, including a viable alternative to the use of DMSO as a solvent, considering its toxicity in cell culture and interference in the antioxidant activity tests. Thus, the goal of this study was to evaluate alternative solvents to DMSO and validate an analytical spectrophotometric method using a suitable solvent for the antioxidant assays of radical scavenging activity (DPPH and ABTS), ROS (HOCl, OH● , O2 -● , H2O2), RNS (NO● ), and anti-H. pylori activity. Among the evaluated solvents, propylene glycol at pH 7.5 was the solvent of choice. The results suggest less interference in the assays compared to DMSO and that it is a viable alternative from a technological point of view. The results show a strong antioxidant activity of paepalantine in comparison to Trolox®. In addition, it was observed a significant effect on H. pylori culture with MIC of 128 μg/ml, MBC of 256 μg/ml, and a synergism of its sub-MIC doses with amoxicillin and metronidazole. This demonstrates a possible action on the permeability of bacterial membrane by inhibition of Penicillin-Bindind Proteins (PBPs), as observed through morphological changes using scanning electron microscopy. Therefore, paepalantine is promising for the development of drugs to combat H. pylori and its associated disorders.
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Keywords
Solubility , Antioxidant , Paepalantine , Paepalantina , Estresse oxidativo , Solubilidade