Antinociceptive and anti-inflammatory effects of myricetin 3-O-ß-galactoside isolated from Davilla elliptica: involvement of the nitrergic system.

We aimed to study the antinociceptive effects of myricetin 3-O-ß-galactoside (Mi), a substance isolated from the hydroalcoholic extract of Davilla elliptica. This study examined male Swiss mice, inducible nitric oxide synthase C57B16/J knockout mice (iNOS(-/-)), and their corresponding wild type (WT). Formalin and tail-flick tests were used to evaluate the nociceptive threshold, and the carrageenan-induced paw edema test was used as a model for inflammation. The following drugs were administered to investigate the involvement of the nitrergic and opioidergic systems: L-NAME, a nonspecific nitric oxide synthase (NOS) inhibitor; L-arginine (L-Arg), a precursor for the synthesis of nitric oxide (NO); D-arginine (D-Arg), an inactive isomer for the synthesis of NO; aminoguanidine (Am), an inducible nitric oxide synthase (iNOS) inhibitor; and naloxone, a nonselective antagonist of opioid receptors. The results showed that oral pretreatment with Mi caused a dose-dependent inhibition of the inflammatory phase of the formalin test and did not alter motor performance. Intraperitoneal injection of L-NAME caused a reduction in the licking time during the second phase of the formalin test. The administration of L-Arg (but not D-Arg) reversed the antinociceptive effect of L-NAME. Furthermore, pre-administration of aminoguanidine potentiated the antinociceptive effect. Mi did not cause an antinociceptive effect in iNOS knockouts and led to a reduction in the nitrite concentration in the paws of mice. Carrageenan-induced paw edema was reduced in Swiss mice and WT mice when compared to iNOS(-/-) mice. Pre-administration of naloxone (NLX) did not reverse the antinociceptive effect of Mi, excluding the opioidergic system as a mediator of the antinociceptive effect. Thus, the results suggest that the antinociceptive and anti-inflammatory effects of myricetin 3-O-ß-galactoside are related to peripheral inhibition of nitric oxide synthesis, mainly iNOS.

Bioguided isolation of myricetin-3-O-ß-galactopyranoside with antinociceptive activity from the aerial part of Davilla elliptica St.-Hil.

ETHNOPHARMACOLOGICAL RELEVANCE: Davilla elliptica St.-Hil. (Dilleniaceae) is a medicinal plant traditionally used in Brazil to treat inflammatory processes, to relieve pain, as diuretic, gastro- and hepatoprotective agents. AIM OF THE STUDY: To undertake the fractionation of the ethanolic extract from Davilla elliptica leaves guided by an antinociceptive assay. MATERIALS AND METHODS: The antinociceptive activity was evaluated through the formalin test in mice. Extract fractionation was performed by percolation through silica gel and partition between immiscible solvents, followed by successive column chromatography over Sephadex LH-20 and preparative RP-HPLC. Structure elucidation of the isolated compound was accomplished by spectroscopic data. RESULTS: The EtOAc and MeOH fractions derived from the crude extract reduced significantly the licking time in the late phase of the formalin test. The bioguided fractionation of the MeOH fraction resulted in the isolation of myricetin-3-O-ß-galactopyranoside, which produced significant inhibition on nociception induced by formalin (ID50=0.26 mg/kg; p.o.). CONCLUSIONS: These results point out that myricetin-3-O-ß-galactopyranoside contributes for the antinociceptive effect of Davilla elliptica extract, a constituent considerably more potent than diclofenac, employed as reference drug.

Perfil lipídico de ratos wistar submetidos á alimentação suplementada com ovo / Lipid profile of Wistar rats subjected to food supplemented with egg

O presente estudo teve como objetivo avaliar o perfil lipídico de ratos Wistar suplementado com ovo em pó, visto as discordâncias científicas quanto ao seu efeito maléfico ou benéfico à saúde humana. Foram utilizados 16 ratos machos da linhagem Wistar, divididos em dois grupos: G1 (controle) e G2 (dieta suplementada com dois ovos/dia), sendo que o estudo teve a duração de 60 dias. A quantidade de ração e água foi de acordo com os parâmetros de referência para ratos, respectivamente 10g/100g e 10 a 12 mL/100g de peso-animal/dia. Os ratos foram sacrificados para realização das análises clínicas (trigliacilglicerol, colesterol total e frações), no início e no final do experimento. Os resultados obtidos demonstraram que o nível de colesterol LDL/mg/dL foi superior nos animais com dieta suplementada com ovos em pó. Em contrapartida, os níveis de triglicérides/mg/dL e VLDL/mg/dL e VLDL/mg/dL foram maiores nos animais do grupo controle. Esses resultados permitem concluir que o consumo do ovo não é responsável majoritariamente pelo aumento da concentração dos lipídeos séricos.