Evaluation and theoretical study on the anti-inflammatory mechanism of 1-nitro-2-phenylethane.

In this study, 1-nitro-2-phenylethane was evaluated with respect to its effects in edema models of acute inflammation induced with carrageenan, dextran, and croton oil. 1-Nitro-2-phenylethane produced inhibition of rat paw edema induced by carrageenan and dextran at the doses of 25 and 50 mg/kg. The same doses caused an inhibition of croton oil-induced ear edema in mice. Our results suggest that 1-nitro-2-phenylethane has anti-inflammatory activity, probably of peripheral origin, acting in the synthesis and/or release of inflammatory mediators. A conformational study of 1-nitro-2-phenylethane was carried out using density functional theory calculations, showing three different groups of conformers corresponding to energy minimum geometries. The stereoelectronic repulsions are responsible for conformational preferences and the one most stable conformer. The prostaglandin endoperoxide synthase mechanism is related more to electrophilic than nucleophilic properties.

The vasorelaxant effects of 1-nitro-2-phenylethane involve stimulation of the soluble guanylate cyclase-cGMP pathway.

1-Nitro-2-phenylethane is the first organic NO2-containing molecule isolated from plants. It possesses interesting hypotensive, bradycardic, and vasodilator properties, but the mode by which it induces vasorelaxation is still unknown. The underlying mechanism involved in the vasodilator effect of 1-nitro-2-phenylethane was investigated in rat aorta. The vasorelaxant effects of 1-nitro-2-phenylethane did not depend on endothelial layer integrity, and the effects were refractory to L-N(G)-nitroarginine methyl ester (L-NAME)-induced nitric oxide synthase inhibition. Vasorelaxation was similarly resistant to treatment with indomethacin, cis-N-(2-phenylcyclopentyl)-azacyclotridec-1-en-2-amine hydrochloride (MDL-12330A), and KT5720, indicating that neither prostaglandin release nor adenylyl cyclase activation is involved. Conversely, methylene blue- and ODQ-induced guanylate cyclase inhibition reduced the vasorelaxation induced by 1-nitro-2-phenylethane. The pharmacological blockade of K(+) channels with tetraethylammonium, glybenclamide, and 4-aminopyridine also blunted vasorelaxation induced by 1-nitro-2-phenylethane. The effects of 1-nitro-2-phenylethane were reversed by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and comparable to the effects induced by sodium nitroprusside. In silico analysis using an Ns H-NOX subunit of guanylate cyclase revealed a pocket on the macromolecule surface where 1-nitro-2-phenylethane preferentially docked. In vitro, 1-nitro-2-phenylethane increased cyclic guanosine 3',5'-monophosphate (cGMP) levels in rat aortic rings, an effect also reversed by ODQ. In conclusion, 1-nitro-2-phenylethane produces vasodilator effects by stimulating the soluble guanylate cyclase-cGMP pathway.

A combined study using ligand-based design, synthesis, and pharmacological evaluation of analogues of the acetaminophen ortho-regioisomer with potent analgesic activity.

A ligand-based drug design study was performed to acetaminophen regioisomers as analgesic candidates employing quantum chemical calculations at the DFT/B3LYP level of theory and the 6-31G* basis set. To do so, many molecular descriptors were used such as highest occupied molecular orbital, ionization potential, H-O bond dissociation energies, and spin densities, which might be related to quench reactivity of the tyrosyl radical to give N-acetyl-p-benzosemiquinone-imine through an initial electron withdrawing or hydrogen atom abstraction. Based on this in silico work, the most promising molecule, orthobenzamol, was synthesized and tested. The results expected from the theoretical prediction were confirmed in vivo using mouse models of nociception such as writhing, paw licking, and hot plate tests. All biological results suggested an antinociceptive activity mediated by opioid receptors. Furthermore, at 90 and 120 min, this new compound had an effect that was comparable to morphine, the standard drug for this test. Finally, the pharmacophore model is discussed according to the electronic properties derived from quantum chemistry calculations.

Anti-inflammatory and antinociceptive activities of Euterpe oleracea Mart., Arecaceae, oil

The oil of the fruits of Euterpe oleracea Mart., Arecaceae (OEO), was evaluated in models of inflammation and hyperalgesia in vivo to study its effects on these conditions. The experimental models contained the writhing test in mice, rat paw edema, granuloma test in rats, vascular permeability in rats, cell migration to the peritoneal cavity in rats and ear erythema induced by croton oil in mice. Doses of 500, 1000 and 1500 mg/kg of OEO were administered orally. The observed number of writhes was inhibited by 33.67, 45.88 and 55.58 percent, respectively. OEO produced a dose-dependent effect, with linear correlation coefficient R=0.99 (y=0.0219x+23.133), and the median effective dose found was 1226.8 mg/kg. The oral administration of 1226.8 mg/kg of OEO inhibited carrageenan-induced edema by 29.18 percent (p<0.05) when compared to the control group. The daily administration of OEO for six days inhibited the formation of granulomatous tissue by 36.66 percent (p<0.01). In ear erythema induced by croton oil, OEO presented a significant inhibition (37.9 percent). In the vascular permeability test, treatment with OEO decreased the response to histamine, inhibiting vascular permeability by 54.16 percent. In carrageenan-induced peritonitis, OEO reduced the number of neutrophils migrating compared to the control group by 80.14 percent. These results suggested that OEO has anti-inflammatory and antinociceptive activities, probably of peripheral origin and linked to prostaglandin biosynthesis inhibition.

Anti-inflammatory activity of aqueous and alkaline extracts from mushrooms (Agaricus blazei Murill).

The effects of aqueous and alkaline extracts from Agaricus blazei Murill, an edible mushroom used as folk medicine in Brazil, Japan, and China to treat several illnesses, were investigated on the basis of the inflammatory process induced by different agents. Oral administration of A. blazei extracts marginally inhibited the edema induced by nystatin. In contrast, when complete Freund's adjuvant was used as the inflammatory stimulus, both extracts were able to inhibit this process significantly (P < .05, analysis of variance followed by Tukey-Kramer multiple comparison post hoc test), although it inhibited the granulomatous tissue induction moderately. These extracts were able to decrease the ulcer wounds induced by stress. Also, administration of extracts inhibited neutrophil migration to the exudates present in the peritoneal cavity after carrageenin injection. Therefore, it is possible that A. blazei extracts can be useful in inflammatory diseases because of activation of the immune system and its cells induced by the presence of polysaccharides such as beta-glucans.

Anti-inflammatory and analgesic activities of Hypericum brasiliense (Willd) standardized extract / Atividades anti-inflamatória e analgésica de extratos padronizados de Hypericum brasiliense (Willd)

As atividades antiinflamatória e antinociceptiva do extrato padronizado de Hypericum brasiliense (HBSE) (Guttiferae) foi avaliada em modelos animais. Ratos Wistar machos foram tratados com extrato de H. brasiliense (50, 250 e 500 mg/kg, v.o.) em solução 3 por cento Tween 80 0,9 por cento NaCl. O tratamento com HBSE (500 mg/kg) mostrou inibição significativa sobre o edema induzido por carragenina comparado ao grupo controle. Nessa dose, o edema foi reduzido em 31,25 por cento na terceira hora (pico do edema) após o tratamento, mas na dose de 50 mg/kg, o edema apresentou redução de 53,13 por cento (p < 0,05). Ainda com a dose de 50 mg/kg, a diminuição do edema induzido por dextrana foi similar ao controle positivo, ciproeptadina. Houve diminuição na formação do tecido granulomatoso (6,6 por cento) comparável ao grupo controle. O HBSE também inibiu o número de contorções abdominais em 46,4 por cento, estatisticamente igual ao controle positivo, tratado com indometacina (42,9 por cento). Na dose de 250 mg/kg, houve inibição do número de contorções em 70,7 por cento quando comparado ao grupo controle (p < 0,001). No teste da placa-quente, foi verificado aumento no tempo de latência com a dose de 50 mg/kg. Os resultados demonstram que o HBSE possui atividade antiinflamatória sobre processos agudos, principalmente quando sua gênese está relacionada à síntese dos derivados do ácido araquidônico, e seu efeito analgésico provavelmente envolve ação sobre o Sistema Nervoso Central.

The anti-inflammatory and antinociceptive activities of the standardized leaves extract (HBSE) of Hypericum brasiliense (Guttiferae) were evaluated in animal models. Male Wistar rats were treated with H. brasiliense extract (50, 250 and 500 mg/kg, p.o.) in 3 percent Tween 80 0.9 percent saline solution. The treatment of the edema induced by carrageenin with HBSE (500 mg/kg) showed significant inhibition when compared to the control group. At this dose, the edema decreased by 31.25 percent in the third hour after treatment (edema peak), but the dose of 50 mg/kg has inhibited the edema by 53.13 percent (p < 0.05). At the dose of 50 mg/kg, the decrease of the edema induced by dextran was similar to that caused by cyproheptadine. The decrease of the formation of granulomatous tissue (6.6 percent) was comparable to the control group. The HBSE inhibited the abdominal constrictions induced by acetic acid. At a dose of 50 mg/kg, the inhibition of the abdominal constrictions (46.4 percent) was comparable to that produced by indomethacin (42.9 percent). A dose of 250 mg/kg inhibited these constrictions by 70.66 percent when compared to control (p < 0.001). In the hot-plate test, an increase in the latency time was observed at a 50 mg/kg dose. These data suggest that HBSE has anti-inflammatory activity on acute process, developed principally by arachdonic acid derivates and analgesic effect due to its probable involvement in the Central Nervous System.

Avaliação toxicológica do óleo essencial de Piper aduncum L. / Toxicological evaluation of the essential oil of Piper aduncum L.

Este trabalho teve como objetivo a avaliação da toxidade aguda e subaguda do óleo essencial de Piper aduncum pela determinação da DL50 em camundongos e a análise dos parâmetros bioquímicos e hematológicos em ratos. A planta é utilizada na medicina popular da região amazônica em diversas doenças e no seu óleo essencial o constituinte majoritário é o fenilpropanóide dilapiol, com propriedades inseticida, fungicida, bactericida, larvicida e moluscicida. A DL50 foi de 2,400 ± 191,7 mg/kg. O óleo essencial não alterou de maneira significativa os parâmetros hematológicos e bioquímicos em relação ao controle no tratamento subagudo, exceto a redução da creatinina. O valor da DL50 e os resultados observados nos parâmetros hematológicos e bioquímicos sugerem que o óleo essencial apresenta toxidade baixa.

The aim of this work was the acute and subacute toxicological evaluation of the essential oil of Piper aduncum with the determination of the LD50 in mice and the analysis of their hematological and biochemical parameters in rats. The plant is used in the Amazon folk medicine for several diseases and the phenylpropanoid dilapiolle is the main constituent of its essential oil, possessing insecticidal, fungicidal, bactericidal, larvicidal and molluscicidal properties. The LD50 was 2.400 ± 191.7 mg/kg. The essential oil did not change the hematological and biochemical parameters in a significant manner when compared with the control in the subacute treatment, excepting the reduction of creatinine. The LD50 and the hematological and biochemical results have suggested that the essential oil presents low toxicity.