INTRODUÇÃOAo longo dos últimos anos, a ocorrência de infecções fúngicas humanas vem apresentando um aumento expressivo, sendo as dermatomicoses as principais infecções responsáveis por esse aumento. Vários fatores estão relacionados ao crescimento dessas infecções fúngicas, entre eles: o melhor diagnóstico laboratorial e clínico, o aumento da sobrevida de pacientes com doenças imunossupressoras e o emprego de medicamentos imunossupressores, utilizados às vezes de forma abusiva, permitindo a instalação de microorganismos convencionalmente saprófitos (Sidrim et al., 1999).Os fungos responsáveis por essas infecções são fungos patógenos (Epidermophyton, Microsporum, Trichophyton, Paracoccidioides, Histoplasma) ou fungos patógenos oportunistas (Candida albicans, Cryptococcus neoformans). O tratamento das micoses humanas não é sempre efetivo, pois os fármacos antifúngicos disponíveis produzem recorrência ou causam resistência, além de apresentarem importante toxicidade. Por esta razão, há uma busca contínua de novos fármacos antifúngicos mais potentes, mas, sobretudo, mais seguros que os existentes. Além das infecções em humanos, os animais também podem ser atacados esporadicamente por fungos muito difíceis de serem combatidos. Além disso, as infecções fúngicas em plantas (espécies de Rhizoctonia, Phytophtora, Sclerotinia, Fusarium, Phomopsis, Colletotrichum, Diaphorte, Macrophomina, Cercospora) representam perdas incalculáveis para a produção agrícola (Zacchino, 2001).Neste contexto, embora a maioria dos antifúngicos existentes no mercado seja de origem sintética, o estudo de produtos naturais voltou a receber a atenção dos cientistas (Yunes, Filho, 2001). Entre as principais ferramentas
The aim of the present study was to assess the analgesic activity of the aerial parts of two Hypericum species native to Southern Brazil, H. caprifoliatum and H. polyanthemum. The antinociceptive effect of the H. polyanthemum cyclohexane extract (POL; 180 mg/kg) and of the H. caprifoliatum methanol (MET) and cyclohexane (CH) extracts (90 mg/kg) was evaluated in the hot-plate (ip and po) and writhing (po) tests using male Swiss CF1 mice weighing 22-27 g (N = 10 per group). All extracts displayed antinociceptive effects in the hot-plate test (MET ip = 48%, MET po = 39%, CH ip = 27%, CH po = 50%, POL ip = 74%, and POL po = 49% compared to control). Pretreatment with naloxone (2.5 mg/kg, sc) abolished the effects of CH and POL, and partially prevented the analgesia induced by MET administered by the ip (but not by the po) route. POL and CH (po) significantly reduced the number of writhes induced by acetic acid, while MET was ineffective in this regard. We conclude that the antinociceptive effects of the H. caprifoliatum (CH) and H. polyanthemum (POL) hexane extracts seem to be mediated by the opioid system. Moreover, the antinociceptive activity of the H. caprifoliatum MET extract seems to depend on at least two chemical substances (or groups of substances) with distinct pharmacokinetic profiles and mechanisms of action. Only the naloxone-insensitive component of MET activity showed good bioavailability following oral administration. Correspondence
Dopamine constitutes about 80% of the content of central catecholamines and has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinsons disease, depression and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to report the structural design of two N-phenylpiperazine derivatives, compound 4: 1-[1-(4-chlorophenyl)-1H-4-pyrazolylmethyl]-4-phenylhexahydropyrazine and compound 5: 1-[1-(4-chlorophenyl)-1H-1,2,3-triazol-4-ylmethyl]-4-phenylhexahydropyrazine, planned to be dopamine ligands, and their dopaminergic action profile. The two compounds were assayed (dose range of 15-40 mg/ kg) in three experimental models: 1) blockade of amphetamine (30 mg/kg, ip)-induced stereotypy in rats; 2) the catalepsy test in mice, and 3) apomorphine (1 mg/kg, ip)-induced hypothermia in mice. Both derivatives induced cataleptic behavior (40 mg/kg, ip) and a hypothermic response (30 mg/kg, ip) which was not prevented by haloperidol (0.5 mg/kg, ip). Compound 5 (30 mg/kg, ip) also presented a synergistic hypothermic effect with apomorphine (1 mg/kg, ip). Only compound 4 (30 mg/kg, ip) significantly blocked the amphetamine-induced stereotypy in rats. The N-phenylpiperazine derivatives 4 and 5 seem to have a peculiar profile of action on dopaminergic functions. On the basis of the results of catalepsy and amphetamine-induced stereotypy, the compounds demonstrated an inhibitory effect on dopaminergic behaviors. However, their hypothermic effect is compatible with the stimulation of dopaminergic function which seems not to be mediated by D 2 /D 3 receptors.
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