Gracioso J S, Paulo M Q, Hiruma Lima C A, Souza Brito A R
Departamento de Farmacologia, F. de Ciências, Médicas, Universidade de Estudial de Campinas, SP, Brazil.
J Pharm Pharmacol. 1998 Dec;50(12):1425-9. doi: 10.1111/j.2042-7158.1998.tb03370.x.
An infusion of the aerial parts of Neurolaena lobata (L.) R. Br. (Compositae-Asteraceae) is used in Caribbean folk medicine to treat several kinds of pain. In this investigation we studied the acute oral toxicity of the hydroalcoholic extract of the plant and the antinociceptive effect of the extract and of its hexane- and chloroform-partitioned fractions, given orally, in nociception and inflammatory models in mice. No signs of toxicity were observed for oral doses up to 5000 mg kg(-1) in mice. Morphine hydrochloride (100 mg kg(-1)), dipyrone sodium (200 mg kg(-1)), the hydroalcoholic extract (1000 mg kg(-1)), and its chloroform- and hexane-partitioned fractions (100 mg kg(-1)) significantly inhibited acetic acid-induced abdominal constriction in mice (100, 95, 47, 62 and 60% inhibition, respectively when compared with the negative control). In the hot-plate test in mice, morphine hydrochloride, the chloroform- and hexane-partitioned fractions, but not the hydroalcoholic extract, resulted in a significant latency increase in all observation times. In the acetic acid-induced abdominal constriction in mice, pretreatment of the animals with naloxone significantly reversed the analgesic effect of morphine, but not that of the hydroalcoholic extract or of its hexane- and chloroform-partitioned fractions. Finally, administration of the hexane- and chloroform-partitioned fractions (100 mg kg(-1)) had a significant anti-oedematogenic effect on carrageenan-induced oedema in mice. These data show that the hydroalcoholic extract of N. lobata and, in particular, its partitioned fractions have significant analgesic properties when assessed through these pain models. Their antinociceptive effect might be the result of interference with the inflammatory process.
羽叶紫背草（Neurolaena lobata (L.) R. Br.，菊科-菊苣族）地上部分的浸剂在加勒比民间医学中用于治疗多种疼痛。在本研究中，我们研究了该植物水醇提取物的急性经口毒性，以及该提取物及其己烷和氯仿分离组分经口给药后在小鼠痛觉感受和炎症模型中的镇痛作用。在小鼠中，口服剂量高达5000 mg kg⁻¹时未观察到毒性迹象。盐酸吗啡（100 mg kg⁻¹）、安乃近钠（200 mg kg⁻¹）、水醇提取物（1000 mg kg⁻¹）及其氯仿和己烷分离组分（100 mg kg⁻¹）均能显著抑制小鼠醋酸诱导的腹部收缩（与阴性对照相比，抑制率分别为100%、95%、47%、62%和60%）。在小鼠热板试验中，盐酸吗啡、氯仿和己烷分离组分在所有观察时间均导致显著的潜伏期延长，而水醇提取物则无此作用。在小鼠醋酸诱导的腹部收缩试验中，用纳洛酮预处理动物可显著逆转吗啡的镇痛作用，但不能逆转水醇提取物及其己烷和氯仿分离组分的镇痛作用。最后，己烷和氯仿分离组分（100 mg kg⁻¹）对小鼠角叉菜胶诱导的水肿具有显著的抗水肿作用。这些数据表明，通过这些疼痛模型评估，羽叶紫背草水醇提取物，尤其是其分离组分具有显著的镇痛特性。它们的镇痛作用可能是干扰炎症过程的结果。
