Department of Pharmacology, Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia,
Adv Exp Med Biol. 2015;838:19-25. doi: 10.1007/5584_2014_79.
Arabinogalactan is a polysaccharide isolated from the roots of the medicinal plant Withania somnifera L. It contains 65% arabinose and 18% galactose. The aim of the present study was to evaluate the antitussive activity of arabinogalactan in conscious, healthy adult guinea pigs and the role of the opioid pathway in the antitussive action. A polysaccharide extract was given orally in a dose of 50 mg/kg. Cough was induced by an aerosol of citric acid in a concentration 0.3 mol/L, generated by a jet nebulizer into a plethysmographic chamber. The intensity of cough response was defined as the number of cough efforts counted during a 3-min exposure to the aerosol. The major finding was that arabinogalactan clearly suppressed the cough reflex; the suppression was comparable with that of codeine that was taken as a reference drug. The involvement of the opioid system was tested with the use of a blood-brain barrier penetrable, naloxone hydrochloride, and non-penetrable, naloxone methiodide, to distinguish between the central and peripheral mu-opioid receptor pathways. Both opioid antagonists acted to reverse the arabinogalactan-induced cough suppression; the reversion was total over time with the latter antagonist. We failed to confirm the presence of a bronchodilating effect of the polysaccharide, which could be involved in its antitussive action. We conclude that the polysaccharide arabinogalactan from Withania somnifera has a distinct antitussive activity consisting of cough suppression and that this action involves the mu-opioid receptor pathways.
阿拉伯半乳聚糖是从药用植物茄科植物睡茄的根部分离得到的一种多糖。它含有 65%的阿拉伯糖和 18%的半乳糖。本研究的目的是评估阿拉伯半乳聚糖在清醒、健康成年豚鼠中的镇咳活性，以及阿片途径在镇咳作用中的作用。多糖提取物以 50mg/kg 的剂量口服给予。用喷射式雾化器将柠檬酸以 0.3mol/L 的浓度雾化成气雾剂，在体积描记室中产生气溶胶，从而诱发咳嗽。咳嗽反应的强度定义为在暴露于气雾剂的 3 分钟内计数的咳嗽次数。主要发现是阿拉伯半乳聚糖明显抑制咳嗽反射；其抑制作用与可待因相当，后者被用作参考药物。使用可穿透血脑屏障的盐酸纳洛酮和不可穿透的甲碘化物纳洛酮来测试阿片系统的参与，以区分中枢和外周μ-阿片受体途径。两种阿片拮抗剂都能逆转阿拉伯半乳聚糖引起的咳嗽抑制；随着时间的推移，后者拮抗剂的逆转是完全的。我们未能证实多糖具有支气管扩张作用，这可能与其镇咳作用有关。我们得出结论，来自茄科植物睡茄的多糖阿拉伯半乳聚糖具有明显的镇咳活性，包括咳嗽抑制，并且这种作用涉及μ-阿片受体途径。
