Piegang Basile Nganmegne, Tigoufack Ignas Bertrand Nzedong, Ngnokam David, Achounna Angèle Sorel, Watcho Pierre, Greffrath Wolfgang, Treede Rolf-Detlef, Nguelefack Télesphore Benoît
Laboratory of Animal Physiology and Phytopharmacology, Department of Animal Biology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
Laboratory of Applied and Environmental Chemistry, Department of Chemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
BMC Complement Altern Med. 2016 Mar 9;16:97. doi: 10.1186/s12906-016-1075-3.
The leaves of Oxyanthus pallidus Hiern (Rubiaceae) are extensively used in the west region of Cameroon as analgesic. These leaves are rich in cycloartanes, a subclass of triterpenes known to possess analgesic and anti-inflammatory properties. The present study aimed at evaluating the analgesic properties of three cycloartanes isolated from Oxyanthus pallidus leaves as well as their aglycones and acetylated derivatives.
Three cycloartanes OP3, OP5 and OP6 obtained by successive chromatography of the crude methanol extract of the leaves were hydrolysed to yield respective aglycone AOP1, AOP2, AOP3 and acetylated to HOP1, HOP2 and HOP3 respectively. Formalin-induced pain model was used to evaluate the acute anti-nociceptive properties of these cycloartanes (5 mg/kg, p.o) in mice and to determine the structure-activity relationship. Acute (24 h) and chronic (10 days) anti-hyperalgesic and anti-inflammatory activities of OP5 were evaluated at the doses of 2.5 and 5 mg/kg/day administered orally. OP6 was also evaluated in acute experiments. The antioxidant and hepato-protective activities of OP5 were evaluated at the end of the chronic treatment.
The mixture and the individual isolated cycloartanes significantly inhibited both phases of formalin-induced pain with percentage inhibition ranging from 13 to 78%. Acid hydrolysis did not significantly affect their antinociceptive activities while acetylation significantly reduced the effects of these compounds during the second phase of pain. OP5 and OP6 induced acute anti-hyperalgesic activity in formalin-induced mechanical hyperalgesia but not an anti-inflammatory effect. Repeated administration of OP5 for 10 days did not induce any anti-hyperalgesic effect. The evaluation of in vivo antioxidant properties showed that OP5 significantly reduced malondialdehyde and increased superoxide dismutase levels in liver without significantly affecting other oxidative stress and hepatotoxic parameters. Chronic administration of OP5 did not cause gastric ulceration.
Cycloartanes isolated from Oxyanthus pallidus possess analgesic effects but lack anti-inflammatory activities. This analgesic effect especially on inflammatory pain may be due to the presence of hydroxyl group in front of the plane. OP5 is devoid of ulcerogenic effect and possess antioxidant properties that might be of benefit to its analgesic properties.
苍白尖药花（茜草科）叶在喀麦隆西部地区被广泛用作镇痛药。这些叶子富含环阿尔廷烷，这是一类已知具有镇痛和抗炎特性的三萜子类化合物。本研究旨在评估从苍白尖药花叶中分离出的三种环阿尔廷烷及其苷元与乙酰化衍生物的镇痛特性。
通过对叶的粗甲醇提取物进行连续色谱法得到三种环阿尔廷烷OP3、OP5和OP6，将它们水解以分别产生各自的苷元AOP1、AOP2、AOP3，并分别乙酰化为HOP1、HOP2和HOP3。采用福尔马林诱导的疼痛模型评估这些环阿尔廷烷（5mg/kg，口服）对小鼠的急性抗伤害感受特性，并确定构效关系。以2.5和5mg/kg/天的口服剂量评估OP5的急性（24小时）和慢性（10天）抗痛觉过敏和抗炎活性。OP6也在急性实验中进行了评估。在慢性治疗结束时评估OP5的抗氧化和肝脏保护活性。
混合物及各个分离出的环阿尔廷烷均能显著抑制福尔马林诱导疼痛的两个阶段，抑制率在13%至78%之间。酸水解对它们的抗伤害感受活性没有显著影响，而乙酰化在疼痛的第二阶段显著降低了这些化合物的作用。OP5和OP6在福尔马林诱导的机械性痛觉过敏中诱导了急性抗痛觉过敏活性，但没有抗炎作用。连续10天给予OP5未诱导任何抗痛觉过敏作用。体内抗氧化特性评估表明，OP5显著降低了肝脏中的丙二醛含量并提高了超氧化物歧化酶水平，而对其他氧化应激和肝毒性参数没有显著影响。长期给予OP5未引起胃溃疡。
从苍白尖药花中分离出的环阿尔廷烷具有镇痛作用，但缺乏抗炎活性。这种镇痛作用，尤其是对炎性疼痛的作用，可能是由于平面前存在羟基。OP5没有致溃疡作用，并具有可能对其镇痛特性有益的抗氧化特性。
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