The Antagonistic Effects of Khellactones on Platelet-Activating Factor, Histamine, and Leukotriene D4.
作者:Yoko AIDA、Toshio KASAMA、Naoki TAKEUCHI、Seisho TOBINAGA
DOI:10.1248/cpb.43.859
日期:——
Khellactones of Peucedanum praeruptorum DUUN, including praeruptorins A (=Pd-Ia, 2) and B (=Pd-II, 11), had an antagonistic effect specifically on platelet aggregation induced by platelet activating factor (PAF) among various aggregating agents examined, and represent a new class of PAF antagonists. We examined the effects of twenty compounds on PAF-induced platelet aggregation and on histamine- and leukotriene D4 (LTD4)-induced contractions in isolated guinea pig ileum. Compounds 2, (±)-cis-3', 4'-diacetylkhellactone (3), (±)-cis-4'-acetyl-3'-crotonoylkhellactone (5), (±)-cis-4'-acetyl-3'-tetrolylkhellactone (6), (±)-cis-4'-acetyl-3'-tigloylkhellactone (7), (±)-cis-4'-acetyl-3'-(2"-methylbutyryl)khellactone (8), (±)-cis-3', 4'-ditigloylkhellactone (10), and 11 all strongly inhibited PAF-induced platelet aggregation. (±)-cis-4'-Acetyl-3'-(2"-methyl-2"-dodecenoyl)khellactone (9), (±)-cis-4'-ethyl-3'-tigloylkhellactone (13), (±)-cis-4'-ethyl-3'-[N-(2"-triethylammonio)ethylcarbamoyl]khellactone iodide (16), (±)-trans-3', 4'-diacetylkhellactone (18), (±)-trans-4'-acetyl-3'-crotonoylkhellactone (19), (±)-trans-4'-acetyl-3'-valerylkhellactone (20), (±)-trans-4'-acetyl-3'-isovalerylkhellactone (21), and (±)-trans-4'-acetyl-3'-tigloylkhellactone (22) were weakly inhibitory. Most of the compounds exhibited noncompetitive antagonist actions on histamine- and LTD4-induced contractions. The potencies of the antagonistic effects on histamine action were in the order 7=22≥2=8=10>6=11=13≥5>19=9 and those on LTD4 action were in the order 6=22=2>10=8>7=9=11≥13. Thus, compounds with potent PAF-antagonistic activities have the following features : cis isomers of khellactone at the C-3' and C-4' positions are more favorable than trans isomers, and the acyl moiety at the C-3' position of khellactone must be of an appropriate molecular size. In the case of histamine- and LTD4-antagonistic activities, both isomers show similar effects and acyl moieties of appropriate size are required at the C-3' and C-4' positions. These results are of interest in regard to the medicinal uses of Peucedanum species as a herbal drug.
白花前胡所含的khellactones类化合物,包括前胡素A(=Pd-Ia,2)和前胡素B(=Pd-II,11),在各种促聚剂中,对血小板活化因子(PAF)诱导的血小板聚集具有特异性的拮抗作用,代表了一类新的PAF拮抗剂。我们研究了20种化合物对PAF诱导的血小板聚集以及对离体豚鼠回肠中组胺和白三烯D4(LTD4)诱导的收缩的影响。化合物2、(±)-顺式-3',4'-二乙酰基khellactone(3)、(±)-顺式-4'-乙酰基-3'-丁烯酰基khellactone(5)、(±)-顺式-4'-乙酰基-3'-四羟基苯甲酰基khellactone(6)、(±)-顺式-4'-乙酰基-3'-惕各酰基khellactone(7)、(±)-顺式-4'-乙酰基-3'-(2"-甲基丁酰基)khellactone(8)、(±)-顺式-3',4'-二惕各酰基khellactone(10)和11均强烈抑制PAF诱导的血小板聚集。(±)-顺式-4'-乙酰基-3'-(2"-甲基-2"-十二碳烯酰基)khellactone(9)、(±)-顺式-4'-乙基-3'-惕各酰基khellactone(13)、(±)-顺式-4'-乙基-3'-[N-(2"-三乙基铵)乙基氨基甲酰基]khellactone碘化物(16)、(±)-反式-3',4'-二乙酰基khellactone(18)、(±)-反式-4'-乙酰基-3'-丁烯酰基khellactone(19)、(±)-反式-4'-乙酰基-3'-戊酰基khellactone(20)、(±)-反式-4'-乙酰基-3'-异戊酰基khellactone(21)和(±)-反式-4'-乙酰基-3'-惕各酰基khellactone(22)的抑制作用较弱。大多数化合物对组胺和LTD4诱导的收缩表现出非竞争性拮抗作用。对组胺作用的拮抗效能顺序为7=22≥2=8=10>6=11=13≥5>19=9,对LTD4作用的拮抗效能顺序为6=22=2>10=8>7=9=11≥13。因此,具有强PAF拮抗活性的化合物具有以下特点:C-3'和C-4'位置的顺式异构体比反式异构体更有利,khellactone的C-3'位置的酰基部分必须具有适当的分子大小。对于组胺和LTD4的拮抗活性,两种异构体显示出类似的效果,C-3'和C-4'位置需要适当大小的酰基部分。这些结果对于作为草药药用的Peucedanum属植物的医疗用途具有重要意义。