TRITERPENOIDS .51. THE ISOLATION AND CHARACTERISATION OF GLABRIC ACID, A NEW TRITERPENOID ACID FROM LIQUORICE ROOT
TRITERPENOIDS .51. THE ISOLATION AND CHARACTERISATION OF GLABRIC ACID, A NEW TRITERPENOID ACID FROM LIQUORICE ROOT
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DOI：
10.1039/jr9560002417
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发表时间：
1956-01-01
期刊：
影响因子：
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通讯作者：
SPRING, FS
中科院分区：
文献类型：
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作者：
BEATON, JM;SPRING, FS
我们在立体化学研究中使用的甘草次酸是按照Ruzicka和Leuenberger描述的方法从光果甘草根中分离出来的。2.酸及其乙酸酯的分离是繁琐的，为了便于纯化，对该方法进行了几次修改。在其中之一中，粗大黄酸被乙酰化，产物用重氮甲烷酯化，粗乙酸甲酯在氧化铝上层析。许多级分的许多结晶产生纯的大黄酸甲酯乙酸酯。从这些结晶中得到的可溶性更高的物质再次在氧化铝上进行色谱分离，以非常小的产率得到二乙酸甲酯C35 H52 O，通过碱水解从其得到母体二羟基酸C1 H1 O2，我们称之为光甘草酸。Glabric酸的特征还在于它的二乙酸酯C1，H1，O，和它的甲酯C1，H1，O，的制备。该酸、其甲酯、其二乙酸酯和二乙酸甲酯都显示出α-不饱和酮的特征紫外吸收，并且不与四硝基甲烷一起产生颜色。因此，格拉伯酸含有一个羧基、一个羰基、两个羟基和一个双键;从这一点和它的分子式C1，HyO 5可以得出它是五环的。尽管其含量非常少，无法进行详细的结构研究，但其与大黄酸的密切关系表明其为羟基大黄酸或羟基-18 α-大黄酸。我们赞成后一种关系，理由如下。一方面，大黄酸及其衍生物的紫外吸收光谱，另一方面，18 α-大黄酸衍生物的紫外吸收光谱，显示出在主极大值的位置上的小的差异。在这方面，光甘草酸类似于18 α-甘草次酸：
THE glycyrrhetic acid used by us during a study of its stereochemistry was isolated from liquorice (Glycyrrhiza glabra) root following a method described by Ruzicka and Leuenberger. 2 The isolation of the acid and its acetate was tedious and several modifications of the method were made in an attempt to facilitate the purification. In one of these, crude glycyrrhetic acid was acetylated, the product esterified with diazomethane, and the crude methyl ester acetate chromatographed on alumina. Many crystallisations of a number of fractions yielded pure methyl glycyrrhetate acetate. The more soluble material from these crystallisations was again chromatographed on alumina to give, in very small yield, a methyl ester diacetate, C35H520,, from which the parent dihydroxy-acid, C,, H,, O,, which we name glabric acid, was obtained by alkaline hydrolysis. Glabric acid was further characterised by the preparation of its diacetate, C,, H,, O,, and its methyl ester, C,, H,, O,. The acid, its methyl ester, its diacetate, and the methyl ester diacetate all show the characteristic ultraviolet absorption of an a@-unsaturated ketone, and do not give a colour with tetranitromethane. Glabric acid consequently contains one carboxyl group, one carbonyl group, two hydroxyl groups, and one double bond; it follows from this and its molecular formula, C,, HyO5, that it is pentacyclic. Although the very small amount available has not permitted a detailed structural study, its close association with glycyrrhetic acid suggests that it is either a hydroxyglycyrrhetic acid or a hydroxy-l8a-glycyrrhetic acid. We favour the latter relation for the following reasons. The ultraviolet absorption spectra of glycyrrhetic acid and its derivatives, on the one hand, and 18a-glycyrrhetic acid derivatives on the other, show small differences in the position of the principal maximum. In this respect, glabric acid resembles 18a-glycyrrhetic acid: