Hispanic Watershed

Clayton, Michelle

doi:10.1017/cbo9781139629102.012

Cited by 1 publication

(2 citation statements)

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“…At all stages care was taken to exclude light as far as possible. For the present work a 5 g column of this material was developed sequentially with 50 ml portions of 2, 5,10,15,20,30,40,60,and SOo/,) and 5 to 5.5 ml fractions were collected. Examination of fractions by gas liquid chromatography showed that cycloartenol (4 mg) was eluted in tubes 28-32 and 24-methylene cycloartanol (55 mg) was eluted in tubes 36-56.…”

Section: 'mentioning

confidence: 99%

“…By analogy with the opening of the cyclopropane ring of cycloartenol by acid catalysis [27,28] a compound such as that shown in the scheme might reasonably be expected to be produced by enzymic action upon cycloeucalenol [23], Such a compound could then lose the 14a-methyl group and this would be facilitated by the newly formed A7 or As bond [29]. By contrast the cyclopropane ring of compounds such as cycloeucalenol and cycloartenol may hinder the loss of the l4a-methyl group [30]. Although the route shown in the Scheme may ultimately prove to be the major pathway a consideration of the retention data of the minor 4a-methyl sterols in larch and also in grapefruit [lo] indicates that some of the enzymes involved may be relatively non-specific, for addition of the C-29 methyl group or reduction of the side chain double bond occurs irrespective of the structure of the sterol nucleus.…”

Section: -Methylene Lophenol 24-ethylidene Lophenolmentioning

confidence: 99%

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Studies on Phytosterol Biosynthesis: the Sterols of Larix decidua Leaves

Goad

Goodwin

1967

European Journal of Biochemistry

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The sterols of Larix decidua leaves consist of B-sitosterol, campesterol, cycloartenol, 24-methylene cycloartanol, cycloeucalenol, 24-methylene lophenol, 24-ethylidene lophenol, together with a number of unidentified 4a-methyl sterols. The pattern of incorporation of [2-14C]mevalonic acid into these compounds has been examined.Recent reports have described the isolation from plants of sterols which may be biosynthetic intermediates between squalene and the typical phytosterols [I -71 and the incorporation of [2J4C] mevalonic acid, [I-'%] acetate and [methyl-14C] methiorline into such compounds has been described [6,7]. During studies in our Department on the biosynthesis of the phytosterol side chain [8] a plant tissue was required which contained ,4-sitosterol as the major sterol component. Preliminary examination by gasliquid chromatography showed that a number of conifer species contained predominantly /3-sitosterol together with minor amounts of campesterol. This paper reports the results of an analysis of the sterols of the newly opened leaves of the deciduous conifer larch ( L a r i x decidua). Some observations on the incorporation of [2-l4CC] mevalonic acid into sterols by the leaves of this tree are also included. EXPERIMENTAL PROCEDUREExperimental methods were generally those described previously [7]. Two batches of larch leaves were collected locally in the springtime of successive years when the leaves had been developing for about two to three weeks. Batch 1The non-saponifiable lipid (6.25 g) was extracted from the leaves (650g) by homogenisation in 1.31 of ethanol followed by addition of 200ml of water and 200 g of potassium hydroxide and refluxing for 2l/, h. The leaf debris was removed by filtration through a pad of glass wool and the non-saponifiable lipids obtained by extraction with diethyl ether in the usual manner. The total sterol (213 mg) was obtained by digitonin precipitation [7,9], the digitonides washed with diethyl ether only and then cleaved with pyridine in the usual way. The sterols were first separated by chromatography on 20 g of alumina (Brockmann grade 111) and eluting with 24'200ml portions of light petroleum containing increasing amounts of diethyl ether ["]. Three sterol fractions were obtained, the 4,4'-dimethyl sterols (24 mg), the 4a-methyl sterols (7.3 mg) and the 4-desmethyl sterols (142.6 mg). These were further purged by preparative thin layer chromatography on silica gel plates incorporating Rhodamine 6 G and with chloroform as developer [7]. Separation of the 4,4'-dimethyl and 4a-methyl fractions into their constituent components (see below) was achieved by acetylation followed by chromatography on thin layers of silica gel impregnated with loo/, silver nitrate with 40°/0 benzene in n-hexane as developer. Sterols were located by spraying with an acetone solution of Rhodamine 6 G followed by examination in ultraviolet light [lo].Batch 2 2.5 kg of larch leaves were extracted exhaustively with acetone followed by diethyl ether-light petroleum (1 : l, v/v) to yield 51 *...

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Section: 'mentioning

confidence: 99%

Section: -Methylene Lophenol 24-ethylidene Lophenolmentioning

confidence: 99%