Serine in sterol synthesis in Euphorbia lathyris seedlings (original) (raw)
Related papers
Sterols and triterpenols in latex and cultured tissues of Euphorbia pulcherrima
Phytochemistry, 1982
Key Word Index-Euphohia pulchenima; Euphorbiaceae; tissue culture; sterols; triterpenols. Abatrad-The sterol and triterpenol constituents of Euphorbi, pufchewima latex and cultured callus tissues were examined by GLC and mass spectrometry. Latex extracts from different varieties contained sitosterol, B-amyrin, germanicol, cycloartenol, /3-amyrin acetate, and germanicol acetate. Capillary GC proflles of these varieties indicated that the triterpene content was essentially identical for examined latices. Cultured tissues derived from petioles and stem internodes synthesized only sitosterol in significant quantities, although trace amounts of several sterols that occur in latex were also detected in cultured tissues. This study supports the interpretation that the pattern of triterpene synthesis in the laticifer of the normal plant is a highly controlled and stable phenomenon among varieties of this species.
Accumulation of phenolic and sterol compounds in Euphorbia hirta (L.)
herbapolonica.pl
Euphorbia hirta is an annual plant grownig commonly in the tropical and subtropical regions of Asia, Africa as well as Central and South America. Extracts from herb reveal diastolic, anti-inflammatory, diuretic and anthelminthic effects. Biologically active compounds of this plant are sterols, saponins, flavonoids and phenolic acids. The results of this study indicate that obtaining relatively high yield of herb and well germinating seeds which retain their germinability after two years of storage is possible in Poladn. Chemical analysis of the herb and callus obtained in vitro has shown that these raw materials accumulate phenolic compounds and sterols in high quantities.
1989
An en7ymatic assay for d **'"-sterol A'"-reductase, an enzyme involved in sterol biosynlhcsis, has been developed for the first time in higher plants. The properties of the microsomal enzyme have been established with respect to cofactor requirements, kinetics and substrate specificity. This enzymatic double-bound reduction is thought to proceed through an electrophilic addition mechanism, involving a C14 putative carbonium ion highenergy intermediate. Using this in vitro assay, ammonium and iminium analogues of this cationic intermediate wcre shown to be potent inhibitors of the reduction reaction. Thus, compounds of the N-alkyl-8-aza-4a,lOdimethyl-trans-decal-3P-01 series strongly inhibited sterol reductase (I5" = 0.07-4 pM) = 10-'), as did the antimycotic agent 15-azasterol (Iso = 0.03 pM); all of these compounds act as reaction-intermediate analogues of the proposed C14 carbonium ion intermediate. Moreover, the in vitro inhibition of the plant sterol rcductase by a series of ammonium-ion-containing fungicides was demonstrated. The relative specificity of these different series of inhibitors toward cycloeucalenol-obtusifoliol isomerase, 4 ' +d7-sterol isomerase and sterol d '"-reductase, was directly studied. The biosynthetic pathway of cholesterol in rat liver, and of ergosterol in yeast, includes a ~l~, '~-s t e r o l intermediate which has been recently shown to be the immediate metabolite of lanosterol demethylation at C32 by thc cytochrome-P450dependent C14a demcthylase, both in rat livcr [l-31 and yeast [4, 51. The existence of an enzyme capable of reducing the ') double bond of S~-cholesta-8,14-dien-3P-o1 has been demonstrated in rat liver homogenate during cholesterol biosynthesis [6] and has been more recently characterized and partially purified [7]. Subsequently, A'-'4-sterol A' "-reductase activity was shown to exist in yeast microsomes, using ignosterol as substrate [8]. Although a ~l*"~)-sterol has been proposed as a possible intermediate in the biosynthesis of sterols in higher plants [9], the isolation of 5a-stigmasta-8,14,24(28)-trien-3P-ol as the major sterol of Vernonia anthrlnzintica [lo], the natural occurrence of Ax~i4-sterols in the cactus Lophocrreus schoottii [I I] and biosynthetic data [12], suggest strongly that d*~14-sterols are the most probable intermediates in the biosynthesis of higher plant stcrols.
Sterol composition and biosynthesis in sorghum: Importance to developmental regulation
Lipids, 1986
Sterol composition and biosynthesis have been examined in seeds, germinating seeds and blades from fally matured leaves ofSorghum bicolor in various stages of development’from seedlings (seven-day plants) to flowering (66-day) plants. The profile of the dominant free sterols of seeds was similar to that of leaf blades; both contained cholesterol, 24α-methylcholesterol (campesterol), 24β-methylcholesterol (dihydrobrassicasterol), 24α-ethylcholesterol (sitosterol) and 24α-ethylcholesta-5,22-dienol (stigmasterol). Sufficient sterol intermediates were identified in the plant to indicate separate post-cycloartenol pathways to sterolic end products. The total free sterol content of the seed (μg/seed) increased somewhat during the 20 hr germination period. However, as the plant developed (seven to 48 days), there was a logarithmic increase in the leaf blade sterol content (μg/leaf blade) which plateaued at the onset of floral differentiation (ca. day 41). Over the next 18 days (48 to 66 days—period of inflorescense development), the sterol content rapidly decreased. In the early stages of plant development, the leaf blade pentacyclic triterpenoid (PT) content was negligible. With the onset of floral differentiation, PT content increased logarithmically, reaching a plateau level that surpassed the sterol content as flowering progressed. These results imply that a critical mass of sterol is associated with sorghum for floral induction. Sterol loss from the leaves of the flowering plants presumably was compensated for by the diversion of 2,3-oxidosqualene (SO) from sterol synthesis to PT production. Additional feeding and trapping experiments with [2-14C]mevalonic acid, [2-3H]cycloartenol, [24-3H]lanosterol [4-14C]sitosterol and [4-14C]cholesterol fed to germinating seeds and leaves from flowering plants demonstrated that sorghum possessed a cycloartenolbased pathway; germinating seeds synthesized 24-alkylsterols but not cholesterol, although cholesterol was identified in both dry and germinating seeds by gas chromatography-mass spectroscopy (GC-MS); and mature leaves synthesized cholesterol and 24α-alkylsterols but not 24β-methylcholesterol.
Sterol metabolism in wheat treated by N -substituted morpholines
Pesticide Science, 1988
Wheat caryopses were treated with racemic fenpropimorph. As shown previously in other plant species, 9~,19-cyclopropyl sterols were found to accumulate markedly. A distinctive feature was a remarkable accumulation of 3l-norcyclobranol, a very rare sterol in nature. A8-sterols were also identified. The ratio A8-sterols: cyclopropyl sterols was shown to depend greatly on the configuration of the methyl substituent in position 2 of fenpropimorph. Whereas cyclopropyl sterols predominated in the case of seedlings treated with the (2S)-2-methyl enantiomer, A8-sterols were shown to be very abundant in plants treated with the (2R)-2-methyl enantiomer. A'sterols were shown also to be more abundant in leaves than in roots. Experiments were conducted to find out whether the phytotoxic response of plants to fenpropimorph could be ascribed to its action on sterol biosynthesis. From the results obtained it appears that this is not the case and thus the phytotoxic effect is probably related to a cellular target other than sterol b iosynt hesis .
Effect of AY-9944 on sterol biosynthesis in suspension cultures of bramble cells
Phytochemistry, 1979
Bramble suspension cultures normally contain A5 sterols (sitosterol, campcsterol, and isofucosterol). When the cells were grown in a medium supplemented with AY-9944, their content of As sterols was greatly decreased and A* sterols accumulated. Six Aa sterols, including three new compounds, (24R)-24-ethyl-5a-cholest-8en-3a-ol, stigmasta-8,Z-24(28)dien-3B-o1, and C-methyl-stigmasta-8,Z-24(28~dien-3/?-ol, were identified. AY-9944 probably inhibited the As-A7 isomerase. A stable cell line growing permanently in an AY-supplemented medium was obtained. INTRODUCITON Strain growing on AY-9944