Lipids of Hevea brasiliensis and Euphorbia coerulescens

The low MW lipids identified in the latices of Hevea brasiliensis and Euphorbia coerulescens were as follows: 2-methylcyclobutanone; 2-methyl-2-hydroxycyclobutanone; 2-methylcyclobutanol; euphol; euphorbol; and tirucallol.     

一品红体细胞胚胎发生与植株再生

一品红不同部位愈伤组织诱导能力存在差异,嫩茎>幼花序>嫩叶。愈伤组织的长势主要受生长素的影响,细胞分裂素对愈伤组织生长有促进作用;但在含6-BA和NAA的培养基中诱导出的愈伤组织,其胚性明显强于单独用NAA诱导出的愈伤组织。液体悬浮培养是一品红体细胞胚胎高频发生的中间步骤。不同浓度BA对一品红体细胞胚的萌发率影响不大,萌发培养基中KNO₃含量加倍可提高萌发率。     

Three serine proteases from the latex of Euphorbia cyparissias

Three serine-centred proteolytic enzymes, euphorbains y-1, ?2 and ?3, were isolated from the latex of Euphorbia cyparissias. These proteases have different specific activities to azocoll and CBZ glycine p-nitrophenyl ester. The pIs and M_rs of y-1, ?2 and ?3 are 5.2 and 67 000, 5.2 and 33 000, and 6.3 and 67 000, respectively. The enzymes, which are glycoproteins, are immunologically distinct from euphorbain 1, but clearly related to that enzyme in amino acid composition.     

Sterols with unusual nuclear unsaturation from three cultured marine dinoflagellates

Several new 4α-methyl sterols with unusual unsaturation in the Δ⁸⁽¹⁴⁾-or Δ¹⁴-positions, 4α,24S-dimethyl-5α-cholest-8 (14)-en-3β-ol, 4α-methyl-24ξ-ethyl-5α-cholest-8(14)-en-3β-ol, 4α-methyl-24(Z)-ethylidene-5α-cholest-8(14)- en-3β-ol, 4α,23 (or 22),24ξ-trimethyl-5α-cholesta-8(14),22-dien-3β-ol, 4α,24S(or 23ξ)-dimethyl-5α-cholest-14-en-3β-ol and 14-dehydrodinosterol, have been isolated from extracts of the cultured marine dinoflagellates Amphidinium carterae, A. corpulentum and Glenodinium sp. 4α-Methyl-24ξ-ethyl-5α-cholestan-3β-ol was isolated from the steryl ester fraction of Glenodinium sp. The structures of these new sterols are based upon extensive 360 MHz ¹H NMR and MS analyses.     

Gas chromatography-mass spectrometry study of sterols from Pinus elliotti tissues

A comparative study of the sterol components of slash pine (Pinus elliottii) callus tissue cultures, seeds, and seedlings was carried out using GC-MS techniques. Cholesterol, desmosterol, campesterol, stigmasterol, sitosterol and cycloeucalenol were identified in all tissues while lophenol and 24-methylenelophenol were identified in only the seed and seedlings. 24-Ethylidenelophenol was detected in trace concentrations in only the seedlings. Sitosterol was the predominant sterol component, i.e. 80·8, 38·1 and 47·8% of the tissue culture, seed and seedling sterols, respectively.     

Quantitative aspects of triacylglycerol metabolism and sterol synthesis from 14C-acetate in etiolated seedlings of Euphorbia lambii

Triacylglycerols occur in both the endosperm and embryo of Euphorbia lambii seeds. Upon germination, the amount of these neutral lipids in the endosperm decreased with 1.06 mg fatty acid day^-1. The embryo contained 1.4 mg fatty acids in the triacylglycerols and this value declined slowly to 0.4 mg seedling^-1 during the 8 day period of endosperm depletion. Radioactive acetate was rapidly taken up by the cotyledons of intact seedlings, translocated throughout the entire seedling, and up to 10.5% of the ¹⁴C proceeded to the sterols and latex triterpenols. Maximum uptake values of 1.4 μmol seedling^-1 day^-1 of acetate were measured. Acetate uptake and subsequent incorporation into sterols and triterpenols decreased substantially in the presence of increasing amounts of sucrose (up to 0.3 M). Traces of acetate did not effect [¹⁴C]-sucrose uptake and corresponding synthesis of [¹⁴C]-sterols and triterpenols, but increased concentrations of acetate (0.05 M and up) reduced both uptake of sucrose and its conversion into unsaponifiable lipids.
The uptake capacity of the cotyledons for [¹⁴C]-glycerol exceeded the daily production in the endosperm, but only a small amount of label proceeded to the sterols and triterpenols. [¹⁴C]-Triacylglycerols were never detected in the seedling, regardless of the labeled substrate used. Although acetate is an efficient precursor in triterpenol and sterol synthesis, the uptake capacity of the cotyledons for this metabolite is too small in relation to the daily production of water soluble substrates in the endosperm. If acetate is released by the endosperm, only a marginal contribution towards triterpenol and sterol synthesis in the seedling is to be anticipated from this substrate.     

Sterols of bryophytes

Sterol compositions of six species of bryophytes were studied. The major sterols identified were campesterol, 22-dihydrobrassicasterol, sitosterol, clionasterol, stigmasterol, cholesterol, 24-methyl-5,22-cholestadienol and 24-methyl-5,7,22-cholestatrienol. The quantitative determinations of the α- and β-epimers of 24-methyl and 24-ethylcholesterols were made based on 220 MHz ¹H NMR spectroscopy and capillary gas chromatography. Sterol compositions of bryophytes from other studies are reviewed, and possible sterol biosynthetic pathways in bryophytes are discussed.     

Sterols and triterpenes of Ilex aquifolium

Sterols of male and female flowers from Ilex aquifolium were found to be mainly 24-ethylcholesterol, with trace amounts of cholesterol, 24-methylcholesterol and 24-ethyl-5,22-cholestadien-3β-ol. Several pentacyclic triterpenes were partially characterized.     

Parallelism in hill activity and anthocyanidin content in Euphorbia pulcherrima

Pigment compositions and Hill activities of red-leafy bracts, red-green leaves and green leaves of E. pulcherrima were studied. Interestingly enough, the chloroplasts from anthocyanidin-containing leaves are intrinsically more active than those from green leaves.     

Sterols of the lichen Pseudevernia furfuracea

A mixture of C₂₇, C₂₈ and C₂₉ sterols was isolated from the lichen Pseudevernia furfuracea and characterized by means of GLC and MS. Mono-, di- and tri-unsaturated sterols were identified as well as a small amount of fully saturated sterols (stanols). Only a part of the total sterols present in the lichen tissue was easily extractable with organic solvents. Another portion was only obtained after saponification of the lichen residue remaining after extraction with organic solvents. The composition of these two fractions difrered considerably, the former contained predominantly 5a,8a-epidioxy-5a-ergosta-6,22-dien-3β-ol (ergosterol peroxide) and 24-ethylcholesta-5,22-dien-3β-ol while in the latter 24-ethylcholesta-5,22-dien- 3β-ol and C₂₈ triene sterols were the main components.     

Terpenoid biosynthesis in Euphorbia latex

The latex of Euphorbia lathyris can utilize acetate, pyruvate and mevalonate for triterpene synthesis in vitro. Acetyl-CoA, hydroxymethylglutarate, hydroxymethylglutaryl-CoA and isopentenyl pyrophosphate were not effective as precursors for triterpene biosynthesis. Acetate is utilized only by the terpenoid pathway and by the tricarboxylic acid cycle; it is not used for fatty acid synthesis in this system. However, phospholipids were found to be efficient acyl donors for triterpene ester synthesis. The observed selectivity of precursor utilization as well as the observed rates for product formation indicate separate sites for triterpenol and triterpene ester synthesis and that one is not precursor for the other.     

Sterols of the fungi: Distribution and biosynthesis

The importance of sterols in the growth and reproduction in fungi is becoming increasingly apparent. This article concerns the composition and biosynthesis of ergosterol in these organisms. Comparison to plant and animal sterol formation are made.