Phytochemistry (v.54, #4)

Index (v).

The microsomal fraction from tulip bulbs (Tulipa fosteriana, L.) contains cytochrome P450 (CYP3, EC 1.14.14.1) and peroxidase (EC 1.11.1.7.) enzymes catalyzing the NADPH — and hydrogen peroxide — dependent oxidation of the xenobiotic substrates, N-nitrosodimethylamine (NDMA), N-nitrosomethylaniline (NMA), aminopyrine and 1-phenylazo 2-hydroxynaphthalene (Sudan I), respectively. Oxidation of these model xenobiotics has also been assessed in a reconstituted electron-transport chain with a partially purified CYP fraction, phospholipid and isolated tulip NADPH:CYP reductase (EC 1.6.2.4.). Peroxidase isolated from tulip bulbs (isoenzyme C) oxidizes these xenobiotics, too. Values of kinetic parameters (K m, V max), requirements for cofactors (NADPH, hydrogen peroxide), the effect of inhibitors and identification of products formed from the xenobiotics by the microsomal fraction, partially purified CYP and peroxidase C were determined. These data were used to estimate the participation of the CYP preparation and peroxidase C in oxidation of two out of the four studied xenobiotics (NMA, Sudan I) in tulip microsomes. Using such detailed study, we found that the CYP-dependent enzyme system is responsible for the oxidation of these xenobiotics in the microsomal fraction of tulip bulbs. The results demonstrate the progress in resolving the role of plant CYP and peroxidase enzymes in oxidation of xenobiotics.
Keywords: Tulipa fosteriana; Cytochrome P450; Peroxidase; Xenobiotics;

Species identification of Radix Astragali (Huangqi) by DNA sequence of its 5S-rRNA spacer domain by X.Q. Ma; J.A. Duan; D.Y. Zhu; T.T.X. Dong; K.W.K. Tsim (363-368).
About 300 species and varieties of Astragalus are identified in China, making the identification of the origin of a particular Astragalus species on the consumer market difficult. A molecular genetic approach was developed to identify various species of Astragalus. Although the 5S-rRNA coding sequence is conserved in higher eukaryotes, the spacer domain of the 5S-rRNA gene has great diversity among different species. The 5S-rRNA spacer domain was amplified by polymerase chain reaction (PCR) from the isolated genomic DNA, and the PCR products (∼300 bp) covering the 5S-rRNA spacer domain were sequenced. The nucleotide sequences of Astragalus membranaceus, A. membranaceus var. mongholicus, A. lehmannianus, A. hoantchy, and of one closely related species Hedysarum polybotrys (Hongqi), were determined. Diversity in DNA sequence and restriction enzyme mapping among various species was found in their 5S-rRNA spacer domains. This is the first report on the detection of 5S-rRNA spacer region sequence of Astragalus, and the results could be used for genetic identification of Huangqi.
Keywords: Astragalus; Fabaceae; DNA sequence; Species identification;

The neutral lipid profiles of nine species of thin trilaminar outer wall (TLS)-containing freshwater and marine microalgae from the class of Chlorophyceae were studied with emphasis on the relationship between the lipid content and the occurrence of insoluble non-hydrolysable biopolymer (i.e. algaenan). All the freshwater microalgae produce a highly aliphatic algaenan. In sharp contrast, no algaenan was isolated from the two marine microalgae, Chlorella marina and Chlorella minutissima marina, supporting the absence of a close relationship between the presence of TLS and the occurrence of algaenan. High molecular weight straight-chain hydrocarbons (C23–C29) were identified in most of the algaenan-producing microalgae and in the algaenan-devoid C. minutissima marina, whereas only low molecular weight hydrocarbons were detected in algaenan-producing Scenedesmus subspicatus and in algaenan-devoid C. marina. Sterols, phytol and fatty alcohols were the major constituents of the polar fraction of the neutral lipids of all the microalgae investigated. High molecular weight saturated or mono-unsaturated alcohols were detected in C. emersonii and in all the microalgae belonging to the genus Scenedesmus. High amounts of saturated C30 and C32 α,ω-diols were also detected in S. subspicatus, S. armatus and S. pannonicus. Three classes of lipids were encountered in very small amounts in the medium polarity fraction of the neutral lipids of the microalgae investigated: (i) Monoesters composed predominantly of saturated C16 or C18 fatty acids and saturated C8, C16 or C18 alcohols and (ii) long-chain methyl ketones from C25 to C31 were detected in several species and (iii) methyl esters of fatty acids ranging from C16 to C28 were identified in all the microalgae. Attempts to use the neutral lipid composition and particularly the unusual long-chain lipids, as specific indicators of the occurrence of algaenan in TLS-containing microalgae were unsuccessful.
Keywords: Chlorella emersonii; Chlorella marina; Chlorella minutissima; Chlorella minutissima marina; Scenedesmus armatus; Scenedesmus communis; Scenedesmus pannonicus; Scenedesmus subspicatus; Tetraedron minimum; Chlorophyceae; Algaenan; Trilaminar outer cell walls; Neutral lipids; Long-chain hydrocarbons; Long-chain alcohols; Long-chain methyl ketones;

Administration of pro-R-methyl-13C-labeled isofucosterol to cultured cells of Oryza sativa revealed that the pro-R and pro-S methyls at C-25 become the pro-R and pro-S methyls at C-25 of sitosterol, respectively. Similar administration experiments using pro-S-methyl-13C-labeled 24-methylenecholesterol established that the pro-R and pro-S methyls at C-25 of 24-methylenecholesterol become the pro-R and pro-S methyls of campesterol, and the pro-S and pro-R methyls of dihydrobrassicasterol, respectively. These results are compatible with our recently proposed ‘syn-SE2′ mechanism’ for double bond isomerization of Δ24(28) into Δ24(25).
Keywords: Oryza sativa; Sterol; Biosynthesis; Gramineace; Isofucosterol; Sitosterol; 24-Ethyldesmosterol; 24-Methyldesmosterol;

Induction of clovamide by jasmonic acid in red clover by Shin-ichi Tebayashi; Atsushi Ishihara; Mitsuya Tsuda; Hajime Iwamura (387-392).
The effect of jasmonic acid (JA) on the secondary metabolism of 5-day-old red clover seedlings was investigated. Induction of the formation of four compounds was found in roots after treatment with 50 μM JA for 48 h, while no induction was observed in the shoots. These compounds, whose formation was induced by JA addition, were isolated and identified as caffeoyl DOPA (clovamide), caffeoyltyrosine, p-coumaroyl DOPA and p-coumaroyltyrosine, by ion-spray MS and 1 H NMR analyses, and by chemical synthesis. Among them, clovamide was the most abundant, while the other amides represented only a minor portion. Clovamide started to increase in amount 24–36 h after treatment and reached a maximum after 96 h (2.81 nmol/mg fr. wt.). The induction of their formation was observed even with 5 μM of JA, and the amount increased with concentrations up to 100 μM. Treatment with 1 mM CuCl2, which elicits accumulation of the phytoalexin maackiain in red clover, caused a decrease in clovamide amount.
Keywords: Trifolium pratense; Leguminosae; Red clover; Hydroxycinnamic acid amide; Clovamide; Jasmonic acid; Induction;

The effect of growth temperature on the long-chain alkenes composition in the marine coccolithophorid Emiliania huxleyi by Vincent Grossi; Danielle Raphel; Claude Aubert; Jean-François Rontani (393-399).
The hydrocarbon fraction of a pure culture of Emiliania huxleyi, composed of a mixture of C31, C33, C37 and C38 polyunsaturated n-alkenes, appeared strongly dependent on the growth temperature of the alga between 8°C and 25°C. The total hydrocarbon content increased linearly with decreasing temperatures. C37 and C38 alkenes (which accounted for more than 90% of the total hydrocarbons) showed distinct changes in distribution compared to C31 and C33 alkenes, suggesting different biological syntheses and/or functions for these two groups of compounds. C37 and C38 alkenes and C37 methyl ketones (alkenones) all showed a trend to lower proportions of the two diunsaturated isomers and to higher proportions of the corresponding trienes with decreasing temperature. Unlike the alkenone unsaturation ratio (U k 37), ratios based on the C37 and C38 alkadi- and trienes could be linearly related to the growth temperature of E. huxleyi only between 15°C and 25°C. The modifications in the distribution of alkenes induced by varying temperature appeared, however, to be twice as fast as the modifications undergone by the alkenones. Although structurally and biochemically related, the distinct evolutions of alkenes and alkenones in response to changes in growth temperature might indicate that these two classes of compounds play two distinct physiological functions. The non-systematic linearity of relationships to temperature of parameters based on alkenes distribution suggested that these compounds are of limited use as paleotemperature indicator in the marine environment in contrast with the alkenones.
Keywords: Emiliania huxleyi; Haptophyceae; Coccolithophorid; Growth temperature; Long-chain alkenes composition; Alkenones;

Occurrence of diacylglyceryltrimethylhomoserines and major phospholipids in some plants by Olga A Rozentsvet; Valery M Dembitsky; Sergey V Saksonov (401-407).
Over 40 higher plant species were examined for the contents of total lipids, phospholipids, diacylglyceryl-N,N,N-trimethylhomoserine (DGTS), phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) by using micro-HPTLC. The results showed a wider range of plants containing betaine lipids. So, DGTS was found in some higher plant species, not studied earlier, belonging to Equisetophyta, Polypodiophyta; the lipid composition of many other species from Spermatophyta was also studied. It was demonstrated that more primitive plant species contained, as a rule, the betaine lipid DGTS. The quantitative data for the distribution of the main phospholipid classes PC, PE, and PG in various plant species and their tissues are given in this paper.
Keywords: Plants; Ferns; DGTS; Lipids; Phospholipids; Occurence;

Anti-inflammatory and immunologically active polysaccharides of Periandra mediterranea by Bettina M.R Pereira; Bernadete P da Silva; Nuno A Pereira; José P Parente (409-413).
Three polysaccharides, glucans with mean M r’s of 1.5 × 105, 3.6 × 104 and 2.1 × 104, were isolated from dried roots of Periandra mediterranea by fractionation on Sephacryl S-300 HR and Sephadex G-25. Chemical and spectroscopic studies indicated that they have a highly branched glucan type structure composed of α-(1→4) linked D-glucopyranose residues with both (3→4) and (4→6) branching points. The polysaccharides enhance phagocytosis in vivo, and exhibit anti-inflammatory activity.
Keywords: Periandra mediterranea; Leguminosae; Roots; Neutral polysaccharides; Glucans; Anti-inflammatory; Immunological activity;

An antimalarial stilbene from Artocarpus integer by Choosak Boonlaksiri; Worrapoj Oonanant; Palangpon Kongsaeree; Prasat Kittakoop; Morakot Tanticharoen; Yodhathai Thebtaranonth (415-417).
Antimalarial activity-guided study of the aerial parts of Artocarpus integer led to the isolation of the prenylated stilbene, trans-4-(3-methyl-E-but-1-enyl)-3,5,2′,4′- tetrahydroxystilbene with an EC50 of 1.7 μg/ml against Plasmodium falciparum in culture. The known stilbenes, trans-4-isopentenyl-3,5,2′,4′-tetrahydroxystilbene and 4-methoxy-2,2-dimethyl-6-(2-(2,4-dihydroxy)phenyl-trans-ethenyl)chromene, were also isolated. Structures of these compounds were deduced on the basis of their spectral data.
Keywords: Artocarpus integer; Moraceae; Jumpada; 3,5,2′,4′-Tetrahydroxystilbene; Antimalarial activity; Plasmodium falciparum;

Betalains from Christmas cactus by Naoko Kobayashi; Jürgen Schmidt; Manfred Nimtz; Victor Wray; Willibald Schliemann (419-426).
The presence of 14 betalain pigments have been detected by their characteristic spectral properties in flower petals of Christmas cactus (Schlumbergera x buckleyi). Along with the known vulgaxanthin I, betalamic acid, betanin and phyllocactin (6′-O-malonylbetanin), the structure of a new phyllocactin-derived betacyanin was elucidated by various spectroscopic techniques and carbohydrate analyses as betanidin 5-O-(2′-O-β-D-apiofuranosyl-6′-O-malonyl)-β-D-glucopyranoside. Among the more complex betacyanins occurring in trace amounts, the presence of a new diacylated betacyanin {betanidin 5-O-[(5″-O-E-feruloyl)-2′-O-β-D-apiofuranosyl-6′-O-malonyl)]-β-D-glucopyranoside} has been ascertained. Furthermore, the accumulation of betalains during flower development and their pattern in different organs of the flower has been examined.
Keywords: Christmas cactus (Schlumbergera x buckleyi); Cactaceae; Flowers; Betalains; Phyllocactin; Betanidin 5-O-(2′-O-β-D-apiofuranosyl-6′-O-malonyl)-β-D-glucopyranoside.;

Six novel tetraterpenoid ethers, lycopanerols B-G, were isolated from lipidic extracts of the green microalga Botryococcus braunii (L race), along with a series of phytyl esters and α- and β-tocopherols. The structures of the compounds were determined by means of spectral analyses including 2D NMR techniques. A biogenetic relationship is proposed between lycopanerols and lycopadiene, the acyclic diunsaturated tetraterpenoid hydrocarbon synthesized by the alga.
Keywords: Botryococcus braunii; Chlorophyceae; Alga; Phytyl esters; Tocopherols; Lycopanerols; Tetraterpenoids; Ether lipids;

A lignan, (8S,8 S,)-(+)-8-hydroxy-oxomatairesinol, has been isolated from the sapwood of Tsuga heterophylla (western hemlock, Pinaceae). The known lignans matairesinol, lariciresinol and secoisolariciresinol were also obtained. The structure of the compound was established by 1D and 2D NMR spectroscopy. Results of the light-irradiation test of the lignans from T. heterophylla are also reported.
Keywords: Tsuga heterophylla; Pinaceae; Western hemlock; Sapwood; Photodiscoloration; Lignan; (+)-8-Hydroxy-oxomatairesinol;

Erratum to “Specificities of the enzymes of N-alkyltropane biosynthesis in Brugmansia and Datura by Henry D. Boswell; Birgit Dräger; W.Russell McLauchlan; Andreas Portsteffen; David J. Robins; Richard J. Robins; Nicholas J. Walton (449).