Phytochemistry (v.57, #3)

The latest hype on Hyp-O-glycosylation codes by Marcia Jane Kieliszewski (319-323).
Contemporary glycobiology reflects the intense interest in glycoproteins and their biological roles. Addition of saccharides by N- or O-glycosylation is precise rather than random and forms a uniquely interactive molecular surface. We designate these well conserved glycomotifs as glycomodules to emphasize their functional significance. Thus, elucidation of the glycosylation codes that determine saccharide addition is a significant goal. The focus here is on the Hyp O-glycosylation of cell wall proteins. This involves two consecutive posttranslational modifications, proline hydroxylation and glycosylation. Peptide sequence rather than conformation seems to determine these modifications. Hyp glycosylation occurs in two distinct modes: Hyp arabinosylation and Hyp galactosylation. The Hyp contiguity hypothesis predicts arabinosylation of contiguous Hyp residues and galactosylation of clustered non-contiguous Hyp. Elucidation of Hyp glycosylation codes involves the design and expression of putative glycomotifs as simple repetitive peptides. Thus, repetitive (Ser-Hyp) n directed Hyp galactosylation resulting in the exclusive addition of arabinogalactan polysaccharide to all the non-contiguous Hyp residues, and a new AGP. Another repetitive peptide from gum arabic glycoprotein, containing both contiguous and non-contiguous Hyp, directed both modes of Hyp glycosylation. Furthermore, expression of the (Ser-Hyp x ) n series confirmed the arabinosylation of contiguous Hyp. Thus, the Hyp contiguity hypothesis is a useful predictive tool in the functional genomics toolbox.
Keywords: Hydroxyproline-rich glycoprotein; Arabinogalactan-protein; Extensin; Glycosylation; Cell walls;

Phytoecdysteroids: biological aspects by Laurence Dinan (325-339).
Phytoecdysteroids are a family of about 200 plant steroids related in structure to the invertebrate steroid hormone 20-hydroxyecdysone. Typically, they are C27, C28 or C29 compounds possessing a 14α-hydroxy-7-en-6-one chromophore and A/B-cis ring fusion (5β-H). In the present review, the distribution, biosynthesis, biological significance and potential applications of phytoecdysteroids are summarised.The structural diversity, biosynthesis, possible functions and applications of phytoecdysteroids are reviewed.
Keywords: Phytoecdysteroid; Distribution; Biological activity; Biosynthesis; 20-Hydroxyecdysone;

Enzymatic halogenation of flavanones and flavones by Panadda Yaipakdee; Larry W Robertson (341-347).
The whole cells and the chloroperoxidase enzyme of Caldariomyces fumago were capable of halogenating the flavanones, naringenin and hesperetin, at C-6 and C-8 in the presence of either Cl or Br. However, they did not act on other test flavones. The biohalogenated products of naringenin and hesperetin were isolated and found to be identical to those obtained from chemical reactions using molecular halogen and hypohalous acid.The enzymatic halogenation of flavanones and flavones using the whole cells and the chloroperoxidase (CPO) enzyme of Caldariomyces fumago has been investigated. Flavanones, naringenin and hesperetin, were found to be biohalogenated whereas other test flavones were not.
Keywords: Caldariomyces fumago; Chloroperoxidase; Enzymatic halogenation; Flavanones; Flavones;

Purification and characterization of isoforms of β-galactosidases in mung bean seedlings by Sing-Chung Li; Jiahn-Wern Han; Kuan-Chung Chen; Ching-San Chen (349-359).
Five isoforms of β-galactosidase (EC, designated as β-galactosidases I–V, were isolated from five-day-old mung bean (Vigna radiata) seedlings. β-Galactosidases II and III were purified to electrophoretic homogeneity by a procedure involving acid precipitation, ammonium sulfate fractionation, chromatography on diethylaminoethyl-cellulose (DEAE-Cellulose) and con A-Sepharose, and chromatofocusing. β-Galactosidases I, II and III have the same molecular mass of 87 kDa, comprising two non-identical subunits with molecular masses of 38 and 48 kDa, while β-galactosidases IV and V have molecular masses of 45 and 73 kDa, respectively. All the enzymes were active against p-nitrophenyl-β-d-galactoside, and to a lesser extent, p-nitrophenyl-α-l-arabinoside and p-nitrophenyl-β-d-fucoside. The enzymes were inhibited by d-galactono-1,4-lactone, d-galactose, Hg2+, Ag+ and sodium dodecyl sulfate (SDS). β-Galactosidases I, II and III were shown to be competitively inhibited by either d-galactono-1, 4-lactone or d-galactose. Isoforms I, II and III have a common optimal pH of 3.6, while isoforms IV and V have pH optima at 3.8 and 4.0, respectively. Isoelectric points of isoforms I, II and III were 7.7, 7.5 and 7.3, respectively. Double immunodiffusion analysis indicated that β-galactosidases I, II, III and V are immunologically similar to each other, while β-galactosidase IV shares partially identical antigenic determinants with the other four isoforms. The purified β-galactosidases II and III were capable of releasing d-galactose residue from the hemicellulose fraction isolated from mung bean seeds.
Keywords: Vigna radiata; Leguminosae; β-Galactosidase; Enzyme purification; Natural substrates;

Feeding experiments with 13C- and fluorine-labelled precursors were performed to reveal the biosynthesis of 2-aminobenzaldehyde in flowers of Robinia pseudoacacia and Philadelphus coronarius. The results are in agreement with the transformation of anthranilic acid to indole followed by oxidative ring opening and hydrolysis of the resulting N-formyl-2-aminobenzaldehyde. This route differs from that observed in Hebeloma sacchariolens (Basidiomycetes) in which anthranilic acid is directly reduced to 2-aminobenzaldehyde.
Keywords: Robinia pseudoacacia; Fabaceae; Philadelphus coronarius; Saxifragaceae; Biosynthesis; Feeding experiments; Flavour components; 2-Aminobenzaldehyde;

Ginsenoside production in different phenotypes of Panax ginseng transformed roots by Anna Mallol; Rosa M Cusidó; Javier Palazón; Merce Bonfill; Carmen Morales; M.Teresa Piñol (365-371).
Transformed roots were obtained after the inoculation of sterile root discs of Panax ginseng C.A. Meyer with Agrobacterium rhizogenes A4. The established hairy root lines displayed three morphological phenotypes when cultured on hormone-free liquid Schenk and Hildebrandt medium. Most of the cultures showed the characteristic traits of hairy roots (HR-M), while others were either callus-like (C-M) or thin (T-M) without branching. The growth rate of the transformed root lines was always higher than that of untransformed roots, showing that the genetic changes caused by the A. rhizogenes transformation conditioned a higher biomass formation. When considering the different transformed root phenotypes, we can observe that the highest ginsenoside production was achieved by HR-M root lines, closely followed by C-M ones, whereas the lowest yield was reached by T-M root phenotype. The study of the integration of the TL-DNA and TR-DNA fragments of the pRiA4 in the root genome showed that the aux1 gene was always detected in HR-M and C-M root phenotypes which presented the highest biomass and ginsenoside productions. This fact suggests a significant role of aux genes in the morphology of Panax ginseng transformed roots. The ginsenoside pattern of transformed roots varied according to their morphology, although the ginsenoside contents of the Rg group was always higher than that of the Rb group. From our results, we can infer the potential of some root phenotypes of Panax ginseng hairy root cultures for an improved ginsenoside production.Transformed roots of Panax showed several phenotypes and different capacity to produce triterpenic saponines. Root phenotype depends on T-DNA fragments integrated into the plant genome.
Keywords: Panax ginseng C.A. Meyer; Araliaceae; Ginseng; Hairy root cultures; rol Genes; aux Genes; Opines; Ginsenosides;

Studies on the biosynthesis of 2-hydroxy-1,4-benzoxazin-3-one (HBOA) from 3-hydroxyindolin-2-one in Zea mays by Peter Spiteller; Erich Glawischnig; Alfons Gierl; Wolfgang Steglich (373-376).
The ring expansion of 3-hydroxyindolin-2-one to 2-hydroxy-1,4-benzoxazin-3-one (HBOA) was investigated by labelling experiments. Action of the cytochrome P450 enzyme BX4 from maize on 3-hydroxyindolin-2-one under an 18O2 atmosphere induced production of 2-hydroxy-1,4-benzoxazin-3-one in which the ring oxygen — but not the 2-hydroxy group of HBOA — is labelled. A mechanism for this transformation is proposed.
Keywords: Zea mays; Gramineae; Biosynthesis; Ring expansion; Mono-oxygenase; P450; HBOA; BX4;

Biotransformation of squamulosone by Curvularia lunata ATCC 12017 by Dwight O Collins; Greg O Buchanan; William F Reynolds; Paul B Reese (377-383).
Squamulosone (aromadendr-1(10)-en-9-one), isolated in large quantity from the plant Hyptis verticillata Jacq. (Labiatae), was incubated with the fungus Curvularia lunata ATCC 12017 in two different growth media. Six metabolites were isolated from each medium, with five of the products being common to both fermentations. All seven metabolites are novel. The insecticidal activity of these aromadendranes was evaluated against the sweet potato weevil Cylas formicarius elegantulus.
Keywords: Curvularia lunata ATCC 12017; Squamulosone; Biotransformation; Hydroxylation; Hyptis verticillata; Aromadendrane; Cadinane; Sesquiterpene;

The lethal toxicity of major components of the essential oils of Ocimum kilimandscharicum and O. kenyense and of selected blends of these against Sitophilus zeamais and Rhyzopertha dominica were compared with those of the full blends of the essential oils. The compounds were assayed in amounts and proportions present in the minimum 100% lethal dose of the oils. Whereas a major component of O. kilimandscharicum was found to be largely responsible for the toxic action of its essential oil against R. dominica, the results with the other treatments indicated that the toxic action of the essential oils were due to the combined effects of different components, either with or without significant individual toxic action of their own against the insects. The significance of the results and their implication in screening and using plants and their phytochemicals for pest and microbial control are highlighted.Some of the constituents of Ocimum oils that were either inactive or had low intrinsic toxicity against Sitophilus zeamais and Rhyzopertha dominica were potently toxic as blends. The significance of these results with respect to screening and using phytochemicals for pest and microbial control are highlighted.
Keywords: Ocimum kilimandscharicum; O. kenyense; Labiateae; Sitophilus zeamais; Rhyzopertha dominica; Essential oils; Blend effects; Synergism;

Identification and ecdysteroid antagonist activity of three oligostilbenes from the seeds of Carex pendula (Cyperaceae) by Yanhui Meng; Pauline C Bourne; Pensri Whiting; Vladimir Šik; Laurence Dinan (393-400).
Methanolic extracts of seeds of several Carex species were found to antagonise the action of 20-hydroxyecdysone in the Drosophila melanogaster microplate-based BII cell bioassay. Bioassay-guided HPLC analysis of seeds of Carex pendula (drooping sedge) provided one previously unknown tetrastilbene (cis-miyabenol A) and two known oligostilbenes (kobophenol B and cis-miyabenol C) as the biologically active compounds (EC50 values were 31, 37 and 19 μM, respectively, vs. 5×10−8 M 20-hydroxyecdysone). The structures and relative stereochemistries of these compounds were deduced by comprehensive 1D- and 2D-NMR experiments. These compounds are isolated from Carex pendula for the first time. In vitro experiments with dipteran and lepidopteran ecdysteroid receptor proteins demonstrate that the oligostilbenes are able to compete with radiolabelled ecdysteroid ([3H]ponasterone A) for occupancy of the ligand binding site. IC50/K i values are similar to the EC50 values obtained in the BII bioassay.
Keywords: Cyperaceae; Carex; Antagonist; Ecdysteroid; Steroid hormone receptor; Stilbenoid;

Ecdysteroids and bufadienolides from Helleborus torquatus (Ranunculaceae) by Yanhui Meng; Pensri Whiting; Vladimir Šik; Huw H Rees; Laurence Dinan (401-407).
Three bufadienolides, hellebortin A (5-[β-d-glucopyranosyloxy]-10,14,16-trihydroxy-19-nor-{5β,10β,14β,16β}-bufa-3,20,22-trienolide [1]), hellebortin B (5-[β-d-glucopyranosyloxy]-3,4-epoxy-14-hydroxy-19-oxo-bufa-20,22-dienolide [2]) and hellebortin C (5-[β-d-glucopyranosyloxy]-3,4-epoxy-10,14-dihydroxy-19-nor-bufa-20,22-dienolide [3]), together with 20-hydroxyecdysone 3-O-β-d-glucoside (4) and 20-hydroxyecdysone (5) have been isolated by bioassay- and RIA-directed HPLC analyses of a methanol extract of the seeds of Helleborus torquatus. The structure and relative stereochemistry of the novel bufadienolide hellebortin A (1) and the structures of hellebortin B (2) and hellebortin C (3) were determined unambiguously by comprehensive analyses of their 1D and 2D NMR data. These five compounds are isolated from Helleborus torquatus for the first time. The biological activities of compound 1, 4 and 5 as ecdysteroid agonists and antagonists have been assessed.Three bufadienolides (hellebortins A–C), together with the known ecdysteroids 20-hydroxyecdysone and 20-hydroxyecdysone 3-glucoside have been identified from seeds of Helleborus torquatus.
Keywords: Ranunculaceae; Ecdysteroid; Bufadienolides; Helleborus torquatus; Hellebortin A (5-[β-d-glucopyranosyloxy]-10, 14, 16-trihydroxy-19-nor-{5β, 10β, 14β, 16β}-bufa-3, 20, 22-trienolide [1]); Hellebortin B (5-[β-d-glucopyranosyloxy]-3, 4-epoxy-14-hydroxy-19-oxo-bufa-20, 22-dienolide [2]); Hellebortin C (5-[β-d-glucopyranosyloxy]-3, 4-epoxy-10, 14-dihydroxy-19-nor-bufa-20, 22-dienolide [3]); Bioassay;

The changes in the emission of volatiles from mature apple fruits in response to larval feeding by the codling moth (Cydia pomonella) under laboratory conditions are reported. A time course experiment investigated the emission of volatiles throughout the period of larval development following infestation. The volatiles consisted mainly of esters, a few aldehydes, and the terpene α-farnesene. Infested apples emitted the same compounds as healthy apples. The quantities of volatiles released were much higher for infested as compared to healthy fruits for an initial three day period. Following this period there was a decrease in volatile emissions (days 6–9), eventually declining back to the levels emitted from healthy apples or below by 9–21 days after infestation. In a separate experiment, the volatile emissions from healthy and artificially damaged fruits were compared to those from herbivore damaged fruits for each of the five larval instars of C. pomonella. The results from the discriminant analysis indicate that the most effective induction of volatiles occurred when fruits were infested with first instar larvae. Induction by first instar larvae was generally higher than after infestation by later instars, and for most compounds it also exceeded the emission from artificially damaged fruits.
Keywords: Malus domestica; Rosaceae; Apple volatiles; Induced response; Cydia pomonella; Larval instars; Solid phase microextraction; Linear discriminant analysis;

Methyl jasmonate increases reported alkamides and ketoalkene/ynes in Echinacea pallida (Asteraceae) by Shannon E. Binns; Iniyal Inparajah; Bernard R. Baum; John T. Arnason (417-420).
Methyl jasmonate (MJ), a naturally-occurring plant cellular signal molecule, was found to induce production of lipophilic secondary metabolites in Echinacea pallida seedlings. Seedling aerial parts were sprayed with 100 ppm MJ, and roots were harvested and extracted 24 h later. Lipophilic root extracts, separated by HPLC, revealed significant increases (P<0.05) in six alkamides or related ketoalkene/ynes produced by 34 day-old plants and in seven compounds produced by 58 day-old plants.
Keywords: Echinacea pallida; Asteraceae; Secondary metabolite induction; Alkamides; Ketoalkene/ynes; Methyl jasmonate;

Antiplatelet activity of N-methoxycarbonyl aporphines from Rollinia mucosa by Reen-Yen Kuo; Fang-Rong Chang; Chung-Yi Chen; Che-Ming Teng; Hsin-Fu Yen; Yang-Chang Wu (421-425).
Bioassay-directed fractionation of the stems of Rollinia mucosa led to the isolation of new N-methoxycarbonyl aporphine alkaloids, romucosine A (1), romucosine B (2), romucosine C (3), and romucosine D (4), along with the known alkaloid, N-methoxylcarbonyl-nornuciferine (5). Alkaloids 1 and 4 exhibited significant inhibition of collagen, arachidonic acid, and platelet activating factor-induced platelet aggregation, and alkaloid 3 also showed an inhibitory effect on arachidonic acid induced platelet aggregation.Four N-methoxycarbonyl aporphine alkaloids, romucosine A (1), romucosine B (2), romucosine C (3), romucosine D (4), and a known alkaloid, N-methoxylcarbonyl-nornuciferine (5), were isolated from the MeOH extracts of the stems of Rollinia mucosa. Among them, alkaloids 1, 3, and 4 showed significant antiplatelet aggregation activity.
Keywords: Rollinia mucosa; Annonaceae; N-Methoxycarbonyl aporphines; Antiplatelet activity;

Benzyl isothiocyanate is the chief or sole anthelmintic in papaya seed extracts by Rohan Kermanshai; Brian E McCarry; Jack Rosenfeld; Peter S Summers; Elizabeth A Weretilnyk; George J Sorger (427-435).
Papaya (Carica papaya) seeds were extracted in an aqueous buffer or in organic solvents, fractionated by chromatography on silica and aliquots tested for anthelmintic activity by viability assays using Caenorhabditis elegans. For all preparations and fractions tested, anthelmintic activity and benzyl isothiocyanate content correlated positively. Aqueous extracts prepared from heat-treated seeds had no anthelmintic activity or benzyl isothiocyanate content although both appeared when these extracts were incubated with a myrosinase-containing fraction prepared from papaya seeds. A 10 h incubation of crude seed extracts at room temperature led to a decrease in anthelmintic activity and fractionated samples showed a lower benzyl isothiocyanate content relative to non-incubated controls. Benzyl thiocyanate, benzyl cyanide, and benzonitrile were not detected in any preparations and cyanogenic glucosides, which were present, could not account for the anthelmintic activity detected. Thus, our results are best explained if benzyl isothiocyanate is the predominant or sole anthelmintic agent in papaya seed extracts regardless of how seeds are extracted.Benzyl isothiocyanate is the major if not sole bioactive principle in papaya seeds that is effective against nematodes. Benzyl thiocyanate, benzyl cyanide, and benzonitrile were not detected in papaya seed preparations and glucogenic cyanides did not account for the anthelmintic activity detected.
Keywords: Carica papaya; Caricaceae; Anthelmintic; Benzyl isothiocyanate; Caenorhabditis elegans; Myrosinase; Nematode;

Lipophyllic antioxidants from Iryanthera juruensis fruits by Dulce H.S Silva; Francisco C Pereira; Maria V.B Zanoni; Massayoshi Yoshida (437-442).
The phytochemical investigation of the hexane extract of Iryanthera juruensis (Myristicaceae) fruits led to the isolation of two tocotrienols and four lignans which exhibited antioxidant activity towards β-carotene on TLC autographic assay. Two inactive quinones and three ω-arylalkanoic acids were also isolated. The isolates were investigated for their redox properties using cyclic voltammetry. The structure elucidation of the new compounds (one tocotrienol, one quinone and three ω-arylalkanoic acids) was based on analysis of spectroscopic data.
Keywords: Iryanthera juruensis; Myristicaceae; Tocotrienol; Plastoquinone; ω-Arylalkanoic acid; Lignan; Antioxidant;

Volatile constituents in mosses (Musci) by Yücel Saritas; Mesmin Mekem Sonwa; Hassan Iznaguen; Wilfried A. König; Hermann Muhle; Rüdiger Mues (443-457).
The essential oils of mosses of the genera Mnium, Plagiomnium, Homalia, Plagiothecium and Taxiphyllum (Musci) have been investigated by gas chromatography and mass spectrometry. The new sesquiterpenes (+)-10-epi-muurola-4,11-diene and 10,11-dihydro-α-cuparenone were isolated by preparative gas chromatography and identified as major constituents of the hydrodistillation products of Mnium hornum (Hedw.) using NMR and mass spectrometry. In addition, (+)-dauca-8,11-diene and two new butenolides, 3,4,5-trimethyl-5-pentyl-5H-furan-2-one and 3,4-dimethyl-5-pentyl-5H-furan-2-one were identified as constituents in Plagiomnium undulatum (Hedw.) T. Kop. Although the amounts of volatiles present in the investigated mosses are generally smaller than in liverworts, the spectrum of terpenoid compounds is similar. The investigated mosses also generate aliphatic compounds of greater abundance and structural variety.The sesquiterpene hydrocarbons (+)-10-epi-muurola-4,11-diene (16) and (−)-10,11-dihydro-α-cuparenone (8) were isolated and identified as constituents of the hydrodistillation products of Mnium hornum (Hedw). In addition, (+)-dauca-8,11-diene (18) and two butenolides were identified as constituents in Plagiomnium undulatum (Hedw.) T. Kop.
Keywords: Mnium hornum; Plagiomnium undulatum; Musci; Terpenoid compounds; Butenolides; Sesquiterpene hydrocarbons; 10-epi-Muurola-4, 11-diene; Dauca-8, 11-diene; 10, 11-Dihydro-α-cuparenone;

High molecular weight lipids were isolated from Chlorella emersonii, Scenedesmus communis and Tetraedron minimum, thin trilaminar outer wall (TLS)-containing freshwater microalgae producing an insoluble non-hydrolysable biopolymer (i.e. algaenan). Molecular weight determination by gel permeation chromatography indicated that their molecular weights range from ca. 400 to 2000 Da. Flash pyrolysis with in situ methylation using tetramethylammonium hydroxide (TMAH) and alkaline hydrolysis showed that the high molecular weight lipids isolated from C. emersonii and S. communis are mainly composed of saturated n-C26 and n-C28 fatty acids and alcohols and of saturated n-C30 and n-C32 α,ω-diols and ω-hydroxy acids. In contrast the high molecular weight lipids isolated from T. minimum are predominantly composed of long-chain fatty acids and ω-hydroxy acids. Aromatic moieties were also identified in small amounts in the thermochemolysate and in the hydrolysate. Chemical structural models containing long-chain mono- and polyesters were proposed for the high molecular weight lipids isolated from the three microalgae in agreement with analytical and spectroscopic data. Structural similarity between the outer cell wall of these microalgae and the cuticular membrane of higher plants is suggested.High molecular weight lipids were isolated from the titled microalgae. TMAH thermochemolysis and hydrolysis of these lipids showed that they consist of mono- and polyesters with chain lengths greater than C50.
Keywords: Chlorella emersonii; Scenedesmus communis; Tetraedron minimum; Long-chain esters; Polyesters; Tetramethylammonium hydroxide (TMAH) thermochemolysis; Trilaminar outer walls (TLS); Algaenan;

Triterpenoid saponins from the stem bark of Elattostachys apetala by Catherine Lavaud; Marie-Laure Crublet; Isabelle Pouny; Marc Litaudon; Thierry Sévenet (469-478).
Six new triterpenoid saponins have been isolated from the stem bark of Elattostachys apetala together with four known triterpenoid saponins. Three of these new compounds are glycosides of a newly described genin, 29-hydroxyhederagenin (1). On the basis of spectral evidence, the structures of the new saponins were concluded to be α-hederin 28-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl] ester (2), sapindoside B 28-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl] ester (3), 3-O-β-d-xylopyranosyl astrantiasaponin VII (4), 3-O-[α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl]-28-O-[β-d-glucopyranosyl-(1→2)-{β-d-glucopyranosyl-(1→6)}-β-d-glucopyranosyl]-29-hydroxyhederagenin (5), 3-O-[α-l-arabinopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl]-28-O-[β-d-glucopyranosyl(1→2)-{β-d-glucopyranosyl(1→6)}-β-d-glucopyranosyl]-29-hydroxyhederagenin (6), and 3-O-[β-d-xylopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyl]-28-O-[β-d-glucopyranosyl-(1→2)-{β-d-glucopyranosyl-(1→6)}-β-d-glucopyranosyl]-29-hydroxyhederagenin (7).
Keywords: Elattostachys apetala; Sapindaceae; Stem bark; Triterpenoid saponins; 29-Hydroxyhederagenin;

The structure of a prenylbenzene derivative isolated previously from a Cuban specimen of the liverwort Plagiochila rutilans is revised to 2-methoxy-6-prenylhydroquinone. The hydroquinone was observed as a prominent component of the NMR and GC–MS fingerprints of five recent specimens of the liverwort from Bolivia, Brazil and Costa Rica. The corresponding quinone was observed as a minor component. Two new methylated derivatives of the hydroquinone were observed as prominent components in one specimen from Bolivia; these were isolated, characterized, and their structures elucidated as 2-methoxy-1-O-methyl-6-prenylhydroquinone and 2-methoxy-4-O-methyl-6-prenylhydroquinone using 1H NMR spectroscopy. The liverwort has a strong peppermint-like odour that is caused by the presence of several menthane monoterpenoids, including notably pulegone, menthone, isomenthone, terpinolene and limonene. One of the Costa Rican specimens contained considerable amounts of the new lactone 3,7-dimethyl-2,6-octadien-1,6-olide as the principal monoterpenoid in place of pulegone. Two Costa Rican specimens distinguished morphologically as Plagiochila standleyi (a taxon closely related to P. rutilans and reduced elsewhere to a variety of that species) are characterized by large amounts of 3-hydroxy-4′-methoxybibenzyl. P. standleyi was also reported to have a peppermint-like odour in the field. Menthane monoterpenoids were again responsible but in this case the major components were limonene, β-phellandrene, α-terpinene and the endoperoxide ascaridole.
Keywords: Plagiochila rutilans; Plagiochila standleyi; Hepaticae; NMR spectroscopy; Structural revision; Chemosystematics; Menthane monoterpenoids; Prenylbenzenes; 3-Methoxy-5-(3-methylbut-2-enyl)-benzene-1,2-diol; 2-Methoxy-6-(3-methylbut-2-enyl)-benzene-1,4-diol; 7-Isopropylidene-4-methyl-6,7-dihydro-5H-oxepin-2-one;

Application of MS and NMR to the structure elucidation of complex sugar moieties of natural products: exemplified by the steroidal saponin from Yucca filamentosa L. by Annick Plock; Gabriele Beyer; Karl Hiller; Egon Gründemann; Eberhard Krause; Manfred Nimtz; Victor Wray (489-496).
An approach, using well characterized procedures, is presented that should be of general applicability for the structural elucidation of complex sugar moieties of natural products. The methods used are exemplified by the structure elucidation of a new gitogenin-based steroidal saponin that has a strong leishmanicidal activity similar to preparations used in clinical practice and has been isolated by bioactivity-guided fractionation of the ethanolic extract of Yucca filamentosa L. leaves. The saponin has been characterized as 3-O-((ß-d-glucopyranosyl-(1→3)- ß-d-glucopyranosy-(1→2))(α-l-rhamnopyranosyl-(1→4)-ß-d-glucopyranosyl-(1→3))-ß-d-glucopyranosyl-(1→4)-ß-d-galactopyranosyl)-25R,5α-spirostan-2α,3ß-diol.
Keywords: Yucca filamentosa L.; Agavaceae; Steroidal saponin; Gitogenin; Leishmaniasis; Sugar analysis;

Soil Biochemistry Volume 10 by Richard G Burns (497).