Phytochemistry (v.56, #1)
Combinatorial biochemistry in plants by Susanne Frick; Anan Ounaroon; Toni M Kutchan (1-4).
Combinatorial chemistry is common place today in chemical synthesis. Virtually thousands of derivatives of a molecule can be achieved by automated systems. The use of biological systems to exploit combinatorial chemistry (combinatorial biochemistry) now has multiple examples in the polyketide field. The modular functional domain structure of polyketide synthases have been recombined through genetic engineering into unnatural constellations in heterologous hosts in order to produce polyketide structures not yet discovered in nature. We present herein an example for a potential type of combinatorial biochemistry in alkaloidal systems using various combinations of Thalictrum tuberosum (meadow rue) O-methyltransferase subunits that result in heterodimeric enzymes with substrate specificities that differ from those of the homodimeric native enzymes.
Keywords: O-Methyltransferases; Alkaloid biosynthesis; Phenylpropanoid biosynthesis; Combinatorial biochemistry;
The chemical diversity and distribution of glucosinolates and isothiocyanates among plants by Jed W. Fahey; Amy T. Zalcmann; Paul Talalay (5-51).
Glucosinolates (β-thioglucoside-N-hydroxysulfates), the precursors of isothiocyanates, are present in sixteen families of dicotyledonous angiosperms including a large number of edible species. At least 120 different glucosinolates have been identified in these plants, although closely related taxonomic groups typically contain only a small number of such compounds. Glucosinolates and/or their breakdown products have long been known for their fungicidal, bacteriocidal, nematocidal and allelopathic properties and have recently attracted intense research interest because of their cancer chemoprotective attributes. Numerous reviews have addressed the occurrence of glucosinolates in vegetables, primarily the family Brassicaceae (syn. Cruciferae; including Brassica spp and Raphanus spp). The major focus of much previous research has been on the negative aspects of these compounds because of the prevalence of certain “antinutritional” or goitrogenic glucosinolates in the protein-rich defatted meal from widely grown oilseed crops and in some domesticated vegetable crops. There is, however, an opposite and positive side of this picture represented by the therapeutic and prophylactic properties of other “nutritional” or “functional” glucosinolates. This review addresses the complex array of these biologically active and chemically diverse compounds many of which have been identified during the past three decades in other families. In addition to the Brassica vegetables, these glucosinolates have been found in hundreds of species, many of which are edible or could provide substantial quantities of glucosinolates for isolation, for biological evaluation, and potential application as chemoprotective or other dietary or pharmacological agents.
Keywords: Cancer; Chemoprotection; Edible plants; Functional food; Myrosinase; Crucifers;
Purification and characterization of a lectin from the mushroom Mycoleptodonoides aitchisonii by Hirokazu Kawagishi; Jun-ichi Takagi; Tomoko Taira; Takeomi Murata; Taichi Usui (53-58).
A lectin was isolated from the mushroom Mycoleptodonoides aitchisonii by means of affinity chromatography on bovine submaxillary mucin (BSM)-Toyopearl and gel filtration on Superose 12 HR10/30 using a FPLC system. This lectin is composed of four identical 16 kDa subunits and the molecular mass of the intact lectin was estimated to be 64 kDa by gel filtration. In a hemagglutination inhibition assay, it exhibited strong sugar-binding specificity towards asialo-BSM among the mono- or oligo-saccharides and glycoproteins tested. The binding specificity of the lectin was also examined by surface plasmon resonance analysis.
Keywords: Mycoleptodonoides aitchisonii; Climacodontaceae; Mushrooms; Fruiting body; Lectin; Surface plasmon resonance;
Tropane alkaloid production by shoot culture of Duboisia myoporoides R. Br. by Nurussaba Khanam; Cheang Khoo; Robert Close; Abdul G Khan (59-65).
This work demonstrates the presence of hyoscyamine and scopolamine at different stages of shoot regeneration from non-organogenic and organogenic calli. The 11-week-old non-organogenic calli contained 0.41±0.03 and 0.23±0.02 μg g−1 dry wt hyoscyamine and scopolamine respectively. However, no root meristem was found in the calli. The alkaloids were absent in 2-week-old organogenic calli. The shoot-buds induced on the non-organogenic and organogenic calli did not contain these alkaloids. Hyoscyamine and scopolamine contents of the 6-week-old non-rooted shoots regenerated from non-organogenic calli were 7.8±0.1 and 6.5±0.4 μg g−1 dry wt respectively and those in the 9-week-old non-rooted shoot regenerated from organogenic calli were 38.5±0.4 and 3.6±0.1 μg g−1 dry wt respectively. Hyoscyamine and scopolamine contents of the 4-week-old roots regenerated from non-organogenic and organogenic calli were higher than those in the non-rooted shoots. Since the presence of hyoscyamine and scopolamine in the non-rooted shoot depends on the stage of differentiation, manipulation of culture environment may improve hyoscyamine and scopolamine contents of the non-rooted shoots.
Keywords: Duboisia myoporoides; Solanaceae; Shoot culture; Tropane alkaloid; Hyoscyamine; Scopolamine;
Metabolism of gibberellins A1 and A3 in fruits and shoots of Prunus avium by Ma Huanpu; Patrick S. Blake; Gordon Browning; June M. Taylor (67-76).
Isotope-labelled GA metabolites were identified by GC–MS, following HPLC fractionation of extracts derived from fruits or shoots, that had been incubated with [2H]- and [3H]- GA1 or [2H]- and [3H]- GA3. GA1 (1) was converted into GA8 (10) by developing fruits and vegetative shoots of sweet cherry (Prunus avium cv. ‘Stella’), while GA3 (4) was converted into GA3-isolactone (17). Other metabolites of each GA were detected but were not identified unequivocally. These included a metabolite of GA1 (1) in fruitlets that was more polar (by reverse phase HPLC) than GA8 (10) and a metabolite of similar polarity to GA87 (6), was obtained after incubating fruitlets with GA3 (4). However, no evidence was obtained to suggest that GA87 (6) was a metabolite of GA3 (4) or that GA85 (2) was a metabolite of GA1 (1) in these tissues, under the conditions used. The pattern of metabolites obtained from vegetative tissues was similar to that from fruitlets. However, the results suggested that GA1 (1) and GA3 (4) were metabolised at a greater rate in shoots from mature trees than in shoots from seedlings, and that GA1 (1) was metabolised more rapidly than GA3 (4) in juvenile and mature shoots. We conclude from these observations that GA3 (4) is not a precursor of GA87 (6) and GA32 (5), also, that GA1 (1) is not a precursor of GA85 (2) and GA86 (3) in developing fruits or in vegetative shoots of sweet cherry.
Keywords: Prunus avium; Rosaceae; Sweet cherry; Metabolism; Identification; Gibberellins; Developing fruits; Growing shoots; GC–MS;
Profiling changes in metabolism of isoflavonoids and their conjugates in Lupinus albus treated with biotic elicitor by P Bednarek; R Frański; L Kerhoas; J Einhorn; P Wojtaszek; M Stobiecki (77-85).
Liquid chromatography with ultraviolet and mass spectrometric detection was applied to monitor changes in profiles of isoflavonoid glycosides and free isoflavonoid aglycones in Lupinus albus L. Four isoflavonoid aglycones, fourteen isoflavonoid glycosides, four flavonol glycosides and flavone glycoside were identified in lupin tissue after LC/ESI/MS analyses. An elicitor preparation from purified yeast cell wall was used to inject the shoots of 3-week old seedlings or to infiltrate the cut lupin leaves. Qualitative and quantitative changes of isoflavonoids were measured at different time points after elicitation. In elicited lupin seedlings increased amounts of prenylated isoflavone aglycones were identified. The concentrations of glycosidic conjugates of isoflavones present in plant tissue were less affected.
Keywords: Lupinus albus; White lupin; Leguminosae; Flavone, flavonol and isoflavone glycosides; Isoflavone aglycones; Liquid chromatography–mass spectrometry; Desorption ionisation techniques; Electrospray; Elicitor;
A distinctive flavonoid chemistry for the anomalous genus Biebersteinia by Jenny Greenham; Dionyssios D Vassiliades; Jeffrey B Harborne; Christine A Williams; John Eagles; Renée J Grayer; Nigel C Veitch (87-91).
Leaf surface extracts of Biebersteinia orphanidis have yielded a complex mixture of five flavones with the unusual 5,7-dihydroxy-6,8-dimethoxy A ring substitution pattern. They are acerosin, hymenoxin, nevadensin, sudachitin and 5,7,4′-trihydroxy-6,8-dimethoxyflavone. Also present at the leaf surface are gardenin B, luteolin, apigenin, acacetin and the coumarin umbelliferone. The internal leaf flavonoids include the 7-glucosides of apigenin, luteolin and tricetin, together with the 7-rutinosides of apigenin and luteolin. This profile differs from those of B. heterostemon and B. odora. It appears that B. orphanidis is as highly distinctive in its flavonoid pattern as it is phytogeographically. The data also confirm the conclusion of other studies, including rbcL and atpB gene sequence analysis, that Biebersteinia is completely unrelated to the Geraniaceae, where it was once placed.
Keywords: Flavonoids; Biebersteinia; Chemotaxonomy;
Bioactive oleanolic acid saponins and other constituents from the roots of Viguiera decurrens by Silvia Marquina; Nora Maldonado; Marı́a Luisa Garduño-Ramı́rez; Eduardo Aranda; Marı́a Luisa Villarreal; Vı́ctor Navarro; Robert Bye; Guillermo Delgado; Laura Alvarez (93-97).
The bisdesmoside oleanolic acid saponin, 3-O-(methyl-β-d-glucuronopyranosiduronoate)-28-O-β-d-glucopyranosyl-oleanolate, along with nine known compounds (two diterpenic acids, one chromene, three triterpenes, one steroidal glycoside, and two monodesmoside oleanolic acid saponins), were obtained from Viguiera decurrens roots. The chemical structure of the bisdesmoside oleanolic saponin was determined by chemical and NMR spectral evidence. A mixture of monodesmoside saponins displayed cytotoxic activity against P388 and COLON cell lines (ED50=2.3 and 3.6 μg/ml, respectively). Two of the known compounds showed insecticidal activity against the Mexican bean beetle larvae (Epilachna varivestis).
Keywords: Viguiera decurrens; Asteraceae; Root; Oleanolic acid; Bisdesmoside; Saponin; Chikusetsusaponin methyl ester; Cytotoxic and insecticidal activity;
Trianthenol: an antifungal tetraterpenoid from Trianthema portulacastrum (Aizoaceae) by Hafiz Rub Nawaz; Abdul Malik; Muhammad Shaiq Ali (99-102).
An antifungal tetraterpenoid named trianthenol 1 has been isolated from the chloroform extract of Trianthema portulacastrum. Its structure was established as 15-hydroxymethyl-2,6,10,18,22,26,30-heptamethyl-14-methylene-17-hentriacontene on the basis of spectroscopic data including high resolution mass and two-dimensional NMR techniques. A benzaldehyde derivative 2, a pentacyclic triterpenoid 3 and benzoic acid derivatives 4–5 are also reported for the first time from Trianthema portulacastrum.
Keywords: Trianthema portulacastrum; Aizoaceae; Antifungal tetraterpenoid; Benzaldehyde derivative; Pentacyclic triterpenoid; Benzoic acid derivatives;
Cytotoxic labdane diterpenoids from Croton oblongifolius by Sophon Roengsumran; Amorn Petsom; Narupat Kuptiyanuwat; Tirayut Vilaivan; Nattaya Ngamrojnavanich; Chaiyo Chaichantipyuth; Songchan Phuthong (103-107).
Three labdane diterpenoids, 2-acetoxy-3-hydroxy-labda-8(17),12(E)-14-triene, 3-acetoxy-2-hydroxy-labda-8(17),12(E)-14-triene, and 2,3-dihydroxy-labda-8(17),12(E),14-triene were isolated from stem bark of Croton oblongifolius. Their structures were established by spectroscopic data, and each was also tested for cytotoxicity against various human tumor cell lines. The latter compound showed non-specific, moderate, cytotoxicities against all the cell lines; whereas the first two compounds were less active.
Keywords: Croton oblongifolius; Euphorbiaceae; Labdane; Diterpenoid; Cytotoxicity;
Phenylbutanoid dimers from the leaves of Alpinia flabellata by Hiroe Kikuzaki; Shoko Tesaki; Sigetomo Yonemori; Nobuji Nakatani (109-114).
Three phenylbutanoid dimers, cis- and trans-1-(2,4,5-trimethoxy-E-styryl)-2-(2,4,5-trimethoxy-Z-styryl)cyclobutane and 1,2-bis(2,4,5-trimethoxy-Z-styryl)- cyclobutane, were isolated from the leaves of Alpinia flabellata Ridley, together with three known compounds (2,4,5-trimethoxybenzaldehyde, 2,4,5-trimethoxycinnamaldehyde and 3,5-dihydroxy-7,4′-dimethoxyflavone). The structures of these compounds were determined by spectroscopic analysis.
Keywords: Alpinia flabellata; Zingiberaceae; Phenylbutanoid;