Showing papers in "Phytochemistry in 1992"

TL;DR: The potential of one- and two-dimensional NMR techniques for the identification of individual sugar residues, their anomeric configuration, interglycosidic linkages, sequencing and the site of any appended group in establishing the structures of naturally occurring oligosaccharides and glycosides is presented.

TL;DR: This review summarizes the literature on the biological activities of limonoid of known structure, and attempts to relate those activities to current concepts of the evolution of the limonoids.

TL;DR: In this paper, 4-methylcatechol, tyrosol, and hydroxytyrosol were identified and characterized as the main polyphenols from olive oil mill waste waters.

TL;DR: Scenedesmus was better able to tolerate very high CO2 concentrations than Chlorella, and both algae had about the same growth rate when the CO2 concentration was in the range 10–30%.

TL;DR: A new rice phytoalexin, sakuranetin (5,4′-dihydroxy-7-methoxyflavanone) was isolated from ultraviolet-irradiated rice leaves and the content in a resistant cultivar after infection with P. oryzae was much higher than in a susceptible cultivar.

TL;DR: Olea europaea leaves, oleuropein, hydroxytyrosol and tyrosol were compared with vitamin E and BHT, with regard to their antioxidative activities, by kinetic studies in model systems as discussed by the authors.

TL;DR: The present results suggest that high IAA levels may be necessary but are not sufficient for the initial events in plant embryogenesis, whereas low IAA Levels are associated with the later stages of embryo development.

TL;DR: No correlation was found between wound-induced resistance against the flea beetle Phyllotreta cruciferae and the presence, absence or change in any glucosinolate in the cotyledons of these species.

TL;DR: In this paper, a method was devised for the quantitative determination of cinnamic acids participating in ester-ether bridges between cell wall polymers based on the different reactivities of free carboxylic acids and their esters towards borohydride reductants and the different susceptibilities of Cinnamic acid ester and benzyl ether linkages to alkaline treatments.

TL;DR: It was shown that a series of metal-sensitive plant enzymes such as alcohol dehydrogenase, glyceraldehyde-3-phosphate dehydration, nitrate reductase, ribulose-1,5-diphosphate carboxylase and urease tolerate Cd2+ in the form of a phytochelatin complex from 10- to 1000-fold the amount as compared with the free metal ion.

TL;DR: Primary sequence studies on the chloroplastic enzyme from C 4 plants show significant similarities to cytosolic NADP-ME in plants and animals, including a sequence motif which is indicative of the NADP + binding site.

TL;DR: A simple, rapid and nondestructive agar gel assay which detects this second stimulant, but not sorgoleone, reliably distinguishes low (Striga resistant) and high ( Striga susceptible) stimulating parental genotypes and progenies from crosses among them.

TL;DR: In this paper, three new acylated cholestane glycosides were found in the bulbs of Ornithogalum saundersiae and their structures were elucidated, on the basis of the spectroscopic data and chemical evidences, and by comparing them with those of known compounds.

TL;DR: In this article, underivatized pyrrolizidine alkaloids (PAs) from natural sources (plants and insects) were analysed by capillary gas chromatography-mass spectrometry.

TL;DR: Examination of the TLS of Chlorella fusca and Nanochlorum eucaryotum indicated that they exhibit morphological features commonly observed in other green microalgae, and the large contribution of hydrocarbon chains in these macromolecules accounts for the important role of fossil TLS in the formation of numerous oil-source rocks.

TL;DR: Salutaridine, the key intermediate in morphine biosynthesis, is formed from ( R )-reticuline by a regio- and stereoselective para-ortho oxidative coupling catalysed by this microsomal cytochrome P-450 enzyme.

TL;DR: The formation of hydroxyl radicals in Fenton-type reactions involving ferric-EDTA chelate was enhanced by flavonoid, and the role of the iron chelator on the influence of flavonoids on hydroxym radical formation inFenton- type reactions is discussed.

TL;DR: In this paper, the absolute configurations of diastereomeric aglycones were established as (6 R, 9 R ) and (6R, 9 S ), respectively, by CD correlation as well as 1 H NMR analysis of their corresponding ( R )-(−)-α-phenylpropionic acid esters.

TL;DR: In this paper, 27 Al NMR spectroscopy was applied to the analysis of intact tea leaves and model Al complexes such as Al-catechin, Al-F, Alphenolic acid and Al-organic acid.

TL;DR: Evaluation of the pyrrolizidine alkaloids of Senecio jacobaea and S. erucifolius from different geographic locations revealed the existence of different chemotypes, which were established within each species.

TL;DR: The residue from Forsythia suspensa stems has provided the first evidence for a stereoselective coupling enzyme in lignan biosynthesis, and presumably accounts for the low levels of (-)-pinoresinol encountered in this system when coniferyl alcohol is used as a substrate.

TL;DR: In this article, the ponganones III-XI from the root bark of Pongamia pinnata were determined to be (2 S )-3′,4′-dimethoxy-6″,6″-dimethylpyrano[2″,3″:7,8]-flavanone (III), (2S )-6, 3′, 4′, 5′-trimethoxy -6- O -γ,γdimethylallyl-3, 4]-methylenedioxy-6-

TL;DR: A collection of 12 natural and synthetic sesquiterpene lactones with eudesmanolide skeletons have been prepared and tested as allelochemicals in this paper.

TL;DR: The chemical structures of two major anthocyanins in purple sweet potato, Ipomoea batatas cv Yamagawamurasaki, have been identified as 3-caffeylferulysophoroside-5-glucosides of cyanidin and peonidin by FAB-MS and NMR.

TL;DR: A new curcumin analogue has been isolated from the rhizomes of Curcuma xanthorrhiza along with four known Curcuminoids, and its structure has been determined as 1-(4-hydroxy-3,5-dimethoxyphenyl)-7-(4hydrox-3-methoxymethyl)-(1E,6E)-1,6-heptadiene)-3,4-dione by spectral data as mentioned in this paper.

TL;DR: Six anthocyanins were isolated from cell suspension cultures of an Afghan cultivar of Daucus carota by PC or HPLC and unusual 1H NMR chemical shifts and 1H NOE data indicate an intramolecular copigmentation of the aglycone with these aromatic residues.

TL;DR: In this article, novel chromans, hericenones F, G and H were isolated from the mushroom Hericium erinaceum, and these compounds stimulated the synthesis of nerve growth factor (NGF) in vitro.

TL;DR: Seven ferulic acid esters of 1-alkanols ranging in carbon length from C16 to C28 were synthesized and an HPLC protocol for their separation developed and hexadecyl and octadecyl ferulates were predominant.

TL;DR: The metabolism of purine nucleotides and purine alkaloids are reviewed in tea and coffee plants and the activity of the three N -methyltransferases is considered.

TL;DR: Umbelliferone, 13 lignans and an unusual compound 2-(3,4-methylenedioxyphenyl)propane-1,3-diol, were isolated from the leaves of Juniperus chinensis as discussed by the authors.