Stereochemistry of 2-aminopimelic acid and related amino acids in three species of asplenium

We previously reported two free D-amino acids, D-2-aminopimelic acid (D-APA) and trans-3,4-dehydro-D-2-aminopimelic acid (D-Δ-APA), from Asplenium unilaterale. In the present work we isolated 4-hydroxy-2-aminopimelic acid (OH-APA) from the same plant and determined it to be the α-L-form. We also investigated the configurations of these amino acids isolated from A. prolongatum and A. wilfordii which are morphologically distinct from A. unilaterale. In A. prolongatum, APA was the D- and OH-APA was the L-isomer. In contrast, APA from A. wilfordii was partially racemized and the degree of racemization was significantly different in plant material collected in July and November, L:D = 3:2 and 3:7, respectively. In A. wilfordii OH-APA was almost pure L- and Δ-APA was mostly the D-isomer.     

l-3-(3′-Carboxy-4′-hydroxyphenyl)alanine (3-carboxytyrosine) in seeds of Neonotonia wightii (Glycine wightii) and its possible systematic significance

l-3-(3′-Carboxy-4′-hydroxyphenyl)alanine (3-carboxytyrosine) constitutes 3% of the seeds of Neonotonia wightii (Glycine wightii); it has also been detected in the seeds of 3 species belonging to 2 other genera of the Glycineae. The systematic significance of these findings is discussed.     

A reappraisal of the free amino acids in seeds of Crotalaria Juncea (Leguminosae)

The seeds of Crotalaria juncea have been reported at different times to contain β-hydroxy-N-methyl-dl-norvaline and δ-hydroxynorleucine, which are isomers. We detected only one non-protein amino acid in seeds obtained from various sources; it has been isolated its identity as δ-hydroxynorleucine confirmed.     

Free amino acids in Crotalaria seeds

The free amino acids of seeds of 163 species of Crotalaria have been identified. Their pattern of distribution is compared with recent classifications of the genus and the possible ecological significance of their presence is discussed. Attention is drawn to the occurrence of toxic amino acids.     

‘Uncommon’ amino acids in the seeds of 64 species of Caesalpinieae

Characteristic associations of free amino acids occur in the seeds of various groups of species within the Caesalpinieae. Guilandina species are distinctive in accumulating 4-ethylideneglutamic acid in their seeds, Gymnocladus and Gleditzia species in accumulating isomers of 3-hydroxy-4-methylglutamic acid, Bussea species in accumulating azetidine-2-carboxylic acid, Peltophorum species in accumulating a previously undescribed imino acid tentatively identified as a derivative of 4-hydroxypipecolic acid.     

Free amino acids and γ-glutamyl peptides in fagaceae

Amino acids have been investigated in seeds and fresh parts of members of the Fagaceae. Seeds from the genus Fagus contain willardiine, 5-hydroxy-6-methylpipecolic acids, N-[N-(3-amino-3-carboxypropyl)-3-amino-3-carboxypropyl]azetidine-2-carboxylic acid and γ-glutamyl peptides, mainly γ-glutamylphenylalanine. These compounds are nearly or totally absent from leaves of F. silvatica and from seedlings and immature seeds of F. silvatica var. purpurea; instead, the seedlings contain large amounts of γ-l-glutamyl-l-isoleucine and γ-l-glutamyl-l-leucine. γ-l-Glutamyl-l-tryptophan and γ-l-glutamyl-γ-l-glutamyl-l-phenylalanine, not previously known from nature, have been isolated from seeds of F. silvatica var. purpurea. The structures have been confirmed by syntheses. 4-Hydroxypipecolic acid (with trans-configuration) has been identified in seeds of F. japonica Maxim. and F. sieboldii Endl. None of the above compounds was found in Quercus or Castanea species whereas argininosuccinic acid was identified in Castanea sativa.     

Free amino acids in the seeds of Acacia species

Free amino acids in the seeds of 80 species of Acacia have been determined. In addition to confirming the known difference in seed amino acid ‘patterns’ shown by species of the series Gummiferae on the one hand and species of the series Phyllodineae and Botryocephalae on the other, we have found that species of the series Vulgares Benth. show two additional ‘patterns’. One of these is common to some of the Afro-Asian species of the series which have been analysed and the other is common to species from America and Africa. One of the ‘marker’ amino acids of the Afro-Asian group is the neurotoxic lathyrogen α-amino-β-oxalylaminopropionic acid. The possible taxonomic and phylogenetic significance of these results is discussed, with special reference to five species A. albida, A. confusa, A. heterophylla, A. coulteri and A. kauaiensis.     

Free protein amino acids of some Mediterranean Siphonales

Fifteen free protein amino acids have been quantitatively determined in nine green algae belongin to the order Siphonales. In all the species examined, aspartic acid, glutamic acid, alanine, glycine and serine dominate. Wide differences of the relative amounts of these amino acids in the various regardless of the genus were observed.     

Non-protein amino acids of Acacia species and their effect on the feeding of the acridids Anacridium melanorhodon and Locusta migratoria

The leaves of Acacia species have been found to contain homoarginine, pipecolic acid and 4-hydroxy-pipecolic acid. The nymphs of the tree locust Anacridium melanorhodon, which feed on the leaves of Acacia species, were not inhibited from feeding on palatable media containing concentrations of these amino acids equivalent to, or greater than, those found in the leaves. The graminivorous Locusta migratoria was more sensitive to these compounds, inhibitory effects being observed at concentrations comparable to those found in the leaves. The inhibitory effects of mixtures of homoarginine and pipecolic acid were additive in A. melanorhodon but not in L. migratoria. Three of the non-protein amino acids found in the seeds of Acacia species, 2,3-diaminopropionic acid, 2-amino-3-acetylaminopropionic acid and 2-amino-3-oxalylaminopropionic acid, were more effective inhibitors of feeding in Anacridium than were the leaf amino acids.     

Distribution and systematic significance of basic non-protein amino acids and amines in the Tephrosieae

Seeds of 310 species within the four major genera, Millettia, Tephrosia, Derris, Lonchocarpus and 25 minor satellite genera of the Tephrosieae, were analysed both qualitatively and semiquantitatively for basic non-protein amino acids and amines. This survey revealed that a notable feature of the tribe is the accumulation in the seeds of unusual guanidino derivatives (including canavanine, enduracididine, 2-aminoimidazole, γ-hydroxyhomoarginine and tetrahydrolathyrine) and amines, several of which are not known outside this group. It is significant that none has yet been found in the tropical Sophoreae nor have they been found in the Dalbergiese excluding Lonchocarpinae. This gives credence to the view that Tephrosieae should be broadened to include Dalbergieae subtribe Lonchocarpinae. The results of this study show that there are chemically defined subgeneric groups within the large genera Millettia, Derris and Lonchocarpus. Some of these chemically defined groups coincide with morphologically defined subgenera, while others do not.     

Free amino acids in some sponges

Most invertebrates, particularly those of marine origin, have relatively high concentrations of free amino acids which are considered an important constituent of their osmoregulatory mechanisms [1]. Very little information is available on the free amino acid distribution in Porifera [2,3]. Common amino acids in some sponges were recognised by paper chromatography by Inskip and Cassidy [4] and Ackermann et al. [5,6] included a few sponges in their survey of the occurence of nitrogen compounds in marine invertebrates. More recently Bergquist and Hartman [7] surveyed semiquantitatively the distribution of free amino acids in several sponges. In the present paper we report on the amino acid composition of 12 species of sponges belonging to the class Demospongiae as a part of a study on the metabolites of Porifera [8]. Fresh sponges were extracted with aqueous ethanol. The organic solvent was removed and the aqueous solution, after removal of the ether soluble compounds, was separated into cationic, anionic and neutral fractions by ion-exchange chromatography. The cation fraction was analysed for amino acids using an automatic amino acid analyser. The results, which are presented in Table 1, show that all species of sponges examined have a similar composition in common amino acids. Glycine almost always appears as the dominant protein amino acid, followed by high concentrations of alanine and glutamic acid, whereas relatively lower concentrations of basic amino acids are present. In Axinella cannabina, Chondrosia reniformis, Chondrilla nucula, Cliona viridis and Hymeniacidon sanguinea, glycine represents more than 77% of the total amino acids. The high percentage of free glycine (90.4%) in Chondrosia reniformis is noteworthy. The anionic and the neutral fractions were examined for sulfur-containing amino acids using PC. Taurine (Table 2) was detected in all the Porifera examined; this is in agreement with previous observations [5–7]. N-Methyltaurine was identified in some of the species examined, whereas neither N,N-dimethyltaurine nor N,N,N-trimethyltaurine were found.     

Synthesis of α- and β-N-oxalyl-l-α,β-diaminopropionic acids and their isolation from seeds of Lathyrus sativus

The α- and β-N-oxalyl derivatives of l-α,β-diaminopropionic acid have been chemically synthesized and also isolated from seed extracts of Lathyrus sativus. Chemical and physical properties of the natural and synthetic isomers were in good agreement. The toxicity of the α-isomer to chicks was evaluated and compared with that of the β-isomer.     

4-Carboxy-4-hydroxy-2-aminoadipic acid and other acidic amino acids in Caylusea abyssinica

Two diastereoisomers of 4-carboxy-4-hydroxy-2-aminoadipic acid have been isolated from leaves and inflorescences of Caylusea abyssinica. Green parts of the plant also contain appreciable amounts of the two diastereoisomers of 4-hydroxy-4-methylglutamic acid, 3-(3-carboxyphenyl)alanine, (3-carboxyphenyl)glycine, 3-(3-carboxy-4-hydroxyphenyl)alanine, (3-carboxy-4-hydroxyphenyl)glycine and in low concentration 2-aminoadipic acid, saccharopine [(2S, 2′S)-N⁶-(2-glutaryl)lysine] and some γ-glutamyl peptides. The acidic amino acids were separated from other amino acids on an Ecteola ion exchange column with M pyridine as eluant.     

l-threo- and l-erythro-2-amino-3-hydroxyhex-4-ynoic acids: New amino acids from Tricholomopsis rutilans

2-Amino-3-hydroxyhex-4-ynoic acid, reported previously from Tricholomopsis rutilans, was shown to be a mixture of its threo- and erythro-forms. They were separated from each other and characterized by elementary analysis, optical rotation, TLC, IR, NMR spectra, catalytic hydrogenation, and by chemical synthesis. Their configurations were determined by the comparison of their hydrogenation products with known threo- and erythro-2-amino-3-hydroxyhexanoic acids.     

Sulphate ester of trans-4-hydroxypipecolic acid in seeds of Peltophorum

An acidic compound isolated from seed of the legume Peltophorum africanum has been characterised on the basis of FAB-MS, EIMS, ¹³C and ¹H NMR as trans-4-hydroxypipecolic acid-4-sulphate. This is the first naturally occurring sulphate ester of a non-protein amino acid to be described. The possible systematic significance of the distribution of the ester within Peltophorum and related genera is considered.     

Free amino acids of maize seedlings

The free amino acids were determined in different parts of maize seedlings (seeds, roots and shoots), 0, 2, 4 and 6 days after sowing.     

Sugar amino acids in designing new molecules

Emulating the basic principles followed by Nature to build its vast repertoire of biomolecules, organic chemists are developing many novel multifunctional building blocks and using them to create ‘nature-like’ and yet unnatural organic molecules. Sugar amino acids constitute an important class of such polyfunctional scaffolds where the carboxyl, amino and hydroxyl termini provide an excellent opportunity to organic chemists to create structural diversities akin to Nature’s molecular arsenal. This article describes some of our works on various sugar amino acids and many other related building blocks, like furan amino acids, pyrrole amino acids etc. used in wide-ranging peptidomimetic studies. Published in 2005.Based on the invited lecture presented at the XVII International Symposium on Glycoconjugates held in January 12–16, 2003 at Bangalore, India.     

Potentiation of l-canavanine-induced developmental anomalies in the tobacco hornworm, Manduca sexta, by some amino acids

The growth and development of final-stadium tabacco hornworm Manduca sexta (Sphingidae) larvae fed a 2.5 mM l-canavanine-containing diet is disrupted markedly. Such canavanine-mediated disruption of larval growth is intensified greatly when these organisms are fed a canavanine-containing diet supplemented with a 1 : 10 molar ratio of l-arginine, l-citrulline, l-ornithine or l-2,4-diaminobutyric acid, the larvae possess enhanced haemolymph volume (oedema) and a significant mortality results from incomplete larval-pupal ecdysis. Two other compounds, 3-aminobutyric acid and l-2,3-diaminopropionic acid, do not produce larvae showing oedema but most larvae fail to complete larval-pupal ecdysis. 4-Aminobutyric acid, l-threonine and l-glutamic acid are much less potent but they still manifest appreciable developmental aberrations. Eighteen other tested compounds have no discernible effect. In general, compounds accentuating the biological activity of canavanine have: an α-carboxyl and α-amino group; a carbon skeleton of no less than 2 nor more than 4 carbon atoms; and and ω-amino group.