Peder Olesen Larsen

Azetidine-2-carboxylic acid derivatives from seeds of Fagus silvatica L. and a revised structure for nicotianamine

Abstract 2( S ),3′( S )- N -(3-Amino-3-carboxypropyl)azetidine-2-carboxylic acid and 2( S ),3′( S ),3″( S )- N -[ N -(3-amino-3-carboxypropyl)-3-amino-3-carboxypropyl]azetidine-2-carboxylic acid have been isolated from seeds of Fagus silvatica L. (beechnuts). The structures have been established by PMR- and 13 C-NMR-spectroscopy and by synthesis from l -azetidine-2-carboxylic acid. The second of the new amino acids is identical with nicotianamine. previously isolated from Nicotiana tabacum but assigned a different formula. The ring opening reactions of azetidine-2-carboxylic acid in neutral solution have been studied and the chemical and possibly biochemical precursor role of this amino acid for various amino acids including the two new ones described here, nicotianine [ N -(3-amino-3-carboxypropyl)nicotinic acid] and methionine is discussed.

Acide 2(R)-amino-3-butenoique (vinylglycine) dans les carpophores de Rhodophyllus nidorosus

Abstract 2(R)-amino-3-butenoic acid (vinylglycine), the simplest β,γ-unsaturated α-amino acid, has been isolated from the mushroom Rhodophyllus nidorosus (Fr.) Quel. The amino acid occurs as partly racemized d -form. The structure has been confirmed by comparison with synthetic material.

Free amino acids and γ-glutamyl peptides in seeds of Fagus silvatica☆

Abstract The contents of amino acids and peptides have been investigated in seeds of Fagus silvatica L. (beechnuts). In addition to the common amino acids, the following compounds have been isolated and identified: 4-hydroxyproline (probably the cis - l -isomer), N 5 -acetylornithine, 3-(2-furoyl)- l -alanine, methionine sulfoxide (probably an artefact), pipecolic acid (probably partially racemized d -isomer), l -willardiine (with a small amount of the d -isomer), N -(3-amino-3-carboxypropyl)azetidine-2-carboxylic acid, N -[ N -(3-amino-3-carboxypropyl)-3-amino-3-carboxypropyl]azetidine-2-carboxylic acid, 2( S ),5( S ),6( S )-5-hydroxy-6-methylpipecolic acid, 2( S ),5( R ),6( S )-5-hydroxy-6-methylpipecolic acid, γ-glutamylalanine, γ-glutamylglutamic acid, γ-glutamylisoleucine, γ-glutamylleucine, γ-glutamylmethionine sulfoxide (probably an artefact), γ-glutamylphenylalanine, γ-glutamyltyrosine, γ-glutamylvaline, glutathione, γ-glutamylwillardiine, and γ-glutamylphenylalanylwillardiine. γ-Glutamylphenylalanine and willardiine are the dominating components of the amino acid fraction. The isolations were performed by use of ion exchange chromatography, taking advantage of the different pK-values of the amino acids, mainly on acid resins in the 3-chloropyridinium form with aq. 3-chloropyridine as eluant and on basic resins in the acetate form with aqueous acetic acid as eluant. These methods in combination with preparative paper chromatography have permitted the isolation and identification of compounds present in amounts as low as 1/6000 of the dominant ninhydrin-reactive component. The implications of the occurrence of this large variety of compounds in the Fagaceae are briefly discussed.

2(S),4(R)-4-(β-d-Galactopyranosyloxy)-4-isobutyl-glutamic acid: A new amino acid in Reseda odorata

Abstract 2( S ),4( R )-4-(β- d -Galactopyranosyloxy)-4-isobutylglutamic acid (I) has been isolated from the flowers of Reseda odorata , wherein it occurs in substantial quantity. Hydrolysis of I gives d -galactose, 2( S ),4( R )-4-hydroxy-4-isobutylglutamic acid (II) and 3( R ),5( S )-3-hydroxy-3-isobutyl-2-pyrrolidone-5-carboxylic acid (III) and its treatment with nitrous acid yields a galactoside of a non-nitrogenous hydroxy acid lactone (IV). The structures of I and its degradation products are supported by PMR, 13 C-NMR and other spectroscopic methods. 13 C-NMR spectroscopy of the model compound 2-(β- d -galactopyranosyloxy)isobutyric acid confirmed the structure of the natural product. The S - (or l -) configuration at C(2) in the amino acid moiety of I has been established by the use of the Clough—Lutz—Jirgenson rule and the R -configuration at C(4) of the same unit has been assigned tentatively. I represents the first example of a glycoside of a higher plant amino acid in which the carbohydrate residue is linked to an aliphatic hydroxy group.

Free amino acids and γ-glutamyl peptides in fagaceae

Abstract 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 .

Base-catalysed Neber-type rearrangement of glucosinolates [1-(β-D-glucosylthio)-N-(sulphonato-oxy)alkylideneamines]

Allylglucosinolate in aqueous base produces vinylglycine (2-aminobut-3-enoic acid), thioglucose, and sulphate by a reaction of the first order with regard to both glucosinolate and hydroxide ion. No deuterium is introduced at C-2 of the amino-acid when the reaction is performed in D2O. The reaction presumably takes place through a Neber-type rearrangement, starting with concerted loss of a hydrogen atom at C-2 in the aglucone, bond formation between C-2 and the nitrogen atom, and loss of sulphate, followed by fast addition of water to the resulting azirine, ring opening of the hydroxyaziridine produced, and finally hydrolysis of the thioester thus obtained. Benzylglucosinolate correspondingly yields phenylglycine, thioglucose, and sulphate in aqueous base but in this case other products, including benzaldehyde, benzyl cyanide, cyanide, and thiocyanate, are observed. Both vinylglycine and phenylglycine are produced in partly racemised forms but with an excess of the L-isomer. The reaction of the glucosinolates is facilitated by a high kinetic acidity of the hydrogens at C-2 in the aglucone, but glucosinolates other than the allyl and benzyl compounds can also give α-amino-acids with aqueous base, although only at elevated temperature.

Tyrosine O-glucoside and dopamine 3-O-glucoside in seeds of Entada pursaetha

Abstract l -Tyrosine O -glucoside (I) and dopamine-3- O -glucoside (II) have been isolated from seeds of Entada pursaetha DC. The structures have been established by spectroscopic methods, identification of hydrolysis products and comparison with synthetic material. Syntheses are described of II, dopamine 4-glucoside and tyramine- O -glucoside.

Two diasteoisomers of 5-hydroxy-6-methylpipecolic acid from seeds of Fagus silvatica L.☆

Two diastereoisomers of 5-hydroxy-6-methylpipecolic acid have been isolated from beechnuts. The configurations of the two amino acids have been assigned as (2S, 5S, 6S) (1) and (2S, 5R, 6S) (2). The determination of structure and configuration for the two new amino acids is mainly based on spectroscopic and rotatory evidence. The 13C-NMR and 1H-NMR spectra of the three ionic forms of the two amino acids and of S-pipecolic acid and (2S, 5R)-5-hydroxypipecolic acid and the CD-curves of the cations and amfoions of 1, 2, and (2S, 5R)-5-hydroxypipecolic acid have been recorded.

Intermediates in the metabolism of m-carboxy-substituted aromatic amino acids in plants: Phenylpyruvic acids, mandelic acids, and phenylglyoxylic acids

Tracer experiments with 14C-labelled precursors in Iris times hollandica cv. Wedgwood, Reseda Iutea L. And Keseda Odorata L. have demonstrated that 3-(3-carboxyphenyl) alanine and 3-(3-carboxy-4-hydroxyphenyl) alanine can be derived from the corresponding pyruvic acids, presumably by unspecific transaminations, and that (3-carboxyphenyl) glycine and (3-carboxy-4-hydroxyphenyl) glycine can be derived from the corresponding phenylglyoxylic acids. The glycine derivatives are derived from the alanine derivatives, and the corresponding mandelic acids are intermediates in these transformations. The corresponding phenylacetic acids are incorporated only slightly into the glycine derivatives, indicating that oxidation at the benzylic position in the C6-C3 compounds takes place early in the transformation. The corresponding cinamic acids are not metabolized at all in the plants.

γ-Glutamylwillardiine and γ-glutamylphenylalanylwillardiine from seeds of Fagus silvatica

Abstract γ- l -Glutamyl- l -willardiine [γ- l -glutamyl-3-(1-uracil)- l - l -alanine] and γ-glutamylphenylalanylwillardiine have been isolated from seeds of Fagus silvatica . The structures have been established by spectroscopy, hydrolysis to give the constituent amino acids, and for the tripeptide end-group determination and partial hydrolysis to give the two constituent dipeptides.