Janet D. Lloyd

Kernel (1 → 3) (1 → 4)-β-d-glucan content of oat genotypes*

A method for the estimation of (1 → 3) (1 → 4)-β- d -glucan in oats - involving alkali extraction at 45 °C, precipitation with Calcofluor and the colorimetric estimation of glucose - has been modified and compared with a hydrazinolysis procedure. Close agreement between the methods was found for oat kernels and for oat bran samples. This indicates that the β-glucan of oats was completely soluble under the conditions used. Comparison of the modified Calcofluor method with previous results also showed a reasonable agreement for total β-glucan content. The modified Calcofluor method which is suitable for small samples has been used to analyse kernels from 100 diverse oat genotypes. Significant genotype differences were found and kernel β-glucan levels ranged from 3·2 to 6·3 %. Associations between β-glucan and other kernel and plant characteristics were weak, indicating that it is possible to manipulate the β-glucan content of high-yielding oat varieties by plant breeding. However, the modified Calcofluor method gave a low value for β-glucan content, compared with the hydrazinolysis procedure, with a sample of barley and appears unsuitable for this species.

Variation in the kernel (1→3)(1→4)-β-D-glucan content of oat cultivars and wild Avena species and its relationship to other characteristics

Kernel (1 → 3) (1 → 4)-β-n-glucan, kernel protein and mean kernel size have been estimated in six cultivars of oats ( Avena sativa ) L, and eight wild Avena species grown at two levels of nitrogen fertility in a pot experiment. In the oat cultivars, kernel protein and kernel β-glucan were both increased at the higher nitrogen fertility level. Comparison with the results from field grown material which had still higher kernel protein contents indicated that this association between β-glucan and protein occurred over a wide range of kernel protein levels. However cultivar differences were more distinct at lower fertility levels. Six of the eight Avena species had a mean kernel size that was substantially lower than the cultivars. However the protein contents of the Avena species were in general higher and they showed a wider range of β-glucan contents. Although higher nitrogen fertility increased grain protein in the wild species, β-glucan was only significantly increased in one species. Kernel β-glucan content was independent of both kernel protein and mean kernel size in the wild species. Results show that phenotypic variations in kernel protein are associated with concomitant variations in β-glucan in oat cultivars and furthermore that wild Avena species may be useful additional sources of variation for this characteristic.

Intermediates for incorporation of tetrahydroxypipecolic acid analogues of α- and β-d-mannopyranose into combinatorial libraries: unexpected nanomolar-range hexosaminidase inhibitors. Synthesis of α- and β-homomannojirimycin

Abstract Homoazasugars have the distinction as a class of natural products in that most of them have been synthesised before they were isolated. Syntheses of α- 1 and β-homomannojirimycin 2 rely on the stereoselective and chemoselective sodium cyanoborohydride reduction of a [2.2.2] bicyclic imino lactone ( 6 ) to give a single [2.2.2] bicyclic amino-lactone ( 7 ). Methanolysis of 7 under basic conditions is accompanied by efficient epimerisation of the first formed α-amino-ester ( 8 ) to the more stable β-amino-ester ( 9 ) in which the 2,6-substitutents are equatorial. Both 7 and 9 are suitable intermediates for the incorporation of tetrahydroxypipecolic acid derivatives into combinatorial libraries containing α- and β-C-glycosyl analogues of aza- d -mannopyranose, respectively. Methylamides derived from 7 and 9 are shown to be specific and potent inhibitors of two β-N-acetylglucosaminidases but have no effect on an α-N-acetylgalactosaminidase. The synthesis of α- 14 and β- 17 manno-pipecolic acids is also reported.

Evaluation of a rapid method for estimating free amino acids in silages

Winters, A., Lloyd, J. D., Jones, R., Merry, R. J. (2002). Evaluation of a rapid method for estimating free amino acids in silages. Animal Feed Science and Technology, 99, (1-4), 177-187. Free amino acids; Silage; Protein breakdown; Ninhydrin assay Sponsorship: MAFF

Synthesis of an eight carbon homologue of α-homomannojirimycin via a bicyclic aminolactone

Abstract A thermally induced intramolecular 1,3-dipolar cycloaddition of an azidoester and subsequent sodium cyanoborohydride reduction of the resulting bicyclic vinylogous urethane to give a bicyclic aminolactone allows access to an eight carbon homologue of α-homomannojirimycin which is a weak fucosidase inhibitor. Intermediates with both an α- and β-amino acid moiety are described and may be useful for incorporation of homopipecolic acids into novel peptide libraries.

Open-chain acetonides of D-galactono-1,4-lactone as starting materials for pyrrolidines, azepanes and 5-azidomethyltetrahydrofuran-2-carboxylates: monomers for polyhydroxylated nylon and for tetrahydrofuran carbopeptoids

Treatment of D-galactono-1,4-lactone with dimethoxypropane in acetone in the presence of tosic acid forms methyl 2,3:5,6-di-O-isopropylidene-D-galactonate 6 (with only the secondary hydroxy group at C-4 unprotected) and methyl 2,3:4,5-di-O-isopropylidene-D-galactonate 5 (with only the primary hydroxy group at C-6 unprotected) in yields of 20% and 78%, respectively. The value of such easily accessible intermediates is illustrated by the synthesis of 1,4-dideoxy-1,4-imino-D-glucitol 16 (a pyrrolidine), and for the efficient preparation of 6-azido-6-deoxy-D-galactono-1,4-lactone 22. The conversion of 22 to a seven-membered galactonolactam 21 (a tetrahydroxycaprolactam) may provide access to hydroxylated nylon polymers. The galactonolactam 21 has no significant inhibitory effect on a number of glycosidases. Reaction of 22 with triflic anhydride gives two epimeric 5-(azidomethyl)tetrahydrofuran-2-carboxylates which provide starting materials for two series of carbopeptoids, one of which probably has a helical structure and the other a structure reminiscent of a β-turn.