Stephen V. Evans

Potent competitive inhibition of α-galactosidase and α-glucosidase activity by 1,4-dideoxy-1,4-iminopentitols: syntheses of 1,4-dideoxy-1,4-imino-d-lyxitol and of both enantiomers of 1,4-dideoxy-1,4-iminoarabinitol

Abstract The syntheses of 1,4-dideoxy-1,4-imino-D-lyxitol (3), 1,4-dideoxy-1,4-imino- d -arabinitol (4) and 1,4-dideoxy-1,4-imino- l -arabinitol (5) are reported; (3) is a potent competitive inhibitor of α-galactosidase (green coffee beans) and (4) a competitive inhibitor of α-glucosidase (Brewers yeast) suggesting that iminopentitols have considerable potential as glycosidase inhibitors. (4) was found to be identical to an alkaloid recently isolated from Angylocalyx boutiqueanus .

Glycosidase inhibition by plant alkaloids which are structural analogues of monosaccharides

Abstract ]The inhibitory activities of three plant alkaloids, deoxynojirimycin, 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine and 1,5 dideoxy-1,5-imino- D -mannitol towards glycosidases from several sources have been compared. These are structural analogues of D -glucose, D -fructose and D -mannose respectively. The occurrence of 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine in Lonchocarpus sericeus seed is confirmed and has been shown to be responsible for the glucosidase inhibition wrongly attributed to 1,5-dideoxy-1,5-imino- D -mannitol in a previous report.

The role of the secondary plant compound 2,5-dihydroxymethyl 3,4-dihydroxypyrrolidine as a feeding inhibitor for insects

The cyclic amino alditol 2,5‐dihydroxymethyl 3,4‐dihydroxypyrrolidine (DM DP) has recently been shown to be an inhibitor of various glucosidases. We have investigated its role as a plant protective chemical against a range of phytophagous insects by examining its effects on development, feeding behaviour and functioning of taste receptors. We have shown that it can inhibit feeding and can be toxic. The mechanisms by which these effects are achieved are discussed in the context of the molecular structure of the compound.

Design synthesis and preliminary evaluation of a potent α- mannosidase inhibitor: 1,4-dideoxy-1,4-imino-D-mannitol

1,4-Dideoxy-1,4-imino-D-mannitol (1), synthesised from benzyl α-D-mannopyranoside, is a potent competitive inhibitor of the hydrolysis of p-nitrophenyl α-D-mannopyranoside catalysed by Jack Bean α-mannosidase (Cnavalia ensiformis); this is the first report of the specific inhibition of a glycosidase by a pyrrolidine analogue of a furanose sugar.

Lack of glycosidase inhibition by, and isolation from xanthocercis zambesiaca (leguminosae) of, 4-O-(β-D-glucopyranosyl)-fagomine [1,2,5-trideoxy-4-O-(β-D-glucopyranosyl)-1,5-imino-D-arabino-hexitol], a novel glucoside of a polyhydroxylated piperidine alkaloid

Abstract A COSY spectrum has been used to determine the position of inter-residue linkage in 4-O-(β-D-glucopyranosyl) fagomine (1) an example of a new class of glycosides of polyhydroxylated piperidine alkaloids isolated from seed of the legume Xanthocercis zambesiaca . (Bak.) Dunn. Unlike a number of polyhydroxylated piperidines, neither the glucoside (1) nor free fagomine [1,2,5-trideoxy-1,5-imino-D- arabino hexitol] (3) showed any inhibitory activity towards glycosidase enzymes from a variety of sources.

Synthesis from D-glucose of 1,5-dideoxy-1,5-imino-L-fucitol, a potent α-L-fucosidase inhibitor

1,5-Dideoxy-1,5-imino-L-fucitol (1), synthesised from methyl α-D-glucopyranoside, is a potent competitive inhibitor of the hydrolysis of p-nitrophenyl α-L-fucopyranoside catalysed by α-L-fucosidase (ex. bovine epididymis) causing 50% inhibition of enzymic activity at 2.5 × 10–8M.

Para-aminophenylalanine in Vigna: possible taxonomic and ecological significance as a seed defence against bruchids

Abstract Seeds of eight wild species and varieties from Vigna subgenera Plectotropis and Vigna were screened for the non-protein amino acid p-aminophenylalanine (PAPA), previously reported to have a restricted taxonomic distribution and to be a growth inhibitor of Escherichia coli. The compound was detected in five wild species and its distribution found to have taxonomic value for assessing members of Plectotropis and intrageneric links with other taxa. Although quantitative variation in PAPA was detected between species and also between varieties of V. vexillata, toxicity tests confirmed that the levels detected in all accessions were sufficient for PAPA to be an important component of resistance against two important pest bruchids of Vigna and Phaseolus crops. The taxonomic and ecological significance of these findings is discussed.

Detrimental effects of 2,5-Dihydroxymethyl-3,4-dihydroxypyrrolidine in some tropical legume seeds on larvae of the bruchid Callosobruchus maculatus

The secondary plant compound 2,5‐Dihydroxymethyl‐3,4‐dihydroxypyrrolidine (DMDP), an analogue of β‐D‐fructofuranose, is lethal to the larvae of the bruchid beetle Callosobruchus maculatus F. when incorporated into artificial diets at levels greater than 0.03%. In the range 0.003% to 0.03% the compound reduces larval survival in a dose‐dependent manner. The α‐D‐glucosidase digestive enzyme demonstrated in homogenates of the alimentary tract of the larvae is strongly inhibited by the compound in a competitive manner.

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

Abstract 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.

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

Abstract An acidic compound isolated from seed of the legume Peltophorum africanum has been characterised on the basis of FAB-MS, EIMS, 13 C and 1 H 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.