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Cucumbers have been anecdotally claimed to have anti-inflammatory activity for a long time, but the active principle was not identified. idoBR1, (2 R ,3 R ,4 R ,5 S )-3,4,5-trihydroxypiperidine-2-carboxylic acid, is an iminosugar amino acid isolated from fruits of certain cucumbers, Cucumis sativus (Cucurbitaceae). It has no chromophore and analytically behaves like an amino acid making detection and identification difficult. It has anti-inflammatory activity reducing lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α) in THP-1 cells and ex vivo human blood. It showed selective inhibition of human α-l-iduronidase and sialidases from both bacteria ( Tannerella forsythia ) and human THP-1 cells. idoBR1 and cucumber extract reduced the binding of hyaluronic acid (HA) to CD44 in LPS-stimulated THP-1 cells and may function as an anti-inflammatory agent by inhibiting induced sialidase involved in the production of functionally active HA adhesive CD44. Similar to the related iminosugars, idoBR1 is excreted unchanged in urine following consumption. Its importance in the diet should be further evaluated., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

A practical synthesis of the very rare sugar d-idose and the stable building blocks for d-idose, d-iduronic, and d-idonic acids from ido -heptonic acid requires only isopropylidene protection, Shing silica gel-supported periodate cleavage of the C6-C7 bond of the heptonic acid, and selective reduction of C1 and/or C6. d-Idose is the most unstable of all the aldohexoses and a stable precursor which be stored and then converted under very mild conditions into d-idose is easily prepared.

DMDP acetic acid [N-carboxymethyl-2,5-dideoxy-2,5-imino-D-mannitol] 5 from Stevia rebaudiana is the first isolated natural amino acid derived from iminosugars bearing an N-alkyl acid side chain; it is clear from GCMS studies that such derivatives with acetic and propionic acids are common in a broad range of plants including mulberry, Baphia, and English bluebells, but that they are very difficult to purify. Reaction of unprotected pyrrolidine iminosugars with aqueous glyoxal gives the corresponding N-acetic acids in very high yield; Michael addition of both pyrrolidine and piperidine iminosugars and that of polyhydroxylated prolines to tert-butyl acrylate give the corresponding N-propionic acids in which the amino group of β-alanine is incorporated into the heterocyclic ring. These easy syntheses allow the identification of this new class of amino acid in plant extracts and provide pure samples for biological evaluation. DMDP N-acetic and propionic acids are potent α-galactosidase inhibitors in contrast to potent β-galactosidase inhibition by DMDP.

Reverse aldol opening renders amides of 3-hydroxyazetidinecarboxylic acids (3-OH-Aze) unstable above pH 8. Aze, found in sugar beet, is mis-incorporated for proline in peptides in humans and is associated with multiple sclerosis and teratogenesis. Aze-containing peptides may be oxygenated by prolyl hydroxylases resulting in potential damage of the protein by a reverse aldol of the hydroxyazetidine; this, rather than changes in conformation, may account for the deleterious effects of Aze. This paper describes the synthesis of 3-fluoro-Aze amino acids as hydroxy-Aze analogues which are not susceptible to aldol cleavage. 4-(Azidomethyl)-3-fluoro-Aze and 3,4-difluoroproline are new peptide building blocks. trans,trans-2,4-Dihydroxy-3-fluoroazetidine, an iminosugar, inhibits the growth of pancreatic cancer cells to a similar degree as gemcitabine.

All 16 stereoisomeric N-methyl 5-(hydroxymethyl)-3,4-dihydroxyproline amides have been synthesized from lactones accessible from the enantiomers of glucuronolactone. Nine stereoisomers, including all eight with a (3R)-hydroxyl configuration, are low to submicromolar inhibitors of β-N-acetylhexosaminidases. A structural correlation between the proline amides is found with the ADMDP-acetamide analogues bearing an acetamidomethylpyrrolidine motif. The proline amides are generally more potent than their ADMDP-acetamide equivalents. β-N-Acetylhexosaminidase inhibition by an azetidine ADMDP-acetamide analogue is compared to an azetidine carboxylic acid amide. None of the amides are good α-N-acetylgalactosaminidase inhibitors.

X-ray crystallography firmly established the relative stereochemistry of the title compound, C16H20N2O3. The acetonide ring adopts an envelope conformation with one of the O atoms as the flap and the piperidine ring adopts a slightly twisted boat conformation. The absolute configuration was determined by use of d-ribose as the starting material. The compound exists as O-H⋯O hydrogen-bonded chains of mol-ecules running parallel to the b axis.

The Ho crossed aldol condensation provides access to a series of carbon branched iminosugars as exemplified by the synthesis of enantiomeric pairs of isoDMDP, isoDGDP, and isoDAB, allowing comparison of their biological activities with three linear isomeric natural products DMDP, DGDP, and DAB and their enantiomers. L-IsoDMDP [(2S,3S,4R)-2,4-bis(hydroxymethyl)pyrrolidine-3,4-diol], prepared in 11 steps in an overall yield of 45% from d-lyxonolactone, is a potent specific competitive inhibitor of gut disaccharidases [K(i) 0.081 μM for rat intestinal maltase] and is more effective in the suppression of hyperglycaemia in a maltose loading test than miglitol, a drug presently used in the treatment of late onset diabetes. The partial rescue of the defective F508del-CFTR function in CF-KM4 cells by L-isoDMDP is compared with miglustat and isoLAB in an approach to the treatment of cystic fibrosis.

The absolute stereochemistry of the title compound, C(9)H(15)NO(7), was determined from the use of d-glucuronolactone as the starting material. The compound crystallizes as the zwitterion. The five-membered ring adopts an envelope conformation with the -CH(2)OH-substituted C atom forming the flap. An intramolecular N-H⋯O hydrogen-bond occurs. In the crystal, the compound exists as a three-dimensional O-H⋯O intermolecular hydrogen-bonded network with each mol-ecule acting as a donor and acceptor for four hydrogen bonds.

The enantiomers of glucuronolactone are excellent chirons for the synthesis of the 10 stereoisomeric 2,5-dideoxy-2,5-iminohexitols by formation of the pyrrolidine ring by nitrogen substitution at C2 and C5, with either retention or inversion of configuration; the stereochemistry at C3 may be adjusted during the synthesis to give seven stereoisomers from each enantiomer. A definitive side-by-side comparison of the glycosidase inhibition of a panel of 13 glycosidases showed that 8 of the 10 stereoisomers showed significant inhibition of at least one glycosidase.

X-ray crystallography confirmed the formation, structure and relative stereochemistry of the title compound, C(15)H(19)NO(3), which contains a sterically congested four-membered azetidine ring system. The absolute configuration was determined by the use of l-arabinose as the starting material.

The six-membered boronate ester ring of the title compound, C(13)H(16)BNO(6), adopts an envelope conformation with the C atom bearing the dimethyl substituents at the flap. The O-B-C-C torsion angles between the boronate group and the benzene ring are 72.5 (2) and 81.0 (2)°. The 4-nitro-benzoate unit adopts a slightly twisted conformation, with dihedral angles between the benzene ring and the nitrate and methyl ester groups of 17.5 (2) and 14.4 (3)°, respectively. In the crystal, inversion-related pairs of mol-ecules show weak π-π stacking inter-actions [centroid-centroid distance = 4.0585 (9) Å and inter-planar spacing = 3.6254 (7) Å].

X-ray crystallography firmly established the relative stereochemistry of the title compound, C(17)H(22)N(2)O(3). The absolute configuration was determined by use of 2-C-methyl-d-ribonolactone as the starting material. The compound exists as O-H⋯N hydrogen-bonded chains of mol-ecules running parallel to the a-axis.

X-ray crystallography unequivocally confirmed the stereochemistry of the 2-C-methyl group in the title mol-ecule, C(10)H(16)O(5), in which the 1,5-lactone ring exists in a boat conformation. The absolute stereochemistry was determined by the use of d-ribose in the synthesis. The crystal exists as O-H⋯O hydrogen bonded chains of mol-ecules running parallel to the a axis with each mol-ecule acting as a donor and acceptor for one hydrogen bond.

The structure determination confirms the stereochemistry of the title compound, C(12)H(17)NO(3), which contains a four-membered azetidine ring system. The absolute configuration was determined by the use of d-glucose as the starting material. In the crystal, O-H⋯O and O-H⋯N hydrogen bonds link the mol-ecules into layers in the ab plane.

Reaction of 3-O-benzyl-1,2-O-isopropyl-idene-α-xylo-pentodialdo-1,4-furan-ose with N,N-diethyl-2-(dimethyl-sulfuranil-idene)acetamide gave stereoselectively an ep-oxy-amide, which was regioselectively opened by NaN(3) in dimethyl formamide to give the title compound, C(21)H(30)N(4)O(6). X-ray crystallography confirmed the relative stereochemistry of the title compound and the absolute configuration was determined by the use of d-glucose as the starting material. There are two mol-ecules in the asymmetric unit (Z' = 2). The crystal structure consists of two types of chains of O-H⋯O hydrogen-bonded mol-ecules running parallel to the b axis, with each mol-ecule acting as a donor and acceptor of one hydrogen bond.

The crystal structure unequivocally confirms the relative stereochemistry of the title compound, C(6)H(13)FO(5) [6-de-oxy-6-fluoro-d-galactitol or (2S,3R,4R,5S)-6-fluoro-hexane-1,2,3,4,5-penta-ol]. The absolute stereochemistry was determined from the use of d-galactose as the starting material. In the crystal, the molecules are linked by O-H⋯O and O-H⋯F hydrogen bonds, forming a three-dimensional network with each mol-ecule acting as a donor and acceptor for five hydrogen bonds.

The crystal structure unequivocally confirms the relative stereochemistry of the title compound, C(6)H(11)FO(5). The absolute stereochemistry was determined by the use of d-galactose as the starting material. The compound exists as a three-dimensional O-H⋯O hydrogen-bonded network with each mol-ecule acting as a donor and acceptor for four hydrogen bonds.

The relative stereochemistry of the title compound, C(10)H(15)N(3)O(5), was confirmed by the crystal structure determin-ation. The absolute configuration was determined from the use of d-lyxonolactone as the starting material. The six-membered ring adopts a boat conformation with the larger azide group, rather than the methyl group, in the bowsprit position. In the crystal structure, a bifurcated inter-molecular O-H⋯O/O-H⋯N hydrogen bond links mol-ecules into chains running parallel to the b axis.

X-ray crystallography defines the relative configuration at the three-stereogenic centres in the title compound N-benzyl-l-XYLNAc, C(14)H(20)N(2)O(3). The five-membered pyrrolidine ring adopts an envelope conformation with the N atom lying out of the plane of the other four atoms. In the crystal structure, inter-molecular O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds link the mol-ecules into chains along [100]. The carbonyl group O atom acts as an acceptor for a bifurcated hydrogen bond. The absolute configuration is determined by the use of l-glucuronolactone as the starting material for the synthesis.

The crystal structure of the title compound, C(12)H(18)N(2)O(8), exists as O-H⋯O hydrogen-bonded layers of mol-ecules running parallel to the ab plane. Each mol-ecule is a donor and acceptor for six hydrogen bonds. The absolute stereochemistry was determined by the use of d-glucuronolactone as the starting material.

In the title compound, C(13)H(21)N(3)O(6), the six-membered ring adopts a twist-boat conformation with the azide group in the bowsprit position. The azide group is disordered over two sets of sites in a 0.642 (10):0.358 (10) ratio. The crystal structure consists of O-H⋯O hydrogen-bonded trimer units. The absolute configuration was determined from the use of d-mannose as the starting material.

X-ray crystallography unequivocally confirmed the stereochemistry of the 2-C-methyl group in the title mol-ecule, C(10)H(16)O(6), in which the 1,5-lactone ring exists in a boat conformation. The use of d-galactose in the synthesis determined the absolute stereochemistry. The crystal exists as O-H⋯O hydrogen-bonded layers in the ab plane, with each mol-ecule acting as a donor and acceptor for two hydrogen bonds.

X-Ray crystallography unequivocally determined the stereochemistry of the thymine base in the title compound, C(14)H(18)N(2)O(7). The absolute stereochemistry was determined from the use of d-ribose as the starting material. There are two independent mol-ecules in the asymmetric unit (Z' = 2) which exist as N-H⋯O hydrogen-bonded pairs in the crystal structure.

The crystal structure of the title compound, C(6)H(11)NO(5), establishes the relative configuration at the four stereogenic centres; the absolute configuration is determined by the use of d-glucuronolactone as the starting material for the synthesis. Mol-ecules are linked by inter-molecular O-H⋯O and N-H⋯O hydrogen bonds into a three-dimensional network, with each mol-ecule acting as a donor and acceptor for five hydrogen bonds.

The chemical name of the title compound in the paper by Jenkinson, Fenton, Booth, Fleet & Watkin [Acta Cryst. (2009), E65, o610-o611] is corrected.[This corrects the article DOI: 10.1107/S1600536809006357.].

The crystal structure of the title compound, C(13)H(14)O(5), establishes (i) the (S) - rather than (R) - configuration at the acetal carbon and (ii) that both the acetal and the lactone form five- rather than six-membered rings; the absolute configuration is determined by the use of 2-C-methyl-d-ribono-1,4-lactone as the starting material. The compound consists of hydrogen-bonded chains of mol-ecules running along the a axis; there are no unusual packing features. Only classical hydrogen bonding has been considered.

The title mol-ecule, C(7)H(15)NO(5), the major product from selective enzymatic oxidation followed by hydrogeno-lysis of the corresponding azido-heptitol, was found by X-ray crystallography to exisit in a chair conformation with three axial hydroxyl groups. One of the hydroxymethyl groups is disordered over two sets of sites in a 0.590 (3):0.410 (3) ratio. In the crystal, O-H⋯O, O-H⋯(O,O), O-H⋯N and N-H⋯O hydrogen bonding occurs.

X-ray crystallography confirmed the structure of the title triazole, C(11)H(15)N(3)O(5), formed from a single-step reaction of a sugar azide with a brominated ylid. The absolute configuration was determined by the use of d-ribose as the starting material. The six-membered ring is in a half-chair conformation. The crystal structure exists as chains of O-H⋯O hydrogen-bonded moleclues running parallel to the b axis.

X-ray crystallography unequivocally confirmed the stereochemistry of the C atom at position 2 in the carbon scaffold of the title mol-ecule, C(10)H(18)O(4). The pyran-ose ring exists in a chair conformation with the methyl group on the C atom in the 2 position in an equatorial configuration. The absolute stereochemistry was determined from the starting material. The crystal structure consists of O-H⋯O hydrogen-bonded chains of mol-ecules running parallel to the b axis.

X-ray crystallographic analysis has established that the major product from the protection of d-glucoronolactone with benzaldehyde is (1S)-1,2-O-benzyl-idene-α-d-glucurono-6,3-lactone, C(13)H(12)O(6), rather than the R epimer. The crystal structure exists as O-H⋯O hydrogen-bonded chains of mol-ecules lying parallel to the a axis. The absolute configuration was determined by the use of d-glucuronolactone as the starting material.

The reaction of 5-azido-5-de-oxy-2,3-O-isopropyl-idene-2-C-methyl-d-ribose with N,N-diethyl-2-(dimethyl-sulfuranyl-idene)acetamide gave the title compound, C(15)H(26)N(4)O(5), as the major product arising from initial formation of an epoxide which was subsequently opened by intra-molecular attack of the free 4-hydroxyl group. X-ray crystallography confirmed the relative stereochemistry of the title compound and the absolute configuration was determined by the use of d-ribose as the starting material. The crystal structure contains chains of mol-ecules running parallel to the a axis, being linked by weak bifurcated O-H⋯(N,N) hydrogen bonds.

X-ray crystallography unequivocally showed that protection of the free hydroxyl group of 3,5-O-benzyl-idene-d-lyxono-1,4-lactone with diphenyl-diazo-methane proceeded with retention of configuration to give the title compound, C(25)H(22)O(5). The crystal structure consists of layers of inter-locked mol-ecules lying parallel to the a axis.

The absolute and relative configurations of 1-epialexine are established by X-ray crystallographic analysis, giving (1S,2R,3R,7S,7aS)-1,2,7-trihydroxy-3-(hydroxymethyl)pyrrolizidine. The compound crystallizes as the hemihydrate C(8)H(15)NO(4) x 0.5H(2)O, with hydrogen bonds holding the water molecule in a hydrophilic pocket between epialexine bilayers. In addition, a comparison was made between results obtained from examination of the Bijvoet pairs from data sets collected using molybdenum and copper radiation.

X-ray crystallography unequivocally confirmed the structure of the title compound, C(12)H(17)N(3)O(4), as (4R)-4-(2-allyl-2H-1,2,3-triazol-4-yl)-1,2-O-isopropyl-idene-l-threose. The absolute configuration was determined by the use of d-glucorono-3,6-lactone as the starting material. The crystal structure consists of hydrogen-bonded chains of mol-ecules running parallel to the a axis. There are no unusual packing features.

L-tagatose was produced directly from L-psicose by subjecting the same biomass suspension to microbial reduction followed by oxidation using a newly isolated bacteria Enterobacter aerogenes 230S. After various optimizations, it was observed that cells grown on xylitol have the best conversion potential. Moreover, E. aerogenes 230S converted L-psicose to L-tagatose at a faster rate in the presence of polyols such as glycerol, D-sorbitol, ribitol, L-arabitol, D-mannitol and xylitol. At 5% substrate concentration, the conversion ratio of L-psicose to L-tagatose was above 60% in the presence of glycerol. Identity of crystalline L-tagatose was confirmed by HPLC analysis, (13)C-NMR spectra, and optical rotation.

The relative configuration of tert-butyl 2-de-oxy-4,5-O-iso-propyl-idene-d-gluconate, C(13)H(24)O(6), an inter-mediate in the synthesis of 2-de-oxy sugars, was determined by X-ray crystallography, and the crystal structure consists of chains of O-H⋯O hydrogen-bonded mol-ecules running parallel to the a axis. There are two mol-ecules in the asymmetric unit. The absolute configuration was inferred from the use of d-erythrono-lactone as the starting material.

The crystalline form of 1-de-oxy-l-mannitol, C(6)H(14)O(5), exists as an extensively hydrogen-bonded structure with each mol-ecule acting as a donor and acceptor for five hydrogen bonds. There are no unusual crystal-packing features; the absolute configuration was determined from the use of 6-de-oxy-l-mannose (l-rhamnose) as the starting material.

Although 6-azido-6-de-oxy-l-galactose in aqueous solution is in equilibrium between the open-chain, furan-ose and pyran-ose forms, it crystallizes solely as 6-azido-6-de-oxy-α-l-galactopyran-ose monohydrate, C(6)H(11)N(3)O(5)·H(2)O, with the six-membered ring adopting a chair conformation. The structure exists as hydrogen-bonded chains, with each mol-ecule acting as a donor and acceptor of five hydrogen bonds. There are no unusual crystal packing features and the absolute configuration was determined from the use of 1-azido-1-de-oxy-d-galactitol as the starting material.

1-De-oxy-d-galactitol, C(6)H(14)O(5), exists in the crystalline form as hydrogen-bonded layers of mol-ecules running parallel to the ac plane, with each mol-ecule acting as a donor and acceptor of five hydrogen bonds.

X-ray crystallography showed that the title compound, C(6)H(12)O(5), crystallizes in the α-pyran-ose form with the six-membered ring in a chair conformation. The crystal structure exists as a three-dimensional hydrogen-bonded network of mol-ecules with each mol-ecule acting as a donor and aceptor for four hydrogen bonds. The absolute configuration was determined by the use of l-fucose as starting material.

X-ray crystallography unequivocally shows that protection of the free hydroxyl group of 3,5-O-benzyl-idene-d-xylono-1,4-lactone with diphenyl-diazo-methane proceeded smoothly to give the title compound, C(25)H(22)O(5), with no accompanying epimerization. Unlike the analogously protected lyxono lactone, the isomeric xylono lactone has two mol-ecules present in the asymmetric unit (Z' = 2). The 5-ring lactones adopt envelope conformations and the 6-ring ketals adopt chair conformations.

Addition of methyl lithium to d-erythrono-1,4-lactone followed by acid deprotection was shown, by X-ray crystallography, to give 1-de-oxy-d-arabinitol, C(5)H(12)O(4), rather than 1-de-oxy-d-ribitol as the major product. The crystal structure exists as hydrogen-bonded chains of mol-ecules running parallel to the c axis which are further linked together by hydrogen bonds. Each mol-ecule is a donor and an acceptor for four hydrogen bonds.

The crystalline form of 1-deoxy-D-tagatose, C6H12O5, is shown to be 1-deoxy-alpha-D-tagatopyranose; the absolute configuration is determined by use of D-lyxono-1,4-lactone as the starting material. The title compound crystallized as concomitant polymorphs from a mixture of ethyl actate and methanol. Although the melting points of the materials differ by 7 K, the molecular conformations are almost identical and, in both polymorphs, each molecule is subject to four O-H...O hydrogen bonds.