Quantification of nitropropanoyl glucosides in karaka nuts before and after treatment.

A high performance liquid chromatography (HPLC) method was developed to assay nitropropanoyl glucosides in the nuts of karaka (Corynocarpus laevigatus) a traditional food of New Zealand Maori. Levels of glucosides, measured as 3-nitropropanoic acid, ranged from 50.25 to 138.62 g kg(-1) (5.0-13.9% w/w) and were highest in nuts from unripe drupes; these levels are higher than any previously reported. Other parts of the drupe also contained nitropropanoyl glucosides but at lower levels than the nut. Treatment procedures to remove the glucosides from the nuts varied in their efficacy with soxhlet extraction removing 98.7% and prolonged boiling and cold water extraction both removing 96%. These findings confirm the traditional methods for preparation of these nuts for consumption.

Anti-staphylococcal activity of C-methyl flavanones from propolis of Australian stingless bees (Tetragonula carbonaria) and fruit resins of Corymbia torelliana (Myrtaceae).

Propolis of Australian stingless bees (Tetragonula carbonaria, Meliponini) originating from Corymbia torelliana (Myrtaceae) fruit resins was tested for its antimicrobial activities as well as its flavonoid contents. This study aimed at the isolation, structural elucidation and antibacterial testing of flavanones of C. torelliana fruit resins that are incorporated into stingless bee propolis. Flavanones of this study were elucidated by spectroscopic and spectrometric methods including UV, 1D and 2D NMR, EI-MS, ESI-MS and HR-MS. The results indicated known C-methylated flavanones namely, 1 (2S)-cryptostrobin, its regioisomer 2 (2S)- stroboponin, 3 (2S)- cryptostrobin 7-methyl ether, and 6 (2S)- desmethoxymatteucinol, and known flavanones 4 (2S)- pinostrobin and 5 (2S)- pinocembrin as markers for C. torelliana fruit resins and one propolis type. Ethanolic preparations of propolis were shown to be active against Staphylococcus aureus (ATCC 25923) and to a lesser extent against Pseudomonas aeruginosa (ATCC 27853). C. torelliana flavanones inhibited the growth of S. aureus therefore contributing to the antibacterial effects observed for Australian stingless bee propolis extracts.

Kinetics of formation of Di-D-fructose dianhydrides during thermal treatment of inulin.

Thermal treatments of solid mixtures of inulin and citric acid result in the formation of di-D-fructose dianhydrides and oligomers derived therefrom. The kinetics of formation of these compounds have been investigated and simulated in computer studies. A mechanism is proposed. The conditions used in this study were analogous to the conditions pertaining to the roasting of chicory, during which similar compounds are formed.

Di-D-fructose dianhydrides and related oligomers from thermal treatments of inulin and sucrose.

Thermal treatment of anhydrous, acidified sucrose or inulin yields caramels containing monosaccharides and oligomers, predominantly dianhydrides and higher oligomers derived by the addition of glycosyl residues to dianhydrides. Fourteen dianhydrides, most of which comprise two fructose moieties, have been identified by mass spectroscopy of the per-O-trimethylsilyl ethers. Thirteen of these dianhydrides have been isolated and characterized; five of the dianhydrides are novel compounds and one of these is a glucose-fructose dianhydride. The dianhydrides and related oligomers are thought to have a prebiotic effect by stimulating the proliferation of bifidobacteria in the large intestine.

Stereoselective thermal transfer of fructose from sucrose to cyclodextrins.

Branched cyclodextrins (CDs) have been formed by the thermal transfer of a fructosyl group from sucrose to O-6 of one of the glucose residues of cyclomaltohexa- and hepta-ose (alpha-CD and beta-CD). In each case the fructosyl group adds almost entirely in the beta configuration. The resultant fructosylcyclodextrins (Fru-CDs) show increased solubility in water and, in the case of Fru-beta-CD increased ability to solubilize sparingly soluble compounds by inclusion, relative to the parent cyclodextrins. However, the Fru-CDs have similar abilities to form complexes as their respective parent CDs. Fru-CDs act as inhibitors of invertase.

Di-D-fructose dianhydrides from the pyrolysis of inulin.

Inulin was pyrolyzed in air to produce di-D-fructose dianhydrides (DFDAs) in approximately 26% yield, three of which were identified by MS, NMR, and comparison with literature data. The mass spectra of the per-O-trimethylsilyl derivatives of the DFDAs are discussed. A mechanism is proposed for the formation of DFDAs from inulin during pyrolysis.

Anhydro sugars and oligosaccharides from the thermolysis of sucrose.

Thermolysis of anhydrous, amorphous, acidified sucrose results in polymerization initially involving the fructosyl cation and later the glucosyl cation. Monomeric and dimeric anhydro sugars form during the thermolysis and are incorporated into the fructoglucan polymer.

Formation of trisaccharides (kestoses) by pyrolysis of sucrose.

Amorphous sucrose, containing citric acid as catalyst, undergoes thermolysis at 100 degrees to yield fructofuranosyl cation and D-glucose. The cation reacts with unchanged sucrose to form all three of the known kestoses, and also their alpha-fructofuranosyl anomers. Two of the latter are resistant to invertase hydrolysis. A new fructosylglucose disaccharide is also formed.