Cyclomaltodextrin glucanotransferase-catalyzed transglycosylation from dextrin to alkanol maltosides.

Maltosides of butanol, octanol, and lauryl alcohol were found for the first time to serve as substrates for cyclomaltodextrin glucanotransferase (CGTase), and glycosyl residue was transfered from dextrin to the substrate affording novel maltosides with 3-4 glucose units.

Rubralactone, rubralides A, B and C, and rubramin produced by Penicillium rubrum.

Rubralactone (1), rubralides A, B and C (2-4), rubramin (5), and 2-formyl-3,5-dihydroxy-4-methylbenzoic acid (6), were isolated from Penicillium rubrum, and their structures established by spectroscopic methods including 2D NMR. The effects on plant growth of 1-6 were examined using the lettuce seedling bioassay. Compound 1 promoted root growth. Compounds 2, 3 and 5 inhibited the growth of lettuce seedlings, but 4 and 6 did not have any inhibitory effect on their growth.

Glucosylation of sucrose laurate with cyclodextrin glucanotransferase.

Sucrose monolauroyl esters were found to serve as substrates for cyclodextrin glucanotransferase (CGTase)-catalyzed transglucosidation reactions, affording new sucrose esters that have an additional 1-3 glucose residues on the pyranose ring of the sucrose moiety in the ester.

Suppression of apolipoprotein B secretion from HepG2 cells by glucosyl hesperidin.

Our previous study has shown that a soluble hesperidin derivative, glucosyl hesperidin (G-hesperidin), preferentially lowers serum triglyceride (TG) level in hypertriglyceridemic subjects through the improvement of very low-density lipoprotein (VLDL) metabolic abnormality. G-Hesperidin has also been found to decrease an elevated serum apolipoprotein B (apo B) level in the hypertriglyceridemic subjects, suggesting a possibility that this compound suppresses excess VLDL secretion in the liver. In the present study, to gain a better understanding of possible mechanisms by which G-hesperidin lowers serum TG, we examined whether this derivative affects apo B secretion from HepG2 human hepatoma cells, a model of hepatic VLDL secretion. As a result, G-hesperidin significantly reduced apo B secretion from the oleate-stimulated HepG2 cells. Furthermore, G-hesperidin significantly suppressed apo B secretion only in the oleate-stimulated cells and failed to act on the cells incubated without oleate. In the oleate-stimulated cells, G-hesperidin significantly decreased cellular cholesteryl ester (CE), although it had no effect on cellular TG or free cholesterol amounts. Moreover, the oleate-stimulated cells had a decrease in cellular apo B amounts by G-hesperidin exposure. These findings indicate that G-hesperidin down-regulates the assembly of apo B-containing lipoproteins via the reduction of CE synthesis augmented with oleate and results in suppressing excess apo B secretion from the cells. This effect is speculated to be associated with the improvement of VLDL metabolic abnormality in hypertriglyceridemic subjects and considered as a mechanism of lowering serum TG.

Three oxygenated cyclohexenone derivatives produced by an endophytic fungus.

Three cyclohexenone derivatives, (4S,5S,6S)-5,6-epoxy-4-hydroxy-3-methoxy-5-methyl-cyclohex-2-en-1-one (1), (4R,5R)-4,5-dihydroxy-3-methoxy-5-methyl-cyclohex-2-en-1-one (2), and (4R,5S,6R)-4,5,6-trihydroxy-3-methoxy-5-methyl-cyclohex-2-en-1-one (3), were isolated from unpolished rice fermented with an xylariaceous endophytic fungus (strain YUA-026). The structures of three compounds were established on the basis of spectroscopic analyses and chemical conversion. The minimum inhibitory concentrations of 1 and 3 were 100 microg/ml and 400 microg/ml against Staphylococcus aureus, 100 microg/ml and 200 microg/ml against Pseudomonas aeruginosa, and 200 microg/ml and >400 microg/ml against Candida albicans, respectively. In addition, 1 and 3 exhibited phytotoxic activity against lettuce.

Glucosyl hesperidin lowers serum triglyceride level in hypertriglyceridemic subjects through the improvement of very low-density lipoprotein metabolic abnormality.

To examine the serum triglyceride (TG)-lowering effect of a soluble hesperidin derivative, glucosyl hesperidin (G-hesperidin), and its mechanisms, we carried out a G-hesperidin administration test in hypertriglyceridemic subjects. G-Hesperidin was administered to the subjects at 500 mg/d for 24 wk. In this study, the subjects were classified into high-TG type (TG > 150 mg/dL), borderline-TG type (TG 110-150 mg/dL) and normal-TG type (TG < 110 mg/dL) on the basis of their initial serum TG values. Among these phenotypes, serum TG level significantly decreased in the high-TG type during the G-hesperidin administration period. It was also observed that elevated values of serum remnant-like particle cholesterol (RLP-C), apolipoprotein (apo) B, apo C-II, apo C-III and apo E occurred in the high-TG type and that these serum levels were significantly reduced by G-hesperidin administration. Moreover, polyacrylamide gel electrophoresis analysis of serum lipoproteins revealed that the very low-density lipoprotein (VLDL)/low-density lipoprotein (LDL) ratio and LDL migration index of the high-TG type were remarkably higher than those of the other phenotypes but that their high values were significantly reduced by the administration. These results indicate that G-hesperidin preferentially lowers serum TG in hypertriglyceridemic subjects and that this effect is possibly caused by the improvement of VLDL metabolic abnormality, leading to the reduction of small dense LDL.

Absolute stereochemistry of acremolactone A, a novel herbicidal epoxydihydropyranyl gamma-lactone from Acremonium roseum I4267.

Acremolactone A was chemically degraded to the bicyclic hemiacetal gamma-lactone and an epoxycyclohexenol, and their stereochemistry was determined by spectroscopic methods. These observations and data from NOE experiments on acremolactone A led to the configurational assignment of all asymmetric carbons in acremolactone A, enabling its stereostructure to be established.

Erinacol (cyatha-3,12-dien-14beta-ol) and 11-O-acetylcyathin A3, new cyathane metabolites from an erinacine Q-producing Hericium erinaceum.

In our search for new cyathane metabolites related to the biosynthesis of erinacine Q in Hericium erinaceum, we isolated a novel cyatha-3,12-dien-14beta-ol named erinacol together with known 11-O-acetylcyathatriol (the erinacine Q aglycon) and new metabolite 11-O-acetylcyathin A(3) from the mycelial extract. The structure of each compound was determined by spectral methods. Possible biosynthetic relationships of these metabolites are discussed from their structural features.