2-Acetyl-1-pyrroline (2-AP) was identified as the major flavor compound in aromatic rice varieties Tainung 71 and 72. In order to understand the mechanism of 2-AP biosynthesis in aromatic rice, we studied the formation of putative precursors, Delta(1)-pyrroline-5-carboxylic acid and methylglyoxal. The endogenous Delta(1)-pyrroline-5-carboxylic acid contents of Tainung 71 and 72 calli reached 191 to 276%, compared to nonaromatic rice Tainung 67. In addition, calli of Tainung 71 and 72 contained 1.30- and 1.36-fold, respectively, higher methylglyoxal levels than that of Tainung 67. Specific enzyme activities of Delta(1)-pyrroline-5-carboxylic acid-synthetic enzyme including Delta(1)-pyrolline-5-carboxylic acid synthetase (P5CS) and ornithine aminotransferase (OAT) increased significantly in aromatic rice varieties. The expression levels of P5CS1 and P5CS2 genes were found to be significantly higher in aromatic rice than nonaromatic rice. Results of a tracer experiment with (15)N-labeled glutamic acid revealed that the nitrogen atom of 2-acetyl-1-pyrroline was derived from glutamic acid. Upregulation of P5CS in aromatic rice Tainung 72 may contribute to the increase of Delta(1)-pyrroline-5-carboxylic acid level and thus leads to the accumulation of an extra amount of 2-acetyl-1-pyrroline.

The effect of growth phase on the membrane-associated phospholipid biosynthetic enzymes CDPdiacylglycerol synthase, phosphatidylserine synthase, phosphatidylinositol synthase, and the phospholipid N-methyltransferases in wild-type Saccharomyces cerevisiae was examined. Maximum activities were found in the exponential phase of cells grown in complete synthetic medium. As cells entered the stationary phase of growth, the activities of the CDP-diacylglycerol synthase, phosphatidylserine synthase, and the phospholipid N-methyltransferases decreased 2.5-to 5-fold. The subunit levels of phosphatidylserine synthase and the cytoplasmic-associated enzyme inositol-1-phosphate synthase were not significantly affected by the growth phase. When grown in medium supplemented with inositol-choline, cells in the exponential phase of growth had reduced CDP-diacylglycerol synthase, phosphatidylserine synthase, and phospholipid N-methyltransferase activities, with repressed subunit levels of phosphatidylserine synthase and inositol-1-phosphate synthase compared with cells grown without inositol-choline. Enzyme activity levels remained reduced in the stationary phase of growth of cells supplemented with inositol-choline. The phosphatidylserine synthase and inositol-1-phosphate synthase subunit levels, however, were derepressed. Phosphatidylinositol synthase (activity and subunit) was not affected by growth in medium supplemented with or without inositol-choline or the growth phase of the culture. The phospholipid composition of cells in the exponential and stationary phase of growth was also examined. The phosphatidylinositol to phosphatidylserine ratio doubled in stationary-phase cells. The phosphatidylcholine to phosphatidylethanolamine ratio was not significantly affected by the growth phase of cells.

Proline dehydrogenase (PRODH) catalyzes the biosynthesis of Delta1-pyrroline-5-carboxylic acid (P5C). The Bacillus subtilis subsp. natto gene for the proline dehydrogenase (BnPRODH) was cloned and expressed in Escherichia coli. Nucleotide sequence analysis of the clone revealed an open-reading frame that encodes 302 amino acid polypeptide with a calculated molecular mass of 34.5 kDa. The deduced amino acid sequence showed sequence similarity to bacterial PRODH and PutA of E. coli. The BnPRODH gene was cloned into pET21b and was expressed at a high level in E. coli BL21(DE3). The expressed protein was purified by using nickel ion affinity column chromatography to homogeneity before characterization. The purified recombinant BnPRODH was used to produce P5C. Model system composed of P5C and methylglyoxal was set up to study the formation of 2-acetyl-1-pyrroline. Our data showed that P5C, derived from the conversion of l-proline by the purified recombinant PRODH, might react directly with methylglyoxal to form 2-AP. P5C/methylglyoxal pathway represents the first report of a biological mechanism by which 2-AP may be synthesized in vitro by PRODH.

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Available online A B S T R A C TThe herbal composition of Coleus forskohlii, Salacia reticulata, and Sesamum indicum, standardized for forskolin, mangiferin, and sesamin, respectively, were shown, in vitro, to inhibit pancreatic lipase with differing degrees and dynamics. In the placebo controlled six weeks clinical study the daily intake of 1000 mg C. forskohlii stand-alone standardized for 10% forskolin, showed statistically significant lowering of total body fat vs. baseline and placebo group (p < 0.05).The computerized tomography showed decrease of total body fat and visceral fat in C. forskohlii group in comparison to the baseline. The potential of three herbal extracts preventing dietary fat absorption was emphasized by the in vitro synergy between C. forskohlii and S. reticulata inhibiting pancreatic lipase at higher rate than the fat-blocking activity generated by each component alone. The in vitro addition of S. indicum to the formula was found to synergistically assist inhibition of the pancreatic lipase in a lower dose range, while moderating the pancreatic lipase inhibition in a higher dose range. This dual mechanism of S. indicum was postulated as a safety mechanism preventing any potential side effects resulting from excessive inhibition of pancreatic lipase activity.

Gut-brain connections may be mediated by an assortment of microbial molecules, which can subsequently traverse intestinal and blood-brain barriers and impact neurological function. Pattern recognition receptors (PRRs) are important innate immune proteins in the gut. Gut microbiota act in concert with the PRRs is a novel target for regulating host-microbe signaling and immune homeostasis, which may involve the pathogenesis of neurodegenerative diseases. Natural food bioactives bestow a protective advantage on neurodegenerative diseases through immunomodulatory effects of the modified gut microbiota or alterations in the landscape of microbiota-produced metabolites via PRRs modulation. In this review, we discuss the effect of natural food bioactives on the gut microbiota and the role of PRRs in the gut-brain crosstalk. We focused on the neuroprotective mechanisms of natural bioactive compounds behind the action of the gut microbiota and PRRs. Research advances in natural food bioactives as antineurodegeneration agents were also presented.

Caffeine-containing products have been consumed for hundreds of years for the delightful flavor and stimulating effects they possess. This group of products includes coffee, tea, and cocoa, as well as some less familiar products such as guaranâ and kola. The two most commonly consumed beverages in the world today are coffee and tea, which are produced by hot water extraction of the roasted bean and leaf respectively.The one common constituent they possess is caffeine, 1,3,7-trimethylxanthine, a white crystalline solid mp 238° C. Caffeine is a stable compound that is not destroyed by the roasting of coffee, the fermentation or roasting of cocoa, or the fermenting or firing of tea. CaffeineAccording to the Merck Index, caffeine is a CNS stimulant, and acts as a diuretic. As will become evident from this volume, caffeinated products possess additional positive health benefits for humans such as antioxidant properties, as well as possible anticarcinogenic activity. The ubiquitous consumption of caffeinated products throughout the world attests to the power these products hold on humans.The symposium upon which this book is based was developed to explore recent advances in the flavor chemistry, physiological effects, and health benefits xi

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