No abstract

Ginger, the rhizome of Zingiber officinale, is a traditional medicine with anti-inflammatory and anticarcinogenic properties. This study examined the growth inhibitory effects of the structurally related compounds 6-gingerol and 6-shogaol on human cancer cells. 6-Shogaol [1-(4-hydroxy-3-methoxyphenyl)-4-decen-3-one] inhibits the growth of human cancer cells and induces apoptosis in COLO 205 cells through modulation of mitochondrial functions regulated by reactive oxygen species (ROS). ROS generation occurs in the early stages of 6-shogaol-induced apoptosis, preceding cytochrome c release, caspase activation, and DNA fragmentation. Up-regulation of Bax, Fas, and FasL, as well as down-regulation of Bcl-2 and Bcl-X(L )were observed in 6-shogaol-treated COLO 205 cells. N-acetylcysteine (NAC), but not by other antioxidants, suppress 6-shogaol-induced apoptosis. The growth arrest and DNA damage (GADD)-inducible transcription factor 153 (GADD153) mRNA and protein is markedly induced in a time- and concentration-dependent manner in response to 6-shogaol.

The objective of the present study is to develop a rapid and convenient method to determine antioxidative activity. It was determined by the inhibition capacity on the hemoglobin-catalyzed peroxidation of linoleic acid. The appropriate conditions for reaction of 4 mM linoleic acid were 0.002% hemoglobin at 37 degrees C for 10 min. Adding methanol to the reaction mixture at <20% showed no significant effect on the peroxidation of linoleic acid. Products formed from hemoglobin-catalyzed peroxidation of linoleic acid were 9- and 13-hydroperoxyoctadecadienoic acid at a ratio of approximately 50:50. Eight synthetic antioxidants were assayed for their antioxidative activity; all of them showed linear response to the logarithm of their concentration. Antioxidative activity from different plant samples was also examined. Tea, ginger, chrysanthemum, and roselle showed higher antioxidative activity. Either hydrophobic or hydrophilic antioxidants were able to be assayed with this method within 15 min.

Lactic acid bacteria were isolated from fish and evaluated for their γ-aminobutyric acid (GABA)-producing abilities. Out of thirty-two isolates, Lactobacillus brevis RK03 showed the highest GABA production ability. The effects of various fermentation parameters including initial glutamic acid level, culture temperature, initial pH, and incubation time on GABA production were investigated via a singleparameter optimization strategy. For industrial large-scale production, a low-cost GABA producing medium (GM) broth was developed for fermentation with L. brevis RK03. We found that an optimized GM broth recipe of 1% glucose; 2.5% yeast extract; 2 ppm each of CaCO3, MnSO4, and Tween 80; and 10 μM pyridoxal phosphate (PLP) resulted in a maximum GABA yield of 62,523 mg/L after 88 h following the addition of 650 mM monosodium glutamate (MSG), for a conversion rate of 93.28%. Our data provide a practical approach for the highly efficient and economic production of GABA. In addition, L. brevis RK03 is highly resistant to gastric acid and bovine bile salt. Thus, the discovery of Lactobacillus strains with the ability to synthesize GABA may offer new opportunities in the design of improved health-promoting functional foods.

The objective of the present study was to purify and characterize the lipoxygenase (LOX) from banana leaf (Giant Cavendishii, AAA), an unutilized bioresource. LOX was extracted, isolated, and purified 327-fold using 25-50% saturation of ammonium sulfate fractionation, hydroxyapatite column separation, and gel filtration on Superdex 200. The molecular mass of the purified LOX was 85 kDa, K(m) was 0.15 mM, and V(max) was 2.4 microM/min.mg using linoleic acid as substrate. Triton X-100 was required in the extraction medium; otherwise, no LOX activity was detected. LOX activity increased with the concentration of Triton X-100 with an optimum at 0.1%. The optimal pH of the purified LOX from banana leaf was 6.2, and optimal temperature was 40 degrees C. The LOX showed the highest reactivity toward 18:2 followed by 18:3 and 20:4. A very low reaction rate was observed toward 20:5 and 22:6. On the basis of retention time in normal phase HPLC, the products of 18:2 or 18:3 catalyzed by purified LOX were hydroperoxyoctadecadienoic acid or hydroperoxyoctadecatrienoic acid. It seems that 9-LOX is the predominant enzyme in banana leaf. Banada leaf dried at 110 degrees C for 2 h developed algal aroma. Banana leaf extract stored at 10 degrees C for 12 h formed an oolong tea-like flavor. Banana leaf extract reacted with 18:2 or soybean oil pretreated with bacterial lipase produced green and melon-like aroma, whereas the same reaction with 18:3 produced a sweet, fruity, cucumber-like flavor note.

Iron deficiency is one of the most concerning deficiency problems in the world. It may generate several adverse effects such as iron deficiency anemia (IDA) and reduced physical and intellectual working capacity. The aim of this study is to evaluate the Fe(II)-binding activity of collagen peptides from fishery by-products. Lates calcarifer, Mugil cephalus, Chanos chanos, and Oreochromis spp are four major cultivated fishes in Taiwan; thousands of scales of these fish are wasted without valuable utilization. In this study, scales of these fish were hydrolyzed by papain plus flavourzyme. Collagen peptides were obtained and compared for their Fe(II)-binding activity. Collagen peptides from Chanos chanos showed the highest Fe(II)-binding activity, followed by those from Lates calcarifer and Mugil cephalus; that from Oreochromis spp exhibited the lowest one. Fe(II)-binding activity of collagen peptides from fish scales was also confirmed with a dialysis method. Molecular weight (MW) distributions of the collagen peptides from scales of four fish are all < 10 kDa, and averaged 1.3 kDa. Hydrolysates of fish scales were further partially purified with ion exchange chromatography. Fractions having Fe(II)-binding activity were obtained and their activity compared. Data obtained showed that collagen peptides from fish scales did have Fe(II)-binding activity. This is the first observation elucidating fish scale collagen possessing this functionality. The results from this study also indicated that collagen peptides from fish scales could be applied in industry as a bioresource.

Lipoxygenase (LOX) activity was identified in a green sea algae (Enteromorpha intestinalis). The oxygen consumption rate of sea algae-catalyzed oxidation of linoleic acid was 1.18 μmol/min·mg of protein. The catalytic rate was 911 times that of shrimp hemolymph LOX and 59 times that of trout gill LOX. Based on retention time in normal phase HPLC analysis and UV absorption spectrosocopy, hydroperoxidation of linoleic acid by sea algae LOX was at the C9 and C13 positions with a ratio of 1.97:1. The products of sea algae LOX treated with arachidonic acid were 12- (or 8-) and 15-HETE (hydroxyeicosatetraenoic acid) on the basis of retention time in reverse phase HPLC analysis. Thus, 12- (or 8-) and 15-LOX were the major LOX isozymes in the sea algae. The optimal pH of sea algae LOX was 7.8 and the optimal temperature was around 35 °C. Different treatments of sea algae generated volatile compounds contributing to flavor notes of clam, oyster, fresh apple, cucumber, mango, and algae identified with the GC-sniffing method. This is the first observation of LOX in marine algae with respect to its possible roles in seafood flavor formation. Keywords: Lipoxygenase; sea algae; seaweed; Enteromorpha intestinalis; flavor

A calcium-stimulated lipoxygenase (LOX) was isolated and purified 103-fold from sea algae (Ulva lactuca) using 40−55% saturation of ammonium sulfate fractionation, MacroPrep-Q ion exchange, and gel filtration on Sephacryl S-300. When this partially purified algal LOX was run on 4−20% polyacrylamide gel electrophoresis (PAGE), two bands with LOX activity were found using activity staining. The apparent molecular masses were estimated as 41 and 116 kDa by PAGE. The LOX activities from the sea algae were stimulated by Ca2+ at 0.2 mM to a maximal activity of about 8.8-fold. The optimal pH of the algal LOX was 7.5, and optimal temperature was 33 °C. At pH ranging from 5.5 to 9.0 and temperature below 40 °C, the algal LOX was stable. The algal LOX showed the highest reactivity toward 18:2 fatty acid followed by 20:4, 20:5, 22:6, and 18:3. Linoleic acid and its esters were peroxidized by algal LOX in the order linoleic acid ≫ monolinolein > dilinolein > methyl linoleate, but no activity was observed on trilinolein. On the basis of retention time in normal phase HPLC, the products of 18:2 reacting with algal LOX were 9- and 13-hydroxyoctadecadienoic acid at a ratio of 86:14; the product from 18:3 was 9-hydroxyoctadecatrienoic acid. Products derived from 20:4 were 12- and 15-hydroxyeicosatetraenoic acid at a ratio of 90:10 using reversed phase HPLC. Fatty acids of 20:5 and 22:6 yielded 12-hydroxyeicosapentaenoic acid and 14-hydroxydocosahexaenoic acid, respectively. It seems that n-9 LOX is the dominant LOX and n-6 LOX is the minor LOX in sea algae. Keywords: Lipoxygenase; sea algae; Ulva lactuca; purification; calcium stimulation