Enzymatic Acylation of Flavonoids from Bamboo Leaves: Improved Lipophilicity and Antioxidant Activity for Oil-Based Foods.

The goal of this study was to expand the applications of bamboo leaf flavonoids (BLFs) by improving their lipophilicity through enzymatic acylation with vinyl cinnamate. Characterization of the acylated BLFs using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, high-resolution electrospray ionization mass spectrometry, electrospray ionization with tandem mass spectrometry, and 1H nuclear magnetic resonance spectroscopy indicated that acylation occurred at the C6-OH position of glucoside moieties. The highest degree of acylation (18.61%) was obtained by reacting BLFs with vinyl cinnamate (1:5, w/w) at 60 °C for 48 h. Acylation significantly improved the lipophilicity of BLFs and their capacity to inhibit lipid peroxidation, as evidenced by the reduced production of lipid hydroperoxides and malondialdehyde in rapeseed oil and rapeseed oil-in-water emulsions during storage at 37 °C for 15 days. The study findings provide important data that will enable the use of BLFs in lipid or lipophilic matrices, such as oil-based foods.

Enzymatic acylation improves the stability and bioactivity of lutein: Protective effects of acylated lutein derivatives on L-O2 cells upon H2O2-induced oxidative stress.

The instability of lutein has limited its wide application especially in the food industry. In this study, enzymatic acylation of lutein with divinyl adipate was investigated. Three new acylated lutein derivatives, lutein-3-O-adipate (compound 1), lutein-3'-O-adipate (compound 2) and lutein-di-adipate (compound 3), were identified and their stabilities and bioactivates were evaluated. Notably, compounds 1-3 showed better thermal, light stability and stronger scavenging capacity to ABTS radical cation (ABTS+) and hydroxyl radical (OH). Most importantly, these acylated lutein derivatives exhibited excellent protective effects on L-O2 cells upon hydrogen peroxide (H2O2)-induced oxidative stress. In particular, the acylated lutein derivative termed compound 3 prevented cellular oxidative stress via restraining the overproduction of reactive oxygen species (ROS), thereby increasing related antioxidant enzymes activity and inhibiting apoptosis by mitochondria pathway. Our research provides important insights into the application of acylated lutein derivatives in food, cosmetic, and pharmaceutical products.

Enzymatic acylation of lutein with a series of saturated fatty acid vinyl esters and the thermal stability and anti-lipid oxidation properties of the acylated derivatives.

Lutein was enzymatically acylated with saturated fatty acid vinyl esters of different lengths of carbon chain (C6 -C14 ) under the action of Candida antarctica lipase B (Novozyme 435). The acylation reaction was optimized by considering substrate molar ratio, reaction solvent, type of enzyme, and reaction time. The highest yield (88%) was obtained using the Novozyme 435 to catalyze the acylation reaction of lutein and vinyl decanoate (lutein/vinyl decanoate molar ratio of 1/10) for 16 h in methyl tert-butyl ether. Ten lutein esters were synthesized, isolated, and purified, which were characterized by Fourier-transform infrared spectroscopy, high-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy. We found that the acylation of lutein improved its antioxidant capacity in lipid system and thermal stability. Our study extended the potential application of lutein in lipophilic food, cosmetic, and pharmaceutical industries. Practical Application: Enzyme acylation of lutein improved its antioxidant capacity in lipid system and thermal stability, extended its potential application in food, cosmetic, and pharmaceutical industries. In addition, our study also provided a new perspective and cognition for the further development and utilization of lutein.

Enzymatic acylation of rutin with benzoic acid ester and lipophilic, antiradical, and antiproliferative properties of the acylated derivatives.

Rutin (3',4',5,7-tetrahydroxy-flavone-3-rutinoside) was enzymatically acylated with benzoic acid and its esters (methyl benzoate and vinyl benzoate) using Thermomyces lanuginosus lipase (Lipozyme TLIM). The acylation reaction was optimized by varying the reaction medium, reaction temperature, acyl donor, substrate molar ratio, and reaction time. The highest conversion yield (76%) was obtained in tert-amyl alcohol (60 °C, 72 hr) using vinyl benzoate (molar ratio of 1:10) as acyl donor. The acylation occurred at the 2'''-OH and 4'''-OH of the rhamnose unit and the 2''-OH position of the glucose moieties. Three novel rutin acylated derivatives (compounds 1-3) were purified and characterized by HR-MS and 1D and 2D NMR spectroscopy. We found that acylation significantly improved lipophilicity, capacity to inhibit lipid peroxidation, anticancer capacity and substantially maintained the antioxidant activity of rutin. This research provides important insights in the acylation of flavonoids with different glycosyl moieties. PRACTICAL APPLICATION: In this study, three novel rutin derivatives were successfully synthesized and the highest conversion yield (76%) was obtained by reacting the rutin and vinyl benzoate at molar ratio of 1:10 in tert-amyl alcohol for 72 hr at 60 °C. Introducing a benzoic acid substituent into rutin molecule significantly improved their lipophilicity and inhibition of lipid peroxidation in lipophilic system. Furthermore, this study demonstrated that acylation significantly improved anticancer capacity and substantially maintained the antioxidant activity.

Comparative study on the phytochemical profiles and cellular antioxidant activity of phenolics extracted from barley malts processed under different roasting temperatures.

Consumption of cereal foods has been related to health improvement, which is partly because of their phytochemicals. To explore the functionality and effective application of barley malt, a widely consumed nutritional food, the entire phytochemical profiles and bioactivities of three common barley malt products obtained under different roasting temperatures were analyzed. Results showed that they are abundant in phenolics including flavonoids with high antioxidative activities, as displayed by cellular antioxidant activity (CAA), oxygen radical absorbance capacity, peroxyl radical scavenging capacity, and DPPH and ABTS radical scavenging assays. Among the three barley malts, the raw barley malt bound extract and the dark barley malt free extract exhibited higher CAA values, while the raw barley malt contained a negligible amount of bound phenolics. An efficacious antiproliferation capacity of the dark barley malt free extract was detected in Caco-2 cells. Results also provide an insight into the positive attributes of thermal processing for the biofunctionality of barley malts, especially through the tuning of the accessibility and variability of beneficial phytochemicals.

Comparative Study of the Emulsifying Properties of a Homologous Series of Long-Chain 6'- O-Acylmaltose Esters.

Emulsifiers derived from renewable resources such as sucrose and fatty acids are high volume commodity chemicals and currently produced by traditional chemical synthesis techniques that lack the capacity to form the most desirable monoesters (of sucrose) in a selective and efficient fashion. The development of new emulsifiers (surfactants) from alternate, structurally simpler but nevertheless abundant disaccharides such as maltose represents a possible solution to this problem. Herein, we report the facile enzymatic preparation of a homologous series of 6'- O-acylmaltose esters and an in-depth evaluation of them revealing that their surfactant properties and thermal stabilities are largely determined by the length of the fatty acid chain. In the first such comparison, we show that the foaming and emulsifying effects of certain of these maltose monoesters are superior to those of their sucrose-derived and commercially exploited counterparts. As such, maltose esters have considerable potential as emulsifiers for use in, for example, the food industry.

C-geranylated flavanones from YingDe black tea and their antioxidant and α-glucosidase inhibition activities.

YingDe black tea is produced from crude tea prepared from leaves of Camellia sinensis var. assamica. In this work, we isolated and identified five novel flavanones, namely, amelliaone A-E (1-5), along with seven known compounds 6-12 from the ethanol extract of YingDe black tea. The structures of these five novel phenolic compounds were determined using extensive 1D and 2D nuclear magnetic resonance spectroscopy experiments. The compounds were further evaluated for antioxidant, α-glucosidase inhibitory, and cytotoxic activities. Compound 1 exhibited higher α-glucosidase inhibitory activity with a half-maximum inhibitory concentration value (IC50) of 10.2µM compared with acarbose (18.2µM).

Two new flavonoids from the bark of Allium chrysanthum.

The isolation and structure elucidation of two new flavonoids, chrysanthumones A and B from the extracts of Allium chrysanthum were reported. Seven known phenolic constituents were also isolated. Their structures were determined on the basis of NMR and MS techniques.

Enzymatic Synthesis of l-Ascorbyl Fatty Acid Esters Under Ultrasonic Irradiation and Comparison of Their Antioxidant Activity and Stability.

A series of novel l-ascorbyl fatty acid esters were synthesized by catalization of Novozym(®) 435 under ultrasonic irradiation and characterized by infrared spectroscopy, electrospray ionization mass spectra, and nuclear magnetic resonance. Their properties especially antioxidant activity and stability were investigated. The results showed that the reducing power, the scavenging activity of hydroxyl radical and 2,2-diphenyl-1-picrylhydrazyl radical were decreased with the increase of the number of carbon atoms in fatty acid. The hydroxyl radical scavenging activity and reducing power of l-ascorbyl saturated fatty acid esters were better than that of tert-butylhydroquinone. The induction period in lipid oxidation of l-ascorbyl saturated fatty acid esters and tert-butylhydroquinone were longer than that of l-ascorbyl unsaturated fatty acid esters and l-ascorbic acid both in soybean oil and lard. Besides, the l-ascorbyl fatty acid esters showed different stabilities in different conditions by comparing with l-ascorbic acid, and the l-ascorbyl saturated fatty acid esters were more stable than l-ascorbyl unsaturated fatty acid esters in ethanol solution.

Acylation of Antioxidant of Bamboo Leaves with Fatty Acids by Lipase and the Acylated Derivatives' Efficiency in the Inhibition of Acrylamide Formation in Fried Potato Crisps.

This study selectively acylated the primary hydroxyl groups on flavonoids in antioxidant of bamboo leaves (AOB) using lauric acid with Candida antarctica lipase B in tert-amyl-alcohol. The separation and isolation of acylated derivatives were performed using silica gel column chromatography with a mixture of dichloromethane/diethyl ether/methanol as eluents. Both thin layer chromatography and high-performance liquid chromatography analyses confirmed the high efficiency of the isolation process with the purified orientin-6″-laurate, isoorientin-6″-laurate, vitexin-6″-laurate, and isovitexin-6″-laurate that were obtained. The addition of AOB and acylated AOB reduced acrylamide formation in fried potato crisps. Results showed that 0.05% AOB and 0.05% and 0.1% acylated AOB groups significantly (p < 0.05) reduced the content of acrylamide in potato crisps by 30.7%, 44.5%, and 46.9%, respectively.

Characterization of phenolic constituents inhibiting the formation of sulfur-containing volatiles produced during garlic processing.

Garlic (Allium sativum L.), which is a widely distributed plant, is globally used as both spice and food. This study identified five novel phenolic compounds, namely, 8-(3-methyl-(E)-1-butenyl)diosmetin, 8-(3-methyl-(E)-1-butenyl)chrysin, 6-(3-methyl-(E)-1-butenyl)chrysin, and Alliumones A and B, along with nine known compounds 6-14 from the ethanol extract of garlic. The structures of these five novel phenolic compounds were established via extensive 1D- and 2D-nuclear magnetic resonance spectroscopy experiments. The effects of the phenolic compounds isolated from garlic on the enzymatical or nonenzymatical formation of sulfur-containing compounds produced during garlic processing were examined. Compound 12 significantly reduced the thermal decomposition of alliin, whereas compound 4 exhibited the highest percentage of alliinase inhibition activity (36.6%).

Characterisation and oxidation stability of monoacylglycerols from partially hydrogenated corn oil.

This study reported the characterisation of some types of monoacylglycerols (MAGs) obtained by the glycerolysis of different partially hydrogenated corn oils (PHCOs) catalysed by Al2O3 loaded with K2CO3 (K2CO3/Al2O3) under the previous selected conditions. A two-stage molecular distillation method of purifying the MAGs was introduced, and the obtained MAG products were more than 90.0 wt.% pure. The fatty acid composition of corn oil significantly changed after hydrogenation sequentially catalysed by Pricat™ Ni catalysts (9908 Ni/kieselguhr and 9920 Ni/Al2O3). The PHCO samples generated typical structures with ß'-form crystals. Moreover, the melting regions of all hydrogenated samples and their MAGs shifted to higher temperatures. The oxidation stability of MAGs has been significantly increased using hydrogenation to change the fatty acid composition.

1,3-Dichloro-2-propanol inhibits progesterone production through the expression of steroidogenic enzymes and cAMP concentration in Leydig cells.

1,3-Dichloro-2-propanol (1,3-DCP) is a well-known food processing contaminant that has been shown to impede male reproductive function. However, its mechanism of action remains elusive. In this study, the effects of 1,3-DCP on progesterone production were investigated using the R2C Leydig cell model. 1,3-DCP significantly reduced cell viability from 7.48% to 97.4% at doses comprised between 0.5 and 6mM. Single cell gel/comet assays and atomic force microscopy assays showed that 1,3-DCP induced early phase cell apoptosis. In addition, 1,3-DCP significantly reduced progesterone production detected by radioimmunoassay (RIA). The results from quantitative polymerase chain reaction and western blotting demonstrated that the mRNA expression levels of steroidogenic acute regulatory protein (StAR), cytochrome P450 side-chain cleavage enzyme and 3ß-hydroxysteroid dehydrogenase were significantly down-regulated in R2C cells. Particularly, the change rhythm of Star expression was highly consistent with progesterone production. Furthermore, the cyclic adenosine monophosphate (cAMP) and the mitochondrial membrane potential mediated by ROS, which are involved in regulating progesterone synthesis were also decreased in response to the 1,3-DCP treatment. Overall, the data presented here suggested that 1,3-DCP interferes with the male steroidogenic capacity mainly by down-regulating the level of cAMP and the key enzymes involved in the androgen synthesis pathway.

A new dipeptide isolated from the bulb of garlic.

(R)-3-(allylthio)-2-((R)-3-(allylthio)-2-aminopropanamido)propanoic acid was isolated from the bulb of garlic, together with four known amino acids. Its structure was elucidated on the basis of 2D NMR and MS techniques. To the best of our knowledge, (R)-3-(allylthio)-2-((R)-3-(allylthio)-2-aminopropanamido)propanoic acid, which showed antibacterial activity against the Staphylococcus aureus antibiotic resistant strain, was the first example of dipeptide from garlic.

Enzymatic hydrolysis preparation of mono-O-lauroylsucrose via a mono-O-lauroylraffinose intermediate.

1'-O-Lauroylsucrose and 6'-O-lauroylsucrose were formed through hydrolysis of the C-6″ galactose group of 1'-O-lauroylraffinose and 6'-O-lauroylraffinose, respectively, in the presence of α-galactosidase. The enzymatic hydrolysis of 1'-O-lauroylraffinose and 6'-O-lauroylraffinose is discussed in detail. Acetic acid-sodium acetate was chosen as the buffer solution of the enzymatic hydrolysis reaction. The optimum conditions for the enzymatic hydrolysis reaction were as follows: buffer solution, pH 3.8; enzymatic time, 48 h; and enzymatic temperature, 37 °C. Under the optimal process conditions, the efficiency of α-galactosidase was ca. 82.6%. The isomers were fully compared in solubility, hydrophile-lipophile balance (HLB) values, critical micelle concentration (CMC), and thermal stability. The results showed that all lauroylsucrose isomers have similar solubilities in polar solvent, HLB values, CMC values, and thermal stabilities.

Enzymatic acylation of isoorientin and isovitexin from bamboo-leaf extracts with fatty acids and antiradical activity of the acylated derivatives.

This study enzymatically acrylates two flavonoids from bamboo-leaf extracts, isoorientin and isovitexin, with different fatty acids as acyl donors using Candida antarctica lipase B (CALB). The conversion yield ranged from 35 to 80% for fatty acids with different chain lengths. Higher isoorientin and isovitexin conversion yields (>75%) were obtained using lauric acid in tert-amyl-alcohol as the reaction medium. (1)H and (13)C nuclear magnetic resonance spectroscopy analysis showed that, in the presence of CALB, acylation occurred at the isoorientin and isovitexin primary hydroxyl group of glucose moiety and only monoesters were detected. Introducing an acyl group into isoorientin and isovitexin significantly improved their lipophilicity but reduced their antiradical activity.

1,2-Bis(4-nitro-benz-yl)diselane.

The title compound, C(14)H(12)N(2)O(4)Se(2), is not chiral, but the mol-ecules assume a chiral conformation in the solid state and crystallize as an aggregate. The central C-Se-Se-C torsion angle is 90.4 (2)°, while the two Se-Se-C-C fragments assume gauche conformations with values of -59.4 (5) and 67.5 (4)°. The dihedral angle between the two benzene rings is 80.74 (14)°.

trans-3,3',4,5'-Tetra-meth-oxy-stilbene.

The title compound, C(18)H(20)O(4), was synthesized by a Wittig-Horner reaction of diethyl 3,4-dimeth-oxy-benzyl-phosphate and 3,5-dimeth-oxy-benzaldehyde. In the crystal, the dihedral angle between the two aromatic rings is 2.47 (12)°. All the meth-oxy groups are almost coplanar with the aromatic ring to which they are attached [C-C-O-C torsion angles = -2.8 (3), -5.2 (4), -176.3 (2) and -178.0 (2)°].

(±)-4a-(4-Nitro-benz-yl)-2,3,4,4a-tetra-hydro-1H-carbazole.

The title mol-ecule, C(19)H(18)N(2)O(2), is built up from three fused rings, viz. phenyl, pyrrole and cyclo-hexane, linked to a nitro-benzyl group. The C atom bearing the nitro-benzyl group is chiral and the compound is a racemate (R/S). The dihedral angle between the nitro-benzyl and indole rings is 57.49 (5)°. The cyclo-hexane ring adopts a slightly distorted chair conformation.