Supercritical Fluid CO2 Extraction and Microcapsule Preparation of Lycium barbarum Residue Oil Rich in Zeaxanthin Dipalmitate.

The scope of this investigation aimed at obtaining and stabilizing bioactive products derived from Lycium barbarum seeds and peels, which were the byproducts in the processing of fruit juice. Zeaxanthin dipalmitate is a major carotenoid, comprising approximately 80% of the total carotenoid content in the seeds and peels. The method of obtainment was supercritical fluid CO2 extraction, studying different parameters that affect the oil yield and content of zeaxanthin dipalmitate. The optimized protocol to enact successful supercritical fluid CO2 extraction included optimum extraction pressure of 250 bar, temperature at 60 °C over a time span of 2.0 h, and a CO2 flow of 30 g/min, together with the use of a cosolvent (2% ethanol). The yields of oil and zeaxanthin dipalmitate under these optimal conditions were 17 g/100 g and 0.08 g/100 g, respectively. The unsaturated fatty acids were primarily linoleic acid (C18:2), oleic acid (C18:1), and γ-linolenic acid (C18:3), with their contents being as high as 91.85 ± 0.27% of the total fatty acids. The extract was a red-colored oil that was consequently microencapsulated through spray-drying with octenylsuccinate starch, gum arabic, and maltodextrin (13.5:7.5:3, w/w) as wall materials to circumvent lipid disintegration during storage and add to fruit juice in a dissolved form. The mass ratio of core material and wall material was 4:1. These materials exhibited the highest microencapsulation efficiency (92.83 ± 0.13%), with a moisture content of 1.98 ± 0.05% and solubility of 66.22 ± 0.24%. The peroxide content level within the microencapsulated zeaxanthin dipalmitate-rich oil remained at one part per eight in comparison to the unencapsulated oil, following fast-tracked oxidation at 60 °C for 6 weeks. This indicated the potential oxidation stability properties of microcapsule powders. Consequently, this microencapsulated powder has good prospects for development, and can be utilized for a vast spectrum of consumer health and beauty products.

Structural characterization, antioxidant and immunomodulatory activities of a neutral polysaccharide from Cordyceps militaris cultivated on hull-less barley.

A water-soluble neutral polysaccharide (SDQCP-1) was isolated from fruit bodies of Cordyceps militaris cultivated on hull-less barley. SDQCP-1 was composed of mannose, glucose and galactose in the mole ratio of 13.3:1.0:9.7, with an average molecular weight of 19.3 kDa. Based on results from methylation analysis, GC-MS and NMR, SDQCP-1 was elucidated to be a glucogalactomannan with a backbone composed of (1→2)-α-D-Manp (48.4 %) and (1 → 4)-ß-D-Glcp (1.2 %) residues. Its side chains were branched at O-6 position of (1→2)-α-D-Manp mainly by (1 → 2)-ß-D-Galf or (1 → 6)-α-D-Manp residues which were terminated mainly with α-D-Galf, α-D-Galp residues. Besides exhibiting a good antioxidant capacity with an ORACFL value of 24.7 mmol Trolox/g and a TEAC value of 202.4 µmol Trolox/g, SDQCP-1 also could stimulate macrophages to release NO, TNF-α, IL-6, and IL-10, and mainly induced M1 polarization of macrophages. The findings indicated that SDQCP-1, from C. militaris cultivated on hull-less barley, could be used as potential natural antioxidant and immunomodulator in functional foods or medicine.

The development of low-calorie sugar and functional jujube food using biological transformation and fermentation coupling technology.

Jujube juice has been used as ingredient in a range of foods and dietary supplements. In this study, an enzyme transformation and fermentation coupling technology was applied to increase the nutritional value of concentrated/extracted Jinsi jujube juice. Two enzymes, D-glucose isomerase (GI) and D-allulose 3-epimerase (DAE), were employed to convert the glucose and fructose to a low-calorie sweeter D-allulose with a concentration of 110 g/L in jujube juice. Furthermore, the mixed cultures of Pediococcus pentosaceus PC-5 and Lactobacillus plantarum M were employed to increase the content of nutrition components related to bioactivities and flavor volatiles in jujube juice. Accordingly, this fermentation accumulated 100 mg/L gamma-aminobutyric acid (GABA), which has neurotransmission, hypotension, diuretic, and tranquilizer effects, and increased the content of branched-chain amino acids (BCAAs) and many free amino acids (Asp, Glu, Gly, and Ala) at different level. The fermentation not only maintained the concentration of native functional components such as cyclic adenosine monophosphate (cAMP) and minerals, but also increased the content of iron (Fe2+) and zinc (Zn2+), which have blood and eyesight tonic function. The value-added jujube juice might serve as a low-calorie and probiotic functional beverage and show high application potential in food industry.

Biosynthesis of dendroketose from different carbon sources using in vitro and in vivo metabolic engineering strategies.

BACKGROUND: Asymmetric aldol-type C-C bond formation with ketones used as electrophilic receptor remains a challenging reaction for aldolases as biocatalysts. To date, only one kind of dihydroxyacetone phosphate (DHAP)-dependent aldolases has been discovered and applied to synthesize branched-chain sugars directly using DHAP and dihydroxyacetone (DHA) as substrate. However, the unstable and high-cost properties of DHAP limit large-scale application. Therefore, biosynthesis of branched-chain sugar from low-cost and abundant carbon sources is essential. RESULTS: The detailed catalytic property of l-rhamnulose-1-phosphate aldolase (RhaD) and l-fuculose-1-phosphate aldolase (FucA) from Escherichia coli in catalyzing the aldol reactions with DHA as electrophilic receptors was characterized. Furthermore, we calculated the Bürgi-Dunitz trajectory using molecular dynamics simulations, thereby revealing the original sources of the catalytic efficiency of RhaD and FucA. A multi-enzyme reaction system composed of formolase, DHA kinase, RhaD, fructose-1-phosphatase, and polyphosphate kinase was constructed to in vitro produce dendroketose, a branched-chain sugar, from one-carbon formaldehyde. The conversion rate reached 86% through employing a one-pot, two-stage reaction process. Moreover, we constructed two artificial pathways in Corynebacterium glutamicum to obtain this product in vivo starting from glucose or glycerol. Fermentation with glycerol as feedstock produced 6.4 g/L dendroketose with a yield of 0.45 mol/mol glycerol, representing 90% of the maximum theoretical value. Additionally, the dendroketose production reached 36.3 g/L with a yield of 0.46 mol/mol glucose when glucose served as the sole carbon resource. CONCLUSIONS: The detailed enzyme kinetics data of the two DHAP-dependent aldolases with DHA as electrophilic receptors were presented in this study. In addition, insights into this catalytic property were given via in silico simulations. Moreover, the cost-effective synthesis of dendroketose starting from one-, three-, and six-carbon resources was achieved through in vivo and in vitro metabolic engineering strategies. This rare branched-chain ketohexose may serve as precursor to prepare 4-hydroxymethylfurfural and branched-chain alkanes using chemical method.

Structural characterization of a pectin-type polysaccharide from Curcuma kwangsiensis and its effects on reversing MDSC-mediated T cell suppression.

Myeloid-derived suppressor cells (MDSCs) accumulate in tumor-bearing hosts and play a major role in tumor-induced immunosuppression. The potent modulatory effects of polysaccharides on the innate and adaptive immune system stimulate antitumor responses. In this study, a polysaccharide with an apparent molecular weight of 14.0 kD was isolated from Curcuma kwangsiensis and designated as CKAP-2. The polysaccharide was characterized through high-performance gel permeation chromatography, chemical derivative analyses, GC-MS, FT-IR, and NMR. Results revealed that CKAP-2 is a highly methyl-esterified pectin-type polysaccharide. It is predominantly composed of a homogalacturonan region and small amounts of type-I rhamonogalacturonan regions. Its degree of methyl-esterification is approximately 62.4%. The effect of CKAP-2 on MDSC-medicated immunosuppression was primarily tested. CKAP-2 recovered the MSC2-supressed proliferation of CD4+ and CD8+ T-cells. This finding suggested that CKAP-2 can reverse MDSC-mediated T-cell suppression and that CKAP-2 can be potentially applied in antitumor therapy.

One-Pot Synthesis of Ginsenoside Rh2 and Bioactive Unnatural Ginsenoside by Coupling Promiscuous Glycosyltransferase from Bacillus subtilis 168 to Sucrose Synthase.

Ginsenosides, the major effective ingredients of Panax ginseng, exhibit various biological properties. UDP-glycosyltransferase (UGT)-mediated glycosylation is the last biosynthetic step of ginsenosides and contributes to their immense structural and functional diversity. In this study, UGT Bs-YjiC from Bacillus subtilis 168 was demonstrated to transfer a glucosyl moiety to the free C3-OH and C12-OH of protopanaxadiol (PPD) and PPD-type ginsenosides to synthesize natural and unnatural ginsenosides. In vitro assays showed that unnatural ginsenoside F12 (3- O-ß-d-glucopyranosyl-12- O-ß-d-glucopyranosyl-20( S)-protopanaxadiol) exhibited remarkable activity against diverse human cancer cell lines. A one-pot reaction by coupling Bs-YjiC to sucrose synthase (SuSy) was performed to regenerate UDP-glucose from sucrose and UDP. With PPD as the aglycon, an unprecedented high yield of ginsenosides F12 (3.98 g L-1) and Rh2 (0.20 g L-1) was obtained by optimizing the conversion conditions. This study provides an efficient approach for the biosynthesis of ginsenosides using a UGT-SuSy cascade reaction.

Antiproliferative Activity of Triterpene Glycoside Nutrient from Monk Fruit in Colorectal Cancer and Throat Cancer.

Colorectal cancer and throat cancer are the world's most prevalent neoplastic diseases, and a serious threat to human health. Plant triterpene glycosides have demonstrated antitumor activity. In this study, we investigated potential anticancer effects of mogroside IVe, a triterpenoid glycoside from monk fruit, using in vitro and in vivo models of colorectal and laryngeal cancer. The effects of mogroside IVe on the proliferation of colorectal cancer HT29 cells and throat cancer Hep-2 cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the expression levels of p53, phosphorylated ERK1/2, and MMP-9 were analyzed by western blotting and immunohistochemistry. The results indicated that mogroside IVe inhibited, in a dose-dependent manner, the proliferation of HT29 and Hep-2 cells in culture and in xenografted mice, which was accompanied by the upregulation of tumor suppressor p53, and downregulation of matrix metallopeptidase 9 (MMP-9) and phosphorylated extracellular signal-regulated kinases (ERK)1/2. This study revealed the suppressive activity of mogroside IVe towards colorectal and throat cancers and identified the underlying mechanisms, suggesting that mogroside IVe may be potentially used as a biologically-active phytochemical supplement for treating colorectal and throat cancers.

Mogrol represents a novel leukemia therapeutic, via ERK and STAT3 inhibition.

Unlike solid tumors, the primary strategy for leukemia treatment is chemotherapy. However, leukemia chemotherapy is associated with adverse drug effects and drug resistance. Therefore, it is imperative to identify novel agents that effectively treat leukemia while minimizing adverse effects. The Raf/MEK/extracellular regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3) pathways have been implicated in leukemia carcinogenesis, and provide novel molecular targets for therapeutic intervention in cancer. Mogrol, a biometabolite of mogrosides found in Siraitia grosvenorii, has exhibited anti-cancer activities; however, the underlying mechanism of this effect remains unclear. To clarify its anti-cancer activity and mechanism of action, we treated K562 leukemia cells with mogrol. Mogrol suppressed leukemia cell growth via inhibition of the ERK1/2 and STAT3 pathways, in particular, through the suppression of p-ERK1/2 and p-STAT3. Inhibition of these pathways suppressed Bcl-2 expression, thereby inducing K562 cell apoptosis. Furthermore, mogrol enhanced p21 expression, resulting in G0/G1 cell cycle arrest. The findings provide new perspectives regarding the role of mogrol in leukemia treatment.

Structural characterization and immunostimulating activity of a levan-type fructan from Curcuma kwangsiensis.

A fructan designated as CKNP with apparent molecular weight of 5.3kD was isolated from the hot water extract of Curcuma kwangsiensis through a combination of ion-exchange chromatography on DEAE 650M and gel filtration on Superdex G-200. CKNP was characterized by chemical derivatization as well as HPLC, GC, and GC-MS technologies. Structural studies revealed that CKNP is composed predominately of fructose (96.8%) and a small amount of glucose (3.2%) with a degree of polymerization (DP) of 30-31. It was deduced to be a levan-type fructan containing a backbone composed of (2→6)-linked ß-d-Fruf residues and single ß-d-Fruf residues as side chains branched at the O-1 position along the backbone. Preliminary in vitro bioactive tests on RAW 264.7 murine macrophage cells revealed that the levan-type fructan from C. kwangsiensis shows significant immunostimulating activity based on its ability to stimulate macrophage proliferation and enhance phagocytosis.

Immobilization of Clostridium cellulolyticum D-psicose 3-epimerase on artificial oil bodies.

The rare sugar D-psicose possesses several fundamental biological functions. D-Psicose 3-epimerase from Clostridium cellulolyticum (CC-DPEase) has considerable potential for use in D-psicose production. In this study, CC-DPEase was fused to the N terminus of oleosin, a unique structural protein of seed oil bodies and was overexpressed in Escherichia coli as a CC-DPEase-oleosin fusion protein. After reconstitution into artificial oil bodies (AOBs), refolding, purification, and immobilization of the active CC-DPEase were simultaneously accomplished. Immobilization of CC-DPEase on AOB increased the optimal temperature but decreased the optimal pH of the enzyme activity. Furthermore, the AOB-immobilized CC-DPEase had a thermal stability and a bioconversion rate similar to those of the free-form enzyme and retained >50% of its initial activity after five cycles of enzyme use. Thus, AOB-immobilized CC-DPEase has potential application in the production of d-psicose at a lower cost than the free-form enzyme.

[Bioconversion of D-fructose to D-allose by novel isomerases].

Rare sugar is a kind of important low-energy monosaccharide that is rarely found in nature and difficult to synthesize chemically. D-allose, a six-carbon aldose, is an important rare sugar with unique physiological functions. It is radical scavenging active and can inhibit cancer cell proliferation. To obtain D-allose, the microorganisms deriving D-psicose 3-epimerase (DPE) and L-rhamnose isomerase (L-RhI) have drawn intense attention. In this paper, DPE from Clostridium cellulolyticum H10 was cloned and expressed in Bacillus subtilis, and L-RhI from Bacillus subtilis 168 was cloned and expressed in Escherichia coli BL21 (DE3). The obtained crude DPE and L-RhI were then purified through a HisTrap HP affinity chromatography column and an anion-exchange chromatography column. The purified DPE and L-RhI were employed for the production of rare sugars at last, in which DPE catalyzed D-fructose into D-psicose while L-RhI converted D-psicose into D-allose. The conversion of D-fructose into D-psicose by DPE was 27.34%, and the conversion of D-psicose into D-allose was 34.64%.

Characteristics and antioxidant activity of Maillard reaction products from psicose-lysine and fructose-lysine model systems.

D-Psicose, an epimer of D-fructose isomerized at C-3 position, is a rare ketohexose that is thought to be beneficial for obese people and diabetic patients as a noncaloric sweetener. In the present study, model Maillard reaction products were obtained from D-psicose (or D-fructose) and L-lysine heating at 120 °C up to 8 h with the initial pH 9.0. The changes in pH, UV-vis absorbance, and free amino groups during the reaction were detected. Moreover, the antioxidant potential of the Maillard reaction products at different intervals was investigated. Although there was almost no difference in the oxygen radical absorbance capacity, the Maillard reaction products from psicose performed better than that from fructose in the radical-scavenging activity of 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt and 1, 1,-diphenyl-2-picryl-hydrazyl. The reducing power of the Maillard reaction products from psicose was also stronger than that from fructose. These results indicated that psicose played an effective role in the Maillard reaction and its Maillard reaction products could act as potential antioxidants in food industry.

Antioxidant effects of Maillard reaction products obtained from ovalbumin and different D-aldohexoses.

Nonenzymatic glycation between ovalbumin (OVA) and seven D-aldohexoses was carried out to study the chemical and antioxidant characteristics of sugar-protein complexes formed in the dry state at 55 degrees C and 65% relative humidity for 2 d through the Maillard reaction (MR). The effects of Maillard reaction products (MRPs) modified with different aldohexoses on radical scavenging, lipid oxidation, and tetrazolium salt (XTT) reducibility were investigated. The results showed that the degree of browning and aggregation and the tryptophan-related fluorescent intensity of glycated proteins displayed a noticeable difference that depended on the sugars used for modification. All the glycated proteins exhibited higher antioxidant activity as compared to a heated control and native OVA, and the antioxidant activity was well correlated with browning development. Furthermore, the order of antioxidant activities for the seven complexes was as follows: altrose/allose-OVAs > talose/galactose-OVAs > glucose-OVA > mannose/glucose-OVAs. This implies that sugar-protein complexes with two sugars known as epimers about C-2 showed a similar antioxidant capacity. From these results, the configuration of a hydroxyl (OH) group about position C-2 did not influence the advanced cross-linking reaction, but the configuration of OH groups about C-3 and C-4 might be very important for formation of MRPs and their antioxidant behaviors.

Evaluation of the site specific protein glycation and antioxidant capacity of rare sugar-protein/peptide conjugates.

Protein-sugar conjugates generated in nonenzymatic glycation of alpha-lactalbumin (LA) with rare sugars [D-allose (All) and D-psicose (Psi)] and alimentary sugars as controls [D-glucose (Glc) and D-fructose (Fru)] were qualitatively determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Mass spectra revealed that the extent of glycation at lysine residues on LA with D-aldose molecules was very much higher than that of glycation with d-ketose molecules. To identify the specific site of glycation, the peptide mapping was established from protease V8 digestion, using a combination of computational cutting of proteins and MALDI-TOF-MS. As compared to peptide mapping, three and seven glycation sites were located in the primary structure of LA-ketose and LA-aldose conjugates, respectively. On the other hand, the antioxidant activities of protein-sugar conjugates and their peptic hydrolysates were investigated by 1,1-diphenyl-2-picrylhydrazyl radical scavenging method. The antioxidant activities of proteins/peptides glycated with rare sugars were significantly higher than those modified with the control sugars. The results indicated that the glycation degree and position were not markedly different between rare sugar and corresponding control sugar, but the antioxidant properties of protein and its hydrolysate were significantly enhanced by modifying with rare sugar.

Preparation of antimicrobial reduced lysozyme compatible in food applications.

The structural and antimicrobial functions of lysozyme reduced with food-compatible reducing agents-cysteine (Cys) and glutathione (GSH)-were investigated. The disulfide bonds were partially reduced by thiol-disulfide exchange reactions under heat-induced denaturing conditions from 55 to 90 degrees C. The results showed that treatment of lysozyme with Cys and GSH resulted in the introduction of new half-cystine residues (2-3 residues/mol of protein). The released SH groups, in turn, rendered the lysozyme molecule more flexible, being accompanied by a dramatic increase in the surface hydrophobicity and exposure of tryptophan residues. As a consequence, the resulting reduced lysozymes were more capable of binding to lipopolysaccharides (LPS) and permeabilizing the bacterial outer membrane, as evidenced by the liposome leakage experiment, than were native or heated lysozyme. Both reduced lysozymes displayed significantly higher antimicrobial activity than native or heated lysozyme against Salmonella enteritidis (SE) in sodium phosphate buffer (10 mM, pH 7.2) at 30 degrees C for 1 h. Their minimal inhibitory concentrations (MICs) against the tested bacteria were about 150- and 25-fold lower than their respective MICs of native or heated lysozyme. The results suggest that partially reduced lysozyme could be used as a potential antimicrobial agent for prevention of SE attack.