Characterization of cAMP as an anti-allergic functional factor in Chinese jujube (Ziziphus jujuba Mill.)

Sea Buckthorn Flavonoid Extracted by High Hydrostatic Pressure Inhibited IgE-Stimulated Mast Cell Activation through the Mitogen-Activated Protein Kinase Signaling Pathway

Sea buckthorn (Hippophaë rhamnoides L.), as one of the Elaeagnaceae family, has the significant function of anti-tumor, anti-inflammation, anti-oxidation, and other physiological activities. High hydrostatic pressure (HHP) extraction has the advantages of being easy and efficient, while maintaining biological activity. In this study, sea buckthorn flavonoid (SBF) was extracted with HHP and purified sea buckthorn flavonoid (PSBF) was isolated by AB-8 macroporous resin column. HPLC analysis was used to quantified them. In addition, the effect of anti-allergy in RBL-2H3 cells by SBF, PSBF, and their flavonoid compounds was evaluated. The results demonstrate the conditions for obtaining the maximum flavonoid amount of SBF: 415 MPa for 10 min, 72% ethanol concentration, and a liquid to solid ratio of 40 mL/g, which increased the purity from 1.46% to 13.26%. Both SBF and PSBF included rutin, quercitrin, quercetin, isorhamnetin, and kaempferol. In addition, quercitrin, kaempferol, and SBF could regulate Th1/Th2 cytokine balance. Moreover, extracellular Ca2+ influx was reduced by quercitrin and PSBF. Furthermore, rutin, quercetin, iso-rhamnetin, and SBF could also inhibit P-p38 and P-JNK expression, thereby suppressing the phosphorylation of the MAPK signaling pathways. Overall, SBF is effective for relieving food allergy and might be a promising anti-allergic therapeutic agent.

Metabolomics and transcriptomics analyses for characterizing the alkaloid metabolism of Chinese jujube and sour jujube fruits

Introduction

Jujube is an important economic forest tree whose fruit is rich in alkaloids. Chinese jujube (Ziziphus jujuba Mill.) and sour jujube (Ziziphus spinosa Hu.) are the two most important species of the jujube genus. However, the mechanisms underlying the synthesis and metabolism of alkaloids in jujube fruits remain poorly understood.

Methods

In this study, the fruits of Ziziphus jujuba 'Hupingzao' and Ziziphus spinosa 'Taigusuanzao' in different harvest stages were used as test materials, we first integrated widely targeted metabolomics and transcriptomics analyses to elucidate the metabolism of alkaloids of jujube fruits.

Results

In the metabolomics analysis, 44 alkaloid metabolites were identified in 4 samples, 3 of which were unique to sour jujube fruit. The differential alkaloid metabolites (DAMs) were more accumulated in sour jujube than in Chinese jujube; further, they were more accumulated in the white ripening stage than in the red stage. DAMs were annotated to 12 metabolic pathways. Additionally, transcriptomics data revealed 259 differentially expressed genes (DEGs) involved in alkaloid synthesis and metabolism. By mapping the regulatory networks of DAMs and DEGs, we screened out important metabolites and 11 candidate genes.

Discussion

This study preliminarily elucidated the molecular mechanism of jujube alkaloid synthesis. The candidate genes regulated the synthesis of key alkaloid metabolites, but the specific regulation mechanism is unclear. Taken together, our results provide insights into the metabolic networks of alkaloid synthesis in Chinese jujube and sour jujube fruits at different harvest stages, thereby providing a theoretical reference for further research on the regulatory mechanism of jujube alkaloids and their development and utilization.

Optimized Extraction of cAMP From Jujube by Ultra-High Pressure Technology and the Anti-allergic Effect for Peanut Allergy Mouse

Jujube contains abundant cyclic adenosine monophosphate (cAMP). In contrast, the extraction technology of cAMP from jujube is still to be explored. In this study, the ultra-high pressure extraction (UHPE) conditions for obtaining the maximum cAMP yield from jujube were optimized. Orthogonal array design (OAD) was applied to evaluate the effects of three variables (pressure, pressure-holding time, and liquid-to-solid ratio) by UHPE on cAMP yield. The results showed that the optimal cAMP yield (1223.2 μg/g) was derived at 300 MPa, 20 min duration, and a liquid-to-solid ratio of 2.5 ml/g. In addition, as an important functional ingredient in jujube, cAMP has potential anti-allergic effect. To develop the functional characteristics of jujube, the effect of cAMP was characterized in vivo with the Balb/c mouse model of peanut allergy, which was established by subcutaneous injection of crude peanut protein extract (PN). The results showed that treatment with cAMP in PN-sensitized mice suppressed the lesions in jejunal tissues and allergic symptoms and restored spleen index. Meanwhile, cAMP treatment reduced serum levels of specific immunoglobulin E (IgE), histamine, as well as interleukin-4 (IL-4) and stimulated the secretion of tumor necrosis factor-α (TNF-α), whereas the serum levels of interleukin-10 (IL-10) were not affected. Our results suggested that cAMP has an anti-allergic effect in PN-sensitized mice.

The inhibition of pectin oligosaccharides on degranulation of RBL-2H3 cells from apple pectin with high hydrostatic pressure assisted enzyme treatment

The conditions for the preparation of pectic oligosaccharides (POS) by high hydrostatic pressure-assisted enzymatic (E-HHP) method were explored. The optimal conditions consisted of the pressure of 350 MPa for 20 min, and enzymolysis for 60 min with 0.011 U/mL enzyme. The products were isolated by ion exchange chromatography, galacturonic acid, di- and tri-galacturonides (Tri-GalA) with high purity were obtained. Additionally, the effects of POS on activation and degranulation of RBL-2H3 mast cells were investigated. It was found that Tri-GalA and POS could attenuate the release of β-hexosaminidase and histamine, reduce the production of IL-4 and inhibit the extracellular Ca²⁺ influx of RBL-2H3 cells. Notably, 150 μg/mL POS significantly alleviated the IgE-mediated allergic reaction of RBL-2H3 cells. These results indicate that POS could be used as an inhibitor in regulating mast cell-mediated allergic inflammatory responses.

Physicochemical and antioxidant activity of fruit harvested from eight jujube (Ziziphus jujuba Mill.) cultivars at different development stages

Jujube is a crop highly resistant to drought and salinity, making it one of the main fruit trees in Xinjiang. The present study evaluated the changes in the physicochemical and antioxidant activities of jujube fruit of eight different cultivars from Xinjiang, China. The developmental stages were selected according to the days after full bloom and fruit peel colour during ripening; these stages included young (S1), fruit core-hardening (S2), green ripening (S3), half-red maturity (S4) and complete red. In present study, different cultivars of jujube fruit showed similar chemical profiles, but their amounts showed great variation. HZ had the highest content of sugars, and JY had the highest content of cAMP and cGMP, while relatively higher levels of ascorbic acid, catechin, epicatechin, rutin, proanthocyanidin and antioxidant activity were found in ‘FS’ than in other cultivars, indicating that ‘FS’ could be used as a potential natural antioxidant. Regarding the development stages of jujube fruit, the moisture, ascorbic acid, total polyphenol, catechin, epicatechin, proanthocyanidin and rutin contents decreased during the development of all jujube cultivars, while the fructose, glucose, sucrose, cAMP, and cGMP contents greatly increased. The antioxidant activity determined by DPPH and ABTS radical scavenging decreased as the fruits matured. Therefore, the results suggest that green jujube (S1) could be used for natural antioxidants (catechin, epicatechin, proanthocyanidin) and that the advanced ripening stage(S5) is the proper picking period for fresh fruit and commercial processing.

Analysis of volatility characteristics of five jujube varieties in Xinjiang Province, China, by HS-SPME-GC/MS and E-nose

In this study, headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC/MS) was used to identify individual volatile compounds in five jujube varieties, and E-nose was used to identify their flavor. The results showed that a total of 45 volatile compounds were detected by GC-MS in the five varieties, and the proportion of acids was the highest (38.29%-54.95%), followed by that of aldehydes (22.94%-47.93%) and esters (6.33%-26.61%). Moreover, different varieties had obviously different volatile components. E-nose analysis showed that the R7 and R9 sensors were more sensitive to the aroma of jujube than other sensors. The strong response of R7 sensor was attributed to terpenes (or structurally similar substances) in jujube fruit, such as 1-penten-3-one, 2-octenal, (E)-2-heptanaldehyde, and (E)-2-hexenal and that of R9 sensor was attributed to the cyclic volatile components such as benzaldehyde, benzoic acid, and methyl benzoate. The multivariate data analysis (PCA, OPLS-DA, and HCA) of the results of GC/MS and E-nose showed that the five varieties could be divided into three groups: (1) Ziziphus jujuba Mill. cv. Huizao (HZ) and Z. jujuba cv. Junzao (JZ). Acids were the main volatile components for this group (accounting for 47.44% and 54.95%, respectively); (2) Z. jujuba cv. Hamidazao (HMDZ). This group had the most abundant volatile components (41), and the concentrations were also the highest (1285.43 µg/kg); (3) Winter jujube 1 (Z. jujuba cv. Dongzao, WJ1) and Winter jujube 2 (Z. jujuba cv. Dongzao, WJ2). The proportion of acids (38.38% and 38.29%) and aldehydes (40.35% and 38.19%) were similar in the two varieties. Therefore, the combination of headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry and E-nose could quickly and accurately identify the volatile components in jujube varieties from macro- and microperspectives. This study can provide guidance for the evaluation and distinguishing of jujube varieties and jujube cultivation and processing.

Geographical and Varietal Traceability of Chinese Jujubes Based on Physical and Nutritional Characteristics

Chinese jujube fruits are known for their high nutritional and functional values. To protect advantageous regional jujube fruits, it is important to monitor quality indicators and trace the origin and variety. In this study, 31 quality indicators of Chinese jujubes collected from 6 main producing areas were determined. According to different origins and varieties, Chinese jujube fruits were divided into five and six categories, respectively. To simplify the parameters, eight of the main characteristics, namely, soluble sugar content, fresh mass, edible rate, Na, Mg, K, Zn, and cyclic adenosine monophosphate (cAMP), were screened based on multiple comparison, correlation analysis, and principal component analysis (PCA). According to the eight main parameters, it was found that that both the categorical and cross-validated classification accuracy of linear discriminant analysis (LDA) were 100%. The discrimination accuracy of the testing set samples based on the orthogonal partial least squares-discriminant analysis (OPLS-DA) model were 90 and 93% for geographical and varietal classification, respectively. This indicated that the eight main parameters could be used as the characteristic parameters for the origin and variety traceability of Chinese jujubes.

Hydrophilic molecularly imprinted polymers functionalized magnetic carbon nanotubes for selective extraction of cyclic adenosine monophosphate from winter jujube

In this work, a green strategy was developed to prepare molecularly imprinted polymers functionalized magnetic carbon nanotubes in aqueous phase under mild conditions for cyclic adenosine monophosphate. Thanks to water solubility of chitosan, a natural polysaccharide which is rich in amino and hydroxyl groups, provided the feasibility to synthesize the green molecularly imprinted polymers for water soluble template in aqueous media. Coupled with high-performance liquid chromatography, the method exhibited a short equilibrium time (6 min), high adsorption capacity (22.42 μg/mg), high magnetic susceptibility, and good selectivity to template molecule with the imprinting factor of 2.94. A good linearity in the range of 0.020-3.0 mg/mL for target was obtained with a correlation coefficient of 0.9998. The limit of detection (signal-to-noise ratio = 3) and limit of quantitation (signal-to-noise ratio = 10) of the magnetic solid phase extraction method for cyclic adenosine monophosphate were 5 and 15 ng/mg, respectively. And the practical application of chitosan-based molecularly imprinted polymers as adsorbent to isolate and determine cyclic adenosine monophosphate in real natural samples (winter jujube) was demonstrated.