Structural elucidation of a polysaccharide from Lonicera japonica flowers, and its neuroprotective effect on cerebral ischemia-reperfusion injury in rat

Publication date: June 2017
Source:International Journal of Biological Macromolecules, Volume 99
Author(s): Danying Su, Shi Li, Wei Zhang, Jing Wang, Jingjing Wang, Manhua Lv
A water-soluble polysaccharide, LJPB2, was purified from Lonicera japonica flowers. The present study was aimed to illustrate its structural features and its neuroprotective effect via anti-oxidant activity on focal ischemia/reperfusion (I/R) injury in rat brain. Via chemical and spectral methods, LJPB2, a polysaccharide with molecular weight of 8.9×10³Da, was composed of arabinose, mannose, glucose, and galactose, in a molar ratio of 1.8: 1.0: 3.6: 3.7. In addition, the linkage analysis revealed that it mainly contained 1, 4, 6-linked mannose, 1, 4-linked glucose and 1, 4-linked galactose, with a highly branched structure of araban and terminal glucose. LJPB2 exhibited a strong capacity of scavenging DPPH free radical in vitro. Moreover, in vivo assay using a commonly used cerebral I/R model demonstrated that LJPB2 could significantly improve the neurological deficit scores and infract volume. In addition, LJPB2 remarkably reduced the MDA level and NO production, and elevated the SOD and GSH-Px enzyme activities in the rat brain tissues. These results certainly indicated that LJPB2 had a distinct neuroprotective effect related to its strong antioxidant capacity in the cerebral ischemia/reperfusion injury.



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Fibulin-4 reduces extracellular matrix production and suppresses chondrocyte differentiation via DKK1- mediated canonical Wnt/β-catenin signaling

Publication date: June 2017
Source:International Journal of Biological Macromolecules, Volume 99
Author(s): Lei Shangguan, Guangzhi Ning, Zhuojing Luo, Yue Zhou
Fibulin-4 is an extracellular matrix (ECM) protein implicated in connective tissue development and elastic fiber formation. However, little is known about the underlying function of Fibulin-4 in cartilage development. The aim of this study was to investigate the role and probable mechanism of Fibulin-4 stimulation in ECM production and chondrocyte differentiation. Fibulin-4 has been observed to be abnormally elevated and matrix metalloproteinases 13 (MMP13) level was highly expressed in human osteoarthritis (OA) chondrocytes. In the chondrogenic cell line ATDC5, Fibulin-4 stimulation profoundly inhibited the expression of ECM gene type II collagen (Col2a1), aggrecan (Acan), and type X collagen (Col10a1). Overexpression of Fibulin-4 attenuated the expression of master transcription factors Sox6, Sox9 and Runx2, but had no effect on the expression of Sox5. Additionally, Fibulin-4 stimulation activated canonical Wnt pathway by reducing the expression of Wnt inhibitor DKK1 but not Sost. Moreover, Fibulin-4 augmented the expression of Wnt/β-catenin signaling target genes like β-catenin and Wnt-3a as well as diminished GSK-3β activation, and DKK1 abolished the effect of Fibulin-4 on chondrocyte differentiation, suggesting that Fibulin-4 is an important regulator of ECM production and chondrocyte differentiation through DKK1-mediated Wnt/β-catenin signaling. Our study provides evidence of a previously unknown link between Fibulin-4 and the canonical Wnt/β-catenin pathway that may contribute to our understanding of the molecular mechanisms of OA.



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Structural insight of an antioxidative arabinogalactan protein of Aegle marmelos fruit gum and it’s interaction with β-lactoglobulin

Publication date: June 2017
Source:International Journal of Biological Macromolecules, Volume 99
Author(s): Kaushik Bera, Sayani Ray, Washim Raja, Bimalendu Ray
The complication of arabinogalactan protein (AGP) structure, a significant ingredient of gum polysaccharides, not merely hinders the allocation of its role, but restricts its utilization as well. Here, we describe structural details of an AGP purified from Aegle marmelos fruit gum. This AGP (310×10³g/mol), which is water-soluble, contains β-1,3-linked galactopyranosyl main chain substituted at O-6 position with side chains containing galactose and arabinose residues. Also data on sugar composition, ring size, glycosidic linkage pattern, anomeric configuration and sequence of monosaccharide units of a number of oligosaccharides produced from this AGP by chemical and enzymatic methods were acquired. Biochemical analysis reveals resemblance in antioxidative potential between this arabinogalactan protein and standard antioxidants. Moreover, mixture of AGP and β-lactoglobulin form stable water soluble complex having binding constant K=2.38×10⁶/M. As gum polysaccharides are important raw materials of food industry discovering an antioxidative gum with the ability of creating stable water soluble complex with β-lactoglobulin may have important implication.



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Structural characterization and bioavailability of ternary nanoparticles consisting of amylose, α-linoleic acid and β-lactoglobulin complexed with naringin

Publication date: June 2017
Source:International Journal of Biological Macromolecules, Volume 99
Author(s): Tao Feng, Ke Wang, Fangfang Liu, Ran Ye, Xiao Zhu, Haining Zhuang, Zhimin Xu
Naringin is a bioflavonoid that is rich in citrus plants and possesses enormous health benefits. However, the use of naringin as a nutraceutical is significantly limited by its low bioavailability. In this study, a novel water-soluble ternary nanoparticle material consisting of amylose, α-linoleic acid and β-lactoglobulin was developed to encapsulate naringin to improve its bioavailability. The physicochemical characteristics of the ternary nanoparticle-naringin inclusion complex were analysed by ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), high-resolution transmission electron microscopy (TEM), X-ray diffractometry (XRD) and particle size distribution. The results confirmed the formation of the ternary nanoparticle-naringin inclusion complex. The encapsulation efficiency (EE) and loading content (LC) of the ternary nanoparticle-naringin inclusion complex were 78.73±4.17% and 14.51±3.43%, respectively. In addition, the results of the ternary nanoparticle-naringin inclusion complex in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) demonstrated that naringin can be gradually released from the complex. In conclusion, ternary nanoparticles are considered promising carriers to effectively improve the bioavailability of naringin.



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Structural characterization and antioxidant activity of polysaccharide from Hohenbuehelia serotina

Publication date: May 2017
Source:International Journal of Biological Macromolecules, Volume 98
Author(s): Xiaoyu Li, Lu Wang, Zhenyu Wang
Previous research found that the polysaccharides isolated from Hohenbuehelia serotina possessed various biological activities, such as antioxidant, immunomodulation and radioprotective effects. However, the structural information of H. serotina polysaccharides has not yet been reported. Therefore, based on the investigation of the antioxidative tracking, a novel polysaccharide named as NTHSP-A1 was isolated from H. serotina by ultrasonic-assistance extraction and anion-exchange and gel permeation chromatography approaches. Structural characterization revealed that NTHSP-A1 had an average molecular weight of 8.09×10³Da and composed of arabinose, mannose, glucose and galactose in a molar ratio of 4:16:28:11. The polysaccharide was semi-crystalline substance with multi-branching structure. The backbone of NTHSP-A1 was shown to contain →3,6)-α-d-Glcp-(1→, with branches substituted at C-3 of →2)-α-l-Arap-(1→, C-3 of α-d-Manp-(1→, and C-6 of →6)-β-d-Galp-(1→, respectively. This study provides a theoretical basis for the further research on the relationship between biological activity and structure of NTHSP-A1.

Graphical abstract

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In vivo cough suppressive activity of pectic polysaccharide with arabinogalactan type II side chains of Piper nigrum fruits and its synergistic effect with piperine

Publication date: June 2017
Source:International Journal of Biological Macromolecules, Volume 99
Author(s): Sadhana Khawas, Gabriela Nosáľová, Sujay Kumar Majee, Kanika Ghosh, Washim Raja, Veronika Sivová, Bimalendu Ray
Piper nigrum L. fruits are not only a prized spice, but also highly valued therapeutic agent that heals many ailments including asthma, cold and respiratory problems. Herein, we have investigated structural features and in vivo antitussive activity of three fractions isolated from Piper nigrum fruits. The water extract (PN-WE) upon fractionation with EtOH yielded two fractions: a soluble fraction (PN-eSf) and a precipitated (PN-ePf) one. The existence of a pectic polysaccharide with arabinogalactan type II side chains (147kDa) in PN-ePf and piperine in PN-eSf were revealed. Moreover, oligosaccharides providing fine structural details of side chains were generated from PN-ePf and then characterized. The parental water extract (PN-WE) that contained both pectic polysaccharide and piperine, after oral administration (50mgkg⁻¹ body weight) to guinea pigs, showed antitussive activity comparable to codeine phosphate (10mgkg⁻¹ body weight). The EtOH precipitated fraction (PN-ePf) containing pectic polysaccharide showed comparatively higher antitussive activity than EtOH soluble fraction (PN-eSf) that contained piperine, but their potencies are lower than the parental water extract. Significantly, the specific airway smooth muscle reactivity of all three fractions remained unchanged. Finally, pectic polysaccharide-piperine combination in parental extract synergistically enhances antitussive effect in guinea pigs.



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The functional and structural stabilization of trypsin by sucrose

Publication date: June 2017
Source:International Journal of Biological Macromolecules, Volume 99
Author(s): Lida Momeni, Sheida Mahmodian, Behzad Shareghi, Ali Akbar Saboury, Sadegh Farhadian
Docking and spectroscopic techniques were performed to probe the stabilizing effect of sucrose on the dynamics, structure and activity of trypsin. The thermodynamic folding properties, melting temperature (Tm), enthalpy change (ΔH°) and entropy change (ΔS°) were measured by thermal stability studies to understand the picture of trypsin folding. Sucrose acted as an enhancer for trypsin stability. Fluorescence spectroscopy revealed the static model of the quenching. The number of binding sites was 1. The Absorption, Fluorescence and circular dichroism spectral analysis illustrated that sucrose could protect the native structural conformation of enzyme and prevent the enzyme unfolding. Fluorescence spectroscopy and the molecular docking technique simulation displayed that the hydrogen bonding and Vander Waals forces played a main role in stabilizing the trypsin-sucrose complex, and the number of direct H-bonds between sucrose and trypsin was low; thus, the direct interactions had little contribution in the stabilizing effect and the indirect interactions caused by the preferential hydration were resulting from a molecular mechanism principally causing the stabilizing effects of sucrose.Upon sucrose conjugation, the kcat/Km value of the enzyme was increased. Tm of the trypsin-sucrose complex was increased due to the higher H-bond formation and the lower surface hydrophobicity after sucrose modification. Sucrose acted as enhancers for trypsin stability and activity. The result shows the ability of sucrose to protect the native structural conformation of trypsin. These results explicitly describe that stabilizing sucrose is preferentially excluded from the surface of trypsin, since water has a higher tendency toward favorable interactions with functional groups of trypsin than with sucrose.



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