Arabinoxylan-Based Particles: In Vitro Antioxidant Capacity and Cytotoxicity on a Human Colon Cell Line

Relationship between the viscoelastic, structural and microstructural characteristics of highly ferulated arabinoxylan-based gels: A theoretical analysis

The viscoelastic, structural, and microstructural characteristics of arabinoxylans (AX) gels depend on the polysaccharide's structure. Higher ferulic acid (FA) contents result in stronger AX gels with greater cross-links and more compact microstructures. This work aimed to conduct a deeper theoretical analysis of the structural characteristics of highly cross-linked AX gels and to establish a relationship with their viscoelastic and microstructural characteristics. Previously characterized highly ferulated AX (5.46 μg/mg AX) formed strong gels (G' = 227 Pa) with a highly cross-linked structure (di-FA = 1.62 μg/mg AX) and a compact microstructure. The distribution of FA residues in the polysaccharide chain was less spaced in the AX (55 nm between two FAs) compared to the AX gel (83 nm between two FAs) due to the oxidation of the FA during the gelling process. The distance between two di-FA decreased from 1658 to 358 nm after gelation, indicating increased cross-linking content. The results demonstrate that AX with highly ferulated structures forms highly cross-linked gels where di-FA distribution within the polymer chains is more frequent. This distribution of cross-links in the polymeric network is reflected in more elastic gels exhibiting more compact microstructures.

Optimally designed PEGylatied arabinoxylan paclitaxel nano-micelles as alternative delivery for Abraxane®: A potential targeted therapy against breast and lung cancers

Paclitaxel (PTX) binds to spindle microtubules and inhibits mitotic division leading to cell death. However, its wide distribution, high absorption, and less selectively, minimize its application in cancer clinics. In this study, isolated arabinoxylans were used to encapsulate PTX, and then both were covered by polyethylene glycol conjugated to folic acid (FA), to strengthen its specificity to cancerous cells. Beclin-1 and P21 were significantly overexpressed by (79.6 ± 0.97 %, p ≤ 0.00001, &62.2 ± 1.15 % p ≤ 0.0001 in MCF-7 cells) and (74.8 ± 8.04 %, p ≤ 0.0001 &75.3 ± 2.3 %, p ≤ 0.0001, in NSCLCs) respectively after their incubation for 48 h with nano-targeted PTX NPs. Similarly, P53 and GSK3 beta-pSer9 were significantly increased by (63.5 ± 1 % p ≤ 0.0001, & 87 ± 1 % p ≤ 0.0001, in MCF) respectively and (81.5 ± 6 % p ≤ 0.01, & 84.8 ± 3.8 % p ≤ 0.001, in A549) respectively. The findings confirmed the activation of acidic/neutral autophagosomes in acridine orange/ethidium bromide (AO/EB) and nuclear fragmentation was clearly shown by 4', 6-diamidino-2 phenylindole (DAPI) nuclear stains. The findings provide the basis for the potential application of arabinoxylans as a great vehicle for the encapsulation of chemotherapeutic agents such as PTX for target delivery, and also as an immune mediator.

Covalent Pectin/Arabinoxylan Hydrogels: Rheological and Microstructural Characterization

This research aimed to evaluate the gelation process of ferulated pectin (FP) and ferulated arabinoxylan (AXF) in a new mixed hydrogel and determine its microstructural characteristics. FP from sugar beet (Beta vulgaris) and arabinoxylan from maize (Zea mays) bran were gelled via oxidative coupling using laccase as a crosslinking agent. The dynamic oscillatory rheology of the mixed hydrogel revealed a maximum storage modulus of 768 Pa after 60 min. The scanning electron microscopy images showed that mixed hydrogels possess a microstructure of imperfect honeycomb. The ferulic acid content of the mixed hydrogel was 3.73 mg/g, and ferulic acid dimer 8-5' was the most abundant. The presence of a trimer was also detected. This study reports the distribution and concentration of ferulic acid dimers, and the rheological and microstructural properties of a mixed hydrogel based on FP and AXF, which has promising features as a new covalent biopolymeric material.

Arabinoxylan from Corn Fiber Obtained through Alkaline Extraction and Membrane Purification: Relating Bioactivities with the Phenolic Compounds

Arabinoxylan has prebiotic properties, as it is able to resist digestion in the small intestine and undergoes fermentation in the large intestine. In this work, arabinoxylan was extracted from corn fiber using an alkaline solution and further purified with membrane processing. It was found that the extracts were mainly composed of xylose (50-52%), arabinose (37-39%), galactose (9%) and glucose (1-4%), with an A/X ratio of 0.72-0.77. All the extracts were composed of phenolic compounds, including ferulic acid derivatives such as dimers, trimers and tetramers. The purified extract had a lower concentration of ferulic and p-coumaric acid (0.004 and 0.02 mg/mgdry_weight, respectively) when compared to raw extract (19.30 and 2.74 mg/mgdry_weight, respectively). The same effect was observed for the antioxidant activity, with purified extracts having a lower value (0.17 ± 0.02 µmol TEAC/mg) when compared to the raw extract (2.20 ± 0.35 µmol TEAC/mg). The purified extract showed a greater antiproliferative effect against the HT29 cell line with EC50 = 0.12 ± 0.02 mg/mL when compared to the raw extract (EC50 = 5.60 ± 1.6 mg/mL). Both raw and purified extracts did not show any cytotoxicity to the Caco-2 cell line in the maximum concentration tested (10 mg/mL).

Fine structural features and antioxidant capacity of ferulated arabinoxylans extracted from nixtamalized maize bran

BACKGROUND

The nixtamalization process improves the nutritional and technological properties of maize. This process generates nixtamalized maize bran as a by-product, which is a source of arabinoxylans (AX). AX are polysaccharides constituted of a xylose backbone with mono- or di-arabinose substitutions, which can be ester-linked to ferulic acid (FA). The present study investigated the fine structural features and antioxidant capacity (AC) of nixtamalized maize bran arabinoxylans (MBAX) to comprehend the structure-radical scavenging capacity relationship in this polysaccharide deeply.

RESULTS

MBAX presented a molecular weight, intrinsic viscosity, and hydrodynamic radius of 674 kDa, 1.8 dL g^-1 , and 24.6 nm, respectively. The arabinose-to-xylose ratio (A/X) and FA content were 0.74 and 0.25 g kg^-1 polysaccharide, respectively. MBAX contained dimers (di-FA) and trimer (tri-FA) of FA (0.14 and 0.07 g kg^-1 polysaccharide, respectively). The main di-FA isomer was the 8-5' structure (80%). Fourier transform infrared spectroscopy confirmed MBAX molecular identity, and the second derivate of the spectral data revealed a band at 958 cm^-1 related to the presence of arabinose disubstitution. ¹ H-Nuclear magnetic resonance spectroscopy showed mono- and di-arabinose substitution in the xylan backbone with more monosubstituted residues. MBAX registered an AC of 25 and 20 μmol Trolox equivalents g^-1 polysaccharide despite a low FA content, using ABTS (2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (1,1-diphenyl-2-picrylhydrazyl) methods, respectively.

CONCLUSION

AC in MBAX could be related to the high A/X ratio (mainly monosubstitution) and the high 8-5' di-FA proportion in this polysaccharide. © 2023 Society of Chemical Industry.

Encapsulation of Polyphenolic Compounds Based on Hemicelluloses to Enhance Treatment of Inflammatory Bowel Diseases and Colorectal Cancer

Inflammatory bowel diseases (IBD) and colorectal cancer (CRC) are difficult to cure, and available treatment is associated with troubling side effects. In addition, current therapies have limited efficacy and are characterized by high costs, and a large segment of the IBD and CRC patients are refractive to the treatment. Moreover, presently used anti-IBD therapies in the clinics are primarily aimed on the symptomatic control. That is why new agents with therapeutic potential against IBD and CRC are required. Currently, polyphenols have received great attention in the pharmaceutical industry and in medicine due to their health-promoting properties. They may exert anti-inflammatory, anti-oxidative, and anti-cancer activity, via inhibiting production of pro-inflammatory cytokines and enzymes or factors associated with carcinogenesis (e.g., matrix metalloproteinases, vascular endothelial growth factor), suggesting they may have therapeutic potential against IBD and CRC. However, their use is limited under both processing conditions or gastrointestinal interactions, reducing their stability and hence their bioaccessibility and bioavailability. Therefore, there is a need for more effective carriers that could be used for encapsulation of polyphenolic compounds. In recent years, natural polysaccharides have been proposed for creating carriers used in the synthesis of polyphenol encapsulates. Among these, hemicelluloses are particularly noteworthy, being characterized by good biocompatibility, biodegradation, low immunogenicity, and pro-health activity. They may also demonstrate synergy with the polyphenol payload. This review discusses the utility and potential of hemicellulose-based encapsulations of polyphenols as support for treatment of IBD and CRC.

Conformational Behavior, Topographical Features, and Antioxidant Activity of Partly De-Esterified Arabinoxylans

This study aimed to investigate the effect of arabinoxylans (AX) partial de-esterification with feruloyl esterase on the polysaccharide conformational behavior, topographical features, and antioxidant activity. After enzyme treatment, the ferulic acid (FA) content in AX was reduced from 7.30 to 5.48 µg FA/mg polysaccharide, and the molecule registered a small reduction in radius of gyration (RG), hydrodynamic radius (Rh), characteristic ratio (C∞), and persistence length (q). A slight decrease in α and a small increase in K constants in the Mark-Houwink-Sakurada equation for partially de-esterified AX (FAX) suggested a reduction in molecule structural rigidity and a more expanded coil conformation, respectively, in relation to AX. Fourier transform infrared spectroscopy spectra of AX and FAX presented a pattern characteristic for this polysaccharide. Atomic force microscopy topographic analysis of FAX showed a more regular surface without larger hollows in relation to AX. The antioxidant activity of FAX, compared to AX, was reduced by 30 and 41% using both 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS+) and 1,1-diphenyl-2-picryl-hydrazyl (DPPH) methods, respectively. These results suggest that feruloyl esterase treatment of AX could offer a strategy to tailor AX chains conformation, morphological features, and antioxidant activity, impacting the development of advanced biomaterials for biomedical and pharmaceutical applications.

Molecular modification, structural characterization, and biological activity of xylans

The differences in the source and structure of xylans make them have various biological activities. However, due to their inherent structural limitations, the various biological activities of xylans are far lower than those of commercial drugs. Currently, several types of molecular modification methods have been developed to address these limitations, and many derivatives with specific biological activity have been obtained. Further research on structural characteristics, structure-activity relationship and mechanism of action is of great significance for the development of xylan derivatives. Therefore, the major molecular modification methods of xylans are introduced in this paper, and the primary structure and conformation characteristics of xylans and their derivatives are summarized. In addition, the biological activity and structure-activity relationship of the modified xylans are also discussed.

Highly cross-linked arabinoxylans microspheres as a microbiota-activated carrier for colon-specific insulin delivery

In vivo evaluation of arabinoxylans (AX) microspheres showed to protect insulin from degradation in the upper gastrointestinal tract and carrier insulin to colon. Insulin-loaded AX microspheres (50 UI/kg) decreased blood glucose level by 39% in diabetic rats with a maximum effect at 18 h post-administration, indicating that insulin remains bioactive. The continuous administration (4 days) of insulin-loaded AX microspheres improved the polyuria and increased the production of short-chain fatty acids, as well as Bifidobacterium and Bacteroides in diabetic rats compared to untreated diabetic rats. AX microspheres are a potential microbiota-activated carrier for colon-specific drug delivery and could be useful as a complementary treatment for diabetes.

Cross-linked arabinoxylan in a Ca2+-alginate matrix reversed the body weight gain of HFD-fed C57BL/6J mice through modulation of the gut microbiome

Here, we compared the effects of different physical forms of arabinoxylan (AX) - a microsphere of cross-linked arabinoxylan (CAX) in a Ca²⁺-alginate matrix (MC) and physical mixture of AX and alginate (PM) on gut microbiota and development of obesity in C57BL/6J mice. Supplementation of MC in high fat (HF) diet to mice for 10 weeks significantly reversed the body weight gain induced by the HF diet, along with less fat accumulation in both livers and the epididymal adipose than the PM group. Microbiome analysis showed that MC significantly altered the gut microbiota composition with a noticeable increase of butyrogenic bacteria of Lachnospiraceae. The butyrate produced by MC fermentation and the increased abundance of Lachnospiraceae might be the underlying mechanism of the anti-obesity effect of MC. The results indicated that the physical forms of dietary fiber are closely associated with its health benefits, and MC might be served as a new functional food ingredient to prevent obesity.

Fermentation of Ferulated Arabinoxylan Recovered from the Maize Bioethanol Industry

Maize by-product from the bioethanol industry (distiller’s dried grains with solubles, DDGS) is a source of ferulated arabinoxylan (AX), which is a health-promoting polysaccharide. In the present study, AX from DDGS was fermented by a representative colonic bacterial mixture (Bifidobacterium longum, Bifidobacterium adolescentis, and Bacteroides ovatus), and the effect of the fermented AX (AX-f) on the proliferation of the cell line Caco-2 was investigated. AX was efficiently metabolized by these bacteria, as evidenced by a decrease in the polysaccharide molecular weight from 209 kDa to < 50 kDa in AX-f, the release of ferulic acid (FA) from polysaccharide chains (1.14 µg/mg AX-f), and the short-chain fatty acids (SCFA) production (277 µmol/50 mg AX). AX-f inhibited the proliferation of Caco-2 cells by 80–40% using concentrations from 125–1000 µg/mL. This dose-dependent inverse effect was attributed to the increased viscosity of the media due to the polysaccharide concentration. The results suggest that the AX-f dose range and the SCFA and free FA production are key determinants of antiproliferative activity. Using the same polysaccharide concentrations, non-fermented AX only inhibited the Caco-2 cells proliferation by 8%. These findings highlight the potential of AX recovered from the maize bioethanol industry as an antiproliferative agent once fermented by colonic bacteria.

Covalently Cross-Linked Nanoparticles Based on Ferulated Arabinoxylans Recovered from a Distiller’s Dried Grains Byproduct

The purpose of this investigation was to extract ferulated arabinoxylans (AX) from dried distillers’ grains with solubles (DDGS) plus to investigate their capability to form covalently cross-linked nanoparticles. AX registered 7.3 µg of ferulic acid/mg polysaccharide and molecular weight and intrinsic viscosity of 661 kDa and 149 mL/g, correspondingly. Fourier transform infrared spectroscopy (FTIR) was used to confirm the identity of this polysaccharide. AX formed laccase induced covalent gels at 1% (w/v), which registered an elastic modulus of 224 Pa and a content of FA dimers of 1.5 µg/mg polysaccharide. Scanning electron microscopy pictures of AX gels exhibited a microstructure resembling a rough honeycomb. AX formed covalently cross-linked nanoparticles (NAX) by coaxial electrospray. The average hydrodynamic diameter of NAX determined by dynamic light scattering was 328 nm. NAX presented a spherical and regular shape by transmission electron microscopy analysis. NAX may be an attractive material for pharmaceutical and biomedical applications and an option in sustainable DDGS use.

Effect of Ultrasound-Treated Arabinoxylans on the Oxidative Stability of Soybean Oil

Arabinoxylans (AX) are polysaccharides with antioxidant activity and emulsifying properties, which make them an attractive alternative for its potential application as a natural antioxidant in oils. Therefore, this work aimed to investigate the effect of ultrasonic treatment of AX on their antioxidant capacity and its ability to improve the oxidative stability of soybean oil. For this purpose, AX were exposed to ultrasonic treatment at 25% (100 W, AX-1) and 50% (200 W, AX-2) power and an operating frequency of 20 KHz during 15 min, and their macromolecular properties (weight average molecular weight (Mw), polydispersity index and intrinsic viscosity) were evaluated. The antioxidant capacity of AX was determined by the DPPH assay and Rancimat test. Results showed that ultrasonic treatment did not affect the molecular identity of the polysaccharide but modified its Mw distribution. AX-1 showed the highest antioxidant activity (75% inhibition) at 533 µg/mL by the DPPH method compared to AX and AX-2. AX at 0.25% (w/v) and AX-1 at 0.01% (w/v) exerted the highest protective effects on oxidative stability of soybean oil with induction periods of 7.69 and 5.54 h, respectively. The results indicate that AX could be a good alternative for the potential application as a natural antioxidant in oils.

Feruloylated Arabinoxylans from Maize Distiller’s Dried Grains with Solubles: Effect of Feruloyl Esterase on their Macromolecular Characteristics, Gelling, and Antioxidant Properties

Distiller’s dried grains with solubles (DDGS) are co-products of the maize ethanol industry. DDGS contains feruloylated arabinoxylans (AXs), which can present gelling, antioxidant, and health-promoting effects. However, AXs presenting high ferulic acid (FA) content can exhibit delayed fermentation by the colonic microbiota. Therefore, partial deferuloylation of AXs from DDGS while preserving the polysaccharide gelling and antioxidant properties could add value and favor the sustainable development of bioethanol plants. The aim of this work was to partially deferuloylated AXs from DDGS using feruloyl esterase and to evaluate the polysaccharide macromolecular characteristics, gelling, and antioxidant properties. The AXs presented FA and FA dimer contents of 3.27 and 0.30 µg/mg polysaccharide, respectively, which decreased to 1.26 and 0.20 µg/mg polysaccharide, respectively, in feruloyl esterase-treated AXs (FAXs). The molecular weight and intrinsic viscosity of FAXs were slightly less than those of AXs. The Fourier transform infrared spectroscopy data of AXs and FAXs were similar, confirming that the enzyme did not modify the polysaccharide molecular identity. FAX gels (2% w/v) exhibited a decrease in elasticity by 43% in relation to that of AXs gels. The antioxidant capacity of FAXs was reduced by 32% and 43% (DPPH and ABTS method, respectively), compared with that of AXs. The FAX gelling and antioxidant properties were -comparable to those reported for other AXs in the literature. Feruloyl esterase may offer an interesting approach for the design of functional FAXs as value-added products recovered from DDGS.