Fabrication and characterization of shellac nanofibers with colon-targeted delivery of quercetin and its anticancer activity

In this study, the feasibility of shellac nanofibers as carrier system for colonic delivery of quercetin was evaluated. Firstly, the nanofibers without and with different amounts (2.5 %, 5.0 %, and 7.5 %) of quercetin were fabricated using pure shellac as a carrier by electrospinning. The morphology of nanofibers was bead-shape confirmed by SEM. FTIR, XRD, and DSC analysis showed that quercetin was encapsulated into shellac nanofibers, forming an amorphous complex. The molecular docking simulation indicated quercetin bound well to shellac through hydrogen bonding and van der Waals forces. These nanofibers had higher thermal stability than pure quercetin, and their surface wettability exhibited a pH-responsive behavior. The loading capacity of quercetin varied from 2.25 % to 6.84 % with the increased amount of quercetin, and it affected the stability of nanofibers in food simulants by measuring the release profiles of quercetin. The shellac nanofibers had high gastrointestinal stability, with a minimum quercetin release of 16.87 % in simulated digestive fluids, while the remaining quercetin was delivered to the colon and was released gradually. Moreover, the nanofibers exerted enhanced anticancer activity against HCT-116 cells by arresting cell cycle in G0/G1 phase and inducing cell apoptosis. Overall, shellac nanofibers are promising materials for colon-targeted delivery of active compounds.

Electrospray alginate microgels co-encapsulating degraded Konjac glucomannan and quercetin modulate human gut microbiota in vitro

Alginate microgels co-encapsulating degraded Konjac glucomannan (KGM60) underwent in vitro fecal fermentation and their effects on human microbiota and metabolites were investigated. KGM60 delayed quercetin release and enhanced phenolic metabolites production. Microgels co-encapsulating KGM60 and quercetin increased linear short chain fatty acid but decreased branched chain fatty acid production. Microgels encapsulated with quercetin with or without KGM60 decreased Firmicutes while increased Bacteroidetes over 24 h of fermentation, at genus level promoted Bacteroides growth at 24 h and decreased the abundance of Negativibacillus, Ruminococcus_NK4A214, and Christensenellaceae R_7. Faecalibacterium and Collinsella levels were exclusively promoted by microgels encapsulating KGM60 with or without quercetin, highlighting prebiotic effect of KGM60. Only microgels co-encapsulating both KGM60 and quercetin enhanced Dialister while inhibited Lachnoclostridium, indicating synergism between KGM60 and quercetin. Our study indicates that co-encapsulating KGM60 and quercetin in alginate microgel is effective in modulating human gut microbiota and metabolites production potentially beneficial to gut health.

Indole acetylated high-amylose maize starch: Synthesis, characterization and application for amelioration of colitis

Tryptophan metabolites such as indole-3-acetic acid (IAA) are critical for gut health, through their binding to the aryl hydrocarbon receptor (AhR), and may be useful for treatment of gastrointestinal diseases. Delivery of IAA to the colon is necessary, and one strategy is use of esterified starches which get digested in the colon by gut microbes. High amylose maize starch (HAMS) resists digestion in the upper gastrointestinal tract and is fermented by gut microbiota to release short-chain fatty acids (SCFAs), which are also beneficial to intestinal homeostasis. IAA esterified to HAMS (HAMSIAA) was synthesized with different degrees of substitution (DSs) by controlling the ratio of IAA vs HAMS. Successful incorporation of indole acetyl group was verified by NMR and FTIR spectra. XRD revealed that the crystalline type of HAMSIAA changed from B to V-type. SEM showed the destroyed surface of the starch granules. HAMSIAA with DS ~ 0.3 effectively increased IAA in the colon, to levels unachievable by oral IAA delivery. HAMSIAA increased pathways downstream of AhR activation, including CYP1A1 mRNA expression and IL-22 protein levels, and greatly improved DSS-induced colitis. HAMSIAA could serve as an ideal means for colon-targeted delivery of IAA and a promising nutraceutical for amelioration of inflammatory conditions.

5-Fluorouracil crystal-incorporated, pH-responsive, and release-modulating PLGA/Eudragit FS hybrid microparticles for local colorectal cancer-targeted chemotherapy

5-Fluorouracil (5-FU) is a widely used chemotherapeutic agent for colorectal cancer (CRC) owing to its potent anticancer effects. However, severe systemic side effects and poor drug accumulation in the CRC tissues limit its efficacy. This study aimed to develop 5-FU crystal-incorporated, pH-responsive, and release-modulating poly(d,l-lactide-co-glycolide)/Eudragit FS hybrid microparticles (5FU-EPMPs) for the local CRC-targeted chemotherapy. Approximately 150 μm 5FU-EPMPs were fabricated via the S/O/W emulsion solvent evaporation method, with 7.93 ± 0.24% and 87.23 ± 2.64% 5-FU loading and encapsulation efficiencies, respectively. Drug release profiles in a simulated pH environment of the gastrointestinal tract revealed that premature 5-FU release in the stomach and small intestine was prevented, thereby minimizing systemic 5-FU absorption. After reaching the colon, 5-FU was continuously released for >15 h, allowing long-term exposure of CRC tissues to sufficient 5-FU concentrations. Furthermore, in a CRC mouse model, the 5FU-EPMPs showed potent inhibition of tumor growth without signs of systemic toxicity. Thus, the 5FU-EPMPs represent a promising drug delivery system for local CRC-targeted chemotherapy.

Preparation and characterization of feruloylated oat β-glucan with antioxidant activity and colon-targeted delivery

Ferulic acid (FA) is an effective chemopreventive and therapeutic agent for colorectal cancer. However, FA cannot stably reach the colon through human digestive system, and it can be grafted into oligosaccharides to improve its digestion stability. Therefore, in this study, different degrees of substitution of feruloylated oat β-glucan (FA-OβG) were prepared by grafting FA onto water soluble oat β-glucan. FA grafting changed the crystallinity and surface morphology of OβG, and the thermal stability of the FA-OβG improved. As the DS increased, the antioxidant activity of FA-OβG increased, and FA-OβG III with DS of 0.184 showed the same antioxidant activities compared to the equal amount of free FA. The FA-OβG showed higher stability under gastrointestinal and colonic conditions than free FA. Furthermore, the FA-OβG conjugates exhibited good in vitro anticancer activity against human colorectal cancer cells, while FA-OβG III showed better anticancer activity than an equal amount of free FA.

Enhanced therapeutic efficacy of a novel colon-specific nanosystem loading emodin on DSS-induced experimental colitis

BACKGROUND

Ulcerative colitis (UC) is an intricate enteric disease with a rising incidence that is closely related to mucosa-barrier destruction, gut dysbacteriosis, and immune disorders. Emodin (1,3,8-trihydroxy-6-methyl-9,10-anthraquinone, EMO) is a natural anthraquinone derivative that occurs in many Polygonaceae plants. Its multiple pharmacological effects, including antioxidant, immune-suppressive, and anti-bacteria activities, make it a promising treatment option for UC. However, its poor solubility, extensive absorption, and metabolism in the upper gastrointestinal tract may compromise its anti-colitis effects.

PURPOSE

EMO was loaded in a colon-targeted delivery system using multifunctional biomedical materials and the enhanced anti-colitis effect involving mucosa reconstruction was investigated in this study.

METHODS

EMO-loaded Poly (DL-lactide-co-glycolide)/Eudragit^Ⓡ S100/montmorillonite nanoparticles (EMO/PSM NPs) were prepared by a versatile single-step assembly approach. The colon-specific release behavior was characterized in vitro and in vivo, and the anti-colitis effect was evaluated in dextran sulfate sodium (DSS)-induced acute colitis in mice by weight loss, disease activity index (DAI) score, colon length, histological changes, and colitis biomarkers. The integrity of the intestinal mucosal barrier was evaluated through transwell co-culture model in vitro and serum zonulin-related tight junctions and mucin2 (MUC2) in vivo.

RESULTS

EMO/PSM NPs with a desirable hydrodynamic diameter (~ 235 nm) and negative zeta potential (~ -31 mV) could prevent the premature drug release (< 4% in the first 6 h in vitro) in the upper gastrointestinal tract (GIT) and boost retention in the lower GIT and inflamed colon mucosa in vivo. Compared to free EMO-treatment of different doses in UC mice, the NPs could enhance the remedial efficacy of EMO in DAI decline, histological remission, and regulation of colitis indicators, such as myeloperoxidase (MPO), nitric oxide (NO), and glutathione (GSH). The inflammatory factors including induced nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), TNF-α, and IL-1β were suppressed by EMO/PSM NPs at both mRNA and protein levels. The obtained NPs could also promote the regeneration of the mucosal barrier via reduced fluorescein isothiocyanate (FITC)-dextran leakage in the transwell co-culture model and decreased serum zonulin levels, which was demonstrated to be associated with the upregulated tight junctions (TJs)-related proteins (claudin-2, occludin, and zo-1) and MUC2 at mRNA level. Moreover, the NPs could contribute to attenuating the liver injury caused by free EMO under excessive immune inflammation.

CONCLUSION

Our results demonstrated that EMO/PSM NPs could specifically release EMO in the diseased colon, and effectively enhance the anti-colitis effects of EMO related to intestinal barrier improvement. It can be considered as a novel potential alternative for oral colon-targeted UC therapy by increasing therapeutic efficacy and reducing side-effects.

Chitosan-based particles for protection of proteins during storage and oral administration

Crosslinked chitosan particles have been developed to improve the storage stability of bioactive proteins and to ensure adequate bioavailability by targeting release to the colon. The characteristics of these chitosan-based particles, formed using different molecular weight chitosans and different anion cross-linkers, were demonstrated using small angle X-ray scattering, ζ-potential, particle size, and morphology. An in vitro release study showed that protein release from the particles in the upper gastrointestinal tract was <30%, suggesting the possibility for target release to the colon. Some of the particles were shown to retain colon-targeted protein delivery after storage in PBS buffer. By controlling the structure of the chitosan-based particles, it was possible to both reduce protein leakage during short-term storage and achieve colon-targeted delivery.