Expression and Purification of Recombinant Bowman-Birk Trypsin Inhibitor from Foxtail Millet Bran and Its Anticolorectal Cancer Effect In Vitro and In Vivo

Trypsin inhibitors derived from plants have various pharmacological activities and promising clinical applications. In our previous study, a Bowman-Birk-type major trypsin inhibitor from foxtail millet bran (FMB-BBTI) was extracted with antiatherosclerotic activity. Currently, we found that FMB-BBTI possesses a prominent anticolorectal cancer (anti-CRC) activity. Further, a recombinant FMB-BBTI (rFMB-BBTI) was successfully expressed in a soluble manner in host strain Escherichia coli. BL21 (DE3) was induced by isopropyl-β-d-thiogalactoside (0.1 mM) at 37 °C for 3.5 h by the pET28a vector system. Fortunately, a purity greater than 93% of rFMB-BBTI with anti-CRC activity was purified by nickel-nitrilotriacetic acid affinity chromatography. Subsequently, we found that rFMB-BBTI displays a strikingly anti-CRC effect, characterized by the inhibition of cell proliferation and clone formation ability, cell cycle arrest at the G2/M phase, and induction of cell apoptosis. It is interesting that the rFMB-BBTI treatment had no obvious effect on normal colorectal cells in the same concentration range. Importantly, the anti-CRC activity of rFMB-BBTI was further confirmed in the xenografted nude mice model. Taken together, our study highlights the anti-CRC activity of rFMB-BBTI in vitro and in vivo, uncovering the clinical potential of rFMB-BBTI as a targeted agent for CRC in the future.

Polyphenols from foxtail millet bran ameliorate DSS-induced colitis by remodeling gut microbiome

INTRODUCTION

Polyphenols from plants possess the anti-inflammatory and gut microbiota modulated properties. Foxtail millet (Setaria italica L., FM) has potential medical and nutritional functions because of rich phenolic and other phytochemical components.

METHODS

Here, the study explored the effects of bound polyphenol of inner shell (BPIS) from FM bran on dextran sodium sulfate (DSS)-induced experimental colitis mice.

RESULTS

Results showed that BPIS administration effectively relieved the weight loss, decreased disease active index (DAI) scores, restrained the secretion of pro-inflammatory cytokines TNF-α, IL-6 and IL-1β, increased anti-inflammatory cytokines IL-10, IL-4, IL-5. BPIS prevented gut barrier damage by enhancing tight junction proteins Claudin1, ZO-1 and Occludin, increasing the number of goblet cells and facilitating the gene expressions of mucin family. In addition, BPIS restored the gut microbiota composition and increased the relative abundance of commensal bacteria such as Lachnospiraceae and Rikenellaceae and restrained the growth of S24-7 and Staphylococcaceae. Concentrations of short-chain-fatty acids (SCFAs) generated by gut microbiota were elevated in BPIS treated colitis mice.

CONCLUSION

These data suggest that BPIS effectively ameliorates DSS-induced colitis by preventing intestinal barrier damage and promoting gut microbiota community.

Effect of Mechanical Grinding on the Physicochemical, Structural, and Functional Properties of Foxtail Millet (Setaria italica (L.) P. Beauv) Bran Powder

This study investigated the functional, physicochemical, and structural characteristics of foxtail millet bran powder with different particle sizes. The morphological analysis revealed that the surface roughness declined in conjunction with the particle sizes of the millet bran powder. The Fourier-transform infrared (FTIR) spectra showed that none of the samples generated any additional chemical functional groups. A decrease in the particle sizes of the millet bran powder increased their dissemination and surface areas, as well as the bulk density, tap density, water-holding capacity (WHC), angle of repose (θ) and angle of slide (α), and peak temperature, while the oil holding capacity (OHC) and crystallinity index (CI) value declined. Moreover, fine millet bran powder (54.7 μm) exhibited a higher protein, fat, soluble dietary fiber (SDF), total phenolic content, and antioxidant capacity than its coarse counterpart.

Bowman-Birk Major Type Trypsin Inhibitor Derived from Foxtail Millet Bran Attenuate Atherosclerosis via Remodeling Gut Microbiota in ApoE-/- Mice

Foxtail millet proteins and their hydrolysates have the potential to prevent atherosclerosis (AS). In our present study, a novel Bowman-Birk type major trypsin inhibitor from foxtail millet bran (FMB-BBTI) with an anti-AS effect was obtained by in vitro gastrointestinal bionic digestion. Further, the anti-AS activity of FMB-BBTI was verified by the classic apoE-/- mice model, characterized by the decreases of the inflammatory cytokines (TNF-α and IL-1β) and atherosclerotic plaque. Importantly, FMB-BBTI remodeled the structure of gut microbiota in apoE-/- mice, including the increase of Firmicutes at the phylum level, and the abundance alteration of five genera at the genus level, especially significant enrichment of Lactobacillus. Collectively, FMB-BBTI markedly restrains the AS progress, suggesting that the remodeling of gut microbiota induced by FMB-BBTI may be the critical factor for its anti-AS activity. This study indicates that FMB-BBTI may serve as a vital functional component contributing to the anti-AS potential of foxtail millet bran.

Inhibitory Effects of Bound Polyphenol from Foxtail Millet Bran on Colitis-Associated Carcinogenesis by the Restoration of Gut Microbiota in a Mice Model

Colorectal cancer (CRC) is a common malignant tumor occurring in the colon. It has been known that the gut microbiota is a complex ecosystem and plays an important role in the pathogenesis of colorectal cancer. Our previous study showed that bound polyphenol of the inner shell (BPIS) from foxtail millet bran exhibited significant antitumor activities in cancer cells and nude mice models. In the present study, the anticancer potential of BPIS is evaluated in the azoxymethane (AOM) and dextran sodium sulfate (DSS)-induced mouse CRC model. Results showed that BPIS could decrease the number and volume of tumors and protect the epithelial architecture from damage. Certain biomarkers associated with CRC formation, such as COX-2, EMR1, PCNA, and caspase-3, were strongly changed by BPIS. Moreover, by 16S rRNA gene sequence analysis, it was found that BPIS could remodel the overall structure of the gut microbiota from tumor-bearing mice toward that of the normal counterparts, including two phyla and eight genera, together with regulations on several genes that are responsible for 17 signaling pathways.

Treatment of Peroxidase Derived from Foxtail Millet Bran Attenuates Atherosclerosis by Inhibition of CD36 and STAT3 in Vitro and in Vivo

Atherosclerosis is one of the main causes of cardiovascular diseases. Our previous study indicated that a type of peroxidase derived from foxtail millet bran (FMBP) had prominent antitumor activities. In the present study, we found that FMBP had potential antiatherosclerosis effects. The results showed that FMBP treatment strongly suppressed lipid phagocytosis in both HASMCs and THP-1 cells by 52% and 49%, respectively. Further, FMBP significantly inhibited HASMCs migration by promoting transformation of HASMCs from synthetic to contractile, leading to the decrease of lipid phagocytosis. Simultaneously, FMBP repressed lipid uptake by reducing the expression of CD36 in THP-1 cells. In addition, FMBP reduced the secretion of inflammatory factor IL-1β by inhibiting the expression of STAT3 in THP-1 cells. Interestingly, FMBP also had the same effects in models of atherosclerosis constructed with ApoE-/- mice, including decreased aortic lesion area, repressed aortic sinus CD36 and STAT3 expression, and elevated serum HDL-C concentration. Collectively, these results indicate that FMBP has great potential in preventing the development of atherosclerosis.

Oleochemical Properties for Different Fractions of Foxtail Millet Bran

Foxtail millet (FM) is one of the oldest cultivated grain crops with a variety of nutritions, and foxtail millet bran (FMB), a by-product of FM milling process, is also rich in variety of nutrient substance. There are four classifications of FMB, namely coarse bran (FMCB), skin bran (FMSB), polished bran (FMPB) and mixed bran (FMMB). Because these nutrients are distributed within the different fractions of FMB, we compared some chemical composition and its oleochemical properties of four FMB samples. Results showed that the oil extracted from FMB is high value-added plant oil. It contains abundant unsaturated fatty acid (UFA), with the main UFAs were linoleic acid (65%~69%) and oleic acid (12~17%), which accounted for more than 80% of the lipids. The main triacylglycerols were trilinolein (LLL) and oleodilinolein (OLL). There were no evident difference on fatty acid, triacylglycerol and sterols profiles for FMSB, FMPB and FMMB, but the contents of amino acids, tocols, squalene and oryzanol were different.

Structural, antioxidant and adsorption properties of dietary fiber from foxtail millet (Setaria italica) bran

BACKGROUND

Foxtail millet (Setaria italica) bran is a by-product of millet processing, rich in dietary fiber (DF) and has great application value. A comparative study was conducted to explore the differences in structural and functional properties among millet bran DF, soluble dietary fiber (SDF) and insoluble dietary fiber (IDF).

RESULTS

There was a significant difference in the content of monosaccharides between SDF and IDF, in which xylose, arabinose and glucose were the main compositions. The results of scanning electron microscopy showed that DF and IDF had different forms of network structure, and SDF presented a sign of mutual adhesion. The total phenolic and flavonoid contents were 0.54 and 0.08 g kg^-1 in SDF. Antioxidant activity of SDF was higher than that of IDF based on the evaluation of free radical scavenging and iron reducing capacity in vitro. Meanwhile, the glucose dialysis retardation index of IDF and SDF was 12.59% and 9.26% at 30 min, respectively. And, there was no significant difference in the adsorption capacity of glucose among different samples (P > 0.05). Furthermore, SDF had strong α-amylase inhibition (17.92% inhibition rate) and sodium cholate adsorption capacities; the adsorption amount was 16.76 g kg^-1 in 2.00 g L^-1 sodium cholate solution.

CONCLUSION

Foxtail millet bran DF, especially SDF, has good functional properties and would be a suitable ingredient for health-beneficial food production. However, the relevant verification trials in vivo need to be carried out in the next steps. © 2019 Society of Chemical Industry.

Anti-inflammatory effects of millet bran derived-bound polyphenols in LPS-induced HT-29 cell via ROS/miR-149/Akt/NF-κB signaling pathway

The pro-inflammatory and anti-inflammatory maladjustment has been acknowledged as one of the chief causations of inflammatory diseases and even cancers. Previous studies showed that plant-derived polyphenolic compounds were the most potent anti-oxidant and anti-inflammatory agents among all natural compounds. The present study indicates that bound polyphenols of inner shell (BPIS) from foxtail millet bran can display anti-inflammatory effects in LPS-induced HT-29 cells and in nude mice. Mechanistically, BPIS restrained the level of various pro-inflammatory cytokines (IL-1β, IL-6, IL-8), and enhanced the expression level of anti-inflammatory cytokine (IL-10) by blocking the nuclear factor-kappaB (NF-κB)-p65 nuclear translocation. Further, we found the elevated miR-149 expression by BPIS-induced ROS accumulation, directly targeted the Akt expression to block NF-κB nuclear translocation. Taken together, these novel findings provide new insights into the development of BPIS as an anti-inflammatory agent via the signaling cascade of ROS/miR-149/Akt/NF-κB axis.