Structural and emulsifying properties of soybean protein isolate glycated with glucose based on pH treatment.

BACKGROUNDS: In the present study, a glycosylated soybean protein with glucose was prepared after pH treatment under different conditions (5.0, 6.0 7.0, 8.0, 9.0) and the conformation and emulsifying properties of soybean protein isolate (SPI) and soybean protein isolate-glucose (SPI-G) were investigated. RESULTS: The degree of grafting (37.11%) and browning (39.2%) of SPI-G conjugates were obtained at pH 9.0 (P < 0.05). The results of analysis of polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy and Endogenous fluorescence spectroscopy showed that the Maillard reaction between the SPI and glucose occurred and the natural rigid structure of test proteins was stretched and became looser, and thus the tertiary conformation was unfolding. Furthermore, the particle size of the all of samples was reduced under different pH conditions, indicating that pH treatment can increase the flexibility of SPI molecules. The proteins exhibited the best surface hydrophobicity, thermal stability and emulsifying activity (EA) of modified products when subjected to a pH treatment of 9.0, whereas they afforded the best emulsion stability (ES) at pH 8.0. There was a good correlation between the molecular flexibility and emulsifying properties of SPI-G [0.963 (F:EA) and 0.879 (F:ES)] (P < 0.05). CONCLUSION: The present study shows that the structural and emulsification characteristics of natural SPI and SPI-G conjugates have been significantly enhanced via pH treatment and these results provide a theoretical guidance for the application of glycosylated SPI in the food industry. © 2022 Society of Chemical Industry.

The anti-inflammatory effects of apigenin and genistein on the rat intestinal epithelial (IEC-6) cells with TNF-α stimulation in response to heat treatment.

The aims of the present study were to investigate the anti-inflammatory function of two flavonoids apigenin and genistein in rat intestinal epithelial (IEC-6) cells stimulated by tumor necrosis factor-alpha (TNF-α) and to clarify whether the heat treatment of the flavonoids might affect flavonoid activity. The flavonoids at lower dosage (e.g. 5 µmol/L) had no toxic effect but growth promotion on the cells. Meanwhile, the flavonoid pretreatment of the cells before TNF-α stimulation could maintain cellular morphology, decrease the production of prostaglandin E2 and two pro-inflammatory cytokines interleukin-1ß (IL-1ß) and IL-6, but increase the production of two anti-inflammatory cytokines IL-10 and transforming growth factor-ß. Additionally, the flavonoids could block off the nuclear translocation of nuclear factor-kappaB (NF-κB) p65, and suppress the expression of phosphorylated IκBα and p65 induced by TNF-α. Meanwhile, the NF-κB inhibitor BAY 11-7082 shared a similar function with the flavonoids to mediate the production of IL-6/IL-10. Furthermore, in silico analysis also declared that the flavonoids could interact with the IκBα-NF-κB complex at the binding pockets to yield the binding energies ranging from -31.7 to -34.0 kJ/mol. However, the heated flavonoids were consistently less effective than the unheated counterparts to perform these anti-inflammatory effects. It is thus proposed that both apigenin and genistein have anti-inflammatory potential to the TNF-α-stimulated IEC-6 cells by inactivating the NF-κB pathway, while heat treatment of the flavonoids caused a negative impact on these assessed anti-inflammatory effects.

The In Vitro Anti-Inflammatory Activities of Galangin and Quercetin towards the LPS-Injured Rat Intestinal Epithelial (IEC-6) Cells as Affected by Heat Treatment.

Flavonols possess several beneficial bioactivities in vitro and in vivo. In this study, two flavonols galangin and quercetin with or without heat treatment (100 °C for 15-30 min) were assessed for their anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated rat intestinal epithelial (IEC-6) cells and whether the heat treatment caused activity changes. The flavonol dosages of 2.5-20 µmol/L had no cytotoxicity on the cells but could enhance cell viability (especially using 5 µmol/L flavonol dosage). The flavonols could decrease the production of prostaglandin E2 and three pro-inflammatory cytokines interleukin-1ß (IL-1ß), IL-6, and tumor necrosis factor-α, and simultaneously promote the production of two anti-inflammatory cytokines IL-10 and transforming growth factor-ß. The Western-blot results verified that the flavonols could suppress the LPS-induced expression of TLR4 and phosphorylated IκBα and p65, while the molecular docking results also illustrated that the flavonols could bind with TLR4 and NF-κB to yield energy decreases of -(21.9-28.6) kJ/mol. Furthermore, an inhibitor BAY 11-7082 blocked the NF-κB signaling pathway by inhibiting the expression of phosphorylated IκBα/p65 and thus mediated the production of IL-6/IL-10 as the flavonols did, which confirmed the assessed anti-inflammatory effect of the flavonols. Consistently, galangin had higher anti-inflammatory activity than quercetin, while the heated flavonols (especially those with longer heat time) were less active than the unheated counterparts to exert these target anti-inflammatory effects. It is highlighted that the flavonols could antagonize the LPS-caused IEC-6 cells inflammation via suppressing TLR4/NF-κB activation, but heat treatment of the flavonols led to reduced anti-inflammatory efficacy.

Effect of the Zn Supplementation on Immuno-Modulatory Activities of Bovine Lactoferrin in the Murine Splenocytes and RAW264.7 Macrophages.

Lactoferrin (LF) has important bio-functions including immuno-modulation, while essential trace metals may interact with LF and thereby induce property especially bio-activity changes. Bovine LF was thus supplemented with Zn2+ at 0.16, 0.32, and 0.64 mg/g LF to yield 10%, 20%, and 40% Zn-saturation, respectively. Afterwards, bovine LF and the Zn-supplemented LF products at 10-40-µg/mL doses were compared for their immuno-modulatory activities in two immune cells (murine splenocytes and RAW264.7 macrophages), using the stimulation index of the splenocytes, T lymphocyte subpopulations, macrophage phagocytosis, and cytokine production as evaluation reflectors. The results showed that bovine LF and the Zn-supplemented LF products had suppressive effect on the splenocytes and concanavalin A (ConA)- and lipopolysaccharide-stimulated splenocytes, but lower Zn-saturation and lower dose could alleviate and even counteract this suppressive effect (P < 0.05). More importantly, the Zn-supplemented LF product with lower Zn-saturation at lower dose exerted slightly higher macrophage stimulation, increased CD4+/CD8+ ratio of T lymphocyte subpopulations, and were capable of enhancing the interleukin-2 (IL-2), IL-4, and interferon-γ production in the splenocytes or the IL-1ß, IL-6, and tumor necrosis factor-α production in the macrophages significantly (P < 0.05). Contrary to its counterpart at lower dose, the Zn-supplemented LF product with higher Zn-saturation at higher dose mostly showed opposite effects in the two cell models. It is concluded that Zn supplementation has an impact on the immuno-modulation of bovine LF, while Zn-saturation is a key factor to modulate these assessed immune activities.

Modulatory Effect of the Supplemented Copper Ion on In Vitro Activity of Bovine Lactoferrin to Murine Splenocytes and RAW264.7 Macrophages.

Bovine lactoferrin (LF) was supplemented with Cu2+ at three contents of 0.16, 0.32, and 0.64 mg/g LF, respectively. After then, LF and Cu-supplemented LF products were assessed for immuno-modulation in murine splenocytes and RAW264.7 macrophages, using dose levels of 10-40 µg/mL and four evaluation reflectors including stimulation index of splenocytes, T lymphocyte subpopulations, macrophage phagocytosis, and cytokine secretion. The results indicated that LF and Cu-supplemented LF products had suppression on splenocytes as well as concanavalin A (ConA)- or lipopolysaccharide-stimulated splenocytes; however, using lower Cu-supplementation content (i.e., 0.16 mg/g LF) and lower dose level (10 µg/mL) alleviated this suppression significantly (P < 0.05). Compared to LF, Cu-supplemented LF product of lower Cu-supplementation content at lower dose level yielded slightly enhanced macrophage stimulation, increased CD4+/CD8+ ratio of T lymphocyte subpopulations in ConA-stimulated splenocytes, and significant secretion enhancement for interleukin-2 (IL-2), IL-4, interferon-γ (in splenocytes), IL-1ß, and tumor necrosis factor-α (in macrophages) (P < 0.05). Furthermore, Cu-supplemented LF product of higher Cu-supplementation content (i.e., 0.64 mg/g LF) at higher dose level mostly showed opposite effects in the cells, in comparison with its counterpart at lower dose level. It is concluded that Cu-supplementation of LF can alleviate or increase LF's effects on the two immune cells, and moreover, Cu content of supplemented LF is a key factor that modulates these effects.

Copper or Manganese Supplementation Endows the Peptic Hydrolysate from Bovine Lactoferrin with Enhanced Activity to Human Gastric Cancer AGS Cells.

A lactoferrin hydrolysate (LFH) was generated from bovine lactoferrin by pepsin, mixed with Cu2+ and Mn2+ at 0.64-1.28 and 0.28-0.56 mg/g protein, respectively; and then their in vitro effects on human gastric cancer AGS cells were assessed. With incubation times of 24 or 48 h, LFH and its Cu2+/Mn2+ mixtures at 10-30 mg/mL in dose-dependent manner inhibited cell growth; and more, these mixtures showed higher activities than LFH alone. Cell treatments of LFH and the mixtures (25 mg/mL) for 24 h could arrest cell cycle at G0/G1-phase, damage mitochondrial membrane integrity, and induce apoptosis, while the mixtures were also more powerful than LFH to exert these three effects. Higher Cu2+/Mn2+ supplementation level resulted in higher growth inhibition, cell cycle arrest, mitochondrial membrane potential disruption, and apoptosis induction; furthermore, Mn2+ was notable for its higher efficacy than Cu2+ to increase these four effects. Western-blot assay results revealed that four apoptosis-related proteins Bad, Bax, cytochrome c, and p53 were up-regulated, and both caspase-3 and caspase-9 also were cleaved and activated; moreover, two autophagy-related proteins LC3-II and cleaved Beclin-1 were down- and up-regulated, respectively. It is thus concluded that Cu2+ and especially Mn2+ could endow supplemented LFH with increased anti-cancer effects in AGS cells, with two proposed events as enhanced apoptosis induction (via activating apoptosis-related proteins) and autophagy inhibition (via activating autophagy-related proteins).

Report - In vitro immune potentials of a water-soluble polysaccharide extract from Dioscorea opposita planted in Henan Province, China.

Dioscorea opposita is an edible and medicinal plant available in many areas of China. This study aimed to assess in vitro immune potentials of a water-soluble polysaccharide extract from D. opposita planted in Henan Province, China. In vitro effects of the extract on three immune cells (macrophages, natural killer cells and splenocytes) from mice and secretion of eight immune-related molecules in macrophages and splenocytes were evaluated. In total, the extract exhibited a dose-dependent manner on these immunological responses. The extract at dose level of 50µg/ml enhanced respective splenocyte proliferation, macrophage phagocytosis, and natural killer cell activity by 150%, 18% and 47%, increased secretion of interleukin-2 and interferon-γ (from 41.4 and 24.6 pg/ml to 48.8 and 91.5 pg/ml, respectively) but decreased secretion of interleukin-4 (from 38.9 to 27.9 pg/ml) in splenocytes. The extract at the same dose level also stimulated inducible nitric oxide synthase and lysozyme in macrophages, and enhanced secretion of interleukin-6, interleukin-1ß and tumor necrosis factor-α (from 26.6, 73.4 and 39.6 pg/ml to 60.2, 131.0 and 144.7 pg/ml, respectively). It is concluded that water-soluble polysaccharides from D. opposita have immune potentials to the body, via activating immune cells and regulating the secretion of immune-related molecules.

Acid production and conversion of konjac glucomannan during in vitro colonic fermentation affected by exogenous microorganisms and tea polyphenols.

Impacts of exogenous microorganisms and tea polyphenols on acid production and conversion during in vitro colonic fermentation of konjac glucomannan (KGM) were assessed in this study. Colonic fermentation of KGM by the fecal extract of healthy adults resulted in a propionate-rich profile, as acetic, propionic, butyric and lactic acids production were 16.1, 13.0, 3.3 and 20.2 mmol/L, respectively. Inoculation of one of ten exogenous microorganisms in the fermentative systems increased acetic, propionic and butyric acids production by 50-230%, 9-190% and 110-350%, respectively, and also accelerated lactic acid conversion by 14-40%. Tea polyphenols in the fermentative systems showed clear inhibition on both acid production and conversion; however, this inhibition could be partially or mostly antagonised by the inoculated exogenous microorganisms, resulting in improved acid production and conversion. In total, Lactobacillus brevis and Sterptococcus thermophilus were more able to increase acid production, and the propionate-rich profile was not changed in all cases.