Effect of drying method on the production of in vitro short-chain fatty acids and histone deacetylase mediation of cocoa pod husk

We evaluated the effect of cocoa pod husk (CPH) processing (microwave [MW], forced-air drying [FAD], and FAD plus extrusion [FAD-E]), and in vitro gastrointestinal digestion on the in vitro human colonic fermentation metabolism, in vitro bioactivity on human HT-29 colon cancer cell, and the in silico mechanism of selected compounds. CPH as a substrate for human colonic microbiota significantly decrease local pH (MW -0.7, FAD -0.2, and FAD-E -0.3, 24 h) and modifies their metabolic activity (short-chain fatty acids [SCFAs] production). FAD-E generated the highest butyric (7.6 mM/L, 4 h) and FAD the highest acetic and propionic acid levels (71.4 and 36.7 mM/L, 24 h). The in vitro colonic fermented FAD-E sample (FE/FAD-E) caused HT-29 colorectal cancer cells death by inducing damage on membrane integrity and inhibiting (up to 92%) histone-deacetylase (HDAC) activity. In silico results showed that chlorogenic acid, (-)-epicatechin, and (+)-catechin, followed by butyric and propionic acids, are highly involved in the HDAC6 inhibitory activity. The results highlight the potential human health postbiotic benefits of CPH consumption, mediated by colonic microbiota-derived metabolites. PRACTICAL APPLICATION: The enormous amount of CPH (10 tons/1 ton of dry beans) generated by the cocoa industry can be used as a removable source of bioactive compounds with physicochemical functionality and health bioactivity. However, their potential applications and health benefits are insufficiently explored. CPH represents a serious disposal problem; practical and innovative ideas to use this highly available and affordable material are urgent. Research exploring their potential applications can increase the sustainability of the cocoa agro-industry. This paper highlights the value addition that can be achieved with this valuable industrial co-product, generating new functional products and ingredients.

The Impact of Heat Treatment of Quercetin and Myricetin on their Activities to Alleviate the Acrylamide-Induced Cytotoxicity and Barrier Loss in IEC-6 Cells

Two flavonols quercetin and myricetin were assessed for their in vitro activities to attenuate the acrylamide-induced cytotoxicity and barrier loss in rat intestinal epithelial (IEC-6) cells and to identify whether heat treatment of the flavonols might cause activity changes. The results showed that the flavonols could alleviate the acrylamide-caused cell injury, resulting in higher cell viability, lower lactate dehydrogenase release, and less formation of reactive oxygen species. Meanwhile, the flavonols could antagonize the acrylamide-induced barrier dysfunction via decreasing the paracellular permeability, increasing the transepithelial resistance of cell monolayer, and enhancing the expression of three tight junction proteins namely occludin, claudin-1, and zonula occludens-1. The flavonols also could down-regulate the expression of JNK/Src proteins and thus cause lower relative protein ratios of p-JNK/JNK and p-Src/Src, resulting in a suppressed JNK/Src activation. Totally, quercetin was more potent than myricetin to exert these assessed activities, while the heated flavonols obtained lower activity than the unheated ones. It is thus concluded that the flavonols had beneficial activities towards the intestinal epithelial cells with acrylamide exposure by alleviating the acrylamide-induced cytotoxicity and barrier disruption, while heat treatment of the flavonols was unfavorable because it led to a reduced flavonol activity to the cells.

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-1β (IL-1β) and IL-6, but increase the production of two anti-inflammatory cytokines IL-10 and transforming growth factor-β. 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.

Enhanced Growth Inhibition and Apoptosis Induction in Human Colon Carcinoma HT-29 Cells of Soluble Longan Polysaccharides with a Covalent Chemical Selenylation

The selenylated polysaccharides chemically belong to the organic Se-conjugated macromolecules and have recently been attracting more and more attention due to their potential to promote body health or prevent cancers. Longan (Dimocarpus longan L.), as a subtropical fruit, contains soluble and non-digestible polysaccharides that are regarded with health care functions in the body. In this study, the longan polysaccharides (LP) were obtained via enzyme-assisted water extraction, and then chemically selenylated using a reaction system composed of HNO₃–Na₂SeO₃ to yield two selenylated products, namely, SeLP1 and SeLP2, with Se contents of 1.46 and 4.79 g/kg, respectively. The anti-cancer effects of the three polysaccharide samples (LP, SeLP1, and SeLP2) were thus investigated using the human colon cancer HT-29 cells as the cell model. The results showed that SeLP1 and SeLP2 were more able than LP to inhibit cell growth, alter cell morphology, cause mitochondrial membrane potential loss, increase intracellular reactive oxygen and [Ca²⁺]_i levels, and induce apoptosis via regulating the eight apoptosis-related genes and proteins including Bax, caspases-3/-8/-9, CHOP, cytochrome c, DR5, and Bcl-2. It was thereby proven that the selenylated polysaccharides could induce cell apoptosis via activating the death receptor, mitochondrial-dependent, and ER stress pathways. Collectively, both SeLP1 and SeLP2 showed higher activities than LP in HT-29 cells, while SeLP2 was consistently more active than SeLP1 in exerting these assessed anti-cancer effects on the cells. In conclusion, this chemical selenylation covalently introduced Se into the polysaccharide molecules and caused an enhancement in their anti-cancer functions in the cells, while higher selenylation extent was beneficial to the activity enhancement of the selenylated products.

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-1β (IL-1β), IL-6, and tumor necrosis factor-α, and simultaneously promote the production of two anti-inflammatory cytokines IL-10 and transforming growth factor-β. 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.

In Vitro Immunomodulation of the Polysaccharides from Yam (Dioscorea opposita Thunb.) in Response to a Selenylation of Lower Extent

The immunomodulation of chemically selenylated polysaccharides has been attracting more attention recently, but the corresponding performance of the yam polysaccharides (YPS) with lower selenylation extent remains, thus far, unsolved. In this study, the YPS was selenylated with Na₂SeO₃ under acidic conditions generated by HNO₃ to reach two lower selenylation extents, yielding two selenylated YPSs, namely SeYPS-1 and SeYPS-2 with selenium contents of 715 and 1545 mg/kg, respectively. The results indicated that YPS, SeYPS-1, and SeYPS-2 all had in vitro immuno-modulation when using RAW 264.7 macrophages and murine splenocytes as cell models. In detail, the three polysaccharide samples at dose levels of 5–160 μg/mL showed insignificant cytotoxicity to the macrophages and splenocytes with cell exposure times of 12–24 h, because of the measured values of cell viability larger than 100%. However, Na₂SeO₃ at dose levels of 1.3–3.25 μg/mL mostly caused obvious cytotoxic effects on the cells, resulting in reduced cell viability values or cell death, efficiently. The results demonstrated that, compared with YPS, both SeYPS-1 and SeYPS-2 at a lower dose level (5 μg/mL) were more active at promoting phagocytosis activity, increasing the CD4⁺/CD8⁺ ratio of the T-lymphocyte sub-population in the murine splenocyte, improving cytokine secretion, including interleukin-6 (IL-6), IL-1β, and tumor necrosis factor-α in the macrophages, or increasing interferon-γ secretion, but suppressing IL-4 production in the splenocytes. Consistently, SeYPS-2 has more potential than SeYPS-1 at exerting these assessed bioactivities in the cells. Thus, we conclude that a chemical modification of YPS using trace element Se at a lower selenylation extent could bring about higher immunomodulatory activity towards macrophages and splenocytes, while selenylation extent of YPS is a critical factor used to govern the assessed activity changes of YPS.

Galangin and Kaempferol Alleviate the Indomethacin-Caused Cytotoxicity and Barrier Loss in Rat Intestinal Epithelial (IEC-6) Cells Via Mediating JNK/Src Activation

Nonsteroidal anti-inflammatory drugs (NSAIDs) like indomethacin and others are widely used in clinics, but they have the potential to cause severe gastrointestinal damage including intestinal barrier dysfunction. Thus, two flavonols galangin and kaempferol with or without heat treatment (100 °C, 30 min) were assessed for their effect on indomethacin-damaged rat intestine epithelial (IEC-6) cells. In total, the cell exposure of 300 μmol/L indomethacin for 24 h caused cell toxicity efficiently, resulting in decreased cell viability, enhanced lactate dehydrogenase (LDH) release or reactive oxygen species (ROS) production, and obvious barrier loss. Meanwhile, pretreatment of the cells with these flavonols for 24 and 48 h before the indomethacin exposure could alleviate cytotoxicity and especially barrier loss, resulting in increased cell viability and transepithelial resistance, decreased LDH release, ROS production, and paracellular permeability, together with the promoted expression of three tight junction proteins zonula occluden-1, occludin, and claudin-1. Moreover, the intracellular Ca2+ concentration and expression levels of p-JNK and p-Src arisen from the indomethacin damage were also reduced by the flavonols, suggesting an inhibited calcium-mediated JNK/Src activation. Consistently, galangin showed higher activity than kaempferol to the cells, while the heated flavonols were less efficient than the unheated counterparts. It is thus highlighted that the two flavonols could alleviate indomethacin cytotoxicity and combat against the indomethacin-induced barrier loss in IEC-6 cells, but heat treatment of the flavonols would weaken the two beneficial functions.

Heat treatment of galangin and kaempferol inhibits their benefits to improve barrier function in rat intestinal epithelial cells

Flavonols are bioactive substances in plant foods. In this study, two flavonols galangin and kaempferol were heated at 100°C for 30 min prior to assessing their effects on barrier function of rat intestinal epithelial (IEC-6) cells. Both heated and unheated flavonols (2.5-20 µmol/L dosages) were nontoxic to the cells up to 48 h post-treatment, and could promote cell viability values to 102.2-141.2% of control. By treatment with 5 µmol/L flavonols for 24 and 48 h, the treated cells time-dependently showed better improved physical and biological barrier functions than the control cells without any flavonol treatment, including higher transepithelial electrical resistance and antibacterial effect but reduced paracellular permeability and bacterial translocation. The results from real-time PCR and western-blot assays indicated that the cells treated with heated and unheated flavonols of 5 µmol/L dosage had up-regulated mRNA (1.13-1.81 folds) and protein (1.15-5.11 folds) expression for zonula occluden-1, occludin, and claudin-1 that are vital to the tight junctions of the cells. Moreover, protein expression of RhoA and ROCK were down-regulated into 0.41-0.98 and 0.40-0.92 folds, respectively, demonstrating a Rho inactivation that led to enhanced cell barrier integrity via the RhoA/ROCK pathway. Overall, galangin was more active than kaempferol to perform three biofunctions like improving cell barrier function, up-regulating tight junctions protein expression, and down-regulating RhoA/ROCK expression. Moreover, the heated flavonols were less effective than the unheated counterparts to perform these biofunctions. It is concluded that this heat treatment of galangin and kaempferol could inhibit their benefits to improve barrier function of IEC-6 cells.

Impact of heat treatment on anti-oxidative and anti-colon cancer activities of the soluble extracts from black mulberry (Morus nigra L.) using water and ethanol-water solvents

Black mulberry (Morus nigra L.) is an edible fruit with various health functions in the body. In this study, the lyophilized black mulberry was extracted using water and 75% (v/v) ethanol-water, respectively; afterwards, the soluble extracts were subjected to these treatments like ethanol removal, heat treatment at 100 °C for various times, or activated carbon-mediated dephenolization. The assaying results indicated that the used heat treatment led to decreased anthocyanin but increased total phenol and flavonoid contents for the water- and ethanol-extracts, while the dephenolized extracts after the heat treatment also had increased total phenol and flavonoid contents. The performed heat treatment decreased anti-oxidative activities of the water- and ethanol-extracts, resulting in reduced scavenging activities to the DPPH and hydroxyl radicals and lower reducing power for Fe(iii) ions. However, the results from cell experiments also demonstrated that the heat treatment at 100 °C for 45 min caused the water- and ethanol-extracts or dephenolized extracts with higher anti-cancer activity against human colon cancer HCT-116 cells. Overall, the heated extracts were more effective than the unheated counterparts to inhibit cell growth, alter cell morphology, generate more intracellular reactive oxygen species, enhance intracellular Ca2+ level, and reduce mitochondrial membrane potential of the cells. It is thereby concluded that the heat treatment of black mulberry might reduce its anti-oxidation but increase its anti-colon cancer effect due to the occurrence of the Maillard reaction and other unidentified reactions, which will deepen our present knowledge and provide a scientific basis to optimize storage or processing conditions of plant-based foods.

Barrier-promoting efficiency of two bioactive flavonols quercetin and myricetin on rat intestinal epithelial (IEC-6) cells via suppressing Rho activation

Polyphenols are beneficial to human health because of their bio-activities. In this study, two flavonols quercetin and myricetin with or without heat treatment at 100 °C for 30 min were assessed for their barrier-promoting efficiency in rat intestinal epithelial (IEC-6) cells. The results indicated that the heated and unheated flavonols at dose levels of 2.5-20 μmol L-1 had a nontoxic effect on the cells treated for 24 and 48 h but enhanced the values of cell viability larger than 100% (especially at a dose level of 5 μmol L-1). Moreover, the cells exposed to these flavonols of 5 μmol L-1 for 24 and 48 h had improved barrier integrity compared to the control cells without any flavonol treatment, reflected by enhanced transepithelial electrical resistance and anti-bacterial effect but decreased paracellular permeability and bacterial translocation. Moreover, the results from both mRNA and protein expression verified 1.1-3.4 fold up-regulation of zonula occludens-1, occludin, and claudin-1 that are critical to tight junctions and barrier function of cells. Furthermore, the expression of other two proteins RhoA and ROCK in the treated cells was also down-regulated, demonstrating suppressed Rho activation and consequently barrier promotion via the RhoA/ROCK signaling pathway. Overall quercetin, due to its lower molecular polarity, mostly gave higher barrier-promoting efficiency than myricetin, while the heated flavonols were always less efficient than the unheated counterparts to promote barrier integrity of IEC-6 cells. It is thus highlighted that flavonols can provide barrier-promoting effects on intestinal epithelial cells with a promoting efficiency dependent on flavonol polarity; however, heat treatment especially excessive heat treatment of plant foods might lead to damaged flavonol activity.

The Stability and Activity Changes of Apigenin and Luteolin in Human Cervical Cancer Hela Cells in Response to Heat Treatment and Fe2+/Cu2+ Addition

Flavonoids are natural polyphenolic compounds with desired bio-functions but with chemical instability and sensitivity to temperature, oxygen, and other factors. Apigenin and luteolin, two flavones of the flavonoid family in plant foods, were; thus, assessed and compared for their stability, especially the changes in anti-cancer activity in response to the conducted heat treatments and the addition of ferrous or cupric ions. The two flavones in aqueous solutions showed first-order degradation at 20 and 37 °C. The addition of ferrous or cupric ions (except for Cu2+ at 37 °C) enhanced luteolin stability via forming the luteolin-metal complexes; however, Fe/Cu addition (especially at 37 °C) consistently impaired apigenin stability. Using the human cervical cancer Hela cells and two cell treatment times (24 and 48 h), it was evident that heat treatments (37 and 100 °C) or Fe/Cu addition could endow apigenin and luteolin with decreased activities in growth inhibition, DNA damage, intracellular reactive oxygen species (ROS) generation, and apoptosis induction. In general, higher temperature led to greater decrease in these activities, while Fe2+ was more effective than Cu2+ to decrease these activities. The correlation analysis also suggested that the decreased ROS generation of the two flavones in the Hela cells was positively correlated with their decreased apoptosis induction. It is; thus, concluded that the two treatments can influence the two flavones' stability and especially exert an adverse impact on their anti-cancer activities.

In vitro activities of inulin fermentation products to HCT-116 cells enhanced by the cooperation between exogenous strains and adult faecal microbiota

Inulin was fermented by adult faecal microbiota and 10 exogenous strains for 24 or 48 h. The contents of acetate, propionate, butyrate and lactate were quantified in the fermented products, and the growth-inhibitory and apoptosis-inducing effects on a human colon cell line (HCT-116 cells) were assessed. Most of these strains increased contents of acetate, propionate and butyrate, and promoted lactate conversion. Correlation analysis suggested that butyrate and lactate in the fermentation products were positively and negatively correlated with the measured inhibition ratios (p < .05). The results were mostly consistent with the verification trial results using standard acid solutions. The fermentation products could cause apoptosis via inducing DNA fragmentation and increasing total apoptotic populations in the treated cells. Moreover, the fermentation products with higher growth-inhibitory activities demonstrated the increased apoptosis-inducing properties. In conclusion, these strains could cooperate with adult faecal microbiota to confer inulin fermentation products with higher anti-colon cancer activity.