Interaction between Tea Polyphenols and Bile Acid Inhibits Micellar Cholesterol Solubility

Green Tea Catechins Decrease Solubility of Raloxifene In Vitro and Its Systemic Exposure in Mice

PURPOSE

Green tea is a widely consumed beverage. A recent clinical study reported green tea decreased systemic exposure of raloxifene and its glucuronide metabolites by 34-43%. However, the underlying mechanism(s) remains unknown. This study investigated a change in raloxifene's solubility as the responsible mechanism.

METHODS

The effects of green tea extract, (-)-epigallocatechin gallate (EGCG), and (-)-epigallocatechin (EGC) on raloxifene's solubility were assessed in fasted state simulated intestinal fluids (FaSSIF) and fed state simulated intestinal fluids (FeSSIF). EGCG and EGC represent green tea's main bioactive constituents, flavan-3-gallate and flavan-3-ol catechins respectively, and the tested concentrations (mM) match the µg/mg of each compound in the extract. Our mouse study (n = 5/time point) evaluated the effect of green tea extract and EGCG on the systemic exposure of raloxifene.

RESULTS

EGCG (1 mM) and EGC (1.27 mM) decreased raloxifene's solubility in FaSSIF by 78% and 13%, respectively. Micelle size in FaSSIF increased with increasing EGCG concentrations (> 1000% at 1 mM), whereas EGC (1.27 mM) did not change micelle size. We observed 3.4-fold higher raloxifene solubility in FeSSIF compared to FaSSIF, and neither green tea extract nor EGCG significantly affected raloxifene solubility or micelle size in FeSSIF. The mice study showed that green tea extract significantly decreased raloxifene Cmax by 44%, whereas EGCG had no effect. Green tea extract and EGCG did not affect the AUC0-24 h of raloxifene or the metabolite-to-parent AUC ratio.

CONCLUSIONS

This study demonstrated flavan-3-gallate catechins may decrease solubility of poorly water-soluble drugs such as raloxifene, particularly in the fasted state.

From controlled transformed cocoa beans to chocolate: Bioactive properties, metabolomic profile, and in vitro bioaccessibility

This study aimed to characterize the changes in bioactive compounds associated with health benefits during the transformation of cocoa seeds into chocolate and in vitro gastrointestinal digestion. Flavan-3-ols (catechin, epicatechin), methylxanthines (theobromine, caffeine), total phenolic content, antioxidant activity, and metabolomic fingerprint were analyzed. The results indicated that processing stages led to a general decrease in bioactive compound content, attributed to factors such as temperature, pH, and diffusive phenomena. Roasting and chocolate processing particularly affected epicatechin and caffeine contents. In vitro digestion released compounds in response to enzymatic activity and system conditions, with a significant release of amino acids and peptides in the intestinal phase. Catechin and theobromine exhibited higher effective bioaccessibility. The antioxidant activity mirrored the quantification of individual compounds. This research provides valuable insights into the dynamic changes of chemical compounds in cocoa matrices throughout the transformation of cocoa seeds into chocolate and in vitro gastrointestinal digestion.

Anti-obesity Properties of Phytochemicals: Highlighting their Molecular Mechanisms against Obesity

Obesity is a complex, chronic and inflammatory disease that affects more than one-third of the world's population, leading to a higher incidence of diabetes, dyslipidemia, metabolic syndrome, cardiovascular diseases, and some types of cancer. Several phytochemicals are used as flavoring and aromatic compounds, also exerting many benefits for public health. This study aims to summarize and scrutinize the beneficial effects of the most important phytochemicals against obesity. Systematic research of the current international literature was carried out in the most accurate scientific databases, e.g., Pubmed, Scopus, Web of Science and Google Scholar, using a set of critical and representative keywords, such as phytochemicals, obesity, metabolism, metabolic syndrome, etc. Several studies unraveled the potential positive effects of phytochemicals such as berberine, carvacrol, curcumin, quercetin, resveratrol, thymol, etc., against obesity and metabolic disorders. Mechanisms of action include inhibition of adipocyte differentiation, browning of the white adipose tissue, inhibition of enzymes such as lipase and amylase, suppression of inflammation, improvement of the gut microbiota, and downregulation of obesity-inducing genes. In conclusion, multiple bioactive compounds-phytochemicals exert many beneficial effects against obesity. Future molecular and clinical studies must be performed to unravel the multiple molecular mechanisms and anti-obesity activities of these naturally occurring bioactive compounds.

Deciphering the interactions between lipids and red wine polyphenols through the gastrointestinal tract

This paper investigates the mutual interactions between lipids and red wine polyphenols at different stages of the gastrointestinal tract by using the simgi® dynamic simulator. Three food models were tested: a Wine model, a Lipid model (olive oil + cholesterol) and a Wine + Lipid model (red wine + olive oil + cholesterol). With regard to wine polyphenols, results showed that co-digestion with lipids slightly affected the phenolic profile after gastrointestinal digestion. In relation to lipid bioaccessibility, the co-digestion with red wine tended to increase the percentage of bioaccessible monoglycerides, although significant differences were not found (p > 0.05). Furthermore, co-digestion with red wine tended to reduce cholesterol bioaccessibility (from 80 to 49 %), which could be related to the decrease in bile salt content observed in the micellar phase. For free fatty acids, almost no changes were observed. At the colonic level, the co-digestion of red wine and lipids conditioned the composition and metabolism of colonic microbiota. For instance, the growth [log (ufc/mL)] of lactic acid bacteria (6.9 ± 0.2) and bifidobacteria (6.8 ± 0.1) populations were significantly higher for the Wine + Lipid food model respect to the control colonic fermentation (5.2 ± 0.1 and 5.3 ± 0.2, respectively). Besides, the production of total SCFAs was greater for the Wine + Lipid food model. Also, the cytotoxicity of the colonic-digested samples towards human colon adenocarcinoma cells (HCT-116 and HT-29) was found to be significantly lower for the Wine and Wine + Lipid models than for the Lipid model and the control (no food addition). Overall, the results obtained using the simgi® model were consistent with those reported in vivo in the literature. In particular, they suggest that red wine may favourably modulate lipid bioaccessibility - a fact that could explain the hypocholesterolemic effects of red wine and red wine polyphenols observed in humans.

A Comprehensive Review on Beneficial Effects of Catechins on Secondary Mitochondrial Diseases

Mitochondria are the main sites for oxidative phosphorylation and synthesis of adenosine triphosphate in cells, and are known as cellular power factories. The phrase "secondary mitochondrial diseases" essentially refers to any abnormal mitochondrial function other than primary mitochondrial diseases, i.e., the process caused by the genes encoding the electron transport chain (ETC) proteins directly or impacting the production of the machinery needed for ETC. Mitochondrial diseases can cause adenosine triphosphate (ATP) synthesis disorder, an increase in oxygen free radicals, and intracellular redox imbalance. It can also induce apoptosis and, eventually, multi-system damage, which leads to neurodegenerative disease. The catechin compounds rich in tea have attracted much attention due to their effective antioxidant activity. Catechins, especially acetylated catechins such as epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), are able to protect mitochondria from reactive oxygen species. This review focuses on the role of catechins in regulating cell homeostasis, in which catechins act as a free radical scavenger and metal ion chelator, their protective mechanism on mitochondria, and the protective effect of catechins on mitochondrial deoxyribonucleic acid (DNA). This review highlights catechins and their effects on mitochondrial functional metabolic networks: regulating mitochondrial function and biogenesis, improving insulin resistance, regulating intracellular calcium homeostasis, and regulating epigenetic processes. Finally, the indirect beneficial effects of catechins on mitochondrial diseases are also illustrated by the warburg and the apoptosis effect. Some possible mechanisms are shown graphically. In addition, the bioavailability of catechins and peracetylated-catechins, free radical scavenging activity, mitochondrial activation ability of the high-molecular-weight polyphenol, and the mitochondrial activation factor were also discussed.

Antihyperlipidemic effect and increased antioxidant enzyme levels of aqueous extracts from Liupao tea and green tea in vivo

Liupao tea (fermented dark tea) may improve the active function of hyperlipidemia. Utilizing a hyperlipidemia Sprague-Dawley model and UPLC-MS/MS metabolomics, we examined how the effect of Liupao and green tea extracts on hyperlipidemia and antoxidant enzyme levels and compared their constituents. The results showed that the two types of tea could reduce the levels of total cholesterol (TC), total triglyceride, and low-density lipoprotein cholesterol (LDL-C); increase the contents of bile acids and cholesterol in feces; and improve catalase and glutathione peroxidase (GSH-Px) activities. Compared with the model control group, Liupao tea effectively reduced TC and LDL-C levels by 39.53% and 58.55% and increased GSH-Px activity in the liver by 67.07%, which was better than the effect of green tea. A total of 93 compounds were identified from two samples; the amounts of alkaloids and fatty acids increased compared with green tea, and ellagic acid, hypoxanthine, and theophylline with relatively high contents in Liupao tea had a significantly positive correlation with antihyperlipidemic and antioxidant effects. Therefore, Liupao tea had better antihyperlipidemic and antioxidant activities in vivo than green tea, which might be related to the relatively high content of some active substances.

Regular exercise combined with ferulic acid exhibits antiobesity effect and regulates metabolic profiles in high-fat diet-induced mice

Exercise (Ex) has been recognized as an effective way of obesity prevention, but it shows a dual effect on the body's antioxidant system. Ferulic acid (FA) is a kind of phenolic acid with well-known antioxidant capacity and numerous health benefits. Therefore, the aim of the study was to compare the antiobesity effect of Ex, FA, and Ex combined with FA (Ex-FA) in vivo and to illustrate the potential mechanisms. Mice were fed a high-fat diet (HFD) with or without administration of Ex, FA, and Ex-FA for 13 weeks. The body weight, antioxidant ability, Ex performance, and lipid profiles in the serum, liver, and skeletal muscle were compared among the groups, and serum metabolomics analysis was conducted. The results showed that Ex, FA, and Ex-FA exhibited a similar effect on body weight management. Ex had a more beneficial function by alleviating HFD-induced dyslipidemia than FA, while FA exerted a more efficient effect in mitigating lipid deposition in the liver and skeletal muscle. Ex-FA showed comprehensive effects in the regulation of the lipid contents in serum, liver, and skeletal muscle, and provoked enhancement effects on antioxidant ability and Ex capacity. Mice administered with Ex, FA, and Ex-FA showed different metabolic profiles, which might be achieved through different metabolic pathways. The findings of this research implied that Ex coupled with FA could become an effective and safe remedy for the management of dietary-induced obesity.

Tea combats circadian rhythm disorder syndrome via the gut-liver-brain axis: potential mechanisms speculated

Circadian rhythm is an intrinsic mechanism developed by organisms to adapt to external environmental signals. Nowadays, owing to the job and after-work entertainment, staying up late - Circadian rhythm disorders (CRD) are common. CRD is linked to the development of fatty liver, type 2 diabetes, and chronic gastroenteritis, which affecting the body's metabolic and inflammatory responses via multi-organ crosstalk (gut-liver-brain axis, etc.). However, studies on the mechanisms of multi-organ interactions by CRD are still weak. Current studies on therapeutic agents for CRD remain inadequate, and phytochemicals have been shown to alleviate CRD-induced syndromes that may be used for CRD-therapy in the future. Tea, a popular phytochemical-rich beverage, reduces glucolipid metabolism and inflammation. But it is immature and unclear in the mechanisms of alleviation of CRD-mediated syndrome. Here, we have analyzed the threat of CRD to hosts and their offspring' health from the perspective of the "gut-liver-brain" axis. The potential mechanisms of tea in alleviating CRD were further explored. It might be by interfering with bile acid metabolism, tryptophan metabolism, and G protein-coupled receptors, with FXR, AHR, and GPCR as potential targets. We hope to provide new perspectives on the role of tea in the prevention and mitigation of CRD.HighlightsThe review highlights the health challenges of CRD via the gut-liver-brain axis.CRD research should focus on the health effects on healthy models and its offspring.Tea may prevent CRD by regulating bile acid, tryptophan, and GPCR.Potential targets for tea prevention and mitigation of CRD include FXR, AHR and GPCR.A comprehensive assessment mechanism for tea in improving CRD should be established.

Hypolipidaemic and antioxidant effects of various Chinese dark tea extracts obtained from the same raw material and their main chemical components

In order to investigate the hypolipidaemic and antioxidant effects of various dark teas produced from different post-fermentation using the same raw material, a hyperlipidaemia zebrafish model combined with binding bile salts assay and antioxidant assays were performed in this study. Results showed that the hypolipidaemic effect of dark tea extracts increased significantly (p < 0.05) while the antioxidant ability decreased sharply compared with raw material. Particularly, Liupao tea (50%) and Pu-erh tea (48%) showed promising hypolipidaemic potential; however, the antioxidant capacity of Pu-erh tea decreased (31-49%) most dramatically. Besides, the levels of total polyphenols and catechins decreased sharply, but theabrownin, gallic acid, and caffeine increased significantly after post-fermentation. Moreover, the potential mechanisms of regulating hyperlipidaemia by dark tea extracts were discussed. These results suggest that microbial fermentation significantly affects the bioactivity of dark teas, and provide theoretical basis for processing and improving of dark tea products for hyperlipidaemia therapy.

Ripened Pu-Erh Tea Improved the Enterohepatic Circulation in a Circadian Rhythm Disorder Mice Model

Glucolipid metabolism, nitrogen metabolism, and inflammation are closely related to circadian rhythm disorder (CRD). Ripened Pu-erh tea (RPT) shows significant antidyslipidemic, antihyperurecemic, and anti-inflammatory effects. However, it is unclear whether healthy population are affected by CRD and whether long-term consumption of RPT can alleviate it. To investigate this problem, healthy mice were pretreated with RPT (0.25%, w/v) for 60 days and then subjected to CRD for 40 days. Our results indicated that healthy mice showed obesity, and the intestinal and liver inflammation increased after CRD, which were associated with the development of a metabolic disorder syndrome. RPT effectively reversed this trend by increasing the production and excretion rates of bile acid. RPT reshaped the disorder of gut microbiota caused by CRD and promoted the change of archaeal intestinal types from Firmicutes-dominant type to Bacteroidota-dominant type. In addition, by repairing the intestinal barrier function, RPT inhibited the infiltration of harmful microorganisms or metabolites through enterohepatic circulation, thus reducing the risk of chronic liver inflammation. In conclusion, RPT may reduce the risk of CRD-induced obesity in mice by increasing bile acid metabolism. The change of bile acid pool contributes to the reshaping of gut microflora, thus reducing intestinal inflammation and oxidative stress induced by CRD. Therefore, we speculated that the weakening of CRD damage caused by RPT is due to the improvement of bile acid-mediated enterohepatic circulation. It was found that 0.25% RPT (a human equivalent dose of 7 g/60 kg/day) has potential for regulating CRD.

The effect of essential oils on cholesterol content in chicken meat

The study aimed to investigate cholesterol content in chicken breast and thigh muscles by the influence of feed supplements of various content of essential oils. The experiment was carried out under practical conditions in a poultry farm with broiler chickens of the Cobb 500 hybrid combination according to the feed supplement used thyme essential oil, cinnamon essential oil, commercial citrus fruit essential oil, and their combination. The control group was without the use of experimental feed supplements and commercial coccidiostats were used in their feed mixtures. The experiment lasted 40 days in welfare conditions. Broiler chickens were used for sample preparation of breast and thigh muscles with the skin and their analysis for dry matter, fat and cholesterol contents. Samples were analyzed using a Nicolet 6700 FT-IR Fourier transform infrared spectrometer. The results were processed by the SAS system program, version 8.2. The results, which were evaluated, indicated a tendency to reduce the cholesterol content in chicken breast muscle due to cinnamon essential oil and the combination of cinnamon essential oil with citrus fruit essential oil as well as thyme essential oil with citrus fruit essential. In the achieved results of dry matter, fat, and cholesterol content in breast and thigh muscles, the difference between the effects of the used feed supplements based on essential oils and concerning the control group were not statistically significant p >0.05. The correlation was a statistically significant strong linear relation only between dry matter content and fat content due to thyme and cinnamon essential oils. In conclusion, it was stated that the investigation of the feed supplement effect based on essential oils is an open question concerning the production of safe food of animal origin.

In vitro lipid-lowering properties of the fruits of two bignay [Antidesma bunius (L.) Spreng] cultivars as affected by maturity stage and thermal processing

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Crude polyphenols from bignay fruit differing in maturity had varied bioactivities.

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Kalabaw cultivar had higher in vitro lipid-lowering activities than Common cultivar.

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Cholesterol-binding ability of bignay crude polyphenols was similar to the control.

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Thermal processing decreased lipase inhibitory activity of bignay crude polyphenols.

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Bignay fruits have huge potential as functional food in relation to dyslipidemia.

Bignay [Antidesma bunius (L). Spreng] fruit contains an array of polyphenols and information on how these bioactive compounds vary with cultivar type, maturity stage, and process treatment are unclear. Also, the effects of these variations on the lipid-lowering potential of this Philippine indigenous berry have not been reported. This study aimed to evaluate the lipid-lowering properties of the fruits of two bignay cultivars as affected by maturity stage and thermal processing. In vitro lipid-lowering assays revealed that both bignay cultivars had appreciable pancreatic lipase inhibitory activity, bile acid binding capacity, and cholesterol micellar solubility inhibition, which were comparable to those of the known lipid-lowering agents used as positive controls in this study. Freeze-dried samples of the freshly harvested fruits of both bignay cultivars [i.e., Common Cultivar (CC) and Kalabaw cultivar (KC)] had the highest bile acid binding activity (41.9–45.5% for CC and 43.4–54.0% for KC) for all the three maturity stages implying the beneficial effects of fresh bignay fruits related to lipid metabolism. Steam-blanched fruits had the highest pancreatic lipase inhibition activity (17.8–37.4% for CC and 29.2–39.0% for KC), regardless of maturity stage, while water-blanched samples exhibited the highest cholesterol micellar solubility inhibition (39.6–42.2% for CC and 40.2–47.6% for KC). Thermal processing tended to lower the lipid-lowering properties of the bignay fruits relative to their freeze-dried fresh fruits. Results of this study showed the potential of Philippine bignay fruit as a functional food that may be helpful in the management of dyslipidemia.

Ligustrum robustum Alleviates Atherosclerosis by Decreasing Serum TMAO, Modulating Gut Microbiota, and Decreasing Bile Acid and Cholesterol Absorption in Mice

SCOPE

Atherosclerosis (AS) is closely related to gut microbiota. Previous studies demonstrates that Ligustrum robustum (LR), a flavonoid-rich tea like plant, can mitigate several AS-related risk factors and modulate gut microbiota in animal models and human subjects. But its anti-AS effect and mechanisms remain unclear. Therefore, in this study, impacts of LR on AS development are investigated and the potential underlying mechanisms in C57BL/6J and Apoe^-/- mice are explored.

METHODS AND RESULTS

Female C57BL/6J and Apoe^{-/ -} mice are fed a chow diet or high-choline diet, supplemented with vehicle (water) or LR water extract (700 mg kg^-1 ) by gavage for 17 weeks. It is found that LR attenuates diet-induced AS by reducing serum trimethylamine and trimethylamine-N-oxide (TMAO) levels likely by modulating gut microbiota. Moreover, LR increases the abundance of the genus Bifidobacterium, which generates bile salt hydrolase, and thus presumably enhances bile acid (BA) deconjugation and increases fecal BA excretion. Meanwhile, LR increases fecal cholesterol excretion, decreases the levels of serum and hepatic cholesterol, but did not affect short-chain fatty acids in feces.

CONCLUSION

LR attenuates AS development presumably by decreasing serum TMAO levels and increasing fecal BA excretion likely via gut microbial modulation. These effects are accompanied by increases in fecal cholesterol excretion and decreases in serum and hepatic cholesterol.

Phenolic compounds from an Algerian medicinal plant (Pallenis spinosa): simulated gastrointestinal digestion, characterization, and biological and enzymatic activities

Pallenis spinosa is a medicinal plant which is used in folk medicine as curative or preventive remedies for various diseases. Individual phenolic compounds from the methanolic extracts of its flowers, leaves and stem were determined by the high performance liquid chromatography method (HPLC) and total phenolic contents (TPC) were evaluated by Folin-Ciocalteu assay. The stability and bioactivity (antioxidant activity, micellar cholesterol solubility, α-amylase, and angiotensin converting enzymes (ACE) inhibitory effects) of these extracts in the gastrointestinal environment was determined before and after their protection in hydroxypropylmethylcellulose (HPMC) capsules. HPLC analysis revealed the presence of thirteen phenolic compounds with nine flavonoids and four phenolic acids. Except for kaempferol, the twelve other compounds have not been previously detected in the aerial part of the studied plant. Quantification of phenolics by HPLC and Folin Ciocalteu methods revealed that the highest TPC was detected in the flower extracts (104.31 ± 0.80 and 145.73 ± 0.48 mg EGA per g of extract, respectively). Leaf extracts displayed the best antioxidant capacity against the two tested radicals DPPH and ABTS (IC50 = 1.24 ± 0.03 and 0.94 ± 0.02 mg mL-1, respectively), FRAP assay (IC50 = 0.50 ± 0.02 mg mL-1), α-amylase inhibitory (IC50 = 1.25 ± 0.00 mg mL-1) and angiotensin activity with an inhibitory percent of 30.10 ± 0.12%. The best activity shown by stem extracts was against micellar cholesterol solubility (67.57 ± 0.00%). A strong decrease in TPC and their bioactivity was observed after the gastrointestinal digestion (GID) in non encapsulated extracts. These results showed that P. spinosa is a good source of phenolic compounds and GID affects significantly their composition, content and bioactivity.

Circulating bile acids as a link between the gut microbiota and cardiovascular health: impact of prebiotics, probiotics and polyphenol-rich foods

Beneficial effects of probiotic, prebiotic and polyphenol-rich interventions on fasting lipid profiles have been reported, with changes in the gut microbiota composition believed to play an important role in lipid regulation. Primary bile acids, which are involved in the digestion of fats and cholesterol metabolism, can be converted by the gut microbiota to secondary bile acids, some species of which are less well reabsorbed and consequently may be excreted in the stool. This can lead to increased hepatic bile acid neo-synthesis, resulting in a net loss of circulating low-density lipoprotein. Bile acids may therefore provide a link between the gut microbiota and cardiovascular health. This narrative review presents an overview of bile acid metabolism and the role of probiotics, prebiotics and polyphenol-rich foods in modulating circulating cardiovascular disease (CVD) risk markers and bile acids. Although findings from human studies are inconsistent, there is growing evidence for associations between these dietary components and improved lipid CVD risk markers, attributed to modulation of the gut microbiota and bile acid metabolism. These include increased bile acid neo-synthesis, due to bile sequestering action, bile salt metabolising activity and effects of short-chain fatty acids generated through bacterial fermentation of fibres. Animal studies have demonstrated effects on the FXR/FGF-15 axis and hepatic genes involved in bile acid synthesis (CYP7A1) and cholesterol synthesis (SREBP and HMGR). Further human studies are needed to determine the relationship between diet and bile acid metabolism and whether circulating bile acids can be utilised as a potential CVD risk biomarker.

Mechanisms of Interactions between Bile Acids and Plant Compounds-A Review

Plant compounds are described to interact with bile acids during small intestinal digestion. This review will summarise mechanisms of interaction between bile acids and plant compounds, challenges in in vivo and in vitro analyses, and possible consequences on health. The main mechanisms of interaction assume that increased viscosity during digestion results in reduced micellar mobility of bile acids, or that bile acids and plant compounds are associated or complexed at the molecular level. Increasing viscosity during digestion due to specific dietary fibres is considered a central reason for bile acid retention. Furthermore, hydrophobic interactions are proposed to contribute to bile acid retention in the small intestine. Although frequently hypothesised, no mechanism of permanent binding of bile acids by dietary fibres or indigestible protein fractions has yet been demonstrated. Otherwise, various polyphenolic structures were recently associated with reduced micellar solubility and modification of steroid and bile acid excretion but underlying molecular mechanisms of interaction are not yet fully understood. Therefore, future research activities need to consider the complex composition and cell-wall structures as influenced by processing when investigating bile acid interactions. Furthermore, influences of bile acid interactions on gut microbiota need to be addressed to clarify their role in bile acid metabolism.

Characterisation of the molecular interactions between primary bile acids and fractionated lupin cotyledons (Lupinus angustifolius L.)

Interactions between bile acids and plant-based materials, and the related feedback mechanisms in enterohepatic circulation, have been considered targets for lowering cholesterol. This study aimed to identify lupin compounds that interact with primary bile acids on molecular level. Lupin cotyledons were fractionated and bile acid adsorbing activities were investigated using in vitro digestion, equilibrium dialysis and kinetic analyses. Protein- and fibre-enriched fractions significantly (p ≤ 0.05) adsorbed chenodesoxycholic acids (up to 2.33 µmol/100 g DM). Alcohol purification showed that bile acid adsorption is independent of protein and fibre structures. Moreover, high adsorption was observed with an alcohol extract (6.97 µmol chenodesoxycholic acids/100 g DM) that was rich in phytochemicals, such as flavonoids (1842 mg/100 g DM). These results suggest the formation of hydrophobic interactions between polyphenols and bile acids. Further studies of molecular mechanisms are required to define the contributions of polyphenols to the cholesterol-lowering actions of lupins.

Mitigation of nonalcoholic fatty liver disease in high-fat-fed mice by the combination of decaffeinated green tea extract and voluntary exercise

We have shown that combination treatment with decaffeinated green tea extract (GTE) and voluntary exercise (Ex) reduces obesity and insulin resistance in high-fat (HF)-fed mice to a greater extent than either treatment alone. Here, we investigated the effects of GTE-, Ex- or the combination on the development of obesity-related NAFLD. Male C57BL/6 J mice were treated for 16 weeks with HF diet (60% energy from fat), HF supplemented with 7.7 g GTE/kg, HF plus access to a voluntary running wheel, or the combination. We found that treatment of mice with the combination mitigated the development of HF-induced NAFLD to a greater extent than either treatment alone. Combination-treated mice had lower plasma alanine aminotransferase (92% lower) and hepatic lipid accumulation (80% lower) than HF-fed controls: the effect of the single treatments was less significant. Mitigation of NAFLD was associated with higher fecal lipid and nitrogen levels. Combination treated, but not singly treated mice, had higher hepatic expression of genes related to mitochondrial biogenesis (sirtuin 1 [59%]; peroxisome proliferator-activated receptor γ coactivator 1α [42%]; nuclear respiratory factor 1 [38%]; and transcription factor B1, mitochondrial [89%]) compared to the HF-fed controls. GTE-, Ex-, and the combination-treatment groups also had higher hepatic expression of genes related to cholesterol synthesis and uptake, but the combination was not better than the single treatments. Our results suggest the combination of GTE and Ex can effectively mitigate NAFLD. Future studies should determine if the combination is additive or synergistic compared to the single treatments.

In vitro studies on the interactions of blood lipid level-related biological molecules with gallic acid and tannic acid

BACKGROUND

To provide the scientific evidence for a possible new mechanism of hypolipidemic effects of gallic acid (GA) and tannic acid (TA), the binding capacity of GA and TA with blood lipid level-related biological molecules, including fat, cholesterol and cholates, were investigated in vitro. Additionally, we attempted to study the interactions of cholates with GA and TA by spectroscopic methods, high-performance liquid chromatography electrospray-ionization mass spectrometry (HPLC-ESI-MS) analysis and molecular modeling studies.

RESULTS

Our results demonstrated that both GA and TA were capable of binding with the blood lipid level-related biological molecules in vitro. The fat-binding capacity of TA was 122.1% that of GA when the addition of polyphenol was 90 mg. The inhibitory effects of GA and TA on the cholesterol solubility in mixed micelles and liquid egg yolk exhibited a dose-dependent relationship (0.5-2.0 mg mL^-1 ). In cholate-binding tests, TA showed higher affinity for sodium cholate than GA at a concentration of 2.0 mg mL^-1 , while no significant difference in the affinity for sodium deoxycholate was found between GA and TA. Moreover, the data of spectroscopic methods, HPLC-ESI-MS analysis and molecular modeling studies indicated that GA and TA might precipitate cholates through hydrophobic interactions and intermolecular hydrogen bonds rather than covalent bonds.

CONCLUSION

The findings of the present study suggested that the binding capacity of GA and TA with blood lipid level-related biological molecules might play a crucial role in their hypolipidemic effects in animals. © 2019 Society of Chemical Industry.

Calorimetric approach for comparison of Angiopoietin-like protein 4 with other pancreatic lipase inhibitors

Pancreatic lipase (PNLIP) is a digestive enzyme that is a potential drug target for the treatment of obesity. A better understanding of its regulation mechanisms would facilitate the development of new therapeutics. Recent studies indicate that intestinal lipolysis by PNLIP is reduced by Angiopoietin-like protein 4 (ANGPTL4), whose N-terminal domain (nANGPTL4) is a known inactivator of lipoprotein lipase (LPL) in blood circulation and adipocytes. To elucidate the mechanism of PNLIP inhibition by ANGPTL4, we developed a novel approach, using isothermal titration calorimetry (ITC). The obtained results were compared with those of well-described inhibitors of PNLIP - ε-polylysine (EPL), (-)-epigallocatechin-3-gallate (EGCG) and tetrahydrolipstatin. We demonstrate that ITC allows to investigate PNLIP inhibition mechanisms in complex substrate emulsions and that the ITC-based assay is highly sensitive - the lowest concentration for quantification of PNLIP is 1.5 pM. Combining ITC with surface plasmon resonance and fluorescence measurements, we present evidence that ANGPTL4 is a lipid-binding protein that influences PNLIP activity through interactions with components of substrate emulsions (bile salts, phospholipids and triglycerides), and this promotes the aggregation of triglyceride emulsions similarly to the PNLIP inhibitors EPL and EGCG. In the absence of substrate emulsion, unlike in the case of LPL, ANGPTL4 did not induce the inactivation of PNLIP. Our data also prove that due to various interactions with components of substrate systems, the effect of a PNLIP inhibitor depends on whether its effect is measured in a complex substrate emulsion or in a simple substrate system.

Characterization of the direct interaction between apple condensed tannins and cholesterol in vitro

To provide the scientific evidences for a possible new hypocholesterolemic mechanism of apple condensed tannins (ACT), the direct interaction of ACT with cholesterol (CH) was investigated in the present study. Our results suggested that the quenching of ACT fluorescence by CH was carried out according to a static mechanism, while the interaction between ACT and CH in vitro was a spontaneous process. ACT were capable of binding with CH directly, and the CH-binding capacity (35.9-43.9%) of ACT remarkably enhanced with the increase of ACT concentration (0.5-2.0 mg proanthocyanidin B₂ equivalent/mL). Besides, spectroscopic methods and morphological analysis were used to characterize the ACT-CH coprecipitates, the findings indicated that ACT were able to precipitate CH via ionic interactions, hydrophobic interactions and intermolecular hydrogen bonds rather than covalent bonds. In conclusion, the direct interaction of ACT with CH might play a role in their CH-lowering effects in humans and animals.

Review on Bile Acids: Effects of the Gut Microbiome, Interactions with Dietary Fiber, and Alterations in the Bioaccessibility of Bioactive Compounds

Bile acids are cholesterol-derived steroid molecules that serve various metabolic functions, particularly in the digestion of lipids. Gut microbes produce unconjugated and secondary bile acids through deconjugation and dehydroxylation reactions, respectively. Alterations in the gut microbiota have profound effects on bile acid metabolism, which can result in the development of gastrointestinal and metabolic diseases. Emerging research shows that diets rich in dietary fiber have substantial effects on the microbiota and human health. Plant-based foods are primary sources of bioactive compounds and dietary fiber, which are metabolized by microbes to produce different metabolites. However, the bioaccessibility of these compounds are not well-defined. In this review, we discuss the interaction of bile acids with dietary fiber, the gut microbiota, and their role in the bioaccessibility of bioactive compounds. To understand the possible mechanism by which bile acids bind fiber, molecular docking was performed between different dietary fiber and bile salts.

Molecular Mechanism by Which Tea Catechins Decrease the Micellar Solubility of Cholesterol

Tea polyphenols lower the levels of cholesterol in the blood by decreasing the cholesterol micellar solubility. To clarify this mechanism, the interactions between taurocholic acid and (-)-epigallocatechin gallate (EGCg) and its derivatives were investigated. ¹³C NMR studies revealed remarkable chemical-shift changes for the carbonyl carbon atom and the 1″- and 4″-positions in the galloyl moiety. Furthermore, ¹H NMR studies using (-)-EGCg derivatives showed that the number of hydroxyl groups on the B ring did not affect these interactions, whereas the carbonyl carbon atom and the aromatic ring of the galloyl moiety had remarkable effects. The configuration at the 2- and 3-positions of the catechin also influenced these interactions, with the trans-configuration resulting in stronger inhibition activity than the cis-configuration. Additionally, a 1:1 component ratio for the catechin-taurocholic acid complex was determined by electrospray ionization-mass spectrometry. These molecular mechanisms contribute to the development of cholesterol-absorption inhibitors.

Catechins Controlled Bioavailability of Benzo[a]pyrene (B[α]P) from the Gastrointestinal Tract to the Brain towards Reducing Brain Toxicity Using the In Vitro Bio-Mimic System Coupled with Sequential Co-Cultures

The aim of the current study was to examine the preventive effect of green tea catechins on the transport of Benzo[a]pyrene (B[α]P) into the brain using an in vitro bio-mimic system coupled with sequential co-cultures. When 72 μM of catechins was pre-treated, cellular cytotoxicity induced by IC₅₀ of B[α]P in human liver hepatocellular carcinoma (HepG2) and human brain microvascular endothelial cells (HBMECs) was reduced by 27% and 26%, respectively. The cellular integrity measured in HBMECs, which was exposed to IC₅₀ of B[α]P, slowly decreased. However, the pre-treatment of catechins retained cellular integrity that was 1.14 times higher than with the absence of catechins. Co-consumption of catechins reduced not only the bio-accessibility of B[α]P in digestive fluid, but it also decreased absorption of B[α]P in human intestinal epithelial cells (Caco-2) with a HepG2 co-culture system. It was found that approximately a two times lower amount of B[α]P was transported via the blood-brain barrier (BBB) compared to only the B[α]P intake. These results are taken in conjunction with each other support that catechins could be able to prevent brain toxicity induced by B[α]P in the human body by limiting the bio-availability of B[α]P.

Pathophysiological mechanisms of diabetic cardiomyopathy and the therapeutic potential of epigallocatechin-3-gallate

Cardiovascular complications are considered one of the leading causes of morbidity and mortality among diabetic patients. Diabetic cardiomyopathy (DCM) is a type of cardiovascular damage presents in diabetic patients independent of the coexistence of ischemic heart disease or hypertension. It is characterized by impaired diastolic relaxation time, myocardial dilatation and hypertrophy and reduced systolic and diastolic functions of the left ventricle. Molecular mechanisms underlying these pathological changes in the diabetic heart are most likely multifactorial and include, but not limited to, oxidative/nitrosative stress, increased advanced glycation end products, mitochondrial dysfunction, inflammation and cell death. The aim of this review is to address the major molecular mechanisms implicated in the pathogenesis of DCM. In addition, this review provides studies conducted to determine the pharmacological effects of (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol in green tea, focusing on its therapeutic potential against the processes involved in the pathogenesis and progression of DCM. EGCG has been shown to exert several potential therapeutic properties both in vitro and in vivo. Given its therapeutic potential, EGCG might be a promising drug candidate to decrease the morbidity and mortality associated with DCM and other diabetes complications.

Defining Lineage-Specific Membrane Fluidity Signatures that Regulate Adhesion Kinetics

Cellular membrane fluidity is a critical modulator of cell adhesion and migration, prompting us to define the systematic landscape of lineage-specific cellular fluidity throughout differentiation. Here, we have unveiled membrane fluidity landscapes in various lineages ranging from human pluripotency to differentiated progeny: (1) membrane rigidification precedes the exit from pluripotency, (2) membrane composition modulates activin signaling transmission, and (3) signatures are relatively germ layer specific presumably due to unique lipid compositions. By modulating variable lineage-specific fluidity, we developed a label-free “adhesion sorting (AdSort)” method with simple cultural manipulation, effectively eliminating pluripotent stem cells and purifying target population as a result of the over 1,150 of screened conditions combining compounds and matrices. These results underscore the important role of tunable membrane fluidity in influencing stem cell maintenance and differentiation that can be translated into lineage-specific cell purification strategy.

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Membrane rigidification precedes the exit from pluripotency

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Germ layer-specific membrane fluidity signature exists

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Identification of polyphenols as a membrane fluidity modulator

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Fluidity-based adhesion sorting purify differentiated progeny from pluripotency

Substantial Enhancement of the Antioxidant Capacity of an α-Linolenic Acid Loaded Microemulsion: Chemical Manipulation of the Oil-Water Interface by Carbon Dots and Its Potential Application

Various active ingredients play a crucial role in providing and supplementing the nutritional requirements of organisms. In this work, we attempted to chemically manipulate the interfacial microstructure of oil-water microemulsions (ME) with carbon dots (CDs), concentrating on substantially enhancing the antioxidant capacity of α-linolenic acid (ALA). To this end, CDs were synthesized and introduced into an ME. The molecular interaction of surfactant with CDs was investigated by Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The microstructure of the ME was monitored by transmission electron microscopy (TEM) and cryo-electron microscopy (cryo-EM). The cryo-EM result showed the oil-water interface in the ME was better defined after the CDs were loaded, and ¹H NMR proved the CDs were distributed mainly at the interface. On the basis of these results, interfacial models were proposed. Final evaluation results demonstrated the stabilizing effect and oxidation-inhibition ability of the ALA-loaded ME was substantially enhanced after the introduction of the CDs, indicating a "turn off" effect of the interface. Interestingly, CDs do not affect the in vitro release of ALA, indicating a "turn on" effect of the interface. This work provided a successful interface manipulation with a nanocarrier that can be used for a large diversity of food nutraceuticals.

Gastrointestinal interactions, absorption, splanchnic metabolism and pharmacokinetics of orally ingested phenolic compounds

The positive health effects of phenolic compounds (PCs) have been extensively reported in the literature. An understanding of their bioaccessibility and bioavailability is essential for the elucidation of their health benefits. Before reaching circulation and exerting bioactions in target tissues, numerous interactions take place before and during digestion with either the plant or host's macromolecules that directly impact the organism and modulate their own bioaccessibility and bioavailability. The present work is focused on the gastrointestinal (GI) interactions that are relevant to the absorption and metabolism of PCs and how these interactions impact their pharmacokinetic profiles. Non-digestible cell wall components (fiber) interact intimately with PCs and delay their absorption in the small intestine, instead carrying them to the large intestine. PCs not bound to fiber interact with digestible nutrients in the bolus where they interfere with the digestion and absorption of proteins, carbohydrates, lipids, cholesterol, bile salts and micronutrients through the inhibition of digestive enzymes and enterocyte transporters and the disruption of micelle formation. PCs internalized by enterocytes may reach circulation (through transcellular or paracellular transport), be effluxed back into the lumen (P-glycoprotein, P-gp) or be metabolized by phase I and phase II enzymes. Some PCs can inhibit P-gp or phase I/II enzymes, which can potentially lead to drug-nutrient interactions. The absorption and pharmacokinetic parameters are modified by all of the interactions within the digestive tract and by the presence of other PCs. Undesirable interactions have promoted the development of nanotechnological approaches to promote the bioaccessibility, bioavailability, and bioefficacy of PCs.

Theaflavin-3-gallate specifically interacts with phosphatidylcholine, forming a precipitate resistant against the detergent action of bile salt

Black tea is a highly popular beverage, and its pigments, polymerized catechins such as theaflavins (TFs), are attracting attention due to their beneficial health effects. In this study, to test the inhibitory activities of TFs on the intestinal absorption of cholesterol, we investigated their effects on phosphatidylcholine (PC) vesicles in the absence or presence of a bile salt. (−)-Epicatechin gallate, (−)-epigallocatechin gallate, and TFs formed insoluble complexes with PC vesicles. Galloylated TFs such as TF2A, TF2B, and TF3 precipitated far more than other polyphenols. The subsequent addition of taurocholate redispersed the polyphenol-PC complexes, except that a large amount of TF2A remained insoluble. After incubation with taurocholate-PC micelles, TF2A elevated the turbidity of the micelle solution, providing red sediments. The TF2A-specific effect was dependent on the PC concentration. These results suggest that TF2A interacts with PC and aggregates in a specific manner different from catechins and other TFs.

Green Tea Polyphenol EGCG Alleviates Metabolic Abnormality and Fatty Liver by Decreasing Bile Acid and Lipid Absorption in Mice

SCOPE

The tea polyphenol (-)-epigallocatechin-3-gallate (EGCG) has been shown to ameliorate metabolic abnormalities and fatty liver. The present study investigates the mechanisms of actions of EGCG on bile acid homeostasis and lipid metabolism.

METHODS

Male C57BL/6J mice are fed a low-fat diet, a high-fat western-style diet, or a high-fat western-style diet containing 0.32% EGCG. The effects of the treatments on biochemical parameters, gene expression, and lipidomics are analyzed.

RESULTS

EGCG treatment significantly reduces body weight gain, mesenteric fat mass, fasting blood glucose, insulin resistance, serum cholesterol, and severity of fatty liver after treatment for 17 weeks, but most of these effects were less apparent at week 33. At week 17, EGCG treatment significantly elevates the mRNA levels of cholesterol 7α-hydroxylase, HMG-CoA reductase, low-density lipoprotein receptor, and scavenger receptor B1, and partially normalizes the high-fat diet induced lipidomic profile. The intestinal bile acid content is significantly decreased by EGCG, while fecal excretion of bile acids, cholesterol, and total lipids are increased.

CONCLUSION

EGCG decreases bile acid reabsorption, results in lower intestinal bile acid levels, which further decreases the absorption of lipids. These actions contribute to the alleviation of metabolic abnormalities and fatty liver disease caused by the high-fat diet.

In vitro digestion with bile acids enhances the bioaccessibility of kale polyphenols

Kale (Brassica oleracea) polyphenols and dietary fiber have key roles in bile acid binding, and these bile acids enhanced significanlty higher (69.4%) bioaccessibility of certain health-promoting polyphenolics.

Antioxidant and anti-inflammatory effects of polyphenols extracted from Ilex latifolia Thunb

To promote the rational and effective application of Ilex latifolia Thunb., a Chinese bitter tea widely consumed as a health beverage, polyphenols were extracted from its leaves and their cellular antioxidant activity (CAA) and anti-inflammatory effect against mouse macrophage RAW 264.7 cells were analyzed. Results showed that the antioxidant capacity of polyphenols was high, and their CAA values in PBS wash and no PBS wash protocols were 6871.42 ± 85.56 and 25161.61 ± 583.55 μmol QE (quercetin equivalents)/100 g phenolic extracts, respectively. In addition, polyphenols from I. latifolia displayed strong inhibition on LPS-induced NO-production in RAW 264.7 cells. Polyphenol treatment inhibited the release of pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) induced by LPS in a dose-dependent manner by ELISA and mRNA expression analysis. Western blot results showed that the anti-inflammatory activity of polyphenols from I. latifolia might be exerted through inhibiting the activation of MAPKs (ERK and JNK) and NF-κB to decrease NO, COX-2 and pro-inflammatory cytokines production. Thus, the polyphenol enriched extracts from I. latifolia are a good source of natural antioxidants with a beneficial effect against inflammation, and they may be applied as a food supplement and/or functional ingredient.

To promote the application of Ilex latifolia Thunb., a Chinese bitter tea, polyphenols were extracted from its leaves and their cellular antioxidant activity (CAA) and anti-inflammatory effect against mouse macrophage RAW 264.7 cells were analyzed.

Spirogyra neglecta inhibits the absorption and synthesis of cholesterol in vitro

Background

Spirogyra neglecta (SN) has many nutritional benefits and it is commonly used to ameliorate different human conditions including inflammation, gastric ulcer, hyperglycemia, and hyperlipidemia. However, the mechanism of the hypocholesterolemic effect of SN still remains unclear. Therefore, the present study was aimed to evaluate the effect of SN extract particularly on cholesterol absorption and synthesis mechanisms.

Methods

For cholesterol absorption, the uptake of cholesterol was measured by using tritium radiolabeling of cholesterol in Caco-2 cells. Bile acid binding, micelles size, and cholesterol solubility were analyzed in in vitro assays, while cholesterol synthesis was evaluated by using a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase assay kit.

Results

SN extract was found to decrease cholesterol uptake in Caco-2 cells and decreased the solubility of cholesterol in micelles. The SN extract bound to taurocholate, taurodeoxycholate, and glycodeoxycholate bile acids, and increased micelles size. SN has also demonstrated an inhibitory effect on HMG-CoA reductase (HMGR) enzymatic activity. For further experimentation, the treatment combination of SN and ezetimibe (0.04 mg/mL) showed a greater significant reduction in cholesterol uptake than the extract alone.

Conclusion

These observations suggested that inhibitory cholesterol absorption effects of SN could be mediated through the modulation of size and solubility of cholesterol micelles, resulting in interference of cholesterol uptake. In addition, SN inhibited the rate limiting step of cholesterol synthesis. This study provides supporting evidence for the potential usage of SN as a cholesterol lowering agent.

The Powdering Process with a Set of Ceramic Mills for Green Tea Promoted Catechin Extraction and the ROS Inhibition Effect

For serving green tea, there are two prominent methods: steeping the leaf or the powdered leaf (matcha style) in hot water. The purpose of the present study was to reveal chemical and functional differences before and after the powdering process of green tea leaf, since powdered green tea may contribute to expanding the functionality because of the different ingesting style. In this study, we revealed that the powdering process with a ceramic mill and stirring in hot water increased the average extracted concentration of epigallocatechin gallate (EGCG) by more than three times compared with that in leaf tea using high-performance liquid chromatography (HPLC) and liquid chromatography-tandem mass Spectrometry (LC-MS/MS) analyses. Moreover, powdered green tea has a higher inhibition effect of reactive oxygen species (ROS) production in vitro compared with the same amount of leaf tea. Our data suggest that powdered green tea might have a different function from leaf tea due to the higher catechin contents and particles.