Effects of in vitro simulated digestion on the free and bound phenolic content and antioxidant activity of seven species of seaweeds

Insight into the structural characteristics of self-assembled liposome with epigallocatechin gallate/alcohol dehydrogenase

In this study, the encapsulation and structural characteristics of the self-assembled liposome formed by epigallocatechin gallate (EGCG) and alcohol dehydrogenase (ADH) were studied. According to the results, EGCG significantly increased the catalytic activity of ADH with a 33.33 % activation rate and the liposomes were able to entrap EGCG-ADH with an effectiveness of 88.94 %. The self-assembled monolayers had nanometer-sized particles, and the excellent self-assembled system was demonstrated by the low PDI value and high surface absolute potential. The scanning electron microscope showed that the self-assembled liposome was honeycomb, groove-shaped, and rough. The spectroscopic results showed that EGCG-ADH complex was formed through hydrogen bond, which changed the secondary structure of the liposome, and verified EGCG-ADH liposome system was successfully prepared. In vitro digestion experiments showed that the gastrointestinal tolerance and antioxidant activity of EGCG-ADH liposomes were significantly higher than those of free EGCG-ADH.

Metabolomic insights into the profile, bioaccessibility, and transepithelial transport of polyphenols from germinated quinoa during in vitro gastrointestinal digestion/Caco-2 cell transport, and their prebiotic effects during colonic fermentation

The health-promoting activities of polyphenols and their metabolites originating from germinated quinoa (GQ) are closely related to their digestive behavior, absorption, and colonic fermentation; however, limited knowledge regarding these properties hinder further development. The aim of this study was to provide metabolomic insights into the profile, bioaccessibility, and transepithelial transport of polyphenols from germinated quinoa during in vitro gastrointestinal digestion and Caco-2 cell transport, whilst also investigating the changes in the major polyphenol metabolites and the effects of prebiotics during colonic fermentation. It was found that germination treatment increased the polyphenol content of quinoa by 21.91%. Compared with RQ group, 23 phenolic differential metabolites were upregulated and 47 phenolic differential metabolites were downregulated in GQ group. Compared with RQ group after simulated digestion, 7 kinds of phenolic differential metabolites were upregulated and 17 kinds of phenolic differential metabolites were downregulated in GQ group. Compared with RQ group after cell transport, 7 kinds of phenolic differential metabolites were upregulated and 9 kinds of phenolic differential metabolites were downregulated in GQ group. In addition, GQ improved the bioaccessibilities and transport rates of various polyphenol metabolites. During colonic fermentation, GQ group can also increase the content of SCFAs, reduce pH value, and adjust gut microbial populations by increasing the abundance of Actinobacteria, Bacteroidetes, Verrucomicrobiota, and Spirochaeota at the phylum level, as well as Bifidobacterium, Megamonas, Bifidobacterium, Brevundimonas, and Bacteroides at the genus level. Furthermore, the GQ have significantly inhibited the activity of α-amylase and α-glucosidase. Based on these results, it was possible to elucidate the underlying mechanisms of polyphenol metabolism in GQ and highlight its beneficial effects on the gut microbiota.

Green and Sustainable Forward Osmosis Process for the Concentration of Apple Juice Using Sodium Lactate as Draw Solution

China is the world's largest producer and exporter of concentrated apple juice (CAJ). However, traditional concentration methods such as vacuum evaporation (VE) and freeze concentration cause the loss of essential nutrients and heat-sensitive components with high energy consumption. A green and effective technique is thus desired for juice concentration to improve product quality and sustainability. In this study, a hybrid forward osmosis-membrane distillation (FO-MD) process was explored for the concentration of apple juice using sodium lactate (L-NaLa) as a renewable draw solute. As a result, commercial apple juice could be concentrated up to 65 °Brix by the FO process with an average flux of 2.5 L·m-2·h-1. Most of the nutritional and volatile compounds were well retained in this process, while a significant deterioration in product quality was observed in products obtained by VE concentration. It was also found that membrane fouling in the FO concentration process was reversible, and a periodical UP water flush could remove most of the contaminants on the membrane surface to achieve a flux restoration of more than 95%. In addition, the L-NaLa draw solution could be regenerated by a vacuum membrane distillation (VMD) process with an average flux of around 7.87 L∙m-2∙h-1 for multiple reuse, which further enhanced the long-term sustainability of the hybrid process.

Characterization of Proteins Extracted from Ulva sp., Padina sp., and Laurencia sp. Macroalgae Using Green Technology: Effect of In Vitro Digestion on Antioxidant and ACE-I Inhibitory Activity

Macroalgal proteins were extracted from Ulva rigida (URPE) (green), Padina pavonica (PPPE) (brown), and Laurencia obtusa (LOPE) (red) using ultrasound-assisted enzymatic extraction, which is one of the green extraction technologies. Techno-functional, characteristic, and digestibility properties, and biological activities including antioxidant (AOA) and angiotensin-I converting enzyme (ACE-I) inhibitory activities were also investigated. According to the results, the extraction yield (EY) (94.74%) was detected in the extraction of L. obtusa, followed by U. rigida and P. pavonica. PPPE showed the highest ACE-I inhibitory activity before in vitro digestion. In contrast to PPPE, LOPE (20.90 ± 0.00%) and URPE (20.20 ± 0.00%) showed higher ACE-I inhibitory activity after in vitro digestion. The highest total phenolic content (TPC) (77.86 ± 1.00 mg GAE/g) was determined in LOPE. On the other hand, the highest AOACUPRAC (74.69 ± 1.78 mg TE/g) and AOAABTS (251.29 ± 5.0 mg TE/g) were detected in PPPE. After in vitro digestion, LOPE had the highest TPC (22.11 ± 2.18 mg GAE/g), AOACUPRAC (8.41 ± 0.06 mg TE/g), and AOAABTS (88.32 ± 0.65 mg TE/g) (p < 0.05). In vitro protein digestibility of three macroalgal protein extracts ranged from 84.35 ± 2.01% to 94.09 ± 0.00% (p < 0.05). Three macroalgae showed high oil holding capacity (OHC), especially PPPE (410.13 ± 16.37%) (p < 0.05), but they showed minimum foaming and emulsifying properties. The quality of the extracted macroalgal proteins was assessed using FTIR, SDS-PAGE, and DSC analyses. According to our findings, the method applied for macroalgal protein extraction could have a potential the promise of ultrasonication application as an environmentally friendly technology for food industry. Moreover, URPE, PPPE, and LOPE from sustainable sources may be attractive in terms of nourishment for people because of their digestibility, antioxidant properties, and ACE-I inhibitory activities.

Bioavailability and Antioxidant Activity of Rambutan (Nephelium lappaceum) Peel Polyphenols during in Vitro Simulated Gastrointestinal Digestion, Caco-2 Monolayer Cell Model Application, and Colonic Fermentation

The bioavailability of rambutan peel polyphenols (RPPs) was studied via in vitro simulated digestion, a Caco-2 monolayer cell model, and colonic fermentation. Total phenolic content of RPPs decreased with the progress of the simulated digestion. A total of 38 phenolic compounds were identified during the digestion and colonic fermentation, of which 12 new metabolites were found during colonic fermentation. The possible biotransformation pathways were inferred. Geraniin was transformed into corilagin, ellagic acid, and gallic acid during the digestion and colonic fermentation. Ellagic acid could be further transformed into urolithin under the action of intestinal microbiota. The transformation of ellagitannins could be beneficial to transport on Caco-2 monolayer cell. The antioxidant capacity of RPPs increased with the progress of gastrointestinal digestion. Furthermore, RPPs could increase the yield of short-chain fatty acids, decrease the pH value, promote the growth of beneficial bacteria, and inhibit the growth of pathogenic Escherichia coli/Shigella during colonic fermentation.

Cochayuyo (Durvillaea incurvata) Extracts: Their Impact on Starch Breakdown and Antioxidant Activity in Pasta during In Vitro Digestion

Seaweeds, notably cochayuyo (Durvillaea incurvata), are recognized for their rich macro- and micronutrient content, along with their inhibitory effects on the α-glucosidase enzyme. The present study aims to evaluate the effectiveness of this inhibition in actual starchy food products under in vitro gastrointestinal conditions. This study utilized freeze-dried cochayuyo, extracted using hot pressurized liquid extraction with 50% ethanol at 120 °C and 1500 psi. The inhibition mechanism of α-glucosidase was determined, and the polyphenol composition of the extract was analyzed using Ultra-High-Performance Liquid Chromatography. This study further evaluated the extract's impact on starch digestibility, total phenolic content, and antioxidant capacity in pasta (noodles) as representative starchy food under gastrointestinal conditions. The results indicate that the α-glucosidase inhibition mechanism is of mixed type. Phenolic compounds, primarily tetraphloroethol, could contribute to this anti-enzymatic activity. The extract was observed to decrease starch digestibility, indicated by a lower rate constant (0.0158 vs. 0.0261 min-1) and digested starch at an infinite time (77.4 vs. 80.5 g/100 g). A significant increase (~1200 vs. ~390 µmol TROLOX/100 g) in antioxidant activity was also noted during digestion when the extract was used. Thus, this study suggests that the cochayuyo extract can reduce starch digestion and enhance antioxidant capacity under gastrointestinal conditions.

Paramylon and Other Bioactive Molecules in Micro and Macroalgae

Many algae synthesize compounds that have exceptional properties of nutraceutical, pharmacological, and biomedical interest. Pigments, fatty acids, phenols, and polysaccharides are among the main compounds investigated so far. Polysaccharides are the most exploited compounds, widely used in pharmaceutical, food, and chemical industries, which are at present entering into more advanced applications by gaining importance, from a therapeutic point of view, as antioxidant, antimicrobial, antitumor, and immunomodulatory agents. Establishing algae as an alternative supplement would complement the sustainable and environmental requirements in the framework of human health and well-being. This review focuses on the proprieties and uses of the main micro- and macroalgae metabolites, describing their potential for application in the different industrial sectors, from food/feed to chemical and pharmacological. Further, current technologies involved in bioactive molecule extraction strategies are documented.

Polyphenols of Edible Macroalgae: Estimation of In Vitro Bio-Accessibility and Cytotoxicity, Quantification by LC-MS/MS and Potential Utilization as an Antimicrobial and Functional Food Ingredient

Macroalgae are a rich source of polyphenols, and their ingestion promotes various health benefits. However, information on factors contributing to health benefits such as antioxidants, antimicrobial properties, bioaccessibility, and cytotoxicity is less explored and often unavailable. Therefore, this study aims to investigate the above-mentioned parameters for the brown and green macroalgae Sargassum wightii and Ulva rigida, respectively, collected from the southeast coast of India. S. wightii exhibited higher antioxidant activity and moderate antimicrobial activity against major food pathogens in an agar well diffusion assay and in the broth microdilution method (MIC50 being <0.5 mg/mL for all microorganisms tested). Both macroalgae extracts exhibited significantly high bioaccessibility of polyphenols. To evaluate the safety of the extracts, in vitro cytotoxicity by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was carried out on the primary cells: mouse splenic lymphocytes. An almost complete decline in the cell viability was seen at considerably high concentration (50 mg/mL), expressing the reasonably high safety of the extracts. The extracts of both macroalgae were quantified for polyphenols, wherein fucoxanthin (9.27 ± 2.28 mg/kg DW) and phloroglucinol (17.96 ± 2.80 mg/kg DW) were found to be greater in the S. wightii apart from other phenolics, like gallic acid, quercetin, vanillin, and ferulic acid. The results signify the tremendous scope for the value addition of S. wightii through extraction and purification of polyphenols for its potential exploitation in functional foods and nutraceuticals or as an antimicrobial ingredient in active or smart packaging.

Potential Prebiotic and Anti-Obesity Effects of Codium fragile Extract

Polysaccharides from marine algae exhibit beneficial biological activities. In this study, we examined the effect of Codium fragile extract (CFE) on prebiotic and anti-obesity activity through in vitro experiments. CFE increases the growth of specific beneficial microbial populations with concomitant decrease in pathogenic microbes. Further, total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical scavenging activity (DPPH activity) after fermentation with CFE as the carbon source were higher than for glucose as the control. Moreover, CFE inhibited adipocyte differentiation by inducing differentiation-related factors when the induction of 3T3-L1 preadipocytes into adipocytes was induced. Therefore, we suggest that CFE can be used as a prebiotic material with an anti-obesity effect for human health.

Pork Liver Pâté Enriched with Persimmon Coproducts: Effect of In Vitro Gastrointestinal Digestion on Its Fatty Acid and Polyphenol Profile Stability

Agrofood coproducts are used to enrich meat products to reduce harmful compounds and contribute to fiber and polyphenol enrichment. Pork liver pâtés with added persimmon coproducts (3 and 6%; PR-3 and PR-6, respectively) were developed. Therefore, the aim was to study the effect of their in vitro gastrointestinal digestion on: the free and bound polyphenol profile (HPLC) and their colon-available index; the lipid oxidation (TBARs); and the stability of the fatty acid profile (GC). Furthermore, the effect of lipolysis was investigated using two pancreatins with different lipase activity. Forty-two polyphenols were detected in persimmon flour, which were revealed as a good source of bound polyphenols in pâtés, especially gallic acid (164.3 µg/g d.w. in PR-3 and 631.8 µg/g d.w. in PR-6). After gastrointestinal digestion, the colon-available index in enriched pâté ranged from 88.73 to 195.78%. The different lipase activity in the intestinal phase caused significant differences in bound polyphenols' stability, contributing to increased lipid oxidation. The fatty acids profile in pâté samples was stable, and surprisingly their PUFA content was raised. In conclusion, rich fatty foods, such as pâté, are excellent vehicles to preserve bound polyphenols, which can reach the colon intact and be metabolized by the intestinal microbiome.