Stability and metabolism of Arbutus unedo bioactive compounds (phenolics and antioxidants) under in vitro digestion and colonic fermentation

Arbutus unedo L.: From traditional medicine to potential uses in modern pharmacotherapy

ETHNOPHARMACOLOGICAL RELEVANCE

Arbutus unedo L., the strawberry tree (Ericaceae family) is of increasing interest because of its common traditional, industrial, chemical and pharmaceutical uses. The plant is a typical evergreen plant of the Mediterranean basin, as well as of other regions with hot summers and mild rainy winters. This review covers the studies relevant to Arbutus unedo L. utilization in the current pharmacological therapy.

MATERIALS AND METHODS

The available information on traditional uses, phytochemistry and biological activities of Arbutus unedo L. was collected from scientific databases through a search using the keywords 'Arbutus unedo L.' and/or 'strawberry tree' in 'Google Scholar', 'Pubmed', 'Sciencedirect', 'SpringerLink', 'Web of Science - Clarivate Analytics' and 'Wiley'. Unpublished Ph.D. and M.Sc. dissertations were also consulted for chemical composition, biological activities and traditional uses of Arbutus unedo L. and for manual search of additional references.

RESULTS

The fruits of the plant have been traditionally used as antiseptics, diuretics and laxatives in folk medicine, while the leaves have been used due to their diuretic, urinary antiseptic, antidiarrheal, astringent, depurative and antihypertensive properties. According to the scientific literature survey, different extracts obtained from Arbutus unedo L. have demonstrated a high pharmacological potential due to their in vitro and preclinical antibiotic, antifungal, antiparasitic, antiaggregant, antidiabetic, antihypertensive, anti-inflammatory, antitumoral, antioxidant, and spasmolytic properties.

CONCLUSION

This review suggests that A. unedo is a promising source of phytopharmaceutical products. The potential advantages of Arbutus unedo are related with the presence of polyphenolic compounds in its composition. However, further studies are needed to ascertain some profitable effects in humans. The beneficial effects associated with this shrub suggest that Arbutus unedo can be used for the development of new drugs to treat diseases such diabetes, hypertension, among others. Nonetheless, the safety of the Arbutus unedo compounds should also be examined.

Evaluation of postharvest calcium treatment and biopreservation with Lactobacillus rhamnosus GG on the quality of fresh-cut 'Conference' pears

BACKGROUND

Biological preservation with probiotic bacteria has arisen as an alternative to control the growth of foodborne pathogens on food. The objective of this work was to evaluate the effect of postharvest calcium application and biopreservation with Lactobacillus rhamnosus GG on the quality and bioaccessibility of total phenolic content and antioxidant activity in fresh-cut pears.

RESULTS

The immersion of whole pears in a calcium chloride solution did not provide added value. Despite the increase in observed activity of PME and PPO enzymes in fresh-cut pears during storage, the browning index and firmness values were constant for all samples. The antioxidant properties, including antioxidant activity, total phenolic content and vitamin C content, were maintained during storage, but a significant decrease was observed after in vitro simulated digestion. Ca/LGG samples showed the lowest calcium content (1.75 ± 0.00 g kg^-1 ) after 9 d of storage at 4 °C. In general, the overall visual quality scores were higher in fresh-cut pears treated with L. rhamnosus GG than in non-treated pears, with the highest values in the NoCa/LGG (7.7 ± 0.2) samples after 9 d at 4 °C.

CONCLUSION

Fresh-cut pears with a postharvest treatment of calcium and immersed in a solution containing antioxidant agents and probiotic bacteria could be a suitable alternative to dairy products for maintaining the overall quality of fruit for up to 9 d of storage. © 2018 Society of Chemical Industry.

Simulated Gastrointestinal Digestion, Bioaccessibility and Antioxidant Capacity of Polyphenols from Red Chiltepin (Capsicum annuum L. Var. glabriusculum) Grown in Northwest Mexico

Chiltepin, a wild chili mostly used in different traditional foods and traditional medicine in Northwest Mexico, represents a source of polyphenols. However, studies about the bioaccessibility of polyphenols as a parameter to measure the nutritional quality and bioefficacy of them in the fruit after consumption are scarce. Chiltepin showed phenolic acids and flavonoids contents between 387 and 65 μg/g, respectively. Nevertheless, these values decreased after the digestion process. Before digestion, gallic acid, 4-hydroxibenzoinc acid, chlorogenic acid, caffeic acid, p-coumaric acid, quercetin and luteolin were the main polyphenols found in chiltepin by HPLC-DAD and confirmed by FIA-ESI-IT-MS/MS. Gallic and chlorogenic acids were non-detected in the gastric phase, while only p-coumaric acid (5.35 ± 3.89 μg/g), quercetin (5.91 ± 0.92 μg/g) and luteolin (2.86 ± 0.62 μg/g) were found in the intestinal phase. The bioaccessibility of phenolic acids, flavonoids, and total polyphenols after the intestinal phase was around 24, 17 and 23%, respectively. Overall, results indicated that release of polyphenols from chiltepin fruit might be affected by the food matrix and gastrointestinal conditions due to the low bioaccessibility values observed.

The Microencapsulation of Maqui (Aristotelia chilensis (Mol.) Stuntz) Juice by Spray-Drying and Freeze-Drying Produces Powders with Similar Anthocyanin Stability and Bioaccessibility

The microencapsulation of maqui juice by spray-drying and freeze-drying was studied as a strategy to protect anthocyanins in new food formulations in order to improve the anthocyanin retention before consumption and the bioaccessibility. It is well known that the encapsulation method affects both the shape and size of powders, being assumed that undefined forms of freeze-drying powders might affect their stability due to the high permeability to oxygen. The objective of this study was to compare the microencapsulation of maqui juice by spray-drying and freeze-drying, evaluating the stability of specific anthocyanins in yogurt and after in vitro digestion. Results indicated that most relevant differences between spray-drying and freeze-drying powders were the morphology and particle size that affect their solubility (70.4⁻59.5%) when they were reconstituted in water. Nevertheless these differences did not affect the stability of anthocyanins as other research have proposed. Both encapsulation methods generated powders with a high stability of 3-O-monoglycosylated anthocyanins in yogurt (half-life values of 75⁻69 days for delphinidin-3-sambubioside). Furthermore, no significant differences in the bioaccessibility of anthocyanins between maqui juice powders (44.1⁻43.8%) were found. In conclusion, the microencapsulation of maqui juice by freeze-drying is as effective as spray-drying to produce new value-added food formulations with stable anthocyanins.

Beneficial effects of consumption of acerola, cashew or guava processing by-products on intestinal health and lipid metabolism in dyslipidaemic female Wistar rats

This study assessed the effects of diet supplementation with industrial processing by-products of acerola (Malpighia emarginataD.C.), cashew (Anacardium occidentaleL.) and guava (Psidium guajavaL.) fruit on the intestinal health and lipid metabolism of female Wistar rats with diet-induced dyslipidaemia. Female rats were randomly divided into five groups: healthy control, dyslipidaemic control and dyslipidaemic experimental receiving acerola, cashew or guava processing by-products. Fruit processing by-products were administered (400 mg/kg body weight) via orogastric administration for 28 consecutive days. Acerola, cashew and guava by-products caused body weight reduction (3·42, 3·08 and 5·20 %, respectively) in dyslipidaemic female rats. Dyslipidaemic female rats receiving fruit by-products, especially from acerola, presented decreased faecal pH, visceral fat, liver fat and serum lipid levels, as well as increased faecal moisture, faecal fat excretion, faecalBifidobacteriumspp. andLactobacillusspp. counts and amounts of organic acids in faeces. Administration of the tested fruit processing by-products protected colon and liver from tissue damage (e.g. destruction of liver and colon cells and increased fat deposition in hepatocytes) induced by dyslipidaemic diet. Dietary fibres and phenolic compounds in tested fruit by-products may be associated with these positive effects. The industrial fruit processing by-products studied, mainly from acerola, exert functional properties that could enable their use to protect the harmful effects on intestinal health and lipid metabolism caused by dyslipidaemic diet.

Change of phenolics, carotenoids, and antioxidant capacity following simulated gastrointestinal digestion and dialysis of selected edible green leaves

The bio-accessibility of phenolics, flavonoids, rutin, β-carotene and lutein and changes in antioxidant activities in six edible greens during simulating gastro-intestinal conditions has been investigated. It was found that the amount of dialysable phenolics, flavonoids and carotenoids which potentially available for further uptake is varying depending on the leafy type. Bioavailable phenolics after the gastric-phase, intestinal-phase and in dialysable fraction were in the ranges of 13.9-71.8%, 14.4-77.4% and 3.1-12.3% respectively when compared with their fresh leaves. Total antioxidant capacities in the dialysable fractions were significantly lower than their original. Bioactives of Centella asiatica showed comparatively higher bioavailability in all phases with respect to its original content. β-carotene seems more dialysable than lutein in all leaves studied. Higher rutin contents were found in both gastric and intestinal phases than in fresh leaves. These results highlighted that gastrointestinal digestion may substantially affect the absorption of polyphenols and carotenoids present in leafy greens.

Biotransformation and metabolism of three mulberry anthocyanin monomers by rat gut microflora

Anthocyanins (ACNs) are naturally occurring components of human diet. Evidence has accumulated regarding the positive association of their intake with chronic disease. Because microbiota has been considered as a metabolic organ, the bacterial-dependent metabolisms of three types of ACNs from mulberry fruits (cyanidin-3-glucoside (C3G), cyanidin-3-rutinoside (C3R), delphinidin-3-rutinoside (D3R)) during a simulation of large intestine conditions were investigated. ACNs and metabolites were analysed and characterized by high performance liquid chromatography-electrospray ionization-mass spectrum (HPLC-ESI-MS/MS). C3G disappeared after 6h of metabolism, while C3R and D3R were no longer detected after 8h. The metabolism of C3G and C3R mainly resulted in the formation of protocatechuic, vanillic, and p-coumaric acids, as well as 2,4,6-trihydroxybenzaldehyde, while the main metabolites of D3R were gallic acid, syringic acid and 2,4,6-trihydroxybenzaldehyde. This research indicated that the intake of ACNs may result in the appearance of specific metabolites that exert a protective effect in the host physiology.

Biomarkers of carotenoid bioavailability

The use of biomarkers constitutes an essential tool to assess the bioavailability of carotenoids in humans. The present article aims to review several methodological, host-related and modulating factors relevant on assessing and interpreting carotenoid bioavailability. Markers for carotenoid bioavailability can be broadly divided into direct, biochemical or "analytical" markers and indirect, physiological or "functional" indicators. Analytical markers usually refer to biochemical indicators of intake and/or status (short and long term exposure) while functional measures may be interpreted in terms of cumulative exposure, biological effect (bioactivity) or modification of risk factors. Both types of markers display advantages and limitations but, in general, a relationship exists among the type of marker, the biological specimen needed and the time required for a change. Humans may absorb a wide range of carotenes and xanthophylls and many of them may be found in serum and tissues. However, under physiological conditions, the several classes of dietary carotenoids may behave unequally leading to a different systemic profile and, moreover, they can be selectively accumulated at target tissues. In addition, some carotenoids may be chemically and enzymatically modified generating different oxidative metabolites and apocarotenoids. Quantitatively, the biological response upon carotenoid intervention (assessed by analytical and functional markers) is highly variable but the use of large doses and long-term protocols may lead to saturation effects and the loss of linearity in the response. Also, despite carotenoid exposition is considered to be safe, markers of overexposure include clinical signs (i.e. carotenodermia, corneal rings and retinopathy) and biochemical indicators (hypercarotenemia, xanthophyll esters). Overall, both host-related and methodological factors may influence analytical and functional markers to assess carotenoid bioavailability although the different subclasses of carotenoids may not be equally affected.

Role of the small intestine, colon and microbiota in determining the metabolic fate of polyphenols

(Poly)phenols are a large group of compounds, found in food, beverages, dietary supplements and herbal medicines. Owing to interest in their biological activities, absorption and metabolism of the most abundant compounds in humans are well understood. Both the chemical structure of the phenolic moiety and any attached chemical groups define whether the polyphenol is absorbed in the small intestine, or reaches the colon and is subject to extensive catabolism by colonic microbiota. Untransformed substrates may be absorbed, appearing in plasma primarily as methylated, sulfated and glucuronidated derivatives, with in some cases the unchanged substrate. Many of the catabolites are well absorbed from the colon and appear in the plasma either similarly conjugated, or as glycine conjugates, or in some cases unchanged. Although many (poly)phenol catabolites have been identified in human plasma and/or urine, the exact pathways from substrate to final microbial catabolite, and the species of bacteria and enzymes involved, are still scarcely reported. While it is clear that the composition of the human gut microbiota can be modulated in vivo by supplementation with some (poly)phenol-rich commodities, such modulation is definitely not an inevitable consequence of supplementation; it depends on the treatment, length of time and on the individual metabotype, and it is not clear whether the modulation is sustained when supplementation ceases. Some catabolites have been recorded in plasma of volunteers at concentrations similar to those shown to be effective in in vitro studies suggesting that some benefit may be achieved in vivo by diets yielding such catabolites.

Phytochemical Profiles of New Red-Fleshed Apple Varieties Compared with Traditional and New White-Fleshed Varieties

This study is an exhaustive chemical characterization of the phenolic compounds, triterpenes, and organic and ascorbic acids in red-fleshed apple varieties obtained by different breeding programs and using five traditional and new white-fleshed apple cultivars as reference. To carry out these analyses, solid-liquid extraction (SLE) and ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) were used. The results showed that the red-fleshed apples contained, in either the flesh or peel, higher amounts of phenolic acids (chlorogenic acid), anthocyanins (cyanidin-3-O-galactoside), dihydrochalcones (phloretin xylosyl glucoside), and organic acids (malic acid) but a lower amount of flavan-3-ols than the white-fleshed apples. These quantitative differences could be related to an up-regulation of anthocyanins, dihydrochalcones, and malic acid and a down-regulation of flavan-3-ols (anthocyanin precursors) in both the flesh and peel of the red-fleshed apple varieties. The reported results should be considered preliminary because the complete phytochemical characterization of the red-fleshed apple cultivars will be extended to consecutive harvest seasons.

Phytochemical content, cellular antioxidant activity and antiproliferative activity of Adinandra nitida tea (Shiyacha) infusion subjected to in vitro gastrointestinal digestion

Adinandra nitida tea (Shiyacha) is a traditional eminent and flourishing tea with a long history in Southeast Asia.

Mango-bagasse functional-confectionery: vehicle for enhancing bioaccessibility and permeability of phenolic compounds

Study on bioaccessibility and absorption path of mango bagasse phenolics.

Hydrolysis of Dicaffeoylquinic Acids from Ilex kudingcha Happens in the Colon by Intestinal Microbiota

Monocaffeoylquinic acids (mono-CQAs) can be hydrolyzed or metabolized by pancreatin, intestinal brush border esterase, and microbiota in the colon. Data about the conversion of dicaffeoylquinic acids (diCQAs) in digestion are scarce. The diCQA-rich fraction including 3,4-, 3,5-, and 4,5-diCQAs was prepared from Ilex kudingcha, and the conversion in simulated gastricintestine was investigated. Artificial saliva, gastric and pancreatic fluids, Caco-2 monolayer cells, and anaerobic fermentation model were utilized to mimic digestions of the oral cavity, stomach, small intestine, and colon in vitro. The results revealed that diCQAs remained intact in simulated saliva, gastric, and pancreatic fluids and within Caco-2 cells. In anaerobic fermentation with human fecal slurry, diCQAs were hydrolyzed to mono-CQAs and caffeic acid, which were further metabolized to caffeic acid and dihydrocaffeic acid, respectively. The hydrolysis of diCQAs depended on the chemical structures, carbohydrates in the culture medium, and microbial compositions. Our research demonstrated that hydrolysis of diCQAs happened in the colon by intestinal microbiota.

Inhibition of Low-Grade Inflammation by Anthocyanins after Microbial Fermentation in Vitro

The anti-inflammatory effects of anthocyanins (ACNs) on vascular functions are discussed controversially because of their low bioavailability. This study was performed to determine whether microorganism (MO)-fermented ACNs influence vascular inflammation in vitro. Therefore, MO growth media were supplemented with an ACN-rich grape/berry extract and growth responses of Escherichia coli, E. faecalis and H. alvei, as well as ACN fermentation were observed. MO supernatants were used for measuring the anti-inflammatory effect of MO-fermented ACNs in an epithelial-endothelial co-culture transwell system. After basolateral enrichment (240 min), endothelial cells were stimulated immediately or after 20 h with TNF-α. Afterwards, leukocyte adhesion, expression of adhesion molecules and cytokine release were measured. Results indicate that E. coli, E. faecalis and H. alvei utilized ACNs differentially concomitant with different anti-inflammatory effects. Whereas E. coli utilized ACNs completely, no anti-inflammatory effects of fermented ACNs were observed on activated endothelial cells. In contrast, ACN metabolites generated by E. faecalis and H. alvei significantly attenuated low-grade stimulated leukocyte adhesion, the expression of adhesion molecules E-selectin, VCAM-1 and ICAM-1 and cytokine secretion (IL-8 and IL-6), as well as NF-κB mRNA expression with a more pronounced effect of E. faecalis than H. alvei. Thus, MO-fermented ACNs have the potential to reduce inflammation.