Gorse (Ulex europeaus) wastes with 5,6-dimethyl benzimidazole supplementation can support growth of vitamin B12 producing commensal gut microbes

Many commensal gut microbes are recognized for their potential to synthesize vitamin B12, offering a promising avenue to address deficiencies through probiotic supplementation. While bioinformatics tools aid in predicting B12 biosynthetic potential, empirical validation remains crucial to confirm production, identify cobalamin vitamers, and establish biosynthetic yields. This study investigates vitamin B12 production in three human colonic bacterial species: Anaerobutyricum hallii DSM 3353, Roseburia faecis DSM 16840, and Anaerostipes caccae DSM 14662, along with Propionibacterium freudenreichii DSM 4902 as a positive control. These strains were selected for their potential use as probiotics, based on speculated B12 production from prior bioinformatic analyses. Cultures were grown in M2GSC, chemically defined media (CDM), and Gorse extract medium (GEM). The composition of GEM was similar to CDM, except that the carbon and nitrogen sources were replaced with the protein-depleted liquid waste obtained after subjecting Gorse to a leaf protein extraction process. B12 yields were quantified using liquid chromatography with tandem mass spectrometry. The results suggested that the three butyrate-producing strains could indeed produce B12, although the yields were notably low and were detected only in the cell lysates. Furthermore, B12 production was higher in GEM compared to M2GSC medium. The positive control, P. freudenreichii DSM 4902 produced B12 at concentrations ranging from 7 ng mL-1 to 12 ng mL-1. Univariate-scaled Principal Component Analysis (PCA) of data from previous publications investigating B12 production in P. freudenreichii revealed that B12 yields diminished when the carbon source concentration was ≤30 g L-1. In conclusion, the protein-depleted wastes from the leaf protein extraction process from Gorse can be valorised as a viable substrate for culturing B12-producing colonic gut microbes. Furthermore, this is the first report attesting to the ability of A. hallii, R. faecis, and A. caccae to produce B12. However, these microbes seem unsuitable for industrial applications owing to low B12 yields.

Buckwheat (Fagopyrum esculentum) Hulls Are a Rich Source of Fermentable Dietary Fibre and Bioactive Phytochemicals

Pseudo-cereals such as buckwheat (Fagopyrum esculentum) are valid candidates to promote diet biodiversity and nutrition security in an era of global climate change. Buckwheat hulls (BHs) are currently an unexplored source of dietary fibre and bioactive phytochemicals. This study assessed the effects of several bioprocessing treatments (using enzymes, yeast, and combinations of both) on BHs' nutrient and phytochemical content, their digestion and metabolism in vitro (using a gastrointestinal digestion model and mixed microbiota from human faeces). The metabolites were measured using targeted LC-MS/MS and GC analysis and 16S rRNA gene sequencing was used to detect the impact on microbiota composition. BHs are rich in insoluble fibre (31.09 ± 0.22% as non-starch polysaccharides), protocatechuic acid (390.71 ± 31.72 mg/kg), and syringaresinol (125.60 ± 6.76 mg/kg). The bioprocessing treatments significantly increased the extractability of gallic acid, vanillic acid, p-hydroxybenzoic acid, syringic acid, vanillin, syringaldehyde, p-coumaric acid, ferulic acid, caffeic acid, and syringaresinol in the alkaline-labile bound form, suggesting the bioaccessibility of these phytochemicals to the colon. Furthermore, one of the treatments, EC_2 treatment, increased significantly the in vitro upper gastrointestinal release of bioactive phytochemicals, especially for protocatechuic acid (p < 0.01). The BH fibre was fermentable, promoting the formation mainly of propionate and, to a lesser extent, butyrate formation. The EM_1 and EC_2 treatments effectively increased the content of insoluble fibre but had no effect on dietary fibre fermentation (p > 0.05). These findings promote the use of buckwheat hulls as a source of dietary fibre and phytochemicals to help meet dietary recommendations and needs.

Habitual consumption of high-fibre bread fortified with bean hulls increased plasma indole-3-propionic concentration and decreased putrescine and deoxycholic acid faecal concentrations in healthy volunteers

Only 6 to 8 % of the UK adults meet the daily recommendation for dietary fibre. Fava bean processing lead to vast amounts of high-fibre by-products such as hulls. Bean hull fortified bread was formulated to increase and diversify dietary fibre while reducing waste. This study assessed the bean hull: suitability as a source of dietary fibre; the systemic and microbial metabolism of its components and postprandial events following bean hull bread rolls. Nine healthy participants (53·9 ± 16·7 years) were recruited for a randomised controlled crossover study attending two 3 days intervention sessions, involving the consumption of two bread rolls per day (control or bean hull rolls). Blood and faecal samples were collected before and after each session and analysed for systemic and microbial metabolites of bread roll components using targeted LC-MS/MS and GC analysis. Satiety, gut hormones, glucose, insulin and gastric emptying biomarkers were also measured. Two bean hull rolls provided over 85 % of the daily recommendation for dietary fibre; but despite being a rich source of plant metabolites (P = 0·04 v. control bread), these had poor systemic bioavailability. Consumption of bean hull rolls for 3 days significantly increased plasma concentration of indole-3-propionic acid (P = 0·009) and decreased faecal concentration of putrescine (P = 0·035) and deoxycholic acid (P = 0·046). However, it had no effect on postprandial plasma gut hormones, bacterial composition and faecal short chain fatty acids amount. Therefore, bean hulls require further processing to improve their bioactives systemic availability and fibre fermentation.

Confidence does not mediate a relationship between owner experience and likelihood of using weight management approaches for native ponies

Native ponies are at increased risk of obesity and metabolic perturbations, such as insulin dysregulation (ID), a key risk factor for endocrinopathic laminitis. Management and feeding practices can be adapted to maintain healthy body condition and support metabolic health, but owners may inadvertently provide their ponies with inappropriate management leading to obesity and exacerbating risk of metabolic disease. Adoption of preventative weight management approaches (WMAs), including regular monitoring of body condition, providing appropriate preserved forage, promoting seasonal weight loss, and using exercise accordingly, are key in supporting native ponies' metabolic health. The factors influencing the adoption of WMAs, such as owners' experience and confidence, require exploration. The aim of the current study was to understand factors influencing owners' likelihood to undertake certain WMAs, to develop our understanding of suitable intervention targets. A total of 571 responses to an online cross-sectional questionnaire were analysed. Mediation analysis revealed that whilst long term (≥20 years) experience caring for native ponies was associated with owners increased, self-reported confidence in identifying disease and managing their native ponies, this did not translate to an increased likelihood of implementing WMAs. Conversely, respondents who managed ponies with dietary requirements related to obesity, laminitis, or equine metabolic syndrome were more likely to use WMAs related to feeding, seasonal weight management and exercise. Owner confidence was assessed and rejected as a mediator of the relationship between experience and WMA use. These results highlight the need for further work that elucidates the pathways leading owners to undertake action against obesity without the need for ponies to develop overt disease, as well as suggesting a need for long term managers of native ponies to update management practices with preventative care as the focus.

Homemade Nucleic Acid Preservation Buffer Proves Effective in Preserving the Equine Faecal Microbiota over Time at Ambient Temperatures

The equine faecal microbiota is often assessed as a proxy of the microbial community in the distal colon, where the microbiome has been linked to states of health and disease in the horse. However, the microbial community structure may change over time if samples are not adequately preserved. This study stored equine faecal samples from n = 10 horses in four preservation treatments at room temperature for up to 150 h and assessed the resulting impact on microbial diversity and the differential abundance of taxa. Treatments included "COLD" (samples packaged with a cool pack), "CLX" (2% chlorhexidine digluconate solution), "NAP" (nucleic acid preservation buffer), and "FTA" (Whatman FTA™ cards). The samples were assessed using 16S rRNA gene sequencing after storage for 0, 24, 72, and 150 h at room temperature under the different treatments. The results showed effective preservation of diversity and community structure with NAP buffer but lower diversity (p = 0.001) and the under-representation of Fibrobacterota in the FTA card samples. The NAP treatment inhibited the overgrowth of bloom taxa that occurred by 72 h at room temperature. The COLD, CLX, and NAP treatments were effective in preserving the faecal microbiota for up to 24 h at room temperature, and the CLX and NAP treatments improved the yield of Patescibacteria and Fibrobacterota in some cases. The cold and CLX treatments were ineffective in preventing community shifts that occurred by 72 h at room temperature. These findings demonstrate the suitability of the COLD, NAP, and CLX treatments for the room temperature storage of equine faeces for up to 24 h and of NAP buffer for up to 150 h prior to processing.

A grape seed and bilberry extract reduces blood pressure in individuals at risk of developing type 2 diabetes: the PRECISE study, a double-blind placebo-controlled cross-over intervention study

Background

Type 2 Diabetes Mellitus (T2DM) is a major risk factor for the development of cardiometabolic diseases. T2DM prevention is largely based on weight-loss and whole diet changes, but intervention with dietary plant bioactives may also improve metabolic health.

Objective

To assess whether supplementation with bilberry and grape seed extract for 12 weeks improves cardiometabolic outcomes in individuals at risk of developing T2DM, and to determine whether individual treatment response is associated with differences in gut microbiota composition and levels of phenolic metabolites in blood and feces.

Methods

In the randomized, double-blind, placebo-controlled, cross-over PRECISE intervention study, 14 participants, aged ≥45 years, with a BMI >28 kg/m², and having an increased risk of T2DM, received a supplement containing 250 mg of bilberry plus 300 mg of grape seed extract, or 550 mg of a control extract, per day, for 12 weeks each. Blood samples were obtained for the assessment of HbA1c, fasting glucose, oral glucose tolerance tests, insulin, glucagon levels, total, LDL and HDL cholesterol, and phenolic acids. We also assessed advanced glycation end products in the skin, ambulatory 24 hours blood pressure, 7-day dietary intake by weighed food diaries, fecal levels of phenolic metabolites using LC-MS/MS and gut microbiota composition using 16S rRNA gene sequencing analysis.

Results

The combined bilberry and grape seed extract did not affect glucose and cholesterol outcomes, but it decreased systolic and diastolic ambulatory blood pressure by 4.7 (p < 0.001) and 2.3 (p = 0.0009) mmHg, respectively. Eight out of fourteen participants were identified as blood pressure 'responders'. These responders had higher levels of phenylpropionic and phenyllactic acids in their fecal samples, and a higher proportional abundance of Fusicatenibacter-related bacteria (p < 0.01) in their baseline stool samples.

Conclusion

Long-term supplementation with bilberry and grape seed extract can improve systolic and diastolic blood pressure in individuals at risk of T2DM. Individual responsiveness was correlated with the presence of certain fecal bacterial strains, and an ability to metabolize (epi)catechin into smaller phenolic metabolites.Clinical trial registry number: Research Registry (number 4084).

Season, storage and extraction method impact on the phytochemical profile of Terminalia ivorensis

BACKGROUND

Terminalia ivorensis (TI) is used in West African ethnomedicine for the treatment of conditions including ulcers, malaria and wounds. Despite its widespread use, the phytochemical profile of TI remains largely undetermined. This research investigated the effects of extraction method, season, and storage conditions on the phytochemical composition of TI to contribute towards understanding the potential benefits.

METHODS

TI bark was collected in September 2014, September 2018 and February 2018 during the rainy or dry seasons in Eastern Region, Ghana. Samples were extracted sequentially with organic solvents (petroleum ether, chloroform, ethyl acetate and ethanol) or using water (traditional). Metabolites were identified by liquid chromatography-mass spectrometry/mass spectrometry and compared statistically by ANOVA.

RESULTS

A total of 82 different phytochemicals were identified across all samples. A greater yield of the major phytochemicals (44%, p < 0.05) was obtained by water as compared with organic extraction. There was also a higher concentration of metabolites present in cold (63%, p < 0.05) compared with hot water extraction. A significantly (p < 0.05) higher number of phytochemicals were identified from TI collected in the dry (85%) compared to the rainy season (69%). TI bark stored for four years retained 84% of the major phytochemicals.

CONCLUSION

This work provides important information on composition and how this is modified by growing conditions, storage and method of extraction informing progress on the development of TI as a prophylactic formulation or medicine.

Beyond purified dietary fibre supplements - compositional variation between cell wall fibre from different plants influences human faecal microbiota activity and growth in vitro

Dietary fibre is a major energy source for the human gut microbiota, but it is unclear to what extent the fibre source and complexity affect microbial growth and metabolite production. Cell wall material and pectin were extracted from five different dicotyledon plant sources, apples, beet leaves, beetroots, carrots and kale, and compositional analysis revealed differences in the monosaccharide composition. Human faecal batch incubations were conducted with 14 different substrates, including the plant extracts, wheat bran and commercially available carbohydrates. Microbial activity was determined for up to 72 hours by measuring gas and fermentation acid production, total bacteria (by qPCR) and microbial community composition by 16S rRNA amplicon sequencing. The more complex substrates gave rise to more microbiota variation compared to the pectins. The comparison of different plant organs showed that the leaves (beet leaf and kale) and roots (carrot and beetroot) did not give rise to similar bacterial communities. Rather, the compositional features of the plants, such as high arabinan levels in beet and high galactan levels in carrot, appear to be major predictors of bacterial enrichment on the substrates. Thus, in-depth knowledge on dietary fibre composition should aid the design of diets focused on optimising the microbiota. This article is protected by copyright. All rights reserved.

High throughput method development and optimised production of leaf protein concentrates with potential to support the agri-industry

Invasive plants offer an interesting and unconventional source of protein and the considerable investment made towards their eradication can potentially be salvaged through their revalorisation. To identify viable sources, effective and high-throughput screening methods are required, as well as efficient procedures to isolate these components. Rigorous assessment of low-cost, high-throughput screening assays for total sugar, phenolics and protein was performed, and ninhydrin, Lever and Fast Blue assays were found to be most suitable owing to high reliability scores and false positive errors less than 1%. These assays were used to characterise invasive Scottish plants such as Gorse (Ulex europeans), Broom (Cystisus scoparius) and Fireweed (Chamaenerion angustifolium). Protein extraction (alkali-, heat- and enzyme assisted) were tested on these plants, and further purification (acid and ethanol precipitation, as well as ultrafiltration) procedures were tested on Gorse, based on protein recovery values. Cellulase treatment and ethanol precipitation gave the highest protein recovery (64.0 ± 0.5%) and purity (96.8 ± 0.1%) with Gorse. The amino acid profile of the purified protein revealed high levels of essential amino acids (34.8 ± 0.0%). Comparison of results with preceding literature revealed a strong association between amino acid profiles and overall protein recovery with the extraction method employed. The final purity of the protein concentrates was closely associated to the protein content of the initial plant mass. Leaf protein extraction technology can effectively raise crop harvest indices, revalorise underutilised plants and waste streams.

Hemp and buckwheat are valuable sources of dietary amino acids, beneficially modulating gastrointestinal hormones and promoting satiety in healthy volunteers

Purpose

This study evaluated the postprandial effects following consumption of buckwheat, fava bean, pea, hemp and lupin compared to meat (beef); focussing on biomarkers of satiety, gut hormones, aminoacids and plant metabolites bioavailability and metabolism.

Methods

Ten subjects (n = 3 men; n = 7 women; 42 ± 11.8 years of age; BMI 26 ± 5.8 kg/m²) participated in six 1-day independent acute interventions, each meal containing 30 g of protein from buckwheat, fava bean, pea, hemp, lupin and meat (beef). Blood samples were collected during 24-h and VAS questionnaires over 5-h.

Results

Volunteers consumed significantly higher amounts of most amino acids from the meat meal, and with few exceptions, postprandial composition of plasma amino acids was not significantly different after consuming the plant-based meals. Buckwheat meal was the most satious (300 min hunger scores, p < 0.05).Significant increase in GLP-1 plasma (AUC, iAUC p = 0.01) found after hemp compared with the other plant-based meals. Decreased plasma ghrelin concentrations (iAUC p < 0.05) found on plant (hemp) vs. meat meal. Several plasma metabolites after hemp meal consumption were associated with hormone trends (partial least squares-discriminant analysis (PLS-DA): 4-hydroxyphenylpyruvic acid, indole 3-pyruvic acid, 5-hydoxytryptophan, genistein and biochanin A with GLP-1, PYY and insulin; 3-hydroxymandelic acid and luteolidin with GLP-1 and ghrelin and 4-hydroxymandelic acid, benzoic acid and secoisolariciresinol with insulin and ghrelin. Plasma branched-chain amino acids (BCAAs), (iAUC, p < 0.001); and phenylalanine and tyrosine (iAUC, p < 0.05) were lower after buckwheat comparison with meat meal.

Conclusion

Plants are valuable sources of amino acids which are promoting satiety. The impact of hemp and buckwheat on GLP-1 and, respectively, BCAAs should be explored further as could be relevant for aid and prevention of chronic diseases such as type 2 diabetes.

Study registered with clinicaltrial.gov on 12th July 2013, study ID number: NCT01898351.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02711-z.

Invasive Plants Are a Valuable Alternate Protein Source and Can Contribute to Meeting Climate Change Targets

Agriculture has come under pressure to meet global food demands, whilst having to meet economic and ecological targets. This has opened newer avenues for investigation in unconventional protein sources. Current agricultural practises manage marginal lands mostly through animal husbandry, which; although effective in land utilisation for food production, largely contributes to global green-house gas (GHG) emissions. Assessing the revalorisation potential of invasive plant species growing on these lands may help encourage their utilisation as an alternate protein source and partially shift the burden from livestock production; the current dominant source of dietary protein, and offer alternate means of income from such lands. Six globally recognised invasive plant species found extensively on marginal lands; Gorse (Ulex europaeus), Vetch (Vicia sativa), Broom (Cytisus scoparius), Fireweed (Chamaenerion angustifolium), Bracken (Pteridium aquilinum), and Buddleia (Buddleja davidii) were collected and characterised to assess their potential as alternate protein sources. Amino acid profiling revealed appreciable levels of essential amino acids totalling 33.05 ± 0.04 41.43 ± 0.05, 33.05 ± 0.11, 32.63 ± 0.04, 48.71 ± 0.02 and 21.48 ± 0.05 mg/g dry plant mass for Gorse, Vetch, Broom Fireweed, Bracken, and Buddleia, respectively. The availability of essential amino acids was limited by protein solubility, and Gorse was found to have the highest soluble protein content. It was also high in bioactive phenolic compounds including cinnamic- phenyl-, pyruvic-, and benzoic acid derivatives. Databases generated using satellite imagery were used to locate the spread of invasive plants. Total biomass was estimated to be roughly 52 Tg with a protein content of 5.2 Tg with a total essential amino acid content of 1.25 Tg (~24%). Globally, Fabaceae was the second most abundant family of invasive plants. Much of the spread was found within marginal lands and shrublands. Analysis of intrinsic agricultural factors revealed economic status as the emergent factor, driven predominantly by land use allocation, with shrublands playing a pivotal role in the model. Diverting resources from invasive plant removal through herbicides and burning to leaf protein extraction may contribute toward sustainable protein, effective land use, and achieving emission targets, while simultaneously maintaining conservation of native plant species.

Impact of rapeseed pomace extract on markers of oxidative stress and DNA damage in human SH-SY5Y cells

With increased longevity and subsequent rise in people with age-related neurodegenerative diseases, protection of neurons from oxidative stress damage has become an important field of study. For the first time, we highlight the neuroprotective properties of rapeseed pomace (RSP) extract in SH-SY5Y human neuroblastoma cells. We used resazurin to determine cell metabolism, 2,7'-dichlorofluorescin diacetate (H₂ DCFDA) to assess the potential of RSP extracts to shield cells from reactive oxygen species (ROS) induced by H₂ O₂ using flow cytometry, HPLC to analyze for malondialdehyde (MDA) as a lipid peroxidation marker and the COMET assay to assess DNA strand breakage. Protein stress arrays were used to investigate the cellular pathways affected by RSP extract. No effect on cell metabolism in SH-SY5Y cells was observed after RSP extract treatment (up to 1.5 mg/ml). Pretreatment (24 hr) with RSP extract (1 mg/ml), before H₂ O₂ -induced stress, alleviated ROS production and DNA strand breakage by 68%, and 38%, respectively. At protein level, the RSP extract increased the levels of FABP-1, HIF-1α, SOD2, and Cytochrome c proteins. Under H₂ O₂ -induced stress, however, it helped to downregulate p38α levels, a protein kinase which is receptive to stress impulse (mitogen-activated). RSP extract shows very promising cell protective properties in relation to oxidative stress. PRACTICAL APPLICATIONS: Oxidative stress has been associated with numerous diseases for example cancer, diabetes, and many neurological disorders including Parkinson's and Alzheimer's diseases. Hence, there is acceptance among the scientific community of antioxidant therapy and the quest for effective, low cost and readily available sources of natural antioxidants is paramount. Rapeseed plantations are abundant around the world due to the use of rapeseed oil in cooking and as a biofuel. The resulting rapeseed pomace (by-product), specifically its extract, contains high levels of phytochemicals that protect cells against oxidative stress. Therefore, RSP extract can potentially be used/developed as functional food and nutraceuticals in the prevention of many complex neurodegenerative diseases.

Exploring Health-Promoting Attributes of Plant Proteins as a Functional Ingredient for the Food Sector: A Systematic Review of Human Interventional Studies

The potential beneficial effects of plant-based diets on human health have been extensively studied. However, the evidence regarding the health effects of extracted plant-based proteins as functional ingredients, other than soya, is scarce. The aim of this review was to compile evidence on the effects of extracted protein from a wide range of traditional and novel plant sources on glycemic responses, appetite, body weight, metabolic, cardiovascular and muscle health. A comprehensive search of PubMed, EMBASE and The Cochrane Central Register of Controlled Trials (CENTRAL) was conducted through 23 and 27 March 2020 for randomized controlled trials that featured any of the following 18 plant protein sources: alfalfa, duckweed, buckwheat, chickpea, fava bean, hemp, lentil, lupin, mushroom, oat, pea, potato, pumpkin, quinoa, rapeseed, rice, sacha inchi, sunflower. Only interventions that investigated concentrated, isolated or hydrolysed forms of dietary protein were included. Searched health outcome measures were: change in blood glucose, insulin, satiety hormones concentration, subjective assessment of appetite/satiety, change in blood lipids concentration, blood pressure, body weight and muscle health parameters. Acute and sub-chronic studies were considered for inclusion. Applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach we identified 1190 records. Twenty-six studies met the inclusion criteria. Plant protein sources used in interventions were most often pea (n = 16), followed by lupin (n = 4), fava bean (n = 2), rice (n = 2), oat (n = 2), hemp (n = 2) and lentil (n = 1). Satiety and postprandial glycemic response were the most frequently reported health outcomes (n = 18), followed by blood lipids (n = 6), muscle health (n = 5), body weight (n = 5) and blood pressure (n = 4). No studies on the remaining plant proteins in the extracted form were identified through the search. Most studies confirmed the health-promoting effect of identified extracted plant protein sources across glycemic, appetite, cardiovascular and muscular outcomes when compared to baseline or non-protein control. However, the current evidence is still not sufficient to formulate explicit dietary recommendations. In general, the effects of plant protein were comparable (but not superior) to protein originating from animals. This is still a promising finding, suggesting that the desired health effects can be achieved with more sustainable, plant alternatives. More methodologically homogenous research is needed to formulate and validate evidence-based health claims for plant protein ingredients. The relevance of these findings are discussed for the food sector with supporting market trends.

Analysis of polyphenolic metabolites from in vitro gastrointestinal digested soft fruit extracts identify malvidin-3-glucoside as an inhibitor of PTP1B

Protein-tyrosine phosphatase 1B (PTP1B, EC 3.1.3.48) is an important regulator of insulin signalling. Herein, we employed experimental and computational biology techniques to investigate the inhibitory properties of phenolics, identified from four in vitro gastrointestinal digested (IVGD) soft fruits, on PTP1B. Analysis by LC-MS/MS identified specific phenolics that inhibited PTP1B in vitro. Enzyme kinetics identified the mode of inhibition, while dynamics, stability and binding mechanisms of PTP1B-ligand complex were investigated through molecular modelling, docking, molecular dynamics (MD) simulations, and MM/PBSA binding free energy estimation. IVGD extracts and specific phenolics identified from the four soft fruits inhibited PTP1B (P < 0.0001) activity. Among the phenolics tested, the greatest inhibition was shown by malvidin-3-glucoside (P < 0.0001) and gallic acid (P < 0.0001). Malvidin-3-glucoside (Ki = 3.8 µg/mL) was a competitive inhibitor and gallic acid (Ki = 33.3 µg/mL) a non-competitive inhibitor of PTP1B. Malvidin-3-glucoside exhibited better binding energy than gallic acid and the synthetic inhibitor Dephostatin (-7.38 > -6.37 > -5.62 kcal/mol) respectively. Principal component analysis demonstrated malvidin-3-glucoside PTP1B-complex occupies more conformational space where critical WPD-loop displayed a higher degree of motion. MM/PBSA binding free energy for malvidin-3-glucoside to PTP1B was found to be higher than other complexes mediated by Van der Waals energy rather than electrostatic interaction for the other two inhibitors (-80.32 ± 1.25 > -40.64 ± 1.43 > -21.63 ± 1.73 kcal/mol) respectively. Altogether, we have established novel insights into the specific binding of dietary phenolics and have identified malvidin-3-glucoside as an PTP1B inhibitor, which may be further industrially developed for the treatment of type-2 diabetes.

Sapogenol is a Major Microbial Metabolite in Human Plasma Associated with High Protein Soy-Based Diets: The Relevance for Functional Food Formulations

Legumes are a source of health-promoting macro- and micronutrients, but also contain numerous phytochemicals with useful biological activities, an example of which are saponins. Epidemiological studies suggest that saponins may play a role in protection from cancer and benefit human health by lowering cholesterol. Therefore, they could represent good candidates for specialised functional foods. Following the consumption of a soya-rich high-protein weight-loss diet (SOYA HP WL), the concentrations of Soyasaponin I (SSI) and soyasapogenol B (SSB) were determined in faecal samples from human volunteers (n = 10) and found to be between 1.4 and 17.5 mg per 100 g fresh faecal sample. SSB was the major metabolite identified in volunteers' plasma (n = 10) after consumption of the soya test meal (SOYA MEAL); the postprandial (3 h after meal) plasma concentration for SSB varied between 48.5 ng/mL to 103.2 ng/mL. The metabolism of SSI by the gut microbiota (in vitro) was also confirmed. This study shows that the main systemic metabolites of soyasaponin are absorbed from the gut and that they are bioavailable in plasma predominantly as conjugates of sapogenol. The metabolism and bioavailability of biologically active molecules represent key information necessary for the efficient development of functional foods.

The anthocyanins in black currants regulate postprandial hyperglycaemia primarily by inhibiting α-glucosidase while other phenolics modulate salivary α-amylase, glucose uptake and sugar transporters

The hypoglycaemic effects of two Ribes sp. i.e., anthocyanin-rich black currants (BC) were compared to green currants (GC), which are low in anthocyanins to establish which compounds are involved in the regulation of postprandial glycaemia. We determined the effect of the currants on inhibiting carbohydrate digestive enzymes (α-amylase, α-glucosidase), intestinal sugar absorption and transport across CaCo-2 cells. The digestion of these currants was modelled using in vitro gastrointestinal digestion (IVGD) to identify the metabolites present in the digested extracts by LC-MS/MS. Freeze-dried BC and IVDG extracts inhibited yeast α-glucosidase activity (P<.0001) at lower concentrations than acarbose, whereas GC and IVDG GC at the same concentrations showed no inhibition. BC and GC both showed significant inhibitory effects on salivary α-amylase (P<.0001), glucose uptake (P<.0001) and the mRNA expression of sugar transporters (P<.0001). Taken together this suggests that the anthocyanins which are high in BC have their greatest effect on postprandial hyperglycaemia by inhibiting α-glucosidase activity. Phytochemical analysis identified the phenolics in the currants and confirmed that freeze-dried BC contained higher concentrations of anthocyanins compared to GC (39.80 vs. 9.85 g/kg dry weight). Specific phenolics were also shown to inhibit salivary α-amylase, α-glucosidase, and glucose uptake. However, specific anthocyanins identified in BC which were low in GC were shown to inhibit α-glucosidase. In conclusion the anthocyanins in BC appear to regulate postprandial hyperglycaemia primarily but not solely by inhibiting α-glucosidase while other phenolics modulate salivary α-amylase, glucose uptake and sugar transporters which together could lower the associated risk of developing type-2 diabetes.

Folate, genomic stability and colon cancer: The use of single cell gel electrophoresis in assessing the impact of folate in vitro, in vivo and in human biomonitoring

Intake of folate (vitamin B₉) is strongly inversely linked with human cancer risk, particularly colon cancer. In general, people with the highest dietary intake of folate or with high blood folate levels are at a reduced risk (approx. 25%) of developing colon cancer. Folate acts in normal cellular metabolism to maintain genomic stability through the provision of nucleotides for DNA replication and DNA repair and by regulating DNA methylation and gene expression. Folate deficiency can accelerate carcinogenesis by inducing misincorporation of uracil into DNA, by increasing DNA strand breakage, by inhibiting DNA base excision repair capacity and by inducing DNA hypomethylation and consequently aberrant gene and protein expression. Conversely, increasing folate intake may improve genomic stability. This review describes key applications of single cell gel electrophoresis (the comet assay) in assessing genomic instability (misincorporated uracil, DNA single strand breakage and DNA repair capacity) in response to folate status (deficient or supplemented) in human cells in vitro, in rodent models and in human case-control and intervention studies. It highlights an adaptation of the SCGE comet assay for measuring genome-wide and gene-specific DNA methylation in human cells and colon tissue.

Effect of increasing fruit and vegetable intake by dietary intervention on nutritional biomarkers and attitudes to dietary change: a randomised trial

PURPOSE

Low fruit and vegetable consumption is linked with an increased risk of death from vascular disease and cancer. The benefit of eating fruits and vegetables is attributed in part to antioxidants, vitamins and phytochemicals. Whether increasing intake impacts on markers of disease remains to be established. This study investigates whether increasing daily intake of fruits, vegetables and juices from low (approx. 3 portions), to high intakes (approx. 8 portions) impacts on nutritional and clinical biomarkers. Barriers to achieving the recommended fruit and vegetable intakes are also investigated.

METHOD

In a randomised clinical trial, the participants [19 men and 26 women (39-58 years)] with low reported fruit, juice and vegetable intake (<3 portions/day) were randomised to consume either their usual diet or a diet supplemented with an additional 480 g of fruit and vegetables and fruit juice (300 ml) daily for 12 weeks. Nutritional biomarkers (vitamin C, carotenoids, B vitamins), antioxidant capacity and genomic stability were measured pre-intervention, at 4-, 8- and 12 weeks throughout the intervention. Samples were also taken post-intervention after a 6-week washout period. Glucose, homocysteine, lipids, blood pressure, weight and arterial stiffness were also measured. Intake of fruit, fruit juice and vegetables was reassessed 12 months after conducting the study and a questionnaire was developed to identify barriers to healthy eating.

RESULTS

Intake increased significantly in the intervention group compared to controls, achieving 8.4 portions/day after 12 weeks. Plasma vitamin C (35%), folate (15%) and certain carotenoids [α-carotene (50%) and β-carotene (70%) and lutein/zeaxanthin (70%)] were significantly increased (P < 0.05) in the intervention group. There were no significant changes in antioxidant capacity, DNA damage and markers of vascular health. Barriers to achieving recommended intakes of fruits and vegetables measured 12 months after the intervention period were amount, inconvenience and cost.

CONCLUSION

While increasing fruit, juice and vegetable consumption increases circulating level of beneficial nutrients in healthy subjects, a 12-week intervention was not associated with effects on antioxidant status or lymphocyte DNA damage.

TRIAL REGISTRATION

This trial was registered at Controlled-Trials.com; registration ISRCTN71368072.

Dietary carbohydrate rather than protein intake drives colonic microbial fermentation during weight loss

Purpose

High protein weight loss diets are effective in aiding body weight management. However, high protein and low carbohydrate intakes can alter colonic fermentation profiles in humans and may impact on colonic health. This study aims to identify the most important dietary contributors to colonic fermentation during diet-controlled weight loss.

Methods

Overweight or obese male volunteers (n = 18) consumed a body weight maintenance diet (fed at 1.5× basic metabolic rate, BMR) followed by three weight loss diets (fed at 1× BMR) for 10 days each in a cross-over design. Weight loss diets were designed as normal protein (NPWL, 15% of energy from protein, 55% from carbohydrate), normal protein enriched with free amino acids and moderate amounts of carbohydrate (NPAAWL, 15% of energy from protein, 15% from free AA, 40% from carbohydrate) or high protein containing moderate amounts of carbohydrate (HPWL, 30% of energy from protein, 40% from carbohydrate). Faecal samples collected at the end of each diet period were profiled for dietary metabolites using LC–MS/MS.

Results

This study shows that the NPWL diet only induced very minor changes in the faecal metabolome, whereas NPAAWL and HPWL diets decreased carbohydrate-related metabolites (butyrate, ferulic acid) and increased protein-related metabolites. Most faecal metabolites were correlated with dietary carbohydrate and not protein intake.

Conclusion

This study demonstrates that dietary carbohydrate is the main driver of colonic fermentation in humans and that a balance between dietary carbohydrate and protein should be maintained when designing safe, effective and healthy weight loss diets.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1629-x) contains supplementary material, which is available to authorised users.

Herbal remedies for urinary stones used in India and China: A review

ETHANOPHARMACOLOGICAL RELEVANCE

The process of formation or appearance of a urinary stone anywhere in the renal tract is known as urolithiasis. It is a longstanding health problem, known to exist since early age of civilization. Records about symptoms, signs and treatment strategies of urinary stones diseases are found in the several ancient texts of traditional medicines such as Ayurveda, Traditional Chinese Medicine (TCM), Siddha and Unani. In Ayurveda, urolithiasis has been considered as one of the eight most troublesome diseases. Ayurvedic management and cure of urinary stone involves herbal formulas, alkaline liquids and surgical procedures. Whereas, TCM recommends polyherbal drugs, acupuncture and mexibustion for treatment of the urinary stones. Among these therapies, herbal remedies are in practice till today for the treatment and cure urinary stone diseases.

MATERIALS AND METHODS

A comprehensive review of the scientific literature about pathophysiology of urinary stones and antiurolithiatic plants was undertaken using the following bibliographic databases: MEDLINE/PubMed, Scopus, Web of Knowledge and Google Scholar. The search was conducted from publications from all years until Dec., 2015 by combination of the search terms and Boolean operators; 'urinary stone' OR 'kidney stone' AND 'plant' OR 'medicine' OR 'antiurolithiatic plants'. Outputs were restricted to those completed studies only published in English. In this review, literatures about plants which are used as diuretic and/or in treatment urinary tract infections have not also been considered. The Plant List and Royal Botanical Garden, Kew databases were used to authenticate botanical names of plants. Books and monographs published in English were used to collect information about historical records of antiurolithiatic plants.

RESULTS

Recent pharmacological interventions accredited ancient antiurolithiatic claims to several plants and their formulations. The majority of antiurolithiatic plants were found to either dissolve the stones or inhibit the process of urinary stone formation. Plants such as Phyllanthus niruri L. and Elymus repens (L.) Gould, as well as herbal products including 'Wu-Ling-San' formula, 'Cystone' and 'Herbmed' have been proved their utility as promising antiurolithiatic medicines in the different phases of clinical trials. In addition, some of the isolated phytochemicals such as berberine, lupeol, khelin, visnagin, 7-hydroxy-2',4',5'-trimethoxyisoflavone and 7-hydroxy-4'-methoxyisoflavone were reported to have potent antiurolithiatic activity.

CONCLUSION

In ancient medicinal texts, antiurolithiatic potential has been ascribed to several plants and their formulations. Present scientific studies provide scientific evidences for few of these claims however, they are insufficient to establish many of these plants and herbal formulations as therapeutic remedies for the treatment and management of urinary stones. Conversely, findings of pre-clinical and clinical studies about some plants and herbal formulations are promising, which underlines the utility of herbal remedies as alternative medicines for the treatment and management of urinary stones in the future.

Availability and dose response of phytophenols from a wheat bran rich cereal product in healthy human volunteers

SCOPE

Phytophenols present in cereals are metabolised to compounds that could be partly responsible for the reduced risk of chronic diseases and all-cause mortality associated with fibre-rich diets. The bioavailability, form and in vivo concentrations of these metabolites require to be established.

MATERIALS AND METHODS

Eight healthy volunteers consumed a test meal containing a recommended dose (40 g) and high dose (120 g) of ready-to-eat wheat bran cereal and the systemic and colonic metabolites determined quantitatively by LC-MS.

CONCLUSION

Analysis of the systemic metabolomes demonstrated that a wide range of phytophenols were absorbed/excreted (43 metabolites) within 5 h of consumption. These included 16 of the 21 major parent compounds identified in the intervention product and several of these were also found to be significantly increased in the colon. Not all of the metabolites were increased with the higher dose, suggesting some limitation in absorption due to intrinsic factors and/or the food matrix. Many compounds identified (e.g. ferulic acid and major metabolites) exhibit anti-inflammatory activity and impact on redox pathways. The combination of postprandial absorption and delivery to the colon, as well as hepatic recycling of the metabolites at these concentrations, is likely to be beneficial to both systemic and gut health.

Nutritional and Phytochemical Content of High-Protein Crops

Sustainable sources of high-protein plants could help meet future protein requirements. Buckwheat, green pea, fava bean, hemp, and lupin were analyzed by proximate analysis and inductively coupled plasma mass spectrometry to determine their macro- and micronutrient contents, and liquid chromatography-mass spectrometry was used to elucidate the phytochemical profiles. The protein contents ranged from 20 to 43% (w/w), and all samples were found to be rich in insoluble fiber: 9-25% (w/w). The selected crops had a favorable micronutrient profile, with phosphorus levels ranging from 2.22 ± 0.05 to 9.72 ± 0.41 g kg^-1, while iron levels ranged from 20.23 ± 0.86 to 69.57 ± 7.43 mg kg^-1. The crops contained substantial amounts of phytophenolic compounds. In particular, buckwheat was a rich source of pelargonidin (748.17 ± 75.55 mg kg^-1), epicatechin (184.1 ± 33.2 mg kg^-1), quercetin (35.66 ± 2.22 mg kg^-1), caffeic acid (41.74 ± 22.54 mg kg^-1), and 3-hydroxyphenylacetic acid (63.64 ± 36.16 mg kg^-1); hemp contained p-coumaric acid (84.02 ± 8.10 mg kg^-1), cyanidin (58.43 ± 21.01 mg kg^-1), protocatechualdehyde (34.77 ± 5.15 mg kg^-1), and gentisic acid (31.20 ± 1.67 mg kg^-1); and fava bean was the richest source of ferulic acid (229.51 ± 36.58 mg kg^-1) and its 5-5' (39.99 ± 1.10 mg kg^-1) and 8-5 dimers (58.17 ± 6.68 mg kg^-1). Demonstrating that these crops are rich sources of protein, fiber, and phytochemicals could encourage higher consumption and utilization of them as healthy and sustainable ingredients in the food and drink industry.

Wheat bran promotes enrichment within the human colonic microbiota of butyrate-producing bacteria that release ferulic acid

Cereal fibres such as wheat bran are considered to offer human health benefits via their impact on the intestinal microbiota. We show here by 16S rRNA gene-based community analysis that providing amylase-pretreated wheat bran as the sole added energy source to human intestinal microbial communities in anaerobic fermentors leads to the selective and progressive enrichment of a small number of bacterial species. In particular, OTUs corresponding to uncultured Lachnospiraceae (Firmicutes) related to Eubacterium xylanophilum and Butyrivibrio spp. were strongly enriched (by five to 160 fold) over 48 h in four independent experiments performed with different faecal inocula, while nine other Firmicutes OTUs showed > 5-fold enrichment in at least one experiment. Ferulic acid was released from the wheat bran during degradation but was rapidly converted to phenylpropionic acid derivatives via hydrogenation, demethylation and dehydroxylation to give metabolites that are detected in human faecal samples. Pure culture work using bacterial isolates related to the enriched OTUs, including several butyrate-producers, demonstrated that the strains caused substrate weight loss and released ferulic acid, but with limited further conversion. We conclude that breakdown of wheat bran involves specialist primary degraders while the conversion of released ferulic acid is likely to involve a multi-species pathway.

Regulation of GPR55 in rat white adipose tissue and serum LPI by nutritional status, gestation, gender and pituitary factors

The G protein-coupled receptor GPR55 has been proposed as a new cannabinoid receptor associated with obesity in humans. We have investigated the regulation of GPR55 in rat white adipose tissue (WAT) in different physiological and pathophysiological settings involved in energy balance. We compared GPR55 expression with Cannabinoid Receptor type 1 (CB1), which mediates the metabolic actions of endocannabinoids, by real time PCR and western blotting. Circulating levels of lysophosphatidylinositol (LPI), the endogenous ligand of GPR55, were measured by liquid chromatography-mass spectrometry. Both WAT CB1 and GPR55 levels were increased after fasting and recovered after leptin treatment. Their expression was decreased during gestation and increased throughout lifespan. Orchidectomy diminished WAT CB1 and GPR55 expression whereas ovariectomized rats showed increased GPR55 but decreased CB1 levels. Alterations in pituitary functions also modified WAT CB1 and GPR55 levels. Serum LPI levels were inversely regulated by fasting and gonadectomy in comparison to WAT GPR55. Our findings indicate that GPR55 and LPI are regulated by different physiological and pathophysiological settings known to be associated with marked alterations in energy status.

Bound phytophenols from ready-to-eat cereals: comparison with other plant-based foods

Whole-grain diets are linked to reduced risk of several chronic diseases (heart disease, cancer, diabetes, metabolic syndrome) and all-cause mortality. There is increasing evidence that these benefits are associated with the gut microbiota and that release of fibre-related phenolic metabolites in the gut is a contributing factor. Additional sources of these metabolites include fruits and vegetables, but the evidence for their protective effects is less well established. With respect to the availability of bound phytophenols, ready-to-eat cereals are compared with soft fruits (considered rich in antioxidants) and other commonly consumed fruits and vegetables. The results demonstrated that when compared with an equivalent serving of fruits or vegetables, a recommended portion of whole-grain cereals deliver substantially higher amounts of bound phytophenols, which are available for metabolism in the colon. The increased amount of these phenolic metabolites may, in part, explain the evidence for the protective effects of whole-grain cereals.

Major phenylpropanoid-derived metabolites in the human gut can arise from microbial fermentation of protein

SCOPE

Plant secondary metabolites, such as phenolic acids are commonly associated with benefits for human health. Two of the most abundant phenylpropanoid-derived compounds detected in human faecal samples are phenylacetic acid (PAA) and 4-hydroxylphenylacetic acid (4-hydroxyPAA). Although they have the potential to be derived from diets rich in plant-based foods, evidence suggests that these compounds can be derived from the microbial fermentation of aromatic amino acids (AAAs) in the colon.

METHODS AND RESULTS

To identify the bacteria responsible, 26 strains representing 25 of the dominant human colonic species were screened for phenyl metabolite formation. Seven strains produced significant amounts of both PAA and 4-hydroxyPAA. These included five out of seven Bacteroidetes (Bacteroides thetaiotaomicron, Bacteroides eggerthii, Bacteroides ovatus, Bacteroides fragilis, Parabacteroides distasonis), and two out of 17 Firmicutes (Eubacterium hallii and Clostridium bartlettii). These species also produced indole-3-acetic acid (IAA), the corresponding tryptophan metabolite, but C. bartlettii showed 100 times higher IAA production than the other six strains. Four strains were further tested and PAA formation was substantially increased by phenylalanine, 4-hydroxyPAA by tyrosine and IAA by tryptophan.

CONCLUSION

This study demonstrates that certain microbial species have the ability to ferment all three AAAs and that protein fermentation is the likely source of major phenylpropanoid-derived metabolites in the colon.

The L-α-lysophosphatidylinositol/GPR55 system and its potential role in human obesity

GPR55 is a putative cannabinoid receptor, and l-α-lysophosphatidylinositol (LPI) is its only known endogenous ligand. We investigated 1) whether GPR55 is expressed in fat and liver; 2) the correlation of both GPR55 and LPI with several metabolic parameters; and 3) the actions of LPI on human adipocytes. We analyzed CB1, CB2, and GPR55 gene expression and circulating LPI levels in two independent cohorts of obese and lean subjects, with both normal or impaired glucose tolerance and type 2 diabetes. Ex vivo experiments were used to measure intracellular calcium and lipid accumulation. GPR55 levels were augmented in the adipose tissue of obese subjects and further so in obese patients with type 2 diabetes when compared with nonobese subjects. Visceral adipose tissue GPR55 correlated positively with weight, BMI, and percent fat mass, particularly in women. Hepatic GPR55 gene expression was similar in obese and type 2 diabetic subjects. Circulating LPI levels were increased in obese patients and correlated with fat percentage and BMI in women. LPI increased the expression of lipogenic genes in visceral adipose tissue explants and intracellular calcium in differentiated visceral adipocytes. These findings indicate that the LPI/GPR55 system is positively associated with obesity in humans.

High-protein, reduced-carbohydrate weight-loss diets promote metabolite profiles likely to be detrimental to colonic health

BACKGROUND

Diets that are high in protein but reduced in carbohydrate contents provide a common approach for achieving weight loss in obese humans. However, the effect of such diets on microbiota-derived metabolites that influence colonic health has not been established.

OBJECTIVE

We designed this study to assess the effect of diets with reduced carbohydrate and increased protein contents on metabolites considered to influence long-term colonic health, in particular the risk of colorectal disease.

DESIGN

We provided 17 obese men with a defined weight-maintenance diet (85 g protein, 116 g fat, and 360 g carbohydrate/d) for 7 d followed by 4 wk each of a high-protein and moderate-carbohydrate (HPMC; 139 g protein, 82 g fat, and 181 g carbohydrate/d) diet and a high-protein and low-carbohydrate (HPLC; 137 g protein, 143 g fat, and 22 g carbohydrate/d) diet in a crossover design. Fecal samples were analyzed to determine concentrations of phenolic metabolites, short-chain fatty acids, and nitrogenous compounds of dietary and microbial origin.

RESULTS

Compared with the maintenance diet, the HPMC and HPLC diets resulted in increased proportions of branched-chain fatty acids and concentrations of phenylacetic acid and N-nitroso compounds. The HPLC diet also decreased the proportion of butyrate in fecal short-chain fatty acid concentrations, which was concomitant with a reduction in the Roseburia/Eubacterium rectale group of bacteria, and greatly reduced concentrations of fiber-derived, antioxidant phenolic acids such as ferulate and its derivatives.

CONCLUSIONS

After 4 wk, weight-loss diets that were high in protein but reduced in total carbohydrates and fiber resulted in a significant decrease in fecal cancer-protective metabolites and increased concentrations of hazardous metabolites. Long-term adherence to such diets may increase risk of colonic disease.

Anti-inflammatory implications of the microbial transformation of dietary phenolic compounds

Due to the success of therapeutic anti-inflammatory compounds to inhibit, retard, and reverse the development of colon cancer, the identification of dietary compounds as chemopreventives is being vigorously pursued. However, an important factor often overlooked is the metabolic transformation of the food-derived compounds in the gut that may affect their bioactivity. Commonly consumed dietary phenolics (esterified ferulic acid and its 5-5'-linked dimer), which have the potential to undergo predominant microbial transformations (de-esterification, hydrogenation, demethylation, dehydroxylation, and dimer cleavage), were incubated with human microbiota. The metabolites were identified (high-performance liquid chromatography and nuclear magnetic resonance) and confirmed to be present in fresh fecal samples from 4 human volunteers. The potential anti-inflammatory properties were compared by measuring the ability of the parent compounds and their metabolites to modulate prostanoid production in a cell line in which the inflammatory pathways were stimulated following a cytokine-induced insult. The compounds were readily de-esterified and hydrogenated, but no dimer cleavage occurred. Only the monomer underwent demethylation and selective de-hydroxylation. The resultant metabolites had differing effects on prostanoid production ranging from a slight increase to a significant reduction in magnitude. This suggests that the microbial transformation of dietary compounds will have important inflammatory implications in the chemoprevention of colon cancer.

Mechanism of conjugated linoleic acid and vaccenic acid formation in human faecal suspensions and pure cultures of intestinal bacteria

Faecal bacteria from four human donors and six species of human intestinal bacteria known to metabolize linoleic acid (LA) were incubated with LA in deuterium oxide-enriched medium to investigate the mechanisms of conjugated linoleic acid (CLA) and vaccenic acid (VA) formation. The main CLA products in faecal suspensions, rumenic acid (cis-9,trans-11-CLA; RA) and trans-9,trans-11-CLA, were labelled at C-13, as were other 9,11 geometric isomers. Traces of trans-10,cis-12-CLA formed were labelled to a much lower extent. In pure culture, Bifidobacterium breve NCFB 2258 formed labelled RA and trans-9,trans-11-CLA, while Butyrivibrio fibrisolvens 16.4, Roseburia hominis A2-183T, Roseburia inulinivorans A2-192T and Ruminococcus obeum-like strain A2-162 converted LA to VA, labelled in a manner indicating that VA was formed via C-13-labelled RA. Propionibacterium freudenreichii subsp. shermanii DSM 4902T, a possible probiotic, formed mainly RA with smaller amounts of trans-10,cis-12-CLA and trans-9,trans-11-CLA, labelled the same as in the mixed microbiota. Ricinoleic acid (12-OH-cis-9-18 : 1) did not form CLA in the mixed microbiota, in contrast to CLA formation described for Lactobacillus plantarum. These results were similar to those reported for the mixed microbiota of the rumen. Thus, although the bacterial genera and species responsible for biohydrogenation in the rumen and the human intestine differ, and a second route of RA formation via a 10-OH-18 : 1 is present in the intestine, the overall labelling patterns of different CLA isomers formation are common to both gut ecosystems. A hydrogen-abstraction enzymic mechanism is proposed that may explain the role of a 10-OH-18 : 1 intermediate in 9,11-CLA formation in pure and mixed cultures.

Availability of blueberry phenolics for microbial metabolism in the colon and the potential inflammatory implications

Blueberries are a rich source of phenylpropanoid-derived phytochemicals, widely studied for their potential health benefits. Of particular interest for colonic health are the lower molecular weight phenolic acids and their derivatives, as these are the predominant phenolic compounds detected in the colon. Blueberries contained a wide variety of phenolic acids, the majority of which (3371.14 +/- 422.30 mg/kg compared to 205.06 +/- 45.34 mg/kg for the free phenolic acids) were attached to other plant cell-wall components and therefore, likely to become available in the colon. Cytokine-induced stimulation of the inflammatory pathways in colon cells was four-fold up-regulated in the presence of the free phenolic acid fraction. Incubation of the bound phenolic acids with human faecal slurries resulted in qualitative and quantitative differences in the phenolic compounds recovered. The metabolites obtained by incubation with faecal slurries from one volunteer significantly decreased (1.67 +/- 0.69 ng/cm(3)) prostanoid production, whereas an increase (10.78 +/- 5.54 ng/cm(3)) was obtained with faecal slurries from another volunteer. These results suggest that any potential protective effect of blueberry phenolics as anti-inflammatory agents in the colon is a likely result of microbial metabolism. Studies addressing a wide-range of well-characterised human volunteers will be required before such health claims can be fully established.

Salicylate modulates oxidative stress in the rat colon: a proteomic approach

The dietary phenolic compound, salicylic acid, decreases oxidative stress and pro-inflammatory and potentially neo-plastic prostaglandins with a concomitant increase in glutathione peroxidase activity. Salicylic acid, a dietary plant-based phenolic compound and also the main metabolite of aspirin, may contribute to the colon protective effects of plant-based diets. Oxidative stress is a characteristic of pre-cancerous and cancerous colon and inflammatory bowel diseases (IBD) that increase colon cancer risk. The mechanism(s) whereby salicylic acid modulates potentially pro-cancerous activity associated with oxidative stress is further investigated here using a proteomic approach. A rat model of oxidative stress was supplemented with salicylic acid (1 mg/kg diet, mean plasma levels 310+/-32 micromol/l). Soluble colon protein extracts were subjected to 2D PAGE. Salicylic acid modulated proteins, identified using MALDI-TOF and LC/MS/MS, are involved in protein folding, transport, redox, energy metabolism and cytoskeletal regulation. A partial least squares (PLS) analysis approach was used to assist biological interpretation of the altered protein profiles via their associations between previously published biochemical measurements of oxidative stress, prostaglandin levels and increased glutathione peroxidase activity. Early detection of altered homeostasis in colon may assist in identifying pre-pathological features preceding colon tumorigenesis and contribute to an understanding of epidemiological evidence supporting a protective effect of plant-based diets.

EPR investigation into the effects of substrate structure on peroxidase-catalyzed phenylpropanoid oxidation

The plant polymer lignin represents one of the most structurally diverse natural products and results from the oxidative coupling of phenylpropanoid monomers. Peroxidase catalyses the oxidation of phenylpropanoids to their phenoxyl radicals, and the subsequent nonenzymatic coupling controls the pattern and extent of polymerisation. Using EPR spectroscopy, we have demonstrated that for a series of substrates increased methoxylation increases peroxidase-catalyzed oxidation and that this is most easily achieved with the monomeric alcohols. Dimeric compounds, synthesized to represent the initial products of phenylpropanoid coupling, showed a marked decrease in their ability to be oxidized when compared with the monomeric substrates. These findings demonstrate that the structure of the monomer determines the final composition of lignin, which ultimately effects the overall structure. The results indicate that the polymer grows primarily as a result of the reactivity of the monomers and that polymerization to high molecular weight may be restricted to methoxylated species.

Salicylic acid modulates oxidative stress and glutathione peroxidase activity in the rat colon

Oxidative stress is a characteristic of cancerous colon tissue and inflammatory bowel diseases that increase colon cancer risk. Epidemiological evidence supports a protective effect of plant-derived compounds. Aspirin is also protective against colon cancer. The mechanism of action is unclear although salicylic acid, the main metabolite of aspirin, has been shown to decrease the synthesis of pro-inflammatory and potentially neo-plastic prostaglandins. Salicylic acid is found in significant quantities in a plant-based diet. However, in plants salicylic acid is also reported to modulate the expression of numerous enzymes with antioxidant activity. The aim of this study was to assess whether salicylic acid can modulate pro-cancerous biological pathways in the colon. Oxidative stress, prostaglandins and cytosolic glutathione peroxidase (cyGPX) were analysed in proximal, transverse and distal colon from a rat model of diet-induced oxidative stress. Elevated plasma pyruvate kinase activity (1293+/-206 U/ml) and increased indices of lipid peroxidation in colon (proximal 6.4+/-0.84 nM MDA/mg protein; transverse 6.9+/-0.97 nM MDA/mg protein; distal 5.2+/-0.62 nM MDA/mg protein) from rats fed a Vitamin E deficient diet were significantly decreased on supplementation with salicylic acid (plasma pyruvate 546+/-43 U/ml; salicylic acid proximal 3.6+/-0.39 nM MDA/mg protein; transverse 4.5+/-0.61 nM MDA/mg protein; distal 4.4+/-0.27 nM MDA/mg protein). Reductions in oxidative stress and prostaglandin production on supplementation with salicylic acid were associated with an elevation in glutathione peroxidase activity (Vitamin E deficient proximal 0.056+/-0.013 U/mg protein; transverse 0.073+/-0.008 U/mg protein; distal 0.088+/-0.010 U/mg protein; Vitamin E deficient with salicylic acid proximal 0.17+/-0.01 U/mg protein; transverse 0.23+/-0.016 U/mg protein; distal 0.16+/-0.020 U/mg protein). Gpx1 and Gpx2 gene transcripts were not elevated in association with increased activity of the soluble glutathione peroxidase activity. Glutathione peroxidases are key antioxidant enzymes, catalysing the decomposition of potentially toxic lipid peroxides. Gpx activity and regulation of Gpx gene transcription has been shown previously to be complex with activity not necessarily mirrored by a corresponding elevation in gene transcription. By supplementing the diet of Vitamin E deficient rats with salicylic acid (1 g/kg diet), this study assessed effects of salicylic acid on cytosolic glutathione peroxidase activity in the colon. The ability of salicylic acid to modulate antioxidant enzymes in colon tissue may be an important mechanism in inhibiting colon cancer development.

Inhibition of cytokine-induced prostanoid biogenesis by phytochemicals in human colonic fibroblasts

Many of the inflammatory pathways regulating the production of prostanoids are implicated in the development of colon cancer. Diets rich in fruits and vegetables are associated with decreased rates of colon cancer and this may reflect anti-inflammatory properties of some phytochemicals in plant-based foods. In order to ascertain which of the many dietary compounds may be protective, a cell-based screening method was established to determine their effects on the production of prostanoids. By up-regulating prostaglandin H synthase-2 in human colonic fibroblast cells with cytokines, we have investigated the potential protective effect of a structurally related group of phytochemicals on prostanoid biogenesis. Several of the compounds significantly inhibited prostanoid biogenesis, by up to 81% and others enhanced prostanoid production. All of the compounds that enhanced prostanoid production belonged to the hydroxylated benzoic acid family and good correlation was observed with their redox activity and the ability to enhance prostanoid production. Common structural features of the inhibitors were the presence of 4-hydroxyl and 3-methoxyl substituents on the aromatic ring and/or the presence of a three-carbon side-chain on C1.

Antioxidant phenylacetic acid derivatives from the seeds of Ilex aquifolium

Reversed-phase preparative HPLC analysis of the methanol extract of the seeds of Ilex aquifolium afforded two antioxidant phenylacetic acid derivatives, 2,4-dihydroxyphenylacetic acid (1) and 2,4-dihydroxyphenylacetic acid methyl ester (2). The structures were determined by spectroscopic methods. In the DPPH assay for antioxidant activity, the IC(50) values of 1 and 2 were 1.50 x 10(-3) and 2.55 x 10(-3) mg mL(-1), respectively, compared to 2.88 x 10(-5) mg mL(-1) of quercetin, a natural antioxidant.

Copper-homocysteine complexes and potential physiological actions

During the last 2 decades it was proposed that atherogenesis was closely related to the homeostasis of homocysteine (hCys) and/or copper. We hypothesized that the physiological action of hCys may be connected with its ability to form complexes with Cu. Our results showed the presence of two different Cu-hCys complexes. At a molar ratio Cu:hCys 1:1, a blue complex most probably consistent with a tentative dimeric Cu(II)(2)(hCys)(2)(H(2)O)(2) formula was formed, with tetrahedral Cu coordination and anti-ferromagnetic properties. The redox processes between Cu(II) and hCys, in a molar ratio > or =1:3 led to formation of a second yellow Cu(I)hCys complex. Both Cu-hCys complexes affected the metabolism of extracellular thiols more than hCys alone and inhibited glutathione peroxidase-1 activity and mRNA abundance. The biological action of hCys and Cu-hCys complexes involved remodeling and phosphorylation of focal adhesion complexes and paxillin. The adhesive interactions of monocytes with an endothelial monolayer led to the redistribution of both paxillin and F-actin after all treatments, but the diapedesis of monocytes through endothelial cell monolayer was both greater and faster in the presence of the tentative Cu(II)(2)(hCys)(2)(H(2)O)(2) complex. Together, these observations suggest that Cu-hCys complexes actively participate in the biochemical responses of endothelial cells that are involved in the aethiopathogenesis of atherosclerosis.