Enterohepatic circulation of 12α-hydroxylated (12αOH) bile acid (BA) is enhanced depending on the energy intake in high-fat diet-fed rats. Such BA metabolism can be reproduced using a diet supplemented with cholic acid (CA), which also induces simple steatosis, without inflammation and fibrosis, accompanied by some other symptoms that are frequently observed in the condition of non-alcoholic fatty liver in rats. We investigated whether supplementation of the diet with raffinose (Raf) improves hepatic lipid accumulation induced by the CA-fed condition in rats. After acclimation to the AIN-93-based control diet, male Wistar rats were fed diets supplemented with a combination of Raf (30 g/kg diet) and/or CA (0·5 g/kg diet) for 4 weeks. Dietary Raf normalised hepatic TAG levels (two-way ANOVA P < 0·001 for CA, P = 0·02 for Raf and P = 0·004 for interaction) in the CA-supplemented diet-fed rats. Dietary Raf supplementation reduced hepatic 12αOH BA concentration (two-way ANOVA P < 0·001 for CA, P = 0·003 for Raf and P = 0·03 for interaction). The concentration of 12αOH BA was reduced in the aortic and portal plasma. Raf supplementation increased acetic acid concentration in the caecal contents (two-way ANOVA P = 0·001 as a main effect). Multiple regression analysis revealed that concentrations of aortic 12αOH BA and caecal acetic acid could serve as predictors of hepatic TAG concentration (R2 = 0·55, P < 0·001). However, Raf did not decrease the secondary 12αOH BA concentration in the caecal contents as well as the transaminase activity in the CA diet-fed rats. These results imply that dietary Raf normalises hepatic lipid accumulation via suppression of enterohepatic 12αOH BA circulation.

We have recently reported that soluble dietary fibre, glucomannan, increased colonic alkaline phosphatase (ALP) activity and the gene expression without affecting the small-intestinal activity and that colonic ALP was correlated with gut mucins (index of intestinal barrier function). We speculated that dietary fermentable carbohydrates including oligosaccharides commonly elevate colonic ALP and gene expression as well as increase mucin secretion and microbial fermentation. To test this hypothesis, male Sprague–Dawley rats were fed a diet containing 30 % lard with or without 4 % fructo-oligosaccharides (FOS), galacto-oligosaccharides (GOS), raffinose (RAF) and lactulose (LAC), which are non-digestible oligosaccharides or isomalto-oligosaccharides (IMOS; some digestible oligosaccharides) for 2 weeks. Colon ALP activity, the gene expression and gut luminal variables including mucins, organic acids and microbiota were measured. Colonic ALP was significantly elevated in the FOS, RAF and LAC groups, and a similar trend was observed in the GOS group. Colonic expression of intestinal alkaline phosphatase (IAP-I), an ALP gene, was significantly elevated in the FOS, GOS and RAF groups and tended to be increased in the LAC group. Dietary FOS, GOS, RAF and LAC significantly elevated faecal mucins, caecal n-butyrate and faecal ratio of Bifidobacterium spp. Dietary IMOS had no effect on colonic ALP, mucins, organic acids and microbiota. Colon ALP was correlated with mucins, caecal n-butyrate and faecal Bifidobacterium spp. This study demonstrated that non-digestible and fermentable oligosaccharides commonly elevate colonic ALP activity and the expression of IAP-I, with increasing mucins and microbial fermentation, which might be important for protection of gut epithelial homoeostasis.

Obtaining corn hybrid seeds (Zea mays L.) with high vigour depends on the parental lines and the direction of the cross, and this relates to seed desiccation tolerance and composition. This research studied reciprocal crosses between pairs of proprietary, elite parent lines (L1 and L5; L2 and L4) producing hybrid seeds with different qualities attempting to correlate vigour with seed composition, focusing on storage proteins, starch and soluble sugar amounts. Four corn hybrid seed lots produced from reciprocal crosses were compared (HS 15 with HS 51, and HS 24 with HS 42) by assessing germination, vigour, and seedling emergence in the field. Seed composition was assessed in mature, dehydrated seeds. Proteins were extracted, quantified, and analysed by electrophoresis and densitometry. Starch amounts were assessed using a kit and soluble sugars were determined using high performance liquid chromatography with pulsed electrochemical detection. The L1 and L2 lineages, used as female parents, provided seeds with lower vigour; however, the quantification of major protein bands, and sucrose, raffinose and stachyose were similar between seed lot pairs. While both total seed protein and starch varied between reciprocal hybrids for one of the two sets of crosses, the amounts of neither correlated with seed vigour. Interestingly, hybrids with low seed vigour (HS 15, HS 24) accumulated greater amounts of fructose relative to their reciprocal; correlation analysis confirmed these results. We demonstrate different effects on seed vigour dependent on the maternal parent in reciprocal crosses producing hybrid corn seeds. We also show that vigour is negatively correlated with seed reducing sugar contents.

It is important to provide formula-fed infants with a bifidobacteria-enriched gut microbiota similar to those of breastfed infants to ensure intestinal health. Prebiotics, such as certain oligosaccharides, are a useful solution to this problem, but the combinational benefits of these oligosaccharides have not been evaluated. This study investigated the benefits of oligosaccharide combinations and screened for an optimal combination of oligosaccharides to promote healthy gut microbiota of formula-fed infants. In vitro and in vivo experiments were performed to assess the bifidogenic effects of lactulose (LAC) alone and LAC combined with raffinose (RAF) and/or galacto-oligosaccharide (GOS), using a mixed culture model and neonatal mice orally administered with these oligosaccharides and Bifidobacterium breve. In the in vitro culture model, the combination of the three oligosaccharides (LAC–RAF–GOS) significantly increased cell numbers of B. breve and Bifidobacterium longum (P<0·05) compared with either LAC alone or the combination of two oligosaccharides, and resulted in the production of SCFA under anaerobic conditions. In the in vivo experiment, the LAC–RAF–GOS combination significantly increased cell numbers of B. breve and Bacteroidetes in the large intestinal content (P<0·05) and increased acetate concentrations in the caecal content and serum of neonatal mice. Genes related to metabolism and immune responses were differentially expressed in the liver and large intestine of mice administered with LAC–RAF–GOS. These results indicate a synergistic effect of the LAC–RAF–GOS combination on the growth of bifidobacteria and reveal possible benefits of this combination to the gut microbiota and health of infants.

It has been proposed that sucrose and raffinose play a role in the storability of maize seeds. The levels of these sugars in the embryos and the glassy state were compared in maize seeds of contrasting storage stability to determine the relationship between sugar composition, glassy state and the storability of the seed. Sucrose was the predominant sugar but its content was not correlated with good storage. The content of raffinose as a mass fraction of total sugars and the magnitude of the glassy state showed positive correlations with storage stability. It is suggested that in maize seeds dry storage stability is a reflection not of the total soluble sugars, but of the mixture of sucrose with raffinose. Apparently raffinose amplifies the magnitude of the glass signal and this in turn is associated with enhanced storability.

We report preliminary experiments to test the hypothesis that two sugars are involved in the acquisition of desiccation tolerance in immature maize embryos. Sucrose and raffinose were quantified during embryo development, at 16–27 days after pollination (DAP) and during slow dehydration. Embryos were exposed to slow drying either upon excision (18 and 16 DAP) or after an incubation treatment resulting in a decrease in sucrose (18 DAP). The sugars were separated by HPLC with a refractive-index detector; composition was determined by comparing peak areas of interest with those of individual sugar standards. Although further evidence is needed, our results do not appear to support the hypothesis.

Maturing yellow lupin seeds were desiccation tolerant. Glucose, sucrose and cyclitols (mainly D-pinitol, D-chiro-inositol and myo-inositol) were predominant at the early stages of seed growth. Accumulation of the raffinose family oligosaccharides (RFOs) and the galactosyl cyclitols including galactinol, digalactosyl myo-inositol, galactopinitol A, galactopinitol B, trigalactopinitol A, ciceritol, fagopyritol B1 and fagopyritol B2 appeared during seed maturation; their increase correlated with seed germinability after desiccation. The loss of desiccation tolerance after seed germination was also studied. For the desiccation tolerance test, intact seedlings were dried rapidly or slowly followed by rehydration. Soluble carbohydrates were assayed before and after drying. Root tissues were more sensitive to desiccation than hypocotyl tissues and completely lost desiccation tolerance within 36 h of imbibition after both fast and slow-drying treatments. Survival of hypocotyls decreased gradually up to 96 h after imbibition. Loss of RFOs and galactosyl cyclitols in axis tissues preceded visible germination. Loss of desiccation tolerance was accompanied by loss of RFOs and galactosyl cyclitols and an increase in reducing sugars in cotyledon, hypocotyl and radicle tissues. Drying did not induce the accumulation of RFOs and galactosyl cyclitols in seedling tissues.

It has been proposed that gibberellic acid (GA3) promotes germination by overcoming restrictions in sugar production and utilization in afterripening-responsive dormant caryopses. While their germination rates were similar, germination commenced sooner in afterripened wild oat (Avena fatua L.) caryopses than in dormant caryopses treated with GA3 and dormant excised embryos treated with GA3 plus fructose (Fru). Limited germination occurred in dormant excised embryos cultured with GA3 alone. Carbohydrate concentrations were measured over time in dormant caryopses and excised embryos whose germination was induced with GA3 and GA3 plus Fru. The concentration of sucrose (Suc) in the endosperm declined prior to germination of dormant GA3-treated caryopses. Raffinose (Raf) family oligosaccharides in the embryos of dormant GA-treated caryopses remained relatively constant prior to and shortly after the onset of germination. In contrast, Raf family oligosaccharides in the embryos of afterripened caryopses declined prior to germination. Together this suggests Raf family oligosaccharide utilization is not associated with germination per se. Increased starch levels, which occurred in dormant excised embryos treated with Fru and GA3 plus Fru, were associated with dormancy because similar effects were not apparent in afterripened embryos cultured with Fru. An initial decline in the concentration of Raf family oligosaccharides in dormant embryos cultured with GA3 or GA3 plus Fru seems to be a result of the excision process. GA3 appears to stimulate the germination of dormant embryos by enhancing the uptake or utilization of Fru. It appears that GA3 and afterripening-induced changes in carbohydrate utilization in dormant caryopses are different.

Raffinose family oligosaccharides (RFOs) are of almost ubiquitous occurrence in plant seeds. They accumulate during seed development and disappear rapidly during germination. The biosynthesis of raffinose, the first member of the series, proceeds by addition of a galactosyl unit to sucrose. Galactinol, a galactosyl derivative of myo-inositol, acts as a galactosyl donor. It is synthesized from UDP-D-GALACTOSE AND MYO-INOSITOL. STACHYOSE, VERBASCOSE AND AJUGOSE, THE NEXT HIGHER RFOS, ARE EITHER SYNTHESIZED BY GALACTINOL-DEPENDENT GALACTOSYLTRANSFERASES OR BY TRANSFER OF GALACTOSYL UNITS BETWEEN TWO RFO MOLECULES. IN SEEDS, THE METABOLISM OF METHYLATED INOSITOLS, SUCH AS D-ononitol and D-pinitol, is linked with the RFO pathway. In contrast to myo-inositol, these cyclitols are galactosylated by transfer of galactosyl residues from galactinol and not from UDP-D-galactose. However, the resulting galactosyl cyclitols can replace galactinol as galactosyl donors for the biosynthesis of stachyose. These recently discovered branches of the RFO pathway are active in seeds of a range of crop species, especially in legumes. We focus here on the biochemistry and molecular biology of the enzymes of RFO and galactosyl cyclitol biosynthesis. The metabolic control and hormonal regulation of the pathway during seed development and germination is discussed. The controversial role of α-galactosidases, which are believed to hydrolyse RFOs during germination, is reviewed critically.

Relationships between desiccation tolerance and dry matter, water and sugar contents were studied throughout the development of oil palm (Elaeis guineensis Jacq.) zygotic embryos and in immature embryos cultured on a sucrose-enriched medium. Embryo dry weight during in planta development increased between 80 and 140 d after pollination (DAP) and was then stable until maturity. Embryos underwent dehydration until 120 DAP, but their moisture content remained high at maturity (c. 2 g H2O g-1 DW). Desiccation tolerance was acquired between 83 and 104 DAP, and was positively correlated with embryo age and dry weight, and negatively correlated with initial water content during this period. Sucrose, the main soluble sugar present throughout embryo development, accounted for an average of 24% of the dry weight. Glucose and fructose contents decreased to less than 1 mg g-1 DW in embryos at maturity. At 117 DAP, as embryos became tolerant to desiccation, the monosaccharides/sucrose ratio fell to 0.015 and raffinose was detected. Stachyose appeared later in 147-day-old embryos and accumulated until shedding. In vitro culture of immature embryos in the presence of high sucrose concentrations (350 and 700 mM) resulted in an increase in their dry weight and a decrease in their water content, and induced the acquisition of desiccation tolerance. Under these conditions, sucrose accumulated in embryos to 30–40% on a dry weight basis, but neither raffinose nor stachyose was detected. Acquisition of desiccation tolerance by oil palm immature embryos was associated both in planta and in vitro with an accumulation of dry matter, a reduction of moisture content, and a fall in the monosaccharides/sucrose ratio. In planta, survival to dehydration was also related with the deposition of oligosaccharides whereas in vitro, it was related with high sucrose accumulation. The role of sugars in the acquisition of desiccation tolerance in oil palm embryos is discussed.

Germination and carbohydrate metabolism were studied in fresh developing pea (Pisum sativum L., cv Baccara) seeds and after artificial drying at 25°C and various relative humidities (20, 75 and 99% RH) to investigate whether the occurrence of desiccation tolerance was related to sucrose, raffinose and stachyose contents. Seeds became completely tolerant to fast drying at 25°C and 20% RH a few days after the end of reserve accumulation, i.e. when their moisture content dropped to approx. 50% (fresh weight basis). This acquisition of desiccation tolerance was associated with an accumulation of raffinose and stachyose, the latter being more abundant in the embryonic axis than in the cotyledons. The (raffinose+stachyose)/sucrose ratio increased during seed development and reached 1.1 in the axis and 0.2 in the cotyledons just before the onset of desiccation tolerance. When the natural acquisition of desiccation tolerance occurred on the mother plant, artificial drying of isolated seeds induced an increase in oligosaccharide content in the cotyledons. Immature seeds, the moisture content of which was higher than about 60% (fresh weight basis), did not tolerate fast drying (25°C and 20 or 75% RH). Such drying did not result in the synthesis of stachyose and induced an increase in electrolyte leakage, a decrease in the ability of seeds to convert 1-aminocyclopropane 1-carboxylic acid (ACC) to ethylene and an increase in ethane synthesis, thus indicating a deterioration of cell membrane properties and lipid peroxidation. In contrast, immature seeds tolerated drying either in the pods or at 25°C and 99% RH, and such drying induced a decrease in sucrose content, an increase in oligosaccharide content and a (raffinose+stachyose)/sucrose ratio higher than around 1. Soluble sugar contents of dried immature seeds depended on the conditions of dehydration. In cotyledons, the (raffinose+stachyose)/sucrose ratio reached 0.61 when seeds were dried at 25°C and 99% RH, whereas it was as low as 0.15 when drying was performed at 25°C and 20% RH. All the results obtained are consistent with the concept that oligosaccharides may well be involved in the protection of membranes during dehydration.

Correlative evidence indicates that sucrose and α-galactosyl-sucrose oligosaccharides (raffinose family oligosaccharides; RFOs) may be involved in seed longevity. Priming treatments (hydration in water or osmotic solutions followed by drying) can improve short-term seed performance but often result in reduced seed longevity. As RFOs are metabolized quickly following seed imbibition, loss of RFOs during priming could lead to more rapid deterioration in dry storage. This hypothesis was tested by measuring sucrose and oligosaccharide contents and potential longevity of primed seeds. Raffinose contents of whole lettuce (Lactuca sativa L.) seeds declined during hydration and priming and were correlated with decreased median potential viability (p50). However, this relationship was less significant when only the embryonic axes were analysed. In tomato (Lycopersicon esculentum Mill.) and impatiens (Impatiens balsamina L.) seeds, planteose was the major galactosyl-sucrose oligosaccharide and only small quantities of RFOs were present. Planteose contents declined during priming in seeds of both species, while sucrose contents increased or remained constant. Post-priming treatments that restored longevity in primed impatiens and tomato seeds were not accompanied by consistent changes in RFO or planteose contents. Our data do not rule out a role for oligosaccharides in seed longevity, but they make it unlikely that changes in oligosaccharide contents alone are responsible for the reduction in longevity due to priming or its restoration by post-priming treatments.

Oral administration of raffinose, a naturally occurring indigestible oligosaccharide, has reportedly ameliorated atopic dermatitis in human subjects although the mechanism is unknown. The present study investigated the effect of dietary raffinose on allergen-induced airway eosinophilia in ovalbumin-sensitised Brown Norway rats as an atopic disease model. Brown Norway rats were immunised by subcutaneous injection with ovalbumin on day 0 and fed either a control diet or the diet supplemented with raffinose (50 g/kg diet). The rats were exposed to aerosolised ovalbumin on day 20, and broncho-alveolar lavage fluid was obtained on the next day. The number of eosinophils in the fluid was significantly lower in the rats fed the raffinose diet than in those fed the control diet. Dietary raffinose significantly reduced IL-4 and IL-5 mRNA levels in lung tissue and tended to lower ovalbumin-specific Ig E levels. Suppression of eosinophilia by dietary raffinose was still observed in caecectomised and neomycin-administered rats, suggesting little contribution by the colonic bacteria to the effect of raffinose. Intraperitoneal administration of raffinose also suppressed eosinophilia. Significant concentrations of raffinose were detected in portal venous and abdominal arterial plasma after the intragastric administration of raffinose. Overall, the findings suggest that dietary raffinose ameliorates allergic airway eosinophilia at least partly via post-absorptive mechanisms in Brown Norway rats.

The effects of the dietary oligosaccharide raffinose on immune responses, with special reference to its anti-allergic functions, were examined in vivo. First, feeding a diet supplemented with 50 g raffinose/kg to BALB/c mice significantly (P<0·05) increased interleukin (IL) 12 secretion from isolated Peyer's patch (PP) cells in vitro compared with feeding control diet. When isolated PP cells were used as antigen-presenting cells (APC) for CD4+ T-splenocytes isolated from ovalbumin (OVA)-specific T-cell receptor transgenic (Tg) mice in the presence of OVA as antigen, significantly (P<0·05) higher levels of interferon-γ were observed in the cultures using APC from raffinose-fed mice than those cultures using APC from control mice. Second, the diet containing 50 g raffinose/kg or control diet was fed to OVA Tg mice, and subsequently, OVA was added to each diet to prime T cells in vivo. CD4+ T-cells from the mesenteric lymph nodes of the raffinose-fed mice secreted significantly (P<0·05) higher levels of IL-2 and significantly (P<0·05) lower levels of IL-4 following in vitro antigenic stimulation compared with those of the control mice. These present results suggest that feeding raffinose may suppress differentiation of naïve T-helper (Th) cells into Th2 cells in the mesenteric lymphoid nodes. Last, feeding raffinose suppressed rises of serum immunoglobulin E levels in the Tg mice treated with long-term ingestion of OVA. In conclusion, it is suggested that dietary raffinose suppresses serum immunoglobulin E response through suppression of Th2-type immune response against oral antigen in the lymphoid organs located in or near the intestine.

This review presents findings on the influence of natural raffinose series oligosaccharides and synthetic (industrial) products on the productivity of broiler chicken. There is evidence of negative effects on animal health and productivity from the use of raffinose series oligosaccharides, but beneficial effects from synthetic oligosaccharides. Part of this contradiction may be due to differences in the chemical nature of the supplements, the level of supplementation or the duration of feeding. The future for synthetic oligosaccharides is bright, but further adoption of natural sources requires a greater understanding of their chemistry to facilitate the production of beneficial compounds and the elimination of detrimental fractions. Most current literature favours the inclusion of various oligosaccharides in the diet. The cost of production could be minimised by the use of natural ingredients which contain oligosaccharides, or by cheap synthetic products, sources of which are highlighted in this review.