Soya Saponin Research Articles

Soya saponins and prebiotics alter intestinal functions in Ballan wrasse (Labrus bergylta).

A 5-week feeding trial was conducted in the cleaner fish Ballan wrasse (Labrus bergylta) for a better understanding of the basic biology of the intestinal functions and health in this stomach less species. During the trial, Ballan wrasse was fed either a reference diet, the reference diet supplemented with (i) a commercial prebiotic (Aquate™ SG, 0·4 %) expected to have beneficial effects, (ii) soya saponins (0·7 %) expected to induce inflammation or (iii) a combination of the prebiotics and the soya saponins to find a remedy for gut inflammation. Blood, intestinal tissue and gut content from four consecutive intestinal segments (IN1 - IN4) were collected. No significant differences in fish growth were observed between the four dietary groups. Saponin supplementation, both alone and in combination with prebiotics, increased weight index of IN2 and IN3 and decreased blood plasma glucose, cholesterol and total protein. Dry matter of intestinal content and activity of digestive enzymes were not affected by diet. Histomorphological analyses revealed a progressing inflammation with increased infiltration by immune cells particularly into the distal parts of the intestine in fish fed diets with saponins, both alone and in combination with prebiotics. Gene expression profiles obtained by RNA sequencing and quantitative PCR mirrored the histological and biochemical changes induced by the saponin load. The study demonstrated that Ballan wrasse gut health and digestive function may be markedly affected by feed ingredients containing antinutrients.

Soya saponin fails to improve the antioxidation and immune function of laying hens with antibiotics treated

Soya saponin (SS) helps to improve antioxidant and immune function of body, and intestinal bacteria might play an important role here. In the present study, the co-occurring network of the ileal flora was analyzed with 50 mg/kg SS supplemented to the diet, and Romboutsia was found to have evolved into a dominant flora. In addition, the co-occurring network of the flora was changed with the combined antibiotic treated, and the unidentified-cyanobacteria developed into the dominant flora, whereas the relative abundance of Romboutsia was dropped. Dietary SS failed to elevate the relative abundance of Romboutsia with antibiotics treated, at the same time, it was not helpful for the antioxidant and immune function of laying hens. While dietary SS had a little help on the egg-laying performance. Intestinal bacteria did play a key role in the biological functions of SS on laying hens. In conclusion, SS failed to improve the antioxidation and immune function of laying hens with antibiotics treated.

Dietary soya saponin improves the lipid metabolism and intestinal health of laying hens

Soya saponin (SS) is a natural active substance of leguminous plant, which could improve lipid metabolism and regulate immune function. Intestinal flora might play a key role in the biological functions of SS. The objective of this study was to measure the effects of dietary SS on immune function, lipid metabolism, and intestinal flora of laying hens with or without antibiotic treated. The experiment was designed as a factorial arrangement of 3 dietary SS treatments × 2 antibiotic treatments. Birds were fed a basal diet (CON) or a low-SS diet (50 SS) containing 50 mg/kg SS, or a high-SS diet (500 SS) containing 500 mg/kg SS. Birds were cofed with or without antibiotics. The growth experiment lasted for 10 wk. Results showed that birds fed the 50 mg/kg SS diet tended to have lower abdominal fat rate. The gene expression of liver X receptor-α (LxR-α) in liver and serum total cholesterol (TC) were dropped, and the gene expression of acyl-CoA thioesterase 8 (ACOT8) in liver were upregulated. Compared with CON group, the levels of lysozyme, IL-10, and transforming growth factor (TGF-β) in the serum were elevated as along with gene expression of IL-10, TGF-β, and LYZ in ileum of both 50 and 500 SS group. However, the level of secretory immunoglobulin A (sIgA) and Mucin-2 in the ileum were downregulated in the 500 SS group. Additionally, Lactobacillus and Lactobacillus gasseri were the dominant bacteria in the 50 SS group, whereas the relative abundance of Lactobacillus was dropped in the 500 SS group. With combined antibiotics treatment, the α-diversity of bacteria was reduced, and the biological effects of SS were eliminated. In conclusion, the lipid metabolism, immune function, and intestinal flora of the laying hens were improved with the dietary supplementation of 50 mg/kg SS. But dietary 500 mg/kg SS had negative effects on laying hens.

Soya saponin improves egg-laying performance and immune function of laying hens

BackgroundSoya saponin (SS), an active compound in soybean meals, has been widely studied in the medical field. However, it was considered as an anti-nutritional factor in poultry diets. The objective of this experiment was to measure the effects of dietary SS using three dietary treatments on egg-laying performance and immune function of laying hens. Birds were fed a low soybean meal basal diet (CON), a low-SS diet (50 SS) containing 50 mg/kg SS, or a high-SS diet (500 SS) containing 500 mg/kg SS for 10 weeks. At the end of the 5th and 10th week of the trial, samples were collected for analysis.ResultsResults showed that with 50 mg/kg SS supplementation, the egg production rate, feed conversion ratio (FCR), and eggshell quality tended to be improved. Serum follicle stimulating hormone (FSH) and Interleukin-4 (IL-4) levels were also elevated as well as the peripheral blood LPS stimulation index, the proportion of B lymphocytes, and antibody titer of bovine serum albumin (BSA). We also found that mRNA levels of follicle stimulating hormone receptor (FSHR) in ovarian, nuclear transcription factor kappa B (NF-κB), Transforming growth factor (TGF-β) and interferon γ (IFN-γ) in spleen were up-regulated at the end of the trial. Additionally, dietary 50 mg/kg SS improved the ileal flora via up-regulating the relative abundance of Lactobacillus, Romboutsia and Lactobacillus delbrueckii. Although the immune related indicators were improved with 500 mg/kg SS supplemented, it seemed to have a negative influence on the laying-performance. Specifically, serum alanine aminotransferase (ALT), alkaline phosphatase (ALP), and the ratio of IFN-γ to IL-4 were increased in the 500 SS group at the end of the trial. The mRNA levels of gonadotropin releasing hormone 1 (GnRH1) in Hypothalamus, the estrogen related receptor (ERR) in ovaries were downregulated as well as the egg production rate during the trial with 500 mg/kg SS supplemented.ConclusionsThe egg production performance was improved by dietary supplemented with 50 mg/kg SS via increasing ovarian FSHR transcription level and serum estrogen level. A beneficial shift in intestinal microflora was recorded, and the immune function of laying hens was also improved with 50 mg/kg SS supplementation. Surprisingly, the long-term supplementation of 500 mg/kg SS exerted a negative impact on the laying performance and physiological functions of the liver of laying hens.

In vitro study of sodium butyrate on soyasaponin challenged intestinal epithelial cells of turbot (Scophthalmus maximus L.) refer to inflammation, apoptosis and antioxidant enzymes

The study is aimed to investigate the protective effect and potential mechanisms of sodium butyrate (NaBT) on soyasaponins (SA) induced intestinal epithelial cells (IECs) injury in vitro. The primary IECs of turbot were developed and treated with 0.4, 1 and 4 mM NaBT in the presence of 0.4 mg/mL SA for 6 h to explore the protective effects of NaBT. The results showed that the addition of NaBT significantly down-regulated gene expression of inflammatory cytokine TNF-α, IL-1β and IL-8, pro-apoptosis relevant gene BAX, caspase-3, caspase-7 and caspase-9 induced by SA, while up-regulated anti-apoptosis gene Bcl-2. SA stimulation did not induce reactive oxygen species production, but elevated gene expression of antioxidant enzyme heme oxygenase-1 and superoxide dismutase. Moreover, the gene expression of those antioxidant enzyme was further up-regulated in NaBT groups. Furthermore, NaBT supplementation decreased the acid phosphatase and alkaline phosphatase activities and suppressed phosphorylation of p38 and c-Jun N-terminal kinase (JNK). In conclusion, NaBT could mitigate SA-induced inflammation and apoptosis and elevate gene expression of antioxidant enzymes on IECs of turbot and p38 and JNK signaling pathway participated in those processes.

Effect of a diet containing a mixture of soybean isoflavones and soyasaponins on contact hypersensitivity and gut microbiota in mice

AbstractDietary soybean isoflavones (SIs) and soyasaponins (SSs) individually exert inhibitory effects on contact hypersensitivity (CHS), which is an animal model of allergic contact dermatitis (ACD); however, the beneficial effects of diets containing a mixture of SIs and SSs on CHS remain unclear. Here, we investigated the CHS‐suppressive effects of diets containing a mixture of SIs and SSs at physiologically relevant doses, and the role of the gut microbiota. The diets attenuated ear swelling and reduced the number of Gr‐1‐positive cells infiltrating the auricle tissues. Ear swelling was inhibited in the SI‐ and SS‐treated mice compared to the SI‐treated mice. Compared to the CHS controls, the levels of chemokine (C‐X‐C motif) ligand 2 and triggering receptor expressed on myeloid cells‐1 (TREM‐1) were lower in the auricle tissues of SI‐ and SS‐treated mice, whereas TREM‐1 production was not suppressed in SI‐ or SS‐treated mice. In addition, vancomycin treatment had little effect on the CHS‐inhibitory activity of SI and SS diets, whereas ciprofloxacin and metronidazole treatments blocked the effects of SI and SS diets. These antibiotics exhibited differing effects on the microbiota composition deduced from the bacterial 16S ribosomal RNA gene sequences. Therefore, consuming a mixture of SIs and SSs has ACD‐preventive effects and is affected by the gut microbiota.

Soyasaponin A2 Alleviates Steatohepatitis Possibly through Regulating Bile Acids and Gut Microbiota in the Methionine and Choline-Deficient (MCD) Diet-induced Nonalcoholic Steatohepatitis (NASH) Mice.

Nonalcoholic steatohepatitis (NASH) is a chronic progressive disease with complex pathogenesis of which the bile acids (BAs) and gut microbiota are involved. Soyasaponins (SS) exhibits many health-promoting effects including hepatoprotection, but its prevention against NASH is unclear. This study aims to investigate the preventive bioactivities of SS monomer (SS-A2 ) against NASH and further clarify its mechanism by targeting the BAs and gut microbiota. The methionine and choline deficient (MCD) diet-fed male C57BL/6 mice were intervened with obeticholic acid or SS-A2 for 16 weeks. Hepatic pathology is assessed by hematoxylin-eosin and Masson's trichrome staining. BAs in serum, liver, and colon are measured by ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-TQMS). Gut microbiota in caecum are determined by 16S rDNA amplicon sequencing. In the MCD diet-induced NASH mice, SS-A2 significantly reduces hepatic steatosis, lobular inflammation, ballooning, nonalcoholic fatty liver disease activity score (NAS) scores, and fibrosis, decreases Erysipelotrichaceae (Faecalibaculum) and Lactobacillaceae (Lactobacillus) and increases Desulfovibrionaceae (Desulfovibrio). Moreover, SS-A2 reduces serum BAs accumulation and promotes fecal BAs excretion. SS-A2 changes the BAs profiles in both liver and serum and specifically increases the taurohyodeoxycholic acid (THDCA) level. Faecalibaculum is negatively correlated with serum THDCA. SS-A2 alleviates steatohepatitis possibly through regulating BAs and gut microbiota in the MCD diet-induced NASH mice.

Soyasaponin ameliorates obesity and reduces hepatic triacylglycerol accumulation by suppressing lipogenesis in high-fat diet-fed mice.

Soyasaponins are triterpenoid glycosides found in soybean. We investigated whether soyasaponin ameliorates lipid metabolism and its possible mechanisms. In C57BL/6J mice fed a high-fat diet (HFD), soyasaponin (SAP) was orally administered for 9weeks. Additionally, we evaluated the effect of soyasapogenols on 3T3-L1 adipocytes. In HFD-fed mice, the SAP significantly reduced body weight by 7% and relative adipose tissue weight by 35%. X-ray computed tomography demonstrated that the SAP reduced visceral and subcutaneous adipose tissue weights during week 3 of feeding. The SAP reduced sterol regulatory element-binding protein-1c (SREBP-1c) mRNA levels by 32% in the epididymal adipose tissue, significantly decreasing the triacylglycerol (TAG) content by 37% and SREBP-1c and fatty acid synthase mRNA levels by 52% and 61%, respectively, in the liver. In 3T3-L1 adipocytes, soyasapogenol B significantly decreased lipid droplets. The SAP containing soyasaponin A and B as conjugates demonstrate anti-obesity effects by suppressing adipocyte differentiation and lipogenesis, with a preventive effect on hepatic TAG accumulation by suppressing lipogenesis. PRACTICAL APPLICATION: Soyasaponin is one of the oleanane triterpenoids in soybeans. We have demonstrated that soyasaponin potently reduces body weight and white adipose tissue weight, and hepatic triacylglycerol accumulation in high-fat diet-fed mice. Thus, soyasaponin is a beneficial compound to prevent obesity and fatty liver.

Dietary Ala-Gln ameliorated growth suppression and intestinal injury induced by soya saponin in zebrafish

Our previous study showed that dietary soybean saponin (SA) consumption reduced growth performance and damaged the morphology of the intestinal mucosa in zebrafish (Danio rerio). Glutamine (Gln) plays an important role in ameliorating intestinal atrophy. Therefore, the present study tested the hypothesis that dietary alanine-glutamine (Ala-Gln) supplementation ameliorates the growth suppression and intestinal injury induced by dietary SA in zebrafish. Five experimental diets were prepared by supplementing the basal diet with either SA at 0, 5 or 10 g/kg, and Ala-Gln at 0 or 10 g/kg, with adjustment of Ala-Ala to maintain equal nitrogen levels among all diets. Fish with average initial body weight of (9.00 ± 0.13) mg were fed five diets for 4 weeks. The growth performance increased significantly and intestinal morphology was improved by supplementation of Ala-Gln at 10 g/kg. Ala-Gln supplementation improved growth via regulation of the growth hormone (GH)–insulin like growth factor I (IGFI) axis. The experimental diets significantly affected the mRNA expression levels of amino acid and peptide transporters. Dietary Ala-Gln upregulated the mRNA expression levels of glycolysis and fat synthesis-related factors, significantly reduced the activity of AMP-activated protein kinase (AMPK), but stimulated the activity of target of rapamycin (TOR). Overall, Ala-Gln might be broken down into free amino acids, with Gln being absorbed by the intestinal mucosa cells. Dietary Ala-Gln supplementation ameliorated the intestinal injury induced by SA, and promoted the breakdown of carbohydrates and fats for energy, thereby improving the growth performance of zebrafish.

Impact of soymilk consumption on 2,4-dinitrofluorobenzene-induced contact hypersensitivity and gut microbiota in mice

Soymilk is rich in phytochemicals such as soy isoflavones (SIs) and soyasaponins (SSs). Dietary SIs and SSs display inhibitory effects on contact hypersensitivity (CHS), which was reported in a mouse model for allergic contact dermatitis (ACD); however, the beneficial effects of soymilk consumption on CHS remain unknown. Here, we studied the effects of drinking soymilk on CHS and gut microbiota. Soymilk consumption attenuated ear oedema and swelling, decreased the infiltration of Gr-1-positive cells into ear tissues, and reduced the production of chemokine (C-X-C motif) ligand 2 and triggering receptor expressed on myeloid cells-1 in ear tissues. The analysis of bacterial 16S ribosomal RNA gene sequences indicated that CHS caused changes in the gut microbiota structure and that consuming soymilk reduced these changes. These results suggest that soymilk consumption may be of therapeutic value for patients with ACD and may help control the balance of intestinal microbiota.

Study the Hemolytic and Cytotoxic Effects of Saponin Isolated from Soy Bean.

Saponin is an important class of natural products that can be found primarily in many plants, as well asin some marine animals. It has a diverse range of properties, which include pharmacological and medicinalproperties, strong hemolytic properties, as well as antimicrobial, insecticidal, and anticancer activities. Our studyaimed to isolate the saponin from different plant sources (legumes) and to evaluate its hemolytic and cytotoxicactivity in higher plant source. In this study the saponin was extracted from legumes using choloroform andethanol. The concentration of saponin was determined by colorimetric method. Soybean saponin source was loadedon silica gel column chromatography and was detected by thin layer chromatography (TLC), infrared spectroscopy(IR) and confirmed by high performance liquid chromatography (HPLC). In addition the hemolytic activity ofsoybean saponin was evaluated on human blood erythrocyte and the cytotoxic effect on human colon cancer cellline (Coca) was determined by using MTT assay. Our result showed the presence of blue violet spot on thin layerchromatography in soya been saponin and confirmed by IR spectrum by presence of C-H bond of at 2927cm-1, COstretching at 1059 cm-1,C=C bond at 1628cm-1 and OH bond at 3400cm-1. Hemolytic dose (HD50) that madehemolysis for 50% of erythrocyte was 0.412 mg /ml. MTT assay releaved that saponin extracted from soya beanhad IC50 43.4μg/ml against colon cancer cell line in 48hr treatment. In conclusion, Soya saponin inhibits theproliferation of colon cancer and thus it may have therapeutic application in future.

Antimicrobial and pesticidal activities of soya saponin

Antimicrobial and pesticidal activities of soya saponin

Inhibitory effects of dietary soyasaponin on 2,4-dinitrofluorobenzene-induced contact hypersensitivity in mice.

Soyasaponins (SSs) abundant in soybean have anti-inflammatory activities; however, their therapeutic effects on allergic contact dermatitis (ACD) remain unknown. To assess the effects of SS-enriched diets on ACD, we used a mouse model of contact hypersensitivity (CHS). Mice were fed low-dose or high-dose SS-containing diets for 3weeks prior to CHS induction with 2,4-dinitrofluorobenzene (DNFB). The low-dose SS diet attenuated DNFB-induced ear swelling and tissue oedema, and reduced the number of infiltrating Gr-1-positive myeloid cells. Low-dose, but not high-dose, SSs decreased chemokine (C-X-C motif) ligand 2 (CXCL2) and triggering receptor expressed on myeloid cells (TREM)-1 production in ear tissues, compared to a control. Taxonomic 16S rRNA analysis revealed significant alterations in faecal microbiota caused by CHS, which were reversed by low-dose SSs. The low-dose SS and non-CHS groups clustered together, while the high-dose SS group split between CHS and non-CHS clusters. Our results demonstrated that low-dose SSs alleviated CHS symptoms by attenuating inflammation and improving the intestinal microbiota composition, suggesting that dietary SSs may have beneficial effects on ACD.

Soya Saponins Induce Enteritis in Atlantic Salmon (Salmo salar L.).

Soybean meal-induced enteritis (SBMIE) is a well-described condition in the distal intestine of salmonids, and saponins have been implicated as the causal agent. However, the question remains whether saponins alone cause SBMIE. Moreover, the dose-response relationship has not been described. In a 10 week feeding trial with Atlantic salmon, a highly purified (95%) soya saponin preparation was supplemented (0, 2, 4, 6, or 10 g/kg) to two basal diets, one containing fishmeal as the major protein source (FM) and the other 25% lupin meal (LP). Saponins caused dose-dependent increases in the severity of inflammation independent of the basal diet, with concomitant alterations in digestive functions and immunological marker expression. Thus, saponins induced inflammation whether the diet contained other legume components or not. However, responses were often the same or stronger in fish fed the corresponding saponin-supplemented LP diets despite lower saponin exposure, suggesting potentiation by other legume component(s).

Dietary saponins and phytosterols do not affect growth, intestinal morphology and immune response of on-growing European sea bass (Dicentrarchus labrax )

This study was the first to investigate the effect of soy antinutrients, saponins and phytosterols, in on-growing sea bass. Seven diets were formulated: a control diet (fishmeal and fish oil based) and six diets containing 1 or 2 g kg−1 levels of soya saponins, 5 or 10 g kg−1 levels of phytosterols or a combination of 1 g kg−1 saponins + 5 g kg−1 phytosterols or 2 g kg−1 saponins + 10 g kg−1 phytosterols. After a 59 days feeding trial fish were weighed, faeces collected for digestibility studies and plasma sampled for cholesterol quantification. At day 15 and 59, distal intestine (DI) samples were collected for histological evaluation and quantification of maltase (Malt), alkaline phosphatase (AlP) and leucine aminopeptidase (LAP) activities. At day 59, DI was collected for gene expression of AlP, Malt and immune related genes. Antinutrients had no effect on fish performance, digestibility, plasma cholesterol levels and digestive enzymes activities and gene expression. Only mild morphological changes were present in groups fed high levels of saponins + phytosterols. Expression of immune related genes showed no differences between groups. Overall, on-growing sea bass showed high tolerance to dietary antinutrients up to the levels tested.

Effects of Soya Saponins on Feed Intake, Growth Performance, and Cholesterol Metabolism in Juvenile Turbot (Scophthalmus maximus L)

An 8-week feeding trial was conducted to investigate the effects of soya saponins on feed intake, growth performance, and cholesterol metabolism in juvenile turbot (Scophthalmus maximus L). A control diet and two experimental diets were prepared with the supplementation of soya saponins, concentrations being as follows: 0.0% (Diet 1, Control), 0.25% (Diet 2) and 0.5% (Diet 3), respectively. The results showed that 0.25% of dietary soya saponins produced comparable growth performance with the control diet. However, the growth performance of fish fed the diet with 0.5% soya saponins was significantly lower. The selected parameters measured in plasma, liver, and feces of each group were not significantly different. These results suggested that 0.25% dietary soya saponins did not produce negative effects, but but but but 0. 5% of dietary soya saponins significantly reduced fish growth. Dietary soya saponin supplementation to FM-based diet did not significantly affect cholesterol metabolism.

Soyasaponins Prevent H2O2-Induced Inhibition of Gap Junctional Intercellular Communication by Scavenging Reactive Oxygen Species in Rat Liver Cells

It appears to be more practical and effective to prevent carcinogenesis by targeting the tumor promotion stage. Gap junctional intercellular communication (GJIC) is strongly involved in carcinogenesis, especially the tumor promotion stage. Considerable interest has been focused on the chemoprevention activities of soyasaponin (SS), which are major phytochemicals found in soybeans and soy products. However, less is known about the preventive effects of SS (especially SS with different chemical structures) against tumor promoter-induced inhibition of GJIC. We investigated the protective effects of SS-A1, SS-A2, and SS-I against hydrogen peroxide (H2O2)-induced GJIC inhibition and reactive oxygen species (ROS) production in Buffalo rat liver (BRL) cells. The present results clearly show for the first time that SS-A1, SS-A2, and SS-I prevent the H2O2-induced GJIC inhibition by scavenging ROS in BRL cells in a dose-dependent manner at the concentration range of from 25 to 100 μg/mL. Soyasaponins attenuated the H2O2-induced ROS through potentiating the activities of superoxide dismutase and glutathione peroxidase. This may be an important mechanism by which SS protects against tumor promotion. In addition, various chemical structures of SS appear to exhibit different protective abilities against GJIC inhibition. This may partly attribute to their differences in ROS-scavenging activities.

Effects of dietary soy saponins and phytosterols on gilthead sea bream (Sparus aurata) during the on-growing period

Plant ingredients contain antinutritional factors that may affect fish growth performance and health when included in their diets. The present work aimed at studying the effect of two soy purified antinutrients, saponins and phytosterols, on growth, intestinal morphology and immune response of on-growing sea bream. Fish were fed one of seven diets for 48 days: control diet (fishmeal and fish oil based) and six experimental diets containing low (0.1%) or high (0.2%) levels of soya saponins, low (0.5%) or high (1.0%) levels of phytosterols or a combination of 0.1% saponins +0.5% phytosterols or 0.2% saponins +1.0% phytosterols. At day 15 and at the end of the trial pyloric caeca (PC) and distal intestine (DI) samples were collected for histological evaluation. At the end of the trial plasma was sampled for cholesterol analysis and DI was sampled for gene expression of immune and functional genes. Saponins and phytosterols did not affect fish growth, feed utilisation or plasma cholesterol levels. Histologically only a mild increase in the number of eosinophilic granular cells in the PC after 15 and 48 days of feeding in fish fed 0.1% saponins and 0.5% phytosterols, respectively. Gene expression of immune related genes was not affected by the presence of dietary antinutrients. Sea bream in grow-out phase showed high tolerance for saponins and phytosterols either alone or in combination, thus indicating an ability to cope with dietary plant feedstuffs containing such antinutrients, at least within the concentration range used in the present study.

Effects of diet supplementation of soya-saponins, isoflavones and phytosterols on Atlantic salmon (Salmo salar, L) fry fed from start-feeding

A 14-week trial was conducted to investigate the effects of antinutritional factors (ANFs) commonly present in soybean ingredients, singly and in combination, on Atlantic salmon (Salmo salar L.) fed from start-feeding. The experimental diets consisted of a negative control fish meal diet (FM), and a positive control diet with 167 g kg−1 soybean meal inclusion (SBM) and four diets based on the FM diet supplemented with 2 g kg−1 soya-saponins (SAP), 1.5 g kg−1 isoflavones (IFL), 0.3 g kg−1 phytosterols (PHS) or a mixture of these (MIX). Fish fed the SAP diet showed significantly higher growth performance than those fed FM, while the IFL treatment significantly decreased growth performance of salmon fry. Fish fed the IFL diet had significantly lower maltase activity and higher trypsin activity in proximal intestine than fish fed the FM diet. Histological differences were observed in the liver of fish fed the IFL diet, characterized by reduced size of the hepatocytes. Fish fed the PHS and IFL diets showed the highest frequencies of skeletal deformities among the six treatments. In conclusion, the results indicate that purified isoflavones may negatively affect growth performance, intestinal function, liver metabolism and bone formation of salmon fry.

Effects of dietary phytosterols and soy saponins on growth, feed utilization efficiency and intestinal integrity of gilthead sea bream (Sparus aurata) juveniles

The use of plant ingredients in aquafeeds for piscivorous fish species is a reality that exposes fish to a number of antinutritional factors present in plants. The present study is the first to evaluate the effect of two purified antinutrients, saponins and phytosterols, in sea bream juveniles. For that purpose, seven diets were formulated: a control diet (fishmeal and fish oil based) and six experimental diets containing low (1 g kg− 1, SapL) or high (2 g kg− 1, SapH) levels of purified soya saponins, low (5 g kg− 1, PhytL) or high (10 g kg− 1, PhytH) levels of purified phytosterols or a combination of 1 g kg− 1 saponins + 5 g kg− 1 phytosterols (SapPhytL) or 2 g kg− 1 saponins + 10 g kg− 1 phytosterols (SapPhytH). Fish were fed for 48 days in order to evaluate growth performance, feed utilization, plasma cholesterol, and gut health as assessed by histomorphological evaluation and gene expression profiling of immune and functional markers. Fish fed the diets PhytH, SapPhytL and SapPhytH showed better feed utilization and PhytH and SapPhytH showed higher protein utilization than the other groups, although this was not reflected in improved growth performance. Histomorphological analysis of the distal intestine revealed increased variation in supranuclear vacuole sizes after 48 days of feeding diets SapH, SapPhytL and SapPhytH and increased number of intraepithelial leukocytes in response to all dietary treatments except SapL and SapPhytL. Although juvenile sea bream growth was not affected by dietary inclusion of saponins and phytosterols, the results indicated some disturbances of the intestinal mucosal structure that could compromise function and/or protection from potential dietary antigens or opportunistic pathogens.