Structure of cerebroside in Aspergillus oryzae

Koji amazake Maintains Water Content in the Left Cheek Skin of Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled, Parallel-Group, Comparative Trial

Purpose

Improvement in water content and skin barrier function on human skin is believed to be induced by koji amazake, a non-alcoholic beverage derived from rice fermented by Aspergillus oryzae (A. oryzae). In order to scientifically identify the effects of koji amazake on human skin, we performed a randomized, double-blind, placebo-controlled, parallel-group comparative trial and quantified the content of glucosylceramide (GlcCer) which would be responsible for the effects.

Participants and Methods

Healthy adults concerned with their skin dryness were divided into koji amazake (N = 30) or placebo group (N = 30). During this test, the test beverages were ingested at 118 g/day. Their water content and trans-epidermal water loss (TEWL) were measured at 0 week (baseline) and 8 weeks. The content of GlcCer in test beverages was quantified by HPLC-ELSD.

Results

In comparison with the placebo group, the water content in the left cheek of individuals in the koji amazake group was maintained for 8 weeks. In addition, changes in water content from the baseline to 8 weeks differed significantly between the koji amazake (0.19) and placebo groups (-3.98). Unexpectedly, there was no significant difference in the TEWL between koji amazake and placebo group. We analyzed GlcCer in both koji amazake and placebo beverages, which were found to contain 1.35 ± 0.11 and 0.30 ± 0.07 mg/118 g, respectively. The amount of GlcCer in koji amazake was approximately equal to the dosage of plant-derived GlcCer which has the ability to improve water content and TEWL in humans.

Conclusion

Present study has shown that intake of koji amazake contributes to maintain the water content only on the left cheek. The content of GlcCer derived from koji amazake was adequate for maintenance of the water content compared to previous reports. Therefore, it was concluded that GlcCer in koji amazake acts as a functional ingredient.

Glucosylceramide Changes Bacterial Metabolism and Increases Gram-Positive Bacteria through Tolerance to Secondary Bile Acids In Vitro

Glucosylceramide is present in many foods, such as crops and fermented foods. Most glucosylceramides are not degraded or absorbed in the small intestine and pass through the large intestine. Glucosylceramide exerts versatile effects on colon tumorigenesis, skin moisture, cholesterol metabolism and improvement of intestinal microbes in vivo. However, the mechanism of action has not yet been fully elucidated. To gain insight into the effect of glucosylceramide on intestinal microbes, glucosylceramide was anaerobically incubated with the dominant intestinal microbe, Blautia coccoides, and model intestinal microbes. The metabolites of the cultured broth supplemented with glucosylceramide were significantly different from those of broth not treated with glucosylceramide. The number of Gram-positive bacteria was significantly increased upon the addition of glucosylceramide compared to that in the control. Glucosylceramide endows intestinal microbes with tolerance to secondary bile acid. These results first demonstrated that glucosylceramide plays a role in the modification of intestinal microbes.

Intake of Koji Amazake Improves Defecation Frequency in Healthy Adults

Reportedly, the intake of koji amazake, a beverage made from steamed rice fermented by Aspergillus oryzae, improves defecation frequency. However, its functional ingredients and mechanism of action remain unclear. To compare the effects of koji amazake and a placebo beverage on defecation frequency and to identify the functional ingredients and mechanism of action, a randomized, placebo-controlled, double-blind parallel-group comparative trial was performed on two groups. The koji amazake had 302 ± 15.5 mg/118 g of A. oryzae cells, which was not in the placebo. Compared with the placebo group, the koji amazake group showed a significant increase in weekly defecation frequency at 2 weeks (5.09 days vs. 4.14 days), 3 weeks (5.41 days vs. 4.18 days), and 4 weeks (5.09 days vs. 3.95 days), along with an increase in the weekly fecal weight at 4 weeks (724 g vs. 501 g). The intake of koji amazake did not induce significant intergroup differences in the fecal SCFA concentration, whereas it significantly decreased the relative abundance of Blautia and significantly increased that of Bacteroides at 3 weeks. Therefore, koji amazake intake improved defecation frequency, and A. oryzae cells played potentially important roles as functional ingredients.

Glycosphingolipids in Filamentous Fungi: Biological Roles and Potential Applications in Cosmetics and Health Foods

Filamentous fungi are a group of economically important fungi used in the production of fermented foods, industrial enzymes, and secondary metabolites. Glycosphingolipids (GSLs) as constituents of lipid rafts are involved in growth, differentiation, and response to environment stress in filamentous fungi. In addition to these key roles, GSLs are also important in the barrier function of skin to retain moisture as a moisturizing ingredient in cosmetics or health products for their strong biological activity as a functional component. GSLs found in filamentous fungi are divided in two major classes: neutral GSLs (glycosylceramides), glucosylceramides (GlcCers), and/or galactosylceramides (GalCers) and acidic GSLs, mannosylinositol phosphorylceramide (MIPC) and mannosyldiinositol phosphorylceramide [M(IP)₂C]. Glycosylceramides are one of the abundant GSLs in Aspergillus and known to improve skin-barrier function and prevent intestinal impairment as a prebiotic. Some filamentous fungi of Aspergillus spp., synthesizing both GlcCer and GalCer, would be an amenable source to exploit glycosylceramides that wildly adding in cosmetics as moisturizing ingredients or health food as dietary supplements. In this minireview, the types, structures, and biosynthetic pathways of GSLs in filamentous fungi, and the relevance of GSLs in fungal growth, spore formation, and environmental stress response are explained. Furthermore, the advantage, potential development, and application of GlcCer and GalCer from filamentous fungi Aspergillus spp. are also investigate based on the use of plant GlcCer in health foods and cosmetics.

Biological Roles Played by Sphingolipids in Dimorphic and Filamentous Fungi

Filamentous and dimorphic fungi cause invasive mycoses associated with high mortality rates. Among the fungal determinants involved in the establishment of infection, glycosphingolipids (GSLs) have gained increased interest in the last few decades. GSLs are ubiquitous membrane components that have been isolated from both filamentous and dimorphic species and play a crucial role in polarized growth as well as hypha-to-yeast transition. In fungi, two major classes of GSLs are found: neutral and acidic GSLs. Neutral GSLs comprise glucosylceramide and galactosylceramide, which utilize Δ4-Δ8-9-methyl-sphingadienine as a sphingoid base, linked to a C_16-18 fatty acid chain, forming ceramide, and to a sugar residue, such as glucose or galactose. In contrast, acidic GSLs include glycosylinositol phosphorylceramides (GIPCs), composed of phytosphingosine attached to a long or very long fatty acid chain (C_18-26) and to diverse and complex glycan groups via an inositol-phosphate linker. GIPCs are absent in mammalian cells, while fungal glucosylceramide and galactosylceramide are present but diverge structurally from their counterparts. Therefore, these compounds and their biosynthetic pathways represent potential targets for the development of selective therapeutic strategies. In this minireview, we discuss the enzymatic steps involved in the production of fungal GSLs, analyze their structure, and address the role of the currently characterized genes in the biology and pathogenesis of filamentous and dimorphic fungi.

Quantitation and structural determination of glucosylceramides contained in sake lees

Sake lees are solid parts filtered from the mash of sake, the traditional rice wine of Japan, which is brewed with Aspergillus oryzae and Saccharomyces cerevisiae. The moisture-holding activity of sake lees has long been recognized in Japan. However, the constituent responsible for this activity has not been elucidated. In this study, we first determined the structure of the glucosylceramides contained in sake lees. The glucosylceramides contained in sake lees were N-2'-hydroxyoctadecanoyl-l-O-β-D-glucopyranosyl-9-methyl-4,8-sphingadienine (d19:2/C18:0h), N-2'-hydroxyoctadecanoyl-l-O-β-D-glucopyranosyl-4,8-sphingadienine (d18:2/C18:0h), N-2'-hydroxyicosanoyl-l-O-β-D-glucopyranosyl-4,8-sphingadienine (d18:2/C20:0h) and N-2'-hydroxyicosanoyl-l-O-β-D-glucopyranosyl-4,8-sphingadienine (d18:2/C22:0h), which corresponded to those of A. oryzae and rice. The glucosylceramide produced by A. oryzae constituted the most abundant species (43% of the total glucosylceramide) in the sake lees. These results will be of value in the utilization of sake lees for cosmetics and functional foods.

Structural analysis of cerebrosides from Aspergillus fungi: the existence of galactosylceramide in A. oryzae

Glucosylceramide and galactosylceramide were detected in three Aspergillus species: Aspergillus oryzae, Aspergillus sojae and Aspergillus. awamori, using borate-coated TLC. The cerebrosides from A. oryzae were further purified by ion exchange and iatrobeads column chromatographies with or without borate, and determined the composition of sugar, fatty acid and sphingoid base by GC/MS, MALDI-TOF/MS and (1)H-NMR. We identified them as β-glucosylceramide and β-galactosylceramide. The ceramide moiety of both cerebrosides consisted mainly of 2-hydroxystearic acid and either 9-methyl-octadeca-4, 8-sphingadienine or octadeca-4, 8-sphingadienine. To our knowledge, this is the first study to provide evidence for the presence of β-galactosylceramide in A. oryzae.

Structural determination of glucosylceramides in the distillation remnants of shochu, the Japanese traditional liquor, and its production by Aspergillus kawachii

Shochu is traditional Japanese liquor produced from various crops and fungi Aspergillus kawachi or A. awamorii . The amount of unutilized shochu distillation remnants is increasing because of the recent prohibition of ocean dumping of these remnants. In this Article, we first describe the structures of glucosylceramides contained in shochu distillation remnants by fragment ion analysis using ESI-tandem mass spectrometry. Shochu distillation remnant produced from barley contained glucosylceramides d18:2/C16:0h, d18:2/C20:0h, d19:2/C18:1h, and d18:2/C18:0h. Koji (barley fermented with A. kawachii) contained the same glucosylceramides. Shochu distillation remnants produced from rice contained glucosylceramides d18:2/C18:0h and d19:2/C18:1h. The culture broth of A. kawachii contained glucosylceramides d19:2/C18:1h and d19:2/C18:0h. These results indicate that the glucosylceramides contained in crops and those produced by A. kawachii transfer through the processes of fermentation with yeast and distillation to the shochu distillation remnant. This information will enable utilization of shochu distillation remnants and koji as novel sources of sphingolipids.

Glucosylceramide synthase is essential for alfalfa defensin-mediated growth inhibition but not for pathogenicity of Fusarium graminearum

Antifungal defensins, MsDef1 and MtDef4, from Medicago spp., inhibit the growth of a fungal pathogen, Fusarium graminearum, at micromolar concentrations. However, molecular mechanisms by which they inhibit the growth of this fungus are not known. We have characterized a functional role of the fungal sphingolipid glucosylceramide in regulating sensitivity of the fungus to MsDef1 and MtDef4. A null mutation of the FgGCS1 gene encoding glucosylceramide synthase results in a mutant lacking glucosylceramide. The DeltaFggcs1-null mutant becomes resistant to MsDef1, but not to MtDef4. It shows a significant change in the conidial morphology and displays dramatic polar growth defect, and its mycelia are resistant to cell wall degrading enzymes. Contrary to its essential role in the pathogenicity of a human fungal pathogen, Cryptococcus neoformans, GCS1 is not required for the pathogenicity of F. graminearum. The DeltaFggcs1 mutant successfully colonizes wheat heads and corn silk, but its ability to spread in these tissues is significantly reduced as compared with the wild-type PH-1 strain. In contrast, it retains full virulence on tomato fruits and Arabidopsis thaliana floral and foliar tissues. Based on our findings, we conclude that glucosylceramide is essential for MsDef1-mediated growth inhibition of F. graminearum, but its role in fungal pathogenesis is host-dependent.

Membrane lipid profile of an edible basidiomycete Lentinula edodes during growth and cell differentiation

The basidiomycetous mushroom Lentinula edodes (Shiitake) exhibits a unique process of cell differentiation termed "fruiting-body formation". To clarify the relationship between membrane lipids and fruiting-body formation in this fungus, we investigated variations in levels of phospholipids, cerebrosides, fatty acyl residues in the major phospholipids, and fatty acyl and sphingoid base residues in cerebrosides during vegetative growth and fruiting-body formation. PC, PE, and PS were the primary phospholipids in the cells of L. edodes. After a shift in growth temperature of L. edodes mycelia has been shifted from 25 to 18 degrees C, the proportion of unsaturated FA (UFA), such as linoleic acid (18:2) and oleic acid (18:1), increased. In contrast, during fruiting-body formation induced by the temperature downshift to 18 degrees C, 18:2 of PC in the primordia and fruiting bodies decreased, and the UFA of PE and 18:1 of PC increased compared with the proportions in mycelia growing at 18 degrees C. These results showed that the proportions of fatty acyl residues in PC and PE differed during fruiting-body formation in L. edodes. Moreover, the amount of cerebrosides in primordia increased compared with those in mycelia and fruiting bodies and, in these differentiating tissues, the proportion of 2-hydroxypentadecanoic acid increased whereas that of 2-hydroxyoctadecanoic acid decreased compared with that in the mycelia. However, the proportion of sphingoid base residues in cerebrosides did not change during fruiting-body formation in L. edodes.

Structure and biological functions of fungal cerebrosides

Ceramide monohexosides (CMHs, cerebrosides) are glycosphingolipids composed of a hydrophobic ceramide linked to one sugar unit. In fungal cells, CMHs are very conserved molecules consisting of a ceramide moiety containing 9-methyl-4,8-sphingadienine in amidic linkage to 2-hydroxyoctadecanoic or 2-hydroxyhexadecanoic acids, and a carbohydrate portion consisting of one residue of glucose or galactose. 9-Methyl 4,8-sphingadienine-containing ceramides are usually glycosylated to form fungal cerebrosides, but the recent description of a ceramide dihexoside (CDH) presenting phytosphingosine in Magnaporthe grisea suggests the existence of alternative pathways of ceramide glycosylation in fungal cells. Along with their unique structural characteristics, fungal CMHs have a peculiar subcellular distribution and striking biological properties. In Pseudallescheria boydii, Candida albicans, Cryptococcus neoformans, Aspergillus nidulans, A. fumigatus, and Schizophyllum commune, CMHs are apparently involved in morphological transitions and fungal growth. The elucidation of structural and functional aspects of fungal cerebrosides may therefore contribute to the design of new antifungal agents inhibiting growth and differentiation of pathogenic species.

Existence of cerebroside in Saccharomyces kluyveri and its related species

Sphingolipids are ubiquitous compounds derived from ceramide that consist of a sphingoid long-chain base with a 2-amino group amide linked to fatty acid and are present in the membranes of many organisms. As a principal sphingolipid, Saccharomyces cerevisiae contains a free ceramide and its inositol-phosphorylated derivatives (acidic types) but not a neutral glycosylated ceramide, glucosylceramide (cerebroside), which usually appears in eukaryotic cells. When 31 strains accepted in the genera Saccharomyces, Torulaspora, Zygosaccharomyces, and Kluyveromyces were analyzed for sphingolipids, cerebrosides were found in S. kluyveri, Z. cidri, Z. fermentati, K. lactis, K. thermotolerans, and K. waltii. The cerebrosides of S. kluyveri and K. lactis included 9-methyl 4-trans, 8-trans-sphingadienine and its putative metabolic intermediates. A unique characteristic of S. kluyveri was the presence of a trihydroxy sphingoid base, which rarely occurs in fungal cerebrosides. A polymerase chain reaction with primers targeted to the glucosylceramide synthase gene of other microorganisms amplified the fragments of the expected size from S. kluyveri and K. lactis and further extended to the adjacent regions. The presumed protein of S. kluyveri had 54.4% similarity to that of K. lactis, higher than the glucosylceramide synthases from Candida albicans, Pichia pastoris, and other organisms. From these observations, the divergence of S. kluyveri from the lineage of K. lactis in their evolution is discussed.

Yeast sphingolipids

Many advances in our understanding of fungal sphingolipids have been made in recent years. This review focuses on the types of sphingolipids that have been found in fungi and upon the genes in Saccharomyces cerevisiae, the common baker's yeast, that are necessary for sphingolipid metabolism. While only a small number of fungi have been examined, most contain sphingolipids composed of ceramide derivatized at carbon-1 with inositol phosphate. Further additions include mannose and then other carbohydrates. The second major class of fungal sphingolipids is the glycosylceramides, having either glucose or galactose attached to ceramide rather than inositol phosphate. The glycosylceramides sometimes contain additional carbohydrates. Knowledge of the genome sequence has expedited identification of S. cerevisiae genes necessary for sphingolipid metabolism. At least one gene is known for most steps in S. cerevisiae sphingolipid metabolism, but more are likely to be identified so that the 13 known genes are likely to grow in number. The AUR1 gene is necessary for addition of inositol phosphate to ceramide and has been identified as a target of several potent antifungal compounds. This essential step in yeast sphingolipid synthesis, which is not found in humans, appears to be an excellent target for the development of more effective antifungal compounds, both for human and for agricultural use.

Structural characterization of neutral glycosphingolipids from Fusarium species

Glycosphingolipids were extracted from hyphae of Fusarium solani and from an unnamed Fusarium species, and were purified by silica and Iatrobead column chromatography. Their structures were determined by compositional analysis, nuclear magnetic resonance spectroscopy, gas chromatography/mass spectrometry and by fast atom bombardment mass spectrometry of the native and peracetylated materials, which defined their sugar, long-chain base and fatty acid compositions. The locations of the double bonds in the bases were established by 2D NMR spectroscopy and by novel mass spectrometric approaches, including collisional activation of the protonated and lithium-cationized glycosphingolipids, and of the sphingadienene-derived fragment ion at m/z 276. From these results we propose that the structures of the glycosphingolipids from F. solani and Fusarium sp. are N-2'-hydroxyoctadecanoyl-1-O-beta-D-glucopyranosyl-9-methyl-4, 8-sphingadienine and N-2'-hydroxyoctadecenoyl-1-O-beta-D-glucopyranosyl-9-methyl-4, 8-sphingadienine, respectively.

Structural determination of N-2'-hydroxyoctadecenoyl-1-O-beta-D-glucopyranosyl-9-methyl-4, 8-sphingadienine from species of Aspergillus

Ceramide monohexosides from Aspergillus fumigatus 2140 and 2109 strains and Aspergillus versicolor 550 strain, obtained by silica gel 60, and Iatrobeads chromatography were analysed using high-resolution 1D-, 2D-1H-NMR and 13C-NMR spectroscopy and fast atom bombardment mass spectrometry (FAB-MS). The ceramide monohexoside fraction (CMH) from A. fumigatus 2140 and A. versicolor 550 was identified as glucosylceramide, whereas glucose and galactose were present at a ratio of 1:1 in the CMH of A. fumigatus 2109. The major glycosphingolipid has a particular ceramide composition consisting of 9-methyl-4,8-sphingadienine linked to a 2-hydroxyoctadec-3-enoic acid. Although the structures presently described are similar to those of monohexosylceramides from other fungi, including edible ones, this is the first report on their occurrence in species pathogenic in humans.

Cerebroside of the dimorphic human pathogen, Candida albicans

Structural studies on the cerebroside isolated from the yeast form of a dimorphic pathogen, Candida albicans were carried out using fast atom bombardment mass spectrometry (FAB/MS), proton magnetic resonance spectrometry, gas chromatography-mass spectrometry and usual chemical methods. The component sugar was only glucose attached to ceramide in a beta-configuration. The major fatty acid was 2-hydroxystearic acid (62%). The predominant long chain base was identified as 9-methyl-C18-sphinga-4,8-dienine which is widely distributed in fungi and reported to be essential to the fruit-inducing activity of fungi. Therefore, the structure of the main molecular species of the cerebroside was determined to be N-2-hydroxystearoyl-1-O-beta-glucosyl-9-methyl-C18-sphinga-4 ,8-dienine. Cerebroside prepared from the mycelial form of C. albicans has the same structure.

A new cerebroside from Fusicoccum amygdali Del

A homogeneous cerebroside was isolated from a strain of Fusicoccum amygdali Del., a fungus pathogenic to almond and peach. Chemical degradations, together with extensive application of nuclear magnetic resonance and mass spectrometry techniques, led to elucidation of its structure. This corresponds to N-2'-hydroxy-3'-trans-octadecenoyl-1-O-beta-D-glucosyl-9-methyl-cis-4,x-8-sphingadienine.