Intestinal absorption of dietary maize glucosylceramide in lymphatic duct cannulated rats

Abstract

mammalian sphingolipids is sphingosine ( trans -4-sphingenine, d18:1 4t ). Smaller amounts of other sphingoid bases, such as sphinganine (dihydrosphingosine, d18:0) and phytosphingosine (4-hydroxysphinganine, t18:0), are encountered frequently. In higher plants, the structures of sphingoid bases are more complicated than in mammals, because they can be desaturated at the C8-position by a ⌬ 8-sphingolipid desaturase, yielding cis -and trans -isomers of ⌬ 8-unsaturated sphingoid bases (d18:2 4t,8c(t) ) ( 3, 4 ). 9-Methyl-trans -4, trans -8-sphingadienine (d19:2 4t,8t ) is a typical structure found in yeasts ( 5 ). Sphingolipids of marine invertebrates have unique triene types of sphingoid bases with a conjugated diene such as 2-amino-4,8,10-octatriene-1, 3-diol (d18:3 4,8,10 ) and 2-amino-9-methyl-4,8,10-octatriene-1, 3-diol (d19:3 4,8,10 ) ( 6 ). Therefore, sphingolipids having various structures of sphingoid bases are ingested daily from foodstuffs ( 7-9 ).Dietary sphingolipids have gained attention for their potential to protect against infl ammation and cancers in the gut ( 10-13 ). One plausible mechanism for these effects may be via the hydrolysis of complex sphingolipids to bioactive ceramides and sphingosine, because those breakdown products are known to play important roles as intracellular mediators ( 14, 15 ). We previously demonstrated that dietary maize and yeast sphingolipids with sphingoid bases distinct from those of mammals are able to prevent the formation of aberrant crypt foci in 1,2-dimethylhydrazine-treated mice ( 16,17 ). We further showed that sphingoid bases prepared from various dietary sources can induce apoptosis in cancer cells (18)(19)(20).In early studies, Nilsson ( 21-23 ) investigated the digestion and intestinal absorption of sphingolipids containing sphingosine and sphinganine. Dietary sphingolipids can be hydrolyzed to their components, such as sphingoid bases, fatty acids, and the polar head group, by intestinal enzymes and are then taken up by mucosal cells ( 24,25 ). A large portion of sphingosine absorbed Sphingolipids are ubiquitous in all eukaryotic organisms and constitute a family of compounds that have a sphingoid base (long-chain base) with an amide-linked fatty acid and a polar head group. It is well known that there are diverse structures of sphingoid bases in nature ( Fig. 1 ) ( 1, 2 ). The most common sphingoid base of

Selective Absorption of Dietary Sphingoid Bases from the Intestine via Efflux by P-Glycoprotein in Rats

“…Glucosylceramides were prepared from maize by using a silica gel column after lipid extraction and saponification as described previously (17,18). Trans-4,cis-8-sphingadienine (d18:2 4t,8c ) was prepared from maize glucosylceramide after acid hydrolysis and was purified by using high-performance liquid chromatography (HPLC) as described previously (19).…”

“…We previously demon-strated that the digestibility of glucosylceramide derived from higher plants is similar to that of glucosylceramide derived from mammals, but the metabolic fate of plantderived sphingoid bases within enterocytes differs from that of sphingosine (17). A lipid absorption assay of lymph obtained from the thoracic duct revealed that the absorption rate of 4,8-sphingadienine from dietary plant-derived glucosylceramide in the intestine is lower than that of sphingosine (18). According to the results of a study of cultured cells, sphingoid bases, except for sphingosine, appear to be transported out of cells across the apical membranes of enterocytes by P-glycoprotein after absorption (19).…”

Inhibitory Effect of Topical Maize Glucosylceramide on Skin Photoaging in UVA-irradiated Hairless Mice

“…This indicates that a small amount of topical GluCer is enough to inhibit skin photoaging. In our previous study, maize GluCer was only slightly absorbed by the intestine in rats 8,9 . In light of this fi nding, we investigated whether the topical GluCer was absorbed into the skin of the mice in this study.…”

“…However, we have previously reported that dietary maize GluCer was only slightly absorbed by the rat intestine 8,9 . It appears that plant sphingolipids are barely re-utilized in skin, and the mechanism underlying the improving effect of dietary plant sphingolipids on skin barrier functions is still unclear.…”

Gromwell (Lithospermum erythrorhizon) Supplementation Enhances Epidermal Levels of Ceramides, Glucosylceramides, β-Glucocerebrosidase, and Acidic Sphingomyelinase in NC/Nga Mice

“…In fact, dietary GlcCer and SM improve clinical symptoms and epidermal barrier function of AD, 30,31 implying the direct reutilization of dietary GlcCer and SM for Cer generation in epidermis. However, with extremely low absorption of dietary GlcCer in the intestine, 32 the beneficial effects of dietary GlcCer and SM in AD skin is explained rather by the selective upregulation of Cer synthase 3 and 4 mRNAs. 30 On the other hand, ingested LE extracts decrease the serum levels of insulin and leptin, which indirectly mediate a decreased expression of lipogenic genes in the liver.…”