Sphingomyelin-based liposomes were prepared and applied to the stratum corneum side or basal layer side of a three-dimensional (3D) cultured human skin model, and the increase in the type II ceramide (ceramide II) content of the cultured skin model was evaluated. The sphingomyelin-based liposomes were prepared by a high-pressure emulsification method, and the obtained liposomes were characterized; the particle diameter and zeta potential of the liposomes were 155.3 nm and -11.4 mV, respectively. Their spherical shape and lamella structure were observed by transmission electron microscopy. The sphingomyelin-based liposomes or saline were applied to the cultured skin model, and ceramide II was extracted from the skin model. The extracted ceramide II was separated by high-performance thin-layer chromatography and quantified by a densitometer. The amount of ceramide II in the cultured skin model was significantly increased by the application of the sphingomyelin-based liposomes, compared with the nonapplication group. Thus, sphingomyelin-based liposomes are useful for enriching the ceramide level in 3D cultured skin models.

Both soy isoflavone and n-3 polyunsaturated fatty acids are known to reduce the levels of bone-resorbing cytokines; however, the synergistic effects of these food ingredients have not been examined yet. This study was performed to elucidate the effect of concomitant intake of soy isoflavone and fish oil on bone mass in ovariectomized mice. Eight-week-old ddY female mice were subjected to ovariectomy (OVX) or sham surgery, and then fed an AIN-93G with safflower oil (So) as a control lipid source, isoflavone-supplemented safflower oil (So + I), fish oil instead of safflower oil (Fo) or isoflavone-supplemented fish oil (Fo + I) for 4 weeks. Femoral bone mineral density was significantly decreased by OVX; however, this decrease was inhibited by the intake of isoflavone and/or fish oil. Histomorphometric analyses showed that bone volume and trabecular thickness in the distal femoral trabecular bone were significantly lower in the So group than in the sham group, but those were restored in the Fo + I groups. The number of osteoclasts was significantly decreased by isoflavone intake. The increased rate of bone resorption after OVX was inhibited by isoflavone and/or fish oil. The serum concentration of tumor necrosis factor alpha was increased after OVX, but was significantly lower with the combination of isoflavone with fish oil than isoflavone or fish oil alone. The results of this study indicated that the intakes of soy isoflavone and/or fish oil might have ameliorating effects on bone loss due to OVX. Further, the concomitant intake of soy isoflavone and fish oil at a low dose showed better effects on cytokines related with bone resorption.

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