No abstract

It is known that lactoferrin is one of the functional proteins contained in mammalian milk and that it plays an important role in the immune system. In this study, we prepared multi-lamellar liposomal bovine lactoferrin composed of egg yolk phosphatidylcholine and phytosterol for oral delivery, and examined any resulting anti-inflammatory effects. Oral pretreatment of liposomal lactoferrin exhibited more suppressive effects than did nonliposomal lactoferrin on CCl 4 -induced hepatic injury in rats as well as on lipopolysaccharide-induced TNF-alpha production from mouse peripheral blood mononuclear leukocytes. Further investigation revealed that the liposomalization did not exert influence on the absorbability of lactoferrin to the venous blood or lymph following an intraduodenal administration in rats. Furthermore, there was no significant difference exhibited between the antigenicity of liposomal and non-liposomal lactoferrin, which was measured using the passive cutaneous anaphylaxis reaction following oral sensitization to them in guinea pigs. These results suggest that liposomal lactoferrin might act more effectively than conventional lactoferrin in the intestinal site, which is regarded as an active site of orally administered lactoferrin, although the biological mechanism is not fully understood yet. Consequently we propose that liposomal lactoferrin could be a novel active constituent useful for preventive and therapeutic treatment of inflammatory diseases.

To investigate chemopreventive effect of liposomal b b-sitosterol on tumor metastasis, we prepared liposomal b b-sitosterol composed of egg yolk phosphatidylcholine for oral delivery. Although orally administered b b-sitosterol (4 m mmol as b b-sitosterol/mouse) was not absorbed into plasma, the amount of immune response cytokines such as IL-12 and IL-18 was increased in the small intestine after the liposome intake. Moreover, after daily oral administration of the liposome for 7 d, natural killer (NK) cell activity in the mice was increased, suggesting that the immune surveillance activity of mice was enhanced by the liposomal b b-sitosterol intake. Thus, we examined metastatic potential of B16BL6 melanoma cells, which were intravenously injected into mice after sequential administration of liposomal b b-sitosterol for 7 d. The number of metastatic colonies in the lungs was significantly less than that of control group two weeks after the injections of the cells. These results suggest that daily liposomal b b-sitosterol intake prevents tumor metastasis may be due to enhancement of gut immune surveillance systems.

Hyperpigmentation on faces is a highly anxiety-producing symptom, especially for women from the aspect of beauty. We previously reported the skin whitening effect of linoleic acid (LA), 1,2) the mechanism of the whitening effect involving a decrease in tyrosinase level by LA, 3) and clinical trials of liposomal LA for skin hyperpigmentary disorders, such as melasma.4) Although these reports described the whitening effect of LA in transdermal application, and the stabilization of LA by liposomal formulation, it was not confirmed whether LA encapsulated in liposomes enhanced the skin whitening effect. There have been number of reports that describe transdermal application using liposomes on cutaneous absorption, 5-7) on the transdermal delivey of encapsulated drugs 8) and on effective interaction of dermal skin cells with liposomes containing drugs in liposomes.9-11) The synergistic effect of liposomes on active reagents for whitening via transdermal application was also reported.12) Compared to those reagents previously reported, LA is not only effective in whitening but also quite safe.13) Although there are many examples of the transdermal applications of liposomal formulations, little is known about the enhancement of drug efficacy by liposomalization. From this point of view, we were interested in the possible enhancement of LA's whitening activity by encapsulating it in liposomes. The present study clearly demonstrated that LA encapsulation in liposomes significantly enhanced it's whitening efficacy by transdermal application for UV-induced hyperpigmented dorsal skin of brownish guinea pigs. We also observed enhanced whitening efficacy by liposomalization of LA in UV-induced hyperpigmented human skin. MATERIALS AND METHODSWhitening Assay UVB-induced hyperpigmentation was elicited on the backs of brownish guinea pigs weighing about 600 g each (Saitama Experimental Animal Supply Co., Japan) using a modification of the method reported by Imokawa et al.14) Guinea pigs were gently tethered, and four separate areas (2.5 cmϫ2 cm) on the back of each animal were exposed to UVB radiation (ToRex FL20S-E-30/DMR, Toshiba, Japan) three times a week (every other day) for two consecutive weeks. The UVB intensity was 2 mW/cm 2 , and total energy dose was 1 J/cm 2 per exposure. Groups of six or more animals were used in each experiment. The animals were then left for an additional week to allow the UVBinduced hyperpigmentation to stabilize. Test samples were then topically applied daily to the hyperpigmented areas (0.01 ml/cm 2 ) five times per week for 3 successive weeks. The degree of pigmentation was assessed as the L-value measured with a chromameter (CR-200, Minolta, Japan) once every week from the beginning of sample application. The animals were cared for according to the guidelines for the Care and Use of Laboratory Animals of the University of Shizuoka.In the case of human skin assay, persons being tested were 6 healthy men in their 20 s or 30 s. After obtaining informed consents from the volunteers, UVB-induced hyp...