Tomono Uchida

Complexation of Tocotrienol with γ-Cyclodextrin Enhances Intestinal Absorption of Tocotrienol in Rats

To determine the bioavailability of tocotrienol complex with γ-cyclodextrin, the effects of tocotrienol/γ-cyclodextrin complex on tocotrienol concentration in rat plasma and tissues were studied. Rats were administered by oral gavage an emulsion containing tocotrienol, tocotrienol with γ-cyclodextrin, or tocotrienol/γ-cyclodextrin complex. At 3 h after administration, the plasma γ-tocotrienol concentration of the rats administered tocotrienol/γ-cyclodextrin complex was higher than that of the rats administered tocotrienol and γ-cyclodextrin. In order to determine the effect of complexation on tocotrienol absorption, rats were injected with Triton WR1339, which prevents the catabolism of triacylglycerol-rich lipoprotein by lipoprotein lipase, and then administered by oral gavage an emulsion containing tocotrienol, tocotrienol with γ-cyclodextrin, or tocotrienol/γ-cyclodextrin complex. The plasma γ-tocotrienol concentration of the Triton-treated rats administered tocotrienol/γ-cyclodextrin complex was higher than that of the other Triton-treated rats. These results suggest that complexation of tocotrienol with γ-cyclodextrin elevates plasma and tissue tocotrienol concentrations by enhancing intestinal absorption.

Dietary Sesame Seed and Its Lignan, Sesamin, Increase Tocopherol and Phylloquinone Concentrations in Male Rats

We have shown that intake of sesame seed and its lignan increases vitamin E concentrations and decreases urinary excretion levels of vitamin E metabolites in male Wistar rats, suggesting inhibition of vitamin E catabolism by sesame lignan. The aim of this study was to examine whether dietary sesame seed also increased vitamin K concentrations, because its metabolic pathway is similar to that of vitamin E. To test the effect of sesame lignan on vitamin K concentrations, male Wistar rats were fed a control diet or a diet with 0.2% sesamin (a sesame lignan) for 7 d in experiment 1. Liver phylloquinone (PK), menaquinone-4 (MK-4), and γ-tocopherol were greater in rats fed sesamin than in control rats. To test the effect of sesame seed on vitamin K concentrations, male Wistar rats were fed a control diet or a diet with 1, 5, or 10% sesame seed for 3 d in experiment 2. Liver and kidney PK and γ-tocopherol but not MK-4 were greater in rats fed sesame seed than in control rats, although differences in dietary amounts of sesame seed did not affect the PK concentrations. For further confirmation of the effect of sesame seed, male Wistar rats were fed a control diet or a diet with 20% sesame seed for 40 d in experiment 3. Kidney, heart, lung, testis, and brain PK and brain MK-4 were greater in rats fed sesame seed than in control rats. The present study revealed for the first time, to our knowledge, that dietary sesame seed and sesame lignan increase not only vitamin E but also vitamin K concentrations in rat tissues.

Excess α-tocopherol decreases extrahepatic phylloquinone in phylloquinone-fed rats but not menaquinone-4 in menaquinone-4-fed rats

SCOPE The effects of vitamin E on vitamin K metabolism were elucidated by comparing the effect of tocopherol intake on vitamin K concentrations in rats fed phylloquinone (PK) or menaquinone (MK)-4. METHODS AND RESULTS Initially, the dietary effect of RRR-α-tocopherol, but not RRR-γ-tocopherol, in decreasing extrahepatic PK concentrations was confirmed. Subsequently, rats were fed a PK or MK-4-containing diet (0.75 mg/kg) with RRR-α-tocopherol (0, 10, 50, or 500 mg/kg) for 6 weeks. In rats fed PK, α-tocopherol consumption decreased PK in kidney, lung, heart, muscle, testis, and brain but not in serum and liver. However, in rats fed MK-4, α-tocopherol consumption did not decrease MK-4 in serum and tissues. Finally, vitamin K- and E-depleted rats were administered PK or MK-4 (0.2 mg) with RRR-α-tocopherol (0, 1, or 10 mg) by gavage. After PK administration, α-tocopherol was observed to decrease PK in kidney, adrenal gland, lung, testis, and brain but not in serum and liver, whereas, after MK-4 administration, α-tocopherol did not affect MK-4 in serum and tissues. CONCLUSION Excess α-tocopherol decreased extrahepatic PK in rats fed PK but not MK-4 in rats fed MK-4.