To enhance the curcumin absorption by oral administration, liposome-encapsulated curcumin (LEC) was prepared from commercially available lecithins (SLP-WHITE and SLP-PC70) and examined for its interfacial and biochemical properties. A LEC prepared from 5 wt % of SLP-PC70 and 2.5 wt % of curcumin gave a good dispersibility with 68.0% encapsulation efficiency for curcumin, while those from SLP-WHITE did not. Moreover, the resulting LEC using SLP-PC70 was confirmed to be composed of small unilamellar vesicles with a diameter of approximately 263 nm. The resulting LEC was then examined for its effect on bioavailability in Sprague-Dawley (SD) rats. Three forms of curcumin [curcumin, a mixture of curcumin and SLP-PC70 (lecithin), and LEC] were then administered orally to SD rats at a dose of 100 mg curcumin/kg body weight. The pharmacokinetic parameters following curcumin administration were determined in each form. Pharmacokinetic parameters after oral administration of LEC were compared to those of curcumin and a mixture of curcumin and lecithin. High bioavailability of curcumin was evident in the case of oral LEC; a faster rate and better absorption of curcumin were observed as compared to the other forms. Oral LEC gave higher C(max) and shorter T(max) values, as well as a higher value for the area under the blood concentration-time curve, at all time points. These results indicated that curcumin enhanced the gastrointestinal absorption by liposomes encapsulation. Interestingly, the plasma antioxidant activity following oral LEC was significantly higher than that of the other treatments. In addition, the plasma curcumin concentration was significantly correlated to plasma antioxidant activities, and enhanced curcumin plasma concentrations might exert a stronger influence on food functionality of curcumin. The available information strongly suggests that liposome encapsulation of ingredients such as curcumin may be used as a novel nutrient delivery system.
: Koikuchi and tamari shoyu are 2 types of traditional Japanese soy sauce whose low‐molecular‐weight fractions (less than 500 Da) are known to have the most intense umami taste. Given that peptides were also abundant in some umami fractions of both shoyu, further investigation was conducted to evaluate the precise contribution of peptides to the soy sauce tastes. To locate and isolate peptide fractions, separation procedures using Sephadex G‐25 SF, Sephadex G‐10, and reversed‐phase high‐performance liquid chromatography (RP‐HPLC) linked to sensory evaluation (by taste dilution analysis), as well as amino acid analysis were performed. Peptides having glutamyl residue were present in most peptide fractions. However, they all revealed negligible contributions to the intense umami taste of the soy sauces. On the other hand, free Glu, in the presence of sodium salt, as well as free Asp and several sweet‐taste eliciting free amino acids were considered to be the main contributors to the umami taste of the soy sauces. This study of Japanese soy sauces gives a clear explanation of the frequently questioned peptide contribution to the taste of savory food product.
Nine compounds, 3-hydroxy-4,5-dimethoxyphenyl-b- (8), and 3-hydroxy-1-(4-hydroxy-3,5-dimethoxyphenyl)-2-[4-(3-hydroxy-1-( E )-propenyl)-2,6-dimethoxyphenoxy]propyl-b-D-glucopyranoside (9), were isolated from Kokuto noncentrifuged cane sugar. Their structures were elucidated by spectroscopic evidence, mainly based on the NMR technique. Among them, seven new glycosides were identiˆed. The 2-deoxyribose oxidation method was used to measure their antioxidative activity. All of these compounds showed antioxidative activities.
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