Defatted rice bran was treated with water, 50% (v/v) ethanol, ethanol, 50% (v/v) acetone, or acetone. The treatment temperature and time were fixed at 230°C and 5 min, respectively. The treatment with 50% (v/v) acetone produced the highest yield of 0.549 g-extract/g-bran, and the extract exhibited the highest DPPH radical scavenging activity of 0.495 mmol-ascorbic acid/g-extract. The extract obtained with 50% (v/v) acetone showed the higher UV absorbance and highest amount of hydrophobic substances in the HPLC analysis than the other extracts, and it also showed the highest antioxidative ability in both the rancidity test at 105°C and bulk oil system at 60°C for the longest induction period of 4.9 h and 14.4 h, respectively. However, the extracts obtained using various extractants showed no effect on the oxidation rate constant of linoleic acid in the bulk oil system.

View full abstract

Although many active ingredients are used in cosmetic products for moisturizing and whitening the skin, they are often electrolytes, and the stabilities of oil in water (O/W) type emulsion formulae containing electrolytes are generally difficult to control. To solve this problem, formulae containing an α-crystalline phase (α-gel) consisting of water, higher alcohols, and anionic surfactants such as sodium N-stearoyl-N-methyl-taurate (SMT) have been developed. However, in spite of their excellent salt tolerance, these formulae have poor viscosity stability under non-electrolyte conditions, and the viscosity decreases over time. To obtain adequate viscosity stability, the required electrolyte concentration is approximately 1wt%, which is somewhat high for cosmetic applications. To replace the salts, distearyl dimethyl ammonium chloride (DSAC), a cationic surfactant, with an opposite electric charge to SMT, was used in O/W emulsion formulae, resulting in improved viscosity stability at a lower concentration than that of salts. The stabilization mechanism with DSAC was found to be different from that of salts.

View full abstract

Hybrid surfactants were generated through the simple mixing of fluorocarbon and hydrocarbon gemini surfactants in aqueous solutions at 25°C. Disulfide exchange between the disulfide in the spacer chain occurred in the mixed micelles. However, the generation of hybrid gemini surfactants was particularly inhibited by the addition of salt. The suppression of the electrostatic repulsion between the hydrophilic headgroups led to the close packing of the hydrophobic chains in the micelles, resulting in the increased immiscibility of the fluorocarbon and hydrocarbon surfactants. On the other hand, when fluorocarbon–fluorocarbon or hydrocarbon–hydrocarbon surfactants were mixed, equilibrium with a 1:2 ratio of symmetric and dissymmetric gemini surfactants was attained after incubation for 24 h.

View full abstract

Active oxygen has been implicated in the pathogenesis of Parkinson’s disease (PD); therefore, antioxidants have attracted attention as a potential way to prevent this disease. Squalene, a natural triterpene and an intermediate in the biosynthesis of cholesterol, is known to have active oxygen scavenging activities. Squalane, synthesized by complete hydrogenation of squalene, does not have active oxygen scavenging activities. We examined the effects of oral administration of squalene or squalane on a PD mouse model, which was developed by intracerebroventricular injection of 6-hydroxydopamine (6-OHDA). Squalene administration 7 days before and 7 days after one 6-OHDA injection prevented a reduction in striatal dopamine (DA) levels, while the same administration of squalane enhanced the levels. Neither squalene nor squalane administration for 7 days changed the levels of catalase, glutathione peroxidase, or superoxide dismutase activities in the striatum. Squalane increased thiobarbituric acid reactive substances, a marker of lipid peroxidation, in the striatum. Both squalane and squalene increased the ratio of linoleic acid/linolenic acid in the striatum. These results suggest that the administration of squalene or squalane induces similar changes in the composition of fatty acids and has no effect on the activities of active oxygen scavenging enzymes in the striatum. However, squalane increases oxidative damage in the striatum and exacerbates the toxicity of 6-OHDA, while squalene prevents it. The effects of squalene or squalane treatment in this model suggest their possible uses and risks in the treatment of PD.

View full abstract

The reaction of vinyl ethers with carboxylic acids using iodine as a catalyst under solvent-free conditions was investigated. The reaction of saturated carboxylic acids with vinyl ethers gave the corresponding esters. Mechanistic studies revealed the production of the adduct of the vinyl ether with the carboxylic acid, which then rearranged to form the ester. At low temperatures, the reaction of 2-(1-hydroxycyclohexyl)acetic acid (1) and butyl vinyl ether yielded a butyl ester. However, at a reaction temperature of 80°C, both the esterification and the elimination of a water molecule occurred, yielding the unsaturated butyl ester butyl 2-cyclohexenylacetate. The reaction of 2-((1S,2S,4R)-2-hydroxy-1,7,7-trimethylbicyclo[2.2.1]heptan-2-yl)acetic acid (12) with butyl vinyl ether at low temperatures resulted in a mixture of four compounds. However, similar to the high-temperature (>60°C) reaction of 1, the esterification was accompanied by the elimination of a water molecule to give the unsaturated butyl ester (E)-butyl 2-((1S,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene)acetate. While a γ-hydrogen was abstracted to form the endo-type double bond in the reaction of 1, an α-hydrogen was abstracted to form the exo-type double bond in the reaction of 12.

View full abstract

Rapid synthesis of Gemini surfactants (C₁₂-C₂-C₁₂ and C₁₄-C₆-C₁₄) by microwave heating is investigated. The yield of the synthesis of C₁₂-C₂-C₁₂ surfactant using 2.45-GHz microwaves was twice the yield obtained by the oil bath method. Moreover, the value of dielectric loss and microwave penetration depth for the sample solution suggest that the microwave frequency of 915 MHz (0.915 GHz) is preferable over the conventional frequency (2.45 GHz). A novel 915-MHz microwave organic synthesis apparatus with a closed reactor is proposed. The synthesis yields of C₁₂-C₂-C₁₂ obtained using the 915-MHz equipment were three to four times higher than those obtained using the conventional heating method.

View full abstract

Physical properties (chemical adsorption rate, viscoelasticity, thickness, and conformation) for self-assembled monolayers (SAMs) of mercapto oligo (ethylene oxide) methyl ethers on gold were determined by quartz crystal microbalance (QCM). The values of thickness, shear viscosity and elastic shear modulus of SAMs increase with unit number of oligo (ethylene oxide) segment. However, the chemical adsorption rate determined by a Langmuir isotherm does not show such a unit number regularity. Those results suggest that difference in unit number of oligo (ethylene oxide) segment can significantly affects physical properties of SAMs.

View full abstract

The essential oils from aerial parts of Scutellaria laeteviolacea was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The characteristic odor components were also detected in the oil using gas chromatography-olfactometry (GC-O) analysis and aroma extraction dilution analysis (AEDA). As a result, 100 components (accounting for 99.11 %) of S. laeteviolacea, were identified. The major components of S. laeteviolacea oil were found to be 1-octen-3-ol (27.72 %), germacrene D (21.67 %),and β-caryophyllene (9.18 %). The GC-O and AEDA results showed that 1-octen-3-ol, germacrene D, germacrene B, and β-caryophyllene were the most characteristic odor components of the oil. These compounds are thought to contribute to the unique flavor of this plant.

View full abstract