The antioxidative effects of methanol extracts of crude drugs were estimated by an electrochemical method because there are many electrochemically-active substances in natural antioxidants. Twelve kinds of crude drugs, which had been reported to exhibit strong activity in an antioxidative test based on the air oxidation of linoleic acid, were studied. The oxidative capacity calculated from voltammograms of their methanol extracts were compared and examined together with data on their radical scavenging effects. The results showed that the electrochemical behavior in most cases correlated with the radical scavenging effect. Crude drugs which had clear oxidative peaks below +1.2 V and a large oxidative capacity were suggested to have strong radical scavenging effects. It was clear that substances oxidized at lower potentials had stronger radical scavenging effects than those oxidized at higher potentials. Therefore, this electrochemical method can be considered as a rapid and simple method for estimating the antioxidative effects as a radical scavenger.

The present study was designed to examine the relationship between the gastroprotective efficacy of the locally acting antiulcer drug ecabet sodium (ecabet) against ethanol-induced gastric lesions and the amount of the drug bound to the mucosa in comparison with sucralfate in rats. Oral administration of ecabet (25-100 mg/kg) and sucralfate (25-400 mg/kg) dose dependently prevented the formation of ethanol-induced gastric lesions, and dose dependently increased the amount of each drug bound to the gastric mucosa. Pretreatment with the antisecretory agent cimetidine (200 mg/kg, per os) significantly reduced the gastroprotective effect of sucralfate in proportion to a decrease in its binding to the mucosa. The same pretreatment tended to reduce both gastroprotection by ecabet and its binding to the mucosa. In an in vitro study using an everted stomach sac, the binding of sucralfate to the mucosa was more markedly decreased than that of ecabet on increasing the pH. These findings indicate that ecabet and sucralfate protect the gastric mucosa against ethanol in proportion to the amount of each drug bound to the gastric mucosa and that the binding of these drugs to the mucosa is under the influence of intraluminal pH. However, the gastroprotective effect of ecabet seems to be less dependent on intraluminal acidity than that of sucralfate.

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We prepared ultrathin PFSA/PFSA-vinylon/PFSA laminated electrolyte membranes (thickness = 10 μm) for fuel cells without using a reinforcing material. Nafion and Aquivion solutions were used as PFSA polymers. Vinylon was synthesized by formalizing polyvinyl alcohol. From the current-voltage measurements using ultrathin PFSA/PFSA-vinylon/PFSA membranes; the cell resistances are significantly lower than that using a 50 μm Nafion membrane. A high current density was obtained under both low- and high-humidity conditions. Ultrathin PFSA/PFSA-vinylon/PFSA laminated membranes will help to further improve the performance of PEMFCs.

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