Two novel phlorotannins with a molecular weight of 974, temporarily named 974-A and 974-B, were isolated from the polyphenol powder prepared from the edible marine brown alga Ecklonia kurome Okamura, and their chemical structures were determined by spectroscopic method. The isolated yield of the total of 974-A and 974-B was approximately 4% (w/w) from the polyphenol powder. In 974-A, the carbon at the C2′ position in the A ring of phlorofucofuroeckol-A forms a C–C bond with the carbon at the C2″ position of the C ring of triphloretol-B, while in 974-B, phlorofucofuroeckol-B and triphloretol-B form a C–C bond in the same manner as in 974-A. These structures were supported by high resolution-MS/MS data. To evaluate the antioxidant activities, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay and intracellular radical scavenging assay, using 2′,7′-dichlorofluorescin diacetate (DCFH-DA), were performed for 974-A, 974-B, and four known phlorotannins. The results of the DPPH assay showed that the IC50 values of 974-A, 974-B, phlorofucofuroeckol-A, and dieckol were significantly smaller than those of phlorofucofuroeckol-B, phloroglucinol, α-tocopherol, and ascorbic acid. Furthermore, the DCFH-DA assay suggested that 974-A, 974-B, and dieckol reduce intracellular reactive oxygen species most strongly among the tested compounds.

A new type of micro swimming mechanism is examined for the development of medical microrobots working in human blood vessels. The magnetic micro swimming mechanism without the wire for supplying the energy is driven by the alternating magnetic field. The magnetic swimming mechanism is examined in a transparent polyvinylchloride pipe filled with a viscous liquid. The test fluid used in the experiment is glycerin. The Helmholtz coil and a bipolar power supply are used to apply the alternating magnetic field in the experiment. Locomotive characteristics of the swimming mechanism in a viscous liquid are analyzed by a high-speed video camera system. The dynamic behavior of a micro swimming robot in a viscous liquid is revealed.

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