5,5′-Ethylenebis(octaethylporphyrin) 1 and its metallocomplexes with various combination of metals (Zn, Cu, and Ni) 2—10 were prepared. On the basis of 1H and 13C NMR as well as MCD spectra, it was concluded that interactions between the two intramolecular porphyrins become attractive when at least one of the two rings is converted to zinc porphyrin. The phenomenon was explained by dipole–dipole interaction arising from the large polarization in Zn complexes.

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Neoculin occurring in an edible tropical fruit is a heterodimeric protein which has both sweetness and a taste-modifying activity that converts sourness to sweetness. Both the primary and the overall tertiary structures of neoculin resemble those of monocot mannose-binding lectins. This study investigated differences in biochemical properties between neoculin and the lectins. Structural comparison between the mannose-binding sites of lectins and the corresponding regions of neoculin showed that there is at least one amino acid substitution at each site in neoculin, suggesting a reason for the lack of its mannose-binding ability. This was consistent with hemagglutination assay data demonstrating that neoculin had no detectable agglutinin activity. DNA microarray analysis indicated that neoculin had no significant influence on gene expression in Caco-2 cell, whereas kidney bean lectin (Phaseolus vulgaris agglutinin) greatly influenced various gene expressions. These data strongly suggest that neoculin has no lectin-like properties, encouraging its practical use in the food industry.

The shapes of flowers and the cross-compatibility of Curculigo latifolia, which produces a taste-modifying protein, neoculin, were investigated for the purpose of setting fruits in Japan as a resource of neoculin. C. latifolia is an andromonoecious plant, that is, flowers in a lower position in an inflorescence are hermaphrodite with long styles, although flowers in higher positions are staminate with short styles. This shows that 22% of all flowers were hermaphroditic in an inflorescence. By the hand-pollination study, the largest rate of setting C. latifolia fruits was shown by the 5th day from the first flowering. The rates of fruit set were gradually reduced after that day. The number of fruits peaked by the 13th day from first flowering. On the other hand, the rate of fruit setting was shown to be 45% by cross-pollination and 4% by self-pollination. These results indicate that C. latifolia has selfincompatibility. To improve the rate of fruit setting of C. latifolia, it is necessary to pollinate compatible pollen by around the 15th day after the first flowering.