Structure-cytotoxic activity relationship of sesquilignan, morinol A.

The cytotoxic activities of sesquilignans, (7S,8S,7'R,8'R)- and (7R,8R,7'S,8'S)-morinol A and (7S,8S,7'S,8'S)- and (7R,8R,7'R,8'R)-morinol B were compared, showing no significant difference between stereoisomers (IC50=24-35 µM). As a next stage, the effect of substituents at 7, 7', and 7"-aromatic ring on the activity was evaluated to find out the higher activity of (7S,8S,7'R,8'R)-7,7',7"-phenyl derivative 18 (IC50=6-7 µM). In the research on the structure-activity relationship of 7"-position of (7S,8S,7'R,8'R)-7,7',7"-phenyl derivative 18, the most potent compounds were 7,7',7"-phenyl derivative 18 (IC50=6 µM) against HeLa cells. Against HL-60 cells, 7"-(4-nitrophenyl)-7,7'-phenyl derivative 33 and 7"-hexyl-7,7'-phenyl derivative 37 (IC50=5 µM) showed highest activity. We discovered the compounds showed four to sevenfold potent activity than that of natural (7S,8S,7'R,8'R)-morinol A. It was also confirmed that the 7'-benzylic hydroxy group have an important role for exhibiting activity, on the other hand, the resonance system of cinnamyl structure is not crucial for the potent activity.

Heavy oil fraction induces the dysplastic sperm in male mouse.

Heavy oil is one of the most serious pollutants in marine ecosystem. The poisonous influences of the chemical substances contained in heavy oil on many kinds of marine organisms are widely studied. However, the influence of the chemical compounds in heavy oil on our health has not been cleared yet. In order to reveal the poisonous influences of these chemical compounds on mammalian reproductive system, water-soluble fraction (WSF) extracted from heavy oil was administrated to mice for 2 weeks. WSF-administrated mice were crossed with either WSF- or distilled water-administrated group for mating experiment. When WSF-administrated male mice were used as a father, it reduced not only mating ratio, but also neonatal male ratio. The numbers of sperms of WSF-administrated male mice were decreased. In addition, abnormality of sperms such as bent or twisted tail was increased approximately 6-fold by WSF intake. The level of testosterone in serum from WSF-administrated mice was lower than that from control mice. Testosterone is the most important for the spermatogenesis in vertebrate. It is supposed from these findings, the decrease in the number of sperms may relate with the reduction of sex hormone level in serum. It is suggested from these results that the chemical substances in WSF affected the sperm function in reproductive system of male mice.

Mode of action of the immunostimulatory effect of collagen from jellyfish.

We have previously demonstrated that collagen from jellyfish simulated immunoglobulin and cytokine production by human-human hybridoma line HB4C5 cells and by human peripheral blood lymphocytes (hPBL). The mode of action of the collagen as an immunostimulatory factor was investigated. The expression levels of immunoglobulin mRNAs in HB4C5 cells, and those of tumor necrosis factor (TNF)-alpha, interferon (IFN)-gamma, and transforming growth factor (TGF)-beta in hPBL were up-regulated by jellyfish collagen. In addition, this collagen activated IgM production by transcription-suppressed HB4C5 cells that had been treated with actinomycin D. This collagen also enhanced IgM production by translation-suppressed HB4C5 cells that had been treated with sodium fluoride, but was ineffective in accelerating IgM production by HB4C5 cells treated with cycloheximide. Moreover, the intracellular IgM level in HB4C5 cells treated with the post-translation inhibitor, monensin, was increased by this collagen. These results suggest that collagen from jellyfish stimulated not only the transcription activity, but also the translation activity for enhanced immunoglobulin and cytokine production.

Determination of the stereochemistry of the tetrahydropyran sesquineolignans morinols A and B.

The 7',8'-stereochemistry of the tetrahydropyran sesquineolignans morinols A and B was determined as threo via synthetic studies and by comparison of NMR data of 7',8'-threo-morinol and 7',8'-erythro-morinol. This study also confirmed that the biosynthetic process produces enantiomeric mixtures of morinols A and B. This was ascertained by comparing the specific rotations of synthesized morinols A and B with those of naturally occurring morinols A and B.

Immunostimulation effect of jellyfish collagen.

Certain edible large jellyfishes belonging to the order Rhizostomeae are consumed in large quantities in China and Japan. The exumbrella part of the edible jellyfish Stomolophus nomurai was cut and soaked in dilute hydrochloric acid solution (pH 3.0) for 12 h, and heated at 121 degrees C for 20 min. The immunostimulation effects of the jellyfish extract were examined. The jellyfish extract enhanced IgM production of human hybridoma HB4C5 cells 34-fold. IgM and IgG production of human peripheral blood lymphocytes (PBL) were also accelerated, 2.8- and 1.4-fold respectively. Moreover, production of interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha by human PBL was stimulated 100- and 17-fold respectively. Collagenase treatment inactivated the immunostimulation activity of the jellyfish extract. In addition, purified collagen from bovine Achilles' tendon accelerated IgM production of hybridoma cells. These facts mean that collagen has an immunostimulation effect, and that the active substance in jellyfish extract is collagen.

A novel way to express proline-selectively labeled proteins with a wheat germ cell-free protein synthesis system.

For high-throughput protein structural analyses, it is essential to develop a reliable protein overexpression system. Although many protein overexpression systems, such as ones involving Escherichia coli cells, have been developed, the number of overexpressed proteins exhibiting the same biological activities as those of the native ones is limited. A novel wheat germ cell-free protein synthesis system was developed recently, and most of the synthesized proteins that should function in solution were found to be in soluble forms. This suggests the applicability of this protein synthesis method to determination of the functional structures of soluble proteins. In our previous work, we developed a selective labeling technique for amino acids having amide functional groups (other than proline residues) involving the use of several inhibitors for transaminases. This paper in turn describes a proline-selective labeling technique. Based on our results, we have succeeded in constructing a complete amino acid selective labeling technique for the wheat germ cell-free protein synthesis system.