Our laboratory conducts research in environmental
earth science using marine natural products chemistry and chemical ecology as
Due to changes in the global environment, our
ecosystems are also changing significantly. Although this change can be attributed to
numerous factors, our laboratory focuses on investigating the
impact of various chemicals on the environment. With respect to the substances
associated with biological interactions among marine invertebrates, algae, and
microorganisms, we conduct research studies using natural product chemistry as
a starting point.
In addition, we also perform exploratory
research investigations on bioactive substances present in cyanobacteria and
marine organisms as part of the above-mentioned research.
For these research projects, we have been
aggressively developing organism- and cell-based assays as well as enzyme-based
biochemical tests to integrate these developments into chemical research.
We are expanding our research fields from the
isolation of bioactive substances, determination of their structures through
instrumental analysis, and evaluation of their bioactivities to biosynthesis
research at the gene level.
We are specifically working on the following research themes:
1. Seaweed-derived anti-fouling substances
To prevent the attachment of periphyton such
as barnacles, an anti-fouling paint is applied to the hull of ships. Commonly
used organotin compounds and some of the recently introduced alternative paints
are subject to regulation due to their
toxicity. In collaboration with the private sector, we are currently working on
the development and practical application of an anti-fouling substance derived
from a marine invertebrate as a lead compound. We are seeking novel
anti-fouling substances that are effective against seaweeds, cyanobacteria, and
the cypris-form larvae of striped barnacles. Regarding the anti-fouling
substances obtained, we are currently investigating the expression mechanisms underlying
the toxic activity of substances whose ecotoxicities are extremely low. Details
of our biosynthesis research using these substances are described in the next
2. Biosynthesis research on
halogen-containing compounds derived from seaweeds
As described in the previous section, the
anti-fouling substances obtained from seaweeds contain halogens such as bromine.
This property of producing halogen-containing compounds is a major characteristic
of marine organisms. Research has shown that some halogen-containing compounds
have anti-fouling activity, as well as antitumor effects that maybe used as
antitumor drugs. Therefore, to elucidate the biosynthesis mechanisms of
halogen-containing compounds, we conduct research studies focusing on
vanadium-dependent bromoperoxidase present in Laurencia (red alga).
3. Enzyme inhibitory substances produced by
We have previously shown that cyanobacteria
produce various peptides with enzyme inhibitory activity. Attempts to purify
these peptides have been difficult; however, we will continue to perform these
experiments because these compounds may be potentially used as pharmaceutical
drugs. We are also interested in the relationship between the ecology of water
blooms, which occur on a large-scale in eutrophic lakes, and the secondary
metabolites of cyanobacteria. We have recently been collecting marine
cyanobacteria overseas to isolate new bioactive substances. Our cyanobacterial
peptide research projects are mainly based on the use of liquid
chromatography–mass spectrometry (LC/MS) equipment such as micrOTOF and
Orbitrap (university equipment managed by us).
4. Chemical factors that determine the spawning environment of eels
We have recently reached a milestone in our
research on the spawning environment of the Japanese eel by identifying its
spawning area. As a next step, we will identify chemical factors that determine
the spawning environment of this organism.
5. Substances that induce transformation in echinoderms
We have been screening seaweeds and their
surrounding seawater for substances that induce the transformation of sea
urchins and sea cucumbers from larvae to young adults. In collaboration with
the National Center for Stock Enhancement, Japan, we have been conducting
experiments using echinoderm larvae. Our studies have shown that dopamine induces
the transformation of sea cucumbers, and we are currently investigating
dopamine receptors in these organisms.
is known to contain a large amount of chlorosulfolipids, which
are compounds that contain chloride and sulfate groups. Although stereochemical analysis has not been carried out on these compounds in the last 40 years, our successful isolation of
chlorosulfolipids has led to the identification of their steric configuration. Academic interest in chlorosulfolipids, including their synthesis, has rapidly grown in recent years. We are also conducting mass spectrometry (MS) analysis of these compounds.