Our laboratory conducts research in environmental
earth science using marine natural products chemistry and chemical ecology as
foundation.
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
section.
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
cyanobacteria
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).
We are also aiming to explore biosynthesis of structurally unique compounds
we isolated.
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.
