Koji Nakanishi major works Isolation, structural, bioorganic studies bioactive compounds

Koji Nakanishi – pioneer in natural products chemistry

Category : Personalities
Published by : Data Research Analyst, Worldofchemicals.com

Biography & Contributions

Koji Nakanishi is a bioorganic and natural products chemist born on May 11, 1925. He was described as one who has "transformed the field of natural products chemistry."

Koji Nakanishi has determined the structures of over 200 biologically active animal and plant natural products, many of which are endogenous and/or the first member of a new class. These include ginkgolides from the ancient ginkgo tree, first insect molting hormones from plants, new nucleic acid bases, insect antifeedants, antibiotics, first meiosis inducing substance from starfish, crustacean molt inhibitors, shark repellents from fish, tunicate blood pigments, brevetoxins from red-tide dinoflagellates, philanthotoxin (glutamate and nicotinic acetylcholine receptor antagonist) from a wasp, and the human eye pigment involved in macular degeneration.

His studies with retinal analogs and retinal proteins have made seminal contributions in understanding the structural and mechanistic basis of animal vision and phototaxis. His research group succeeded in clarifying relative movements of the retinal and the opsin receptor throughout the visual transduction process; this is the first such study performed with G protein coupled receptors (GPCR) and will contribute in clarifying the mode of action of numerous other GPCRs. It also established the structure and biosynthesis of the fluorescent pigment A2E that leads to the incurable eye disease age-related macular degeneration (AMD) and its involvement in apoptosis.

His spectroscopic contributions include the first applications of the NMR nuclear Overhauser effect in structure determination during the ginkgolide studies (1967), and in particular development of the exciton coupled circular dichroic method (1969), a non-empirical sub-microgram scale technique for determining various aspects of molecular chirality of organic molecules in solution, an extremely versatile technique applicable to compounds ranging from small molecules to various types of ligand / receptor complexes.

Awards

Koji Nakanishi was the winner of many notable awards in his research career like King Faisal International Prize in Science, the Welch Award, the Arthur C. Cope Award, the Imperial Prize of the Japan Academy, the National Academy of Sciences Award in Chemical Sciences, and the Japan Academy Prize, as well as honorary doctorates from Williams College, Georgetown University and the University of Uppsala.

Brevetoxin

Brevetoxin are a suite of cyclic polyether compounds produced naturally by a species of dinoflagellate known as Karenia brevis. Brevetoxins are neurotoxins that bind to voltage-gated sodium channels in nerve cells, leading to disruption of normal neurological processes and causing the illness clinically described as neurotoxic shellfish poisoning. Brevetoxins share the common backbone structure of polyketides, but there are several methyl and oxygen groups that are not typical of a traditional polyketide synthesis.

Some selected examples of such natural products from Nakanishi research work includes

Pristimerin - a widely used ethnobotanical antibiotic

Ginkgolides - a potent inhibitor of platelet activating factor

Illudin S (Lampterol) - a cytotoxic principle in the bioluminescent mushrooms

Antheridiogen - an antheridia-inducing factor of a fern

Ponasterones and phytoecdysteroids, insect/crustacean molting hormones

Taxinine - possesses the skeleton of taxol, the clinically important anticancer drug

Chromomycins - a once clinically used anticancer agent

Cervicarcin - an antitumor antibiotic

Fluorescent tricyclic tRNA base, next to the anticodon (micro scale structure determination with about 300 mg)

Natural (+) abscisic acid - an important plant growth regulator

the potent carcinogens Benzo[a]pyrene and 7,12- Dimethylbenz[a]anthracene 5,6-Oxide adducts with nucleic acids

Brevetoxin B - a red-tide toxin

Periplanone-B - a sex pheromone of the American cockroach

Ipomeamarone, one of the first  phytoalexins

Elusive mitomycin C/DNA adduct

Lienomycin – It is one of the earliest absolute stereochemical analysis of polyene macrolide

Andrimid - the first intracellular bacterial symbion to be studied it exhibits specific antipathogenic activity

Philanthotoxin – a potent noncompetitive inhibitor of glutamate (Glu-R) and nicotinic acetylcholine receptors (nACh-R)

Hydroazulenoid Diterpenes and Sesquiterpenes from a marine alga

Retro-Retinol - new endogenous mammalian B-cell, T-cell growth factor

Precocious sexual inducer (psi Factor) of fungi

Amphikuemin, the first symbiosis-inducing substance to be identified from a marine source Nemadectins a and a2, macrocyclic lactones with potent antiparasitic activity

Malonofungin - an antifungal aminomalonic acid metabolite

4-Hydroxyretinals - visual pigment chromophores in bioluminescent squid

Diepoxins – these are novel metabolites with antifungal and antibacterial activity.

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