Norihito Maru

Pinnarine, another member of the halichlorine family. Isolation and preparation from pinnaic acid.

Pinnarine (1), a new macrocyclic alkaloid, was isolated from the black marine sponge Halichondria okadai. The structure was elucidated on the basis of 2D NMR and comparison with the spectra of the co-isolated known halichlorine. Further confirmation of the structure and the absolute configuration was validated by a synthetic method from authentic pinnaic acid and CD analysis. The isolation of pinnarine also suggested a biogenetic pathway from pinnaic acid to halichlorine.

Sunabedine, a novel toxic bromotyrosine-derivative alkaloid from Okinawan sponge, order Verongida

Sunabedine (1), a new bromotyrosine-derivative alkaloid, was isolated from the Okinawan sponge, order Verongida. The structure of 1 was determined by spectroscopic analyses. 1 showed the cytotoxicity against B16 mouse melanoma cells and toxicity against brine shrimp.

Recent insights into natural venoms

Toxic substances that occur in nature have various structures and functions. In fact, the very novelty of their structures and functions sometimes extends far beyond the realm of human imagination, and the capabilities of these compounds are still largely untapped despite the major advances of modern science. In this report we focus on the most recent developments in this field, with a particular emphasis on natural venoms, marine sunscreen, and marine huge molecules.

Melanin Biosynthesis Inhibitors from Tarragon Artemisia dracunculus

The EtOH extract of tarragon Artemisia dracunculus, a perennial herb in the family Asteraceae, was found to potently inhibit α-melanocyte-stimulating hormone (α-MSH) induced melanin production in B16 mouse melanoma cells. Bioassay-guided fractionation led to the isolation of two alkamide compounds, isobutyl (1) and piperidiyl (2) amides of undeca-2E,4E-dien-8,10-dynoic acid. The respective EC50 values for melanin biosynthesis inhibition were 1.8 and 2.3 μg/mL for 1 and 2.

Sea-Originated Cytotoxic Substances

Cancer accounted for huge number of deaths, which represents about 13% of all deaths worldwide, and the number of the deaths due to cancer is increasing. Natural products and their synthetic analogs are widely used as antitumor drugs. As represented by these drugs, many anticancer drugs originated from cytotoxic compounds. Marine natural products are a gold mine of strong bioactive compounds with unique structures created in evolution of organisms over hundred million years. However, in the field of drug discovery, most studies have focused on plant essences and bacterial metabolites, and candidate compounds from marine origin are still remaining relatively unexplored.