Two New Halogenated Compounds from the Marine Red Alga Laurencia nipponica Yamada from the Kunashiri and Etorofu Islands

Abstract

The red alga Laurencia nipponica comprises various chemical races distributed relative to the ocean current in Japanese coastal areas. We investigated the chemical compositions and chemical races of L. nipponica distributed from the Kunashiri and Etorofu Islands, the confluence of the Soya warm current and Oya‐shio cold current. Two new halogenated secondary metabolites, deacetylneonipponallene (1) and neopacifenol (2), along with four known compounds, deoxyprepacifenol (3), pacifenol (4), halo‐chamigrene diether (5), and isolaurallene (6) were isolated from L. nipponica collected at Chikappunai, Kunashiri Island, while Zaimokuiwa (Kunashiri Island) and Sana (Etorofu Island) populations contained 3, 7‐hydroxylaurene (7), 2,10‐dibromo‐3‐chloro‐9‐hydroxy‐α‐chamigrene (8), and (3Z)‐laurefucin (9). The structures of 1 and 2 were established using spectroscopic methods. The chemical races of L. nipponica distributed in this area were divided into 6‐ and 9‐producing races. Interestingly, both races contained 4 as an additional race‐index, as well as its derivatives, 2 and 5. To the best of our knowledge, this is the first example of a race comprising a mixture of two race‐index compounds, suggesting that the convergence of two currents causes the production of new and diverse chemical races in this species.

Diversity of Halogenated Secondary Metabolites in Okinawan Aplysia argus Including 12‐Hydroxypinnaterpene C and Their Feeding Targets

“…Some of the halogenated secondary metabolites produced by the red algae genus Laurencia are known to possess potent antimicrobial activities [27,28] . However, the compounds we isolated from L. nipponica did not show any antibacterial activity against the plant pathogen Ralstonia solanacearum MAFF730131 in our recent study [29] . Therefore, the discovery of antimicrobial compounds against R. solanacearum are believed to be important.…”

“…[27,28] However, the compounds we isolated from L. nipponica did not show any antibacterial activity against the plant pathogen Ralstonia solanacearum MAFF730131 in our recent study. [29] Therefore, the discovery of antimicrobial compounds against R. solanacearum are believed to be important. In this study, we investigated the antibacterial activities of these compounds against the plant pathogen R. solanacearum to obtain new finding.…”

Marine natural products

“…A Japanese Laurencia yielded two new C 15 acetogenins 936 and 937 , 391 while a Soliera was the source of new aromatic polyketide 938 . 392 An ethanolic extract of a Chinese L. tristicha was the source of 4-isopropylbenzaldehyde-containing products, presumably formed by condensation with acetophenone, as exemplified by 939 .…”

Antifouling Brominated Diterpenoids from Japanese Marine Red Alga Laurencia venusta Yamada

“…Laurencia-derived C 15 acetogenins differ substantially from land plant acetogenins by having enyne or bromoallene end groups, which generally contain the halogen atoms. [12][13][14] Biofouling is a major cause of increased ship fuel consumption and facilitates the spread of invasive marine organisms. Several natural antifouling products have recently been reported, some of which have potent antifouling activity, [15] and identifying the molecular mechanisms of antifouling compounds has increased their industrial importance.…”

“…Acetogenins are secondary metabolites derived from the polyketide pathway and are chemotaxonomic markers for the red algae genus Laurencia. Laurencia ‐derived C 15 acetogenins differ substantially from land plant acetogenins by having enyne or bromoallene end groups, which generally contain the halogen atoms [12–14] …”