The Influence of Phlorotannins and Bromophenols on the Feeding Behavior of Marine Herbivorous Gastropod &amp;lt;i&amp;gt;Turbo cornutus&amp;lt;/i&amp;gt;

Toshiyuki Shibata,Reiji Tanaka,Hideo Miyake,Shigeo Kawaguchi,Taiko Miyasaki

doi:10.4236/ajps.2014.53051

Abstract

The influence of phlorotannins and bromophenols on the feeding behavior of marine herbivores was determined using bioassay of Turbo cornutus. It was found that phloroglucinol and its oligomers isolated from the brown alga Eisenia bicyclis (eckol, fucofuroeckol A, phlorofucofuroeckol A, dieckol, and 8,8’-bieckol) had a deterrent effect against feeding behavior of T. cornutus in the concentration of algal body, respectively. In the case of the examination of 0.1 mM concentration, although fucofuroeckol A and phlorofucofuroeckol A significantly reduced feeding by T. cornutus, phloroglucinol and 8,8’-bieckol did not show any significant influence on feeding behavior, and eckol and dieckol had stimulating activity. 2,4-Dibromophenol and 2,4,6-tribromophenol, which are major components of extracellular secretions from Eisenia and Ecklonia species, caused the death, the torpidity, and the decreased appetite of T. cornutus at the concentration of 0.1 mM. In addition, 2,4-dibromophenol had strong feeding deterrent activity at the concentration of 1 μM. These results indicate that phlorotannins and bromophenols act as chemical defense agents of brown algae against environmental stresses such as the herbivore attack.

Highlights

Phlorotannins of marine algal polyphenols, which have been found exclusively in brown algae, are formed by the polymerization of phloroglucinol (1,3,5-trihydroxybenzene) [1,2]
It is shown that the crude extracts from the brown algae including phlorotannins have a feeding deterrent activity against marine herbivores in the past reports [1,3,5,6]
The aim of this study was mainly to clarify the relationship between the chemical structures of phlorotannins and their influence on the feeding of marine herbivores

Summary

Introduction

Phlorotannins of marine algal polyphenols, which have been found exclusively in brown algae, are formed by the polymerization of phloroglucinol (1,3,5-trihydroxybenzene) [1,2]. Most of the reports on the defensive function of phlorotannins present no findings regarding a “relationship between chemical structures of the compounds and biological activities”, “correlation of the activities and concentration of phlorotannins” and “evaluation of the activities based on actual concentration of the compounds in the algal body”. We isolated the phlorotannins, these being eckol (a phloroglucinol trimer), fucofuroeckol A (a tetramer), phlorofucofuroeckol A (a pentamer), dieckol and 8,8’-bieckol (hexamers) from Japanese Eisenia and Ecklonia species and reported their chemical and local distribution in the algae [8].

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Results