Microfouling inhibitors from the Indian gorgonian Subergorgia reticulata (Ellis and Solander, 1786)

Abstract

<span style="font-size:9.0pt;font-family: " times="" new="" roman";mso-fareast-font-family:calibri;mso-bidi-font-family:mangal;="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="" lang="EN-US">Antifouling research currently focuses on greener ways of biofouling control in view of the International Maritime Organisation (IMO) imposed regulations on toxic biocides. Microfouling, the initial phase of fouling, is an important target to prevent further macrofouling assemblage. In this perspective, the antimicrofouling potential of three calamenene derivatives (<span style="mso-bidi-font-weight:bold">2-methoxy calamenene, <b>1</b>; 2,5-dimethoxy calamenene, <b>2</b> and 2-methoxy, 5-acetoxy calamenene, <b style="mso-bidi-font-weight:normal">3</b> isolated from the<span style="mso-bidi-font-weight:bold"> Indian gorgonian <i style="mso-bidi-font-style: normal">Subergorgia reticulata</i> was investigated. <span style="color:black;mso-bidi-font-weight:bold"> These compounds inhibited growth of five fouling bacterial strains (<i style="mso-bidi-font-style:normal">Bacillus megaterium</i>, <i style="mso-bidi-font-style:normal">Vibrio furnissii</i>, <i style="mso-bidi-font-style:normal">V. fischeri</i>, <i style="mso-bidi-font-style: normal">V. gazogenes</i> and <i style="mso-bidi-font-style:normal">V. parahaemolyticus</i>) as well as the two species of diatoms (<i style="mso-bidi-font-style:normal">Amphora coffeaeformis</i> and <i style="mso-bidi-font-style:normal">Navicula transitans</i>). Of<span style="mso-bidi-font-weight:bold"> these, the highest activity was exhibited by compound <b>3</b> against <i style="mso-bidi-font-style:normal">B. megaterium</i> (MIC, 12.5µg) and <i style="mso-bidi-font-style:normal">N. transitans </i>(EC₅₀,14µg/ml). The environmental-compatibility of this compound was evidenced from the non-toxicity to <i style="mso-bidi-font-style:normal">B. amphitrite</i> nauplii (IC₅₀ 1µg/ml) and <i style="mso-bidi-font-style:normal">Artemia</i> sp. nauplii (IC₅₀ 0.6µg/ml). Analysis of structure-activity relationship suggested that the acetoxy group present in <b>3 </b>may be responsible for the<b> </b>comparatively<b> </b>high antifouling activity exhibited by this compound. </span></span></span></span></span>