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

Abstract

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 (2-methoxy calamenene, 1; 2,5-dimethoxy calamenene, 2 and 2-methoxy, 5-acetoxy calamenene, 3 isolated from the Indian gorgonian Subergorgia reticulata was investigated These compounds inhibited growth of five fouling bacterial strains (Bacillus megaterium, Vibrio furnissii, V fischeri, V gazogenes and V parahaemolyticus) as well as the two species of diatoms (Amphora coffeaeformis and Navicula transitans) Of these, the highest activity was exhibited by compound 3 against B megaterium (MIC, 12.5?g) and N transitans (EC₅₀,14?g/ml) The environmental-compatibility of this compound was evidenced from the non-toxicity to B amphitrite nauplii (IC₅₀ 1?g/ml) and Artemia sp nauplii (IC₅₀ 0.6?g/ml) Analysis of structure-activity relationship suggested that the acetoxy group present in 3 may be responsible for the comparatively high antifouling activity exhibited by this compound.