Insecticidal and Repellent Activit ies of Laurinterol from the Okinawan Red Alga Laurencia nidifica

An ethyl acetate (EtOAc) extract of Laurencia nidifica was found to have toxic effect against brine shrimp larvae (Artemia salina). Bioassay-guided fractionation of the EtOAc extract resulted in the isolation of four known halogenated sesquiterpenes, laurinterol (1), isolaurinterol (2), aplysin (3), and a -bromocuparene (4). Their structures were established on the basis of spectral analysis and comparison with literature data. Among isolated compounds, only laurinterol showed strong toxicity against A. salina. Further experiments revealed that laurinterol also exhibited repellent activity against the maize weevil Sitophilus zeamais , insecticidal activity against the termite Reticulitermes speratus, and acetylcholinesterase (AChE) inhibitory effect . This is the first report of insecticidal and repellent activities of laurinterol.