Seco-germacrane anhydride: Occurrence of a sesquiterpene lactone in the gorgonian coral Menella sp. (Plexauridae)

1. Subject and sourceThegorgoniancoralidentifiedasMenellasp.(Plexauridae)usedinthisinvestigationwascollectedbytrawlingoffthecoastof southern Taiwan in December 2004 at a depth of 100 m. This organism was identified by comparison with previousdescriptions (Fabricius and Alderslade, 2001). A voucher specimen (NMMBA-TW-GC-005) was deposited in the NationalMuseum of Marine Biology and Aquarium, Taiwan.2. Previous workA series of secondary metabolites, including steroids (Deng et al., 1997; Zhang et al., 2006; Chai et al., 2010), guaianelactones (Zhang et al., 2004; Li et al., 2008), briarane diterpenoids, menellin A (a highly oxygenated racemate with C8skeleton) (Chai et al., 2010), picolinic acid N-methyl betaine (Li et al., 1996; Deng et al., 1997), n-hexadecanol, 9H-purin-6-amino-N-dimethyl, thymidine (Deng et al., 1997), and batyl alcohol (Deng et al., 1993, 1997) were isolated from variousgorgonian corals belonging togenus Menella, collected off the South China Sea. In our studies on the chemical constituents ofa gorgonian identified as Menella sp., collected off the waters of Taiwan, various sesquiterpenoids featuring guaiane, linde-nane, and germacrane-type carbon skeletons, containing a