Phycopsis terpnis

Biological specificity is a paramount consideration if one considers two examples, Acanthella pulcherrima [20] and Pseudaxinyssa sp. [68], That thiocyanate ion may be the precursor to marine isothiocyanates should be tested on these organisms since isothiocyantes were the primary representative of the triad. Also, should incorporation of thiocyanate ion by Phycopsis terpnis yield 81 and 82 [48], rather than the unreported corresponding isothiocyanates, the biospecificity of marine organisms will be demonstrated. 

The structure of 5-isothiocyanatopupukeanane (257), a sesquiterpene isothiocyanate from an Axinyssa species from Guam, was determined by X-ray analysis [260]. Two isomeric sesquiterpene thiocyanates, 2-thiocyanatoneopupukeanane (258) and 4-thiocyanatoneopupukeanane (259) were isolated from an unidentified sponge from Pohnpei and from Phycopsis terpnis from Okinawa [261]. A sample of Axinyssa (= Trachyopsis) aplysinoides from Palau yielded a rare thiocyanate, 2-thiocyanatopupukeanane (260), while two specimens from Pohnpei yielded 13-isothiocyanatocubebane (261), 1-isothiocyanatoaromadendrane (262) and 2-thiocyanatoneopupukeanane (258) [262]. This last compound had previously been assigned different stereochemistry at C2 [261]. (-)-4-Thiocyanatoneopupukeanane has been synthesised in an enantiospecific manner (259) [263]. Both enantiomers of 2-thiocyanatoneopupukeanane (258) have been synthesised from (7 )-carvone [264]. 

Pupukeanone. c,sH240, Mr 220.35. A fish toxic metabolite from the nudibranch Phyllidia varicosa with the isotwistane skeleton. The sponges Ciocalypta spp. contain isocyano and Phycopsis terpnis thiocya-nato derivatives of pupukeanone. 

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