Psammaplysins

Psammaplysin E (84), ceratinamine (85), and molokaiamine (86) from the sponge Pseudoceratina purpurea exhibit potent cytotoxicity against P-388 murine leukemia cells with IC50 values of 2.1, 3.4, and 2.1 pg/ml, respectively [74]. Recently, the related waianaeamines have been isolated from an undescribed verongid sponge from Molokai Island [75]. 

The bromotyramine derivatives ceratinamide A (136) and psammaplysin A (137) from the sponge Pseudoceratina purpurea inhibit the settlement and metamorphosis of cyprid larvae of the barnacle Balanus amphitrite (ED50 0.10 and 0.27 (Jg/ml). Interestingly, psammaplysin A induces larval metamorphosis of the ascidian Halocynthia roretzi (ED 0o 1.2 (Jg/ml) [74]. 

Psammaplysins appear to be biogenetically derived from dibromoty-rosine through an intermediate containing an arene oxide and oxime (329). Ianthelline (396) was isolated from the sponge Ianthella ardis collected in the Bahamas and possessed antimicrobial activity (330). 

Bromotyrosine-derived metabolites are often encountered in marine sponges of the families Aplysinidae and Pseudocer-atidae, in particular Pseudoceratina (= Psammaplysilla) purpurea. They show a variety of biological activities, which include antimicrobial, enzyme inhibitory, and antifouling activities. Psammaplysin A (47) is antimicrobial, cytotoxic, and antifouling, whereas psammaplin A (48) is an inhibitor of histone deacetylase (2). The marine sponge lanthella basta synthesizes at least 25 bastadins that are linear or cyclic peptides composed of four bromotyrosine residues [bastadin 5 (49)] and show antimicrobial, cytotoxic, and enzyme inhibitory activities as well as interaction with Ca + channels (21). 

Sponges of the order Verongida contain numerous metabolites having a spiroisoxazoline system, which can be derived from bromotyrosine. A. from Aplysina fis-tularis, C24H26Br4N40s, Mr 818.11, mp. 134-137 °C, [o]d +252° psammaplysin A from Psammaplysilla purpurea with a 1,6-dioxa-2-aza[4,6]undecane system ... 

Ramsey Dm, Islam MA, TumbuU L, Davis RA, Whitchurch CB, McAlpine SR. Psammaplysin F A unique inhibitor of bacterial chromosomal partition. Bioorg Med Chem Lett 2013 23(17) 4862-6. 

It s structure is similar to psammaplysin F (31) and has two additional A-methyl group s at the terminal amine. Psammaplysin H (35) exhibited potent antimalarial activity against the 3D7 line of P. falciparum with an IC50 value of 0.41 pM and has very low toxicity against mammalian cell line s making it as a parasite specific. Psammaplysins I (36) and J (37) were isolated from the sponge of Suberea sp. [27],... 

Psammaplysins S (48) and T (49) also have their hydroxyl derivatives as well. Psammaplysins U-W and its hydroxyl derivatives (52-56) have monoenoic fatty acid side chain s connected with the terminal amine as an amide functionality. Psammaplysin U (52) has Ao-branched fatty acid side chain, while psammaplysins V (54) and W (55) have unbranched fatty acid side chains. Psammaplysins X (57) and Y (59) were isolated from marine sponge of the genus Suberea [29]. Psammaplysin X (57) has 4-chloro-2-methylenecyclopentane-l,3-dione at the A-terminus, while psammaplysin Y (59) has unsubstituted 2-methylenecyclopentane-l,3-dione moiety at its A-terminus (Figure 3). 

Ceratinamides A (68) and B (69), antifouling bromotyrosine derivatives, were isolated from marine sponge Pseudoceratina purpurea through a bioassay -guided isolation (Figure 4) [38]. Ceratinamide A (68) is structurally similar to psammaplysin A (27) and has one formyl group at the A-terminus. 

Scheme 4. Proposed biosynthesis of spirooxepinisoxazoline skeleton of psammaplysins.

Copp, B. R., Ireland, C. M., Barrow, L. R. Psammaplysin C a new cytotoxic dibromotyrosine-derived metabolite from the marine sponge Druinella (= Psammaplysilla)purpurea. J. Nat. Prod. 1992, 55, 822-823. 

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