Plakortis

Some 1,2-dioxanes and 1,2-dioxolanes derivatives such as the two diastereomers of methyl esters of peroxyplakoric acid (A3 and B3) (85) isolated from marine sponges Plakortis sp., have proven to possess good antimalarial activity, with IC50 values of about 50 ng/mL for both compounds. Furthermore, a polyether (86) recently isolated from marine Streptomyces sp. H668 also displayed a useable antimalarial activity, with an IC50 value of about 150 ng/mL. ... 

Ethyl plakortide Z (19) and its two didehydro analogs (20a and 20b) are found in the Papuan sponge Plakortis lita. These compounds are cytotoxic and show some antitumor activity in vitro. ... 

Haterumadioxins A and B were isolated from the Okinawan sponge Plakortis lita. Haterumadioxin A 100 was evaluated against a human cancer cell line panel and found to be effective against a melanoma cancer cell line. An analysis of the results obtained... 

In the marine environment, several polyketides with important medicinal value have been reported in recent years. They have been isolated mainly from marine sponges of the genus Caltyspongia and Plakortis, which yielded potent cytotoxic polyketides, e g., callystatin A, Fig. (52) isolated from Callyspongia trunccitci [285,431], and several cyclic polyketides named plakortides, Fig. (53), isolated from Plakortis lita [432] and Plakortis simplex [433],... 

Campagnuolo C, Fattorusso E, Taglialatela-Scafati O (2003) Plakohypaphorines A-C, Iodine-Containing Alkaloids from the Caribbean Sponge Plakortis simplex. Eur J Org Chem 284... 

Sandler JS, Colin PL, Hooper JNA, Faulkner DJ (2002) Cytotoxic P-Carbolines and Cyclic Peroxides from the Palauan Sponge Plakortis nigra. J Nat Prod 65 1258... 

Two pentacyclic aromatic alkaloids, plakinidines A (217) and B (218) were recently isolated from a Vanuatuan red sponge of the genus Plakortis... 

Fatty acid-derived cychc peroxides are often found in marine sponges of the genus Plakortis the first example was chon-drillin (6). 1,2-Dioxane and 1,2-dioxolane carboxylates were also discovered from Plakortis sponges (9). These cychc oxides show a range of biologic activities, for example, antimicrobial, cytotoxic, and antimalarial activities. 

Artemisinin with its crucial endoperoxide bridge is not the only natural compound exhibiting antiplasmodial activity. An example of the biosynthesis of antiplasmodial endoperoxidic compounds is plakortin, a simple 1,2-dioxane derivative, which is produced by the marine sponge Plakortis simplex [93]. This compound shows activity against chloroquine-resistant strains of Plasmodium falciparum (R falciparum) at submicromolar level. 

Eilatin 33 and eudistone A 48 and B 49 are pyridoacridine alkaloids that possess this ring skeleton. This ring system is also found in a synthetic isomer, isoascidemin 77, of ascididemin 28 (see pyrido[h]acridines and pyrido[2,3,4-fcf]acridines). Three other alkaloids, the plakinidines (A-C) 78-80 from Plakortis sponge, also share this ring system (90JA1,90TL3271). 

Three polycyclic alkaloids that contain this ring system as part of their structures, plakinidines A 78, B 79, and C 80, were isolated from the marine sponge Plakortis sp. (see Section II,C,1 on pyrido[3,2-c]acridines). 

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