Asmarines G and H and Barekol, Three New Compounds from the Marine Sponge Raspailia sp.

Abstract

Four asmarines, the known A and F and two new ones G and H, four diterpenes, the known chelodane, barekoxide, and zaatirin and a new one, barekol, and methyl 3-oxo-cholan-24-oate were isolated from the Kenyan sponge Raspailia sp. The structures of all these compounds were established on the basis of MS and NMR data, and the absolute configuration of barekol was determined from the CD measurements of its keto-derivative. The (15)N chemical shifts of the N atoms of the heterocycles of the asmarines were measured from (15)N HMBC experiments, and the influence of various structural features on the delta(N) values studied.

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

“…The groups of Davies and Sarpong [97] teamed up for the total syntheses of the diterpenoids barekoxide ( 106 , see Scheme 13) [98] and barekol ( 107 ) [99], isolated from the sponges Chelonaplysilla erecta and Raspailia sp. They envisioned a formal [4 + 3]-cycloaddition with an intermediate DVCPR [82].…”

Terpenyl-Purines from the Sea

“…Asmarines A, F, G and H were isolated from the Kenyan sponge Raspailia sp. [69]. Asmarines A, F, I, J and K were isolated from the Nosy Be Islands (Madagascar) sponge Raspailia sp.…”

Marine Alkylpurines: A Promising Group of Bioactive Marine Natural Products

“…From a different Raspailia sp., collected at Wasini Island, Kenya, asmarines G and H, 103 – 104 , were identified together with asmarines A, 97 , and F, 102 , the latter being the major component ( Figure 22 ) [ 75 ]. Similar results were obtained with a Raspailia sp.…”

“…These compounds have proved to be cytotoxic against several tumour cell lines with asmarine B, 98 , being the most potent on human lung and colon carcinomas [ 73 , 75 ]. Not all the asmarines were evaluated because of the small amounts isolated.…”