Brominated Metabolites from the Sponge Aplysina (verongia) thiona

Abstract

In addition to known bromo-compounds 5-11, the new brominated metabolites aplysinolide [1], aplysinimine [2] and two mixed ketals, aplysinketal A {3} and aplysinketal B [4], have been isolated from the sponge Aplysina (Verongia) thiona. Their structures were determined by spectroscopic methods. In addition, an X-ray analysis of compound 3 was performed.Sponges of the order Verongida have yielded a wide variety of brominated compounds with suggested 3,5-dibromotyrosine origin (1). 2,6-Dibromo-4-acetamide-4hydroxycyclohexadienone [5] (2), the hydroxydienoic methyl ester 6 (2), and aeroplysinine 1 [7} (3) were responsible for the antimicrobial activity of the MeOH extract of Aplysina thiona De Laubenfels, a tropical Eastern Pacific sponge of the family Aplysinidae, order Verongida, collected at Puerto Escondido Bay in Oaxaca, Mexico.Aeroplysinine 2 [8} (4), 3,5-dibromo-2-hydroxy-4-methoxyphenylacetamide [9} (5), the hydroxydienoic acid 10 (2), and the bis-oxazolidone derivative 11 (6) were other known constituents isolated from this sponge.The hydroxydienoic methyl ester 6 and the hydroxydienoic acid 10, previously obtained by synthesis from the dienone 5 and the dimethoxyketal 12, respectively (2), have now been isolated from this sponge as natural products. Besides the brominated compounds, ß-sitosterol was obtained from A. thiona.Aplysinolide [1] was assigned formula C12H10O3Br2 based on mass spectral data, which indicated the presence of two bromine atoms (molecular ion cluster at mlz 360, 362, 364) as well as fragments corresponding to the successive loss of Me, HCO, and 43 mass units. The ir spectrum exhibited a band for a carbonyl function (1780 cm-1), while the 'H-nmr spectrum at 400 MHz showed two broad singlets at 2.39 and 2.59, indicating the presence of two geminal vinyl methyl groups, a singlet ( 3.92) for a methoxyl group, and a singlet ( 7.65) for one aromatic proton in a pentasubstituted benzene ring.

Dibromotyrosine derivatives from the ethanol extract of the marine sponge Aplysina sp.: structures, transformations, and origin

“…Because of this, aplysinketal A (15) isolated by recrys tallization still is the only dibromotyrosine ketal with the known stereochemistry found by X ray diffraction analysis. 10 The isolated pairs of stereoisomeric mixed ketals are examples of a rare type of geometrical isomers. Their mol ecules are achiral, since they have a plane of symmetry, in which substituents at the two saturated carbon atoms of the cycle are placed.…”

Lipid composition of the spongeVerongia aerophoba from the Canary Islands

“…The sterol composition was also unusual -besides small amounts of the widespread C 27 -C 29 sterols with C5 double bond, which are accepted to be of dietary origin, the main sterols appeared to possess an unprecedented alkylation at C27. The main sterols appeared to be aplysterol (24,27-dimethyl-cholest-5-en-3β-ol) and 24,27-dimethyl-cholesta-5,25(26)-dien-3β-ol [10][11][12][13][14][15][16][17]. The presence of demospongic acids in Verongia sponges, containing groups causing membrane disordering, is believed to be due to the need of the sponge for membranes possessing fluidity near the middle of the phospholipid bilayer.…”

Brominated Compounds from Marine Sponges of the Genus Aplysina and a Compilation of Their 13C NMR Spectral Data

“…Further evidence that they are artifacts is the formation of dimethoxy and methoxy-ethoxy ketals which can be explained as being formed from an arene (dienone intermediary XII ), which suffers 1,4 additions of methanol, water or ethanol (Figure 2), and displayed a reaction described by Kasperek et al [94,95,121]. However, the methoxy-butoxy and methoxy-pentoxy ketals isolated from Aplysina thiona [109] are not considered reaction products. Aplysinketal A was isolated only in the form of diastereoisomers, and the absence of the dimethoxy ketal indicates the non-existence of reactions during the extraction process [109].…”

“…However, the methoxy-butoxy and methoxy-pentoxy ketals isolated from Aplysina thiona [109] are not considered reaction products. Aplysinketal A was isolated only in the form of diastereoisomers, and the absence of the dimethoxy ketal indicates the non-existence of reactions during the extraction process [109]. It has been suggested that the formation of the C 4 and C 5 chains are formed via lysine and ornithine respectively (Figure 2) [104,114].…”