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Three new sesterterpene sulfates, halisulfates 8-10 (1-3), were isolated from the Australian sponge Darwinella australensis. The structures of these compounds were determined by combined spectroscopic methods. The stereochemistry of the decalin moiety was assigned on the basis of NMR interpretations. Halisulfates 9 and 10 inhibited cell division of sea urchin eggs in moderate concentration.
Suberitenones C and D and suberiphenol, three new sesterterpenes of the suberitane class, were isolated from the sponge Suberites sp. collected from Antarctica. The structures of these compounds were determined on the basis of combined spectral and chemical analyses.
Two new natural scalaranes, 16beta-acetoxy-20,24-dimethyl-12,24-dioxo-25-norscalarane and 12beta-hydroxy-20,24-dimethyl-13,18-oxa-25-norscalarane, were isolated from the Madagascaran sponge Phyllospongiamadagascarensis, together with three previously decribed tetracyclic sesterterpenoids, phyllofolactones F, G, and B, and a new artifactual ethyl ether of scalaradisin B. Structure determinations were based on NMR and other spectral data. Compounds 1 and 2 represent new examples of 20,24-dimethyl-25-norscalarane sesterterpenes, and compound 2 has a seven-membered oxacycle that makes its skeletal system unique.
Five new sesterterpenes, three scalarane-type (1-3) and two linear furanosesterterpenes (4, 5), were isolated from the marine sponge Smenospongia sp. collected from Gagu-Do, Korea. The structures of the new compounds, which exhibited moderate cytotoxicity toward the human leukemia cell line K562, were determined from an analysis of spectroscopic data.
A new scalarane-type pentacyclic sesterterpene, sesterstatin 7 (1), was isolated from the Red Sea sponge Hyrtios erecta, together with 16-epi-scalarolbutenolide (2), 25-dehydroxy-12-epi-deacetylscalarin (3), 3-acetylsesterstatin 1 (4), and 21-acetoxydeoxyscalarin. The structure of 1 was elucidated by spectroscopic data interpretation. Sesterstatin 7 (1) showed 63% inhibition of Mycobacterium tuberculosis (H(37)Rv) at a concentration of 6.25 microg/mL. Compound 2 displayed moderate inhibitory activity, while 3 and 4 were weakly active against the same biological target.
12,13-Didehydrofurospongin-1 and 16 beta-acetoxy-24-methyl-12,24-dioxosclaran-25-al, C21 and C26 sesterterpenes, were isolated from the sponge Carteriospongia flabellifera collected on the Great Barrier Reef, and their structures were determined by spectral analysis. The occurrence of these compounds falls into previously noted chemotaxonomic patterns.
Nine sesterterpenes 1-9 have been isolated from a Dictyoceratid sponge, Strepsichordaia lendenfeldi, collected on the Great Barrier Reef, Australia. Seven of these compounds are new, one [4] had been reported previously as a semisynthetic product, and one [5] had been isolated previously from Carteriospongia foliascens. Unambiguous 13C- and 1H-nmr assignments have been made for 1 based on extensive 1D and 2D high field nmr experiments, which enabled 13C-nmr assignments to be made for 2-9. Significant growth inhibitory effects with tested cancer cell lines are reported for compounds 1-8.
Three new cytotoxic sesterterpenes, 1-3, have been isolated from the marine sponge Hyrtios cf. erectus. Their structures have been determined by interpretation of NMR data. They exhibited cytotoxicity against P-388 murine leukemia cells with IC50 values of 0.4-2.1 micrograms/mL.
Novel scalarane sesterterpenes (1-4) were isolated from a sponge, Hyrtios erecta (order Dictyoceratida). They were characterized by means of spectral analyses, X-ray crystallography, and chemical reactions. Compound 1 showed potent in vitro and in vivo antitumor activities. In addition, the structure-activity relationship was also discussed using computer-assisted structure matching of 1 and aragusterols.
Phyllofolactone C (3) and phyllofolactone D (4), two new minor homoscalarane sesterterpenes, were isolated from the sponge Phyllospongia foliascens collected in the South China Sea. Their structures were assigned by analysis of spectroscopic data.
From the CH(2)Cl(2) extract of the sponge Hyrtios cf. erecta, collected from Fiji, two new sesterterpenes, 1 and 2, and the known compounds isodehydroluffariellolide (3), homofascaplysin A (4), and fascaplysin (5) were isolated. The structures of 1-5 were established employing 1D and 2D NMR spectroscopy and mass spectrometry. All NMR resonances of fascaplysin (5) have been unambiguously assigned. Evaluation of the biological activity of the extracts and pure compounds toward Plasmodium falciparum, Trypanosoma brucei subsp. rhodesiense, Trypanosoma cruzi, hepatitis A virus (HAV), several other microbial targets, and HIV-1-RT and p56(lck) tyrosine kinase revealed new activities for homofascaplysin (4) and fascaplysin (5), both being potently active in vitro against P. falciparum.
Rat adrenal gland preparations were incubated with radioactive cholesterol and 23,24-dinor-5-cholen-3 beta-ol. Steroids were isolated, purified by thin-layer and high performance liquid chromatography and crystallised to constant specific activity. It was found that the rat adrenal gland can utilise 23,24-dinor-5-cholen-3 beta-ol to produce corticosterone. Also, in contrast to the conversion of cholesterol to corticosterone which occurs in the mitochondrial fraction, the conversion of 23,24-dinor-5-cholen-3 beta-ol to corticosterone occurs in the microsomal fraction. It was concluded that the sesterterpene pathway for steroid biosynthesis can function in the rat adrenal gland and that the intermediates are converted to steroid hormones in the microsomal fraction.
A novel sesterterpene, leucosceptrine, was isolated from the medicinal plant Leucosceptrum canum from Nepal. The structure was determined by single-crystal X-ray diffraction and spectroscopic techniques. The biosynthesis of leucosceptrine (1) is proposed here. Leucosceptrine (1) exhibited prolylendopeptidase inhibitory activity.
Two new sesterterpenes, thorectandrol A (1) and B (2), were isolated from extracts of the marine sponge Thorectandra sp. The structures were determined by extensive NMR spectral data analysis. NOE correlations were used to define the relative stereochemistry of 1 and 2, while CD data were used to suggest their absolute stereochemistry. Both compounds 1 and 2 inhibited the growth of MALME-3M (melanoma) and MCF-7 (breast) cancer cell lines in the range 30-40 microg/mL. The known compound palauolol (3) was isolated as well and was also cytotoxic.
Extracts of the marine sponge Thorectandra sp. have been found to contain three new sesterterpenes, thorectandrols C (4), D (5), and E (6), together with the known compounds luffarin R (7), luffarin V (8), and palauolide (9). The structures were determined by extensive NMR spectral data analysis. Their relative stereochemistry was defined using NOE correlations and coupling constants, while CD data were used to suggest their absolute stereochemistry. Cytotoxicity data for compounds 4-9 as well as the previously reported compounds thorectandrols A and B and palauolol (1-3) against six or more human tumor cell lines are also reported.
Two new sesterterpene metabolites, 16-acetoxy-dihydrodeoxoscalarin (1) and astakolactin (2), were isolated from the sponge Cacospongia scalaris, collected from the gulf of Astakos, Greece, along with furoscalarol (3) and deoxoscalarin (4), which have not been reported from C. scalaris in the past. The unpalatability of the sponge to fish was traced by field feeding assays to the fractions containing dihydrofurospongin-2. The structures of the new metabolites were elucidated by interpretation of their NMR data and high-resolution mass spectral measurements.
The marine sponge Lendenfeldia frondosa, collected from the Solomon Islands, has yielded homoscalarane sesterterpenes. Two new metabolites, epihomoscalaralactone IIA [5] and homoscalarate II [10], were accompanied by two known metabolites, homoscalaralactone IIA [1] and homoscalaralactone IIB [7]. These structures were established by analysis of 2D nmr data, trends in 13C-nmr shifts, and comparison of experimental with molecular-mechanics-calculated nmr J's. Each of the alcohols 1, 2, and 3 was converted to its corresponding acetate, 2, 6, and 8, respectively. Compound 6 exhibited moderate anti-inflammatory activity.
Cacospongionolide B [2a], a new cacospongionolide-related sesterterpene, has been isolated from the Adriatic sponge Fasciospongia cavernosa. The structure was elucidated by spectral and chemical means. The antimicrobial activity and brine shrimp and fish lethalities of 2a are reported.