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The composition of the ketosteroid fraction from the Far-East marine prosobranch mollusk Onchidiopsis variegata was determined. The structure of a new steroidal ketone cholesta-4,24-dien-3-one (1e) was established by NMR, IR, UV, and mass spectroscopy. It was proposed that O. variegata feeds on ascidians of the genus Styela.Chemical aspects of the ecology of marine Prosobranchia have been little studied [1] whereas the chemical composition of Far-Eastern representatives of this subclass is virtually unknown. In continuation of our research on secondary metabolites from marine mollusks [2], we established the composition of the ketosteroid fraction from the Far-Eastern prosobranch mollusk Onchidiopsis variegata. The fraction consisted of 10 components: ∆ 4 -3-ketosteroids 1a-h, ∆ 4 -3,6-diketosteroid 2d, and ∆ 4,6 -3-ketosteroid 3d (Table 1). Known compounds were identified based on GC-MS and PMR spectroscopy [3][4][5]. Certain ketosteroids were isolated from the total fraction using HPLC, including the previously unknown component 1e.According to GC-MS and 13 C NMR spectroscopy, the new ketosteroid 1e had molecular formula C 27 H 42 O. The presence of signals in the 13 C NMR spectrum at δ 201.6 (s), 173.6 (s), and 125.8 (d) and absorption bands at 232 nm in the UV spectrum and 1678 cm -1 in the IR spectrum indicated that the structure contained an α,β-unsaturated ketone. The chemical shifts of the allyl proton of an enone fragment (5.72 ppm, s), CH 3 -18 angular protons (0.71 ppm, s), and CH 3 -19 (1.18 ppm, s) in the PMR spectrum agreed with spectral data for ∆ 4 -3-ketosteroids in the literature [3].
The composition of the ketosteroid fraction from the Far-East marine prosobranch mollusk Onchidiopsis variegata was determined. The structure of a new steroidal ketone cholesta-4,24-dien-3-one (1e) was established by NMR, IR, UV, and mass spectroscopy. It was proposed that O. variegata feeds on ascidians of the genus Styela.Chemical aspects of the ecology of marine Prosobranchia have been little studied [1] whereas the chemical composition of Far-Eastern representatives of this subclass is virtually unknown. In continuation of our research on secondary metabolites from marine mollusks [2], we established the composition of the ketosteroid fraction from the Far-Eastern prosobranch mollusk Onchidiopsis variegata. The fraction consisted of 10 components: ∆ 4 -3-ketosteroids 1a-h, ∆ 4 -3,6-diketosteroid 2d, and ∆ 4,6 -3-ketosteroid 3d (Table 1). Known compounds were identified based on GC-MS and PMR spectroscopy [3][4][5]. Certain ketosteroids were isolated from the total fraction using HPLC, including the previously unknown component 1e.According to GC-MS and 13 C NMR spectroscopy, the new ketosteroid 1e had molecular formula C 27 H 42 O. The presence of signals in the 13 C NMR spectrum at δ 201.6 (s), 173.6 (s), and 125.8 (d) and absorption bands at 232 nm in the UV spectrum and 1678 cm -1 in the IR spectrum indicated that the structure contained an α,β-unsaturated ketone. The chemical shifts of the allyl proton of an enone fragment (5.72 ppm, s), CH 3 -18 angular protons (0.71 ppm, s), and CH 3 -19 (1.18 ppm, s) in the PMR spectrum agreed with spectral data for ∆ 4 -3-ketosteroids in the literature [3].
In order to establish Ciona intestinalis as a new bioresource for n-3 fatty acids-rich marine lipids, the animal was fractionated into tunic and inner body tissues prior to lipid extraction. The lipids obtained were further classified into neutral lipids (NL), glycolipids (GL) and phospholipids (PL) followed by qualitative and quantitative analysis using GC-FID, GC-MS, (1)H NMR, 2D NMR, MALDI-TOF-MS and LC-ESI-MS methods. It was found that the tunic and inner body tissues contained 3.42-4.08% and 15.9-23.4% of lipids respectively. PL was the dominant lipid class (42-60%) irrespective of the anatomic fractions. From all lipid fractions and classes, the major fatty acids were 16:0, 18:1n-9, C20:1n-9, C20:5n-3 (EPA) and C22:6n-3 (DHA). The highest amounts of long chain n-3 fatty acids, mainly EPA and DHA, were located in PL from both body fractions. Cholestanol and cholesterol were the dominant sterols together with noticeable amounts of stellasterol, 22 (Z)-dehydrocholesterol and lathosterol. Several other identified and two yet unidentified sterols were observed for the first time from C. intestinalis. Different molecular species of phosphatidylcholine (34 species), sphingomyelin (2 species), phosphatidylethanolamine (2 species), phosphatidylserine (10 species), phosphatidylglycerol (9 species), ceramide (38 species) and lysophospholipid (5 species) were identified, representing the most systematic PL profiling knowledge so far for the animal. It could be concluded that C. intestinalis lipids should be a good alternative for fish oil with high contents of n-3 fatty acids. The lipids would be more bioavailable due to the presence of the fatty acids being mainly in the form of PL.
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