Flavones and flavone glycosides from Halophila johnsonii.

Halophila johnsonii Eiseman is a shallow-water marine angiosperm which contains UV-absorbing metabolites. Studies on methanol extracts of H. johnsonii by means of HPLC-UV, NMR, HPLC-MS resulted in isolation and identification of seven previously unknown flavone glycosides: 5,6,7,3',4',5'-hexahydroxyflavone-7-O-beta-glucopyranoside (1), 5,6,7,3',4',5'-hexahydroxyflavone-7-O-(6''-O-acetyl)-beta-glucopyranoside (2), 6-hydroxyluteolin-7-O-(6''-O-acetyl)-beta-glucopyranoside (3), 6-hydroxyapigenin-7-O-(6''-O-acetyl)-beta-glucopyranoside (4), 6-hydroxyapigenin-7-O-(6''-O-[E]-coumaroyl)-beta-glucopyranoside (5), 6-hydroxyapigenin-7-O-(6''-O-[E]-caffeoyl)-beta-glucopyranoside (6) and 6-hydroxyluteolin-7-O-(6''-O-[E]-coumaroyl)-beta-glucopyranoside (7). Also isolated were three known flavone glycosides, 6-hydroxyluteolin 7-O-beta-glucopyranoside (8), scutellarein-7-O-beta-glucopyranoside (9), and spicoside (10), and five known flavones, pedalitin (11), ladanetin (12), luteolin (13), apegenin (14) and myricetin (15). Qualitative comparison of the flavonoid distribution in the leaf and rhizome-root portions of the plant was also investigated, with the aim of establishing the UV-protecting roles that flavonoids played in the sea grass.

Studies of the biosynthesis of DTX-5a and DTX-5b by the dinoflagellate Prorocentrum maculosum: regiospecificity of the putative Baeyer-Villigerase and insertion of a single amino acid in a polyketide chain.

The biosynthetic origins of the diarrhetic shellfish poisoning toxins DTX-5a and DTX-5b have been elucidated by supplementing cultures of the producing organism Prorocentrum maculosum with stable isotope labeled precursors and determining the incorporation patterns by 13C NMR spectroscopy. The amino acid residue in the sulfated side chain is found to originate from glycine, and oxygen insertion in the chain is shown to occur after polyketide formation.

Fish oil containing phytosterol esters alters blood lipid profiles and left ventricle generation of thromboxane a(2) in adult guinea pigs.

This study was designed to investigate the lipid-lowering ability of a novel dietary ingredient composed of phytosterols esterified to (n-3) polyunsaturated fatty acids (PUFA) [PS(n-3)]. Adult guinea pigs were fed a test diet supplemented with PS(n-3) (25 g/kg) and corn oil (CO, 5 g/kg), whereas the diet fed to control guinea pigs was supplemented with CO only (30 g/kg). Cholesterol was added to both diets (0.8 g/kg). After 3-4 wk of consuming the diets, serum total cholesterol (TC) and triacylglycerol (TAG) in the PS(n-3) group were 36 and 29% lower, respectively, than levels in controls (P < 0.05). The lower TC levels in the PS(n-3) group reflected a 38% reduction in non-HDL cholesterol (non-HDL-C), whereas the HDL-C concentration was unaffected. Analysis of cardiac left ventricle indicated that generation of the proaggregatory, arrhythmic eicosanoid, thromboxane A(2), was >60% lower in the PS(n-3)-supplemented guinea pigs than in CO controls (P < 0.001). This study demonstrates that the TAG-lowering and eicosanoid-modifying properties of the fish oil (n-3) PUFA are retained when they are provided in the diet in ester linkage with hypocholesterolemic phytosterols.