phytosterols and cholesteryl-sulfate

The preparation of steady-state phospholipid liposomes requires cholesterol as a stabilizer, but excessive intake of cholesterol may increase the risk of cardiovascular disease. The sulfated sterols extracted from sea cucumber, mainly including sulfated 24-methylene cholesterol and cholesterol sulfate, have been reported to have a variety of physiological activities. Sulfated sterols are similar to cholesterol in structure and have the potential to replace cholesterol to prepare novel stable multifunctional liposomes, allowing the liposomes to act as carriers for the delivery of less bioavailable nutrients while allowing sulfated sterols in the lipid bilayer to exert physiologically active effects. This study aimed to prepare a novel multifunctional nanoliposome stabilized with sulfated sterols from sea cucumber instead of cholesterol by ultrasound-assisted thin-film dispersion method. The results showed that stable and uniformly dispersed nanoliposomes could be formed when the substitution ratio of sea cucumber-derived cholesterol sulfate was 100% and the ratio of lecithin to cholesterol sulfate was 3:1. Fucoxanthin encapsulated liposome with egg yolk lecithin/sea cucumber-derived cholesterol sulfate/fucoxanthin mass ratio of 6:2:3 was successfully prepared, with an average particle size of 214 ± 3 nm, polydispersity index (PDI) value of 0.297 ± 0.006, the zeta potential of -57.2 ± 1.10 mV, and the encapsulation efficiency of 85.5 ± 0.8%. The results of digestion and absorption in vitro and in vivo showed that liposomes could significantly improve the bioavailability of fucoxanthin and prolong its residence time in serum. As an efficient multifunctional carrier, this novel liposome has great potential for applications in functional foods and biomedicine.

Topics: Animals; Cholesterol; Lecithins; Liposomes; Particle Size; Phytosterols; Sea Cucumbers; Sterols

Cell mortality is a key mechanism that shapes phytoplankton blooms and species dynamics in aquatic environments. Here we show that sterol sulfates (StS) are regulatory molecules of a cell death program in Skeletonema marinoi, a marine diatom-blooming species in temperate coastal waters. The molecules trigger an oxidative burst and production of nitric oxide in a dose-dependent manner. The intracellular level of StS increases with cell ageing and ultimately leads to a mechanism of apoptosis-like death. Disrupting StS biosynthesis by inhibition of the sulfonation step significantly delays the onset of this fatal process and maintains steady growth in algal cells for several days. The autoinhibitory activity of StS demonstrates the functional significance of small metabolites in diatoms. The StS pathway provides another view on cell regulation during bloom dynamics in marine habitats and opens new opportunities for the biochemical control of mass-cultivation of microalgae.

Topics: Cholestadienols; Cholesterol Esters; Diatoms; Ecosystem; Eutrophication; Microalgae; Phylogeny; Phytoplankton; Phytosterols; Signal Transduction; Sitosterols; Sterols; Sulfates; Sulfotransferases

In this necroscopy study the relation between carriage and size of colorectal polyps was correlated with luminal steroid concentrations in respect to malignant risk. Of the 92 subjects entered into the study, 68 had adenomatous polyps of the large bowel, of which 19 had adenomas > 0.9 cm in diameter (large adenomas), 26 in the range 0.5-0.9 cm in diameter (medium adenomas) and 23 of 0.4 cm or less in diameter (small adenomas). Sixty-three percent of subjects carrying large adenomas and 26% of persons carrying small adenomas had an abnormal ratio (> 1.0) of lithocholic acid to deoxycholic acid in intestinal contents as compared to 17% of the adenoma-free comparison group (n = 24). These findings support the suggestion that the ratio of lithocholic acid to deoxycholic acid as a faecal marker may be a useful adjunct to screening procedures for colorectal cancer.

Topics: Adenoma; Aged; Bile Acids and Salts; Biomarkers, Tumor; Cholestanol; Cholesterol; Cholesterol Esters; Colonic Polyps; Deoxycholic Acid; Feces; Female; Gastrointestinal Contents; Humans; Lithocholic Acid; Male; Middle Aged; Phytosterols; Polyps; Rectal Neoplasms; Steroids; Sterols