Introduction: Natural marine compounds have recently developed the focus of amplified exploration attention due to their potential pharmacological functions and minor toxic effects. Cholesterol (cholest-5-en-3β-ol) is the major sterol constituent of animal lipid and fish fat. Oxysterols are oxidation products of cholesterol. Cholestane-3β, 5α, 6β-triol (shortened as triol) is one of the most abundant oxygenated sterols. This triol is derived from cholesterol through autooxidation or in vivo enzymatic procedures and have been recognized in blood, mammalian cells/tissues, and processed foods. Oxysterols indicate vital roles in regulating cholesterol homeostasis, platelet accumulation, apoptosis, and protein prenylation. Recently, oxysterols have been considered as fascinating constituents with miscellaneous biological functions. Furthermore, oxysterols inhibit cell growth, also performs a significant role in the balance among cell division and cell demise.
Methods: Coelomic fluid (up to 2 mL) was withdrawn from animals with a syringe inserted through the peristomial membranes. Extracted coelomic fluid were mixed with a small volume of acetonitrile: methanol (6:4 [v/v]). Oxysterol was deciphered in cell free coelomic fluid from salt stressed and control urchins using high-pressure liquid chromatography-mass spectrometry. For maximal sensitivity and for linearity of the response, the mass spectrometer was activated in multiple-reaction monitoring mode at unit mass resolution. The mass spectrometer was operated in negative electrospray ionization (ESI) mode (even though several analyses worked in positive ion) and the mass spectra collected in the 50–1000 m/z range.
Results: Using LC/MS experiments on coelomic fluid of E. mathaei, one steroid/sterol was identified at m/z 592 as (24R)-Cholesta-5,25-dien-2b,3b,21,24-tetrol 3,21-disulfate with highest content in salt stressed samples. Oxysterols can be ionized readily and lose their hydroxyl/sulphate groups therefore this Oxysterol indicated the major m/z fragment at 369, belonged to cholesterol.
Conclusion: Oxysterols are important cholesterol metabolites involved in cellular membranes permeability and on specific enzyme systems as well as cytotoxic, atherogenic, mutagenic, and carcinogenic actions. Oxysterols have been intensively investigated and many researchers discovered their important natural roles in the human organs/tissues as well as numerous relations to pathological conditions, where diverse oxysterols seem to be promising indicative biomarkers. Oxysterols also have an impact on the physiology of the immune system, from immune cell development and relocation to innate and humoral immune responses.
We deciphered higher content of cholesterol and (24R)-Cholesta-5,25-dien-2b,3b,21,24-tetrol 3,21-disulfate at salt stressed urchins. As an unsaturated lipid, cholesterol is susceptible to oxidation in the same manner as polyunsaturated fatty acids and their esters. Therefore oxysterols may be useful markers of oxidative stress or for monitoring of the progression of various disorders and sulfated stroles are the main circulating sterol in plasma which their functions in plasma are not fully defined. Special derivatives of Cholestane were isolated from Sea urchin D. savignyi and sea star.