LC-MSMS characterisations of scymnol and oxoscymnol biotransformations in incubation mixtures of rat liver microsomes.

The bile alcohol 5ß-scymnol ([24R]-(+)-5ß-cholestan-3α,7α,12α,24,26,27-hexol) is a therapeutic nutraceutical derived from marine sources, however very little is known about its potential for biotransformation as a xenobiotic in higher vertebrates. In this study, biotransformation products of scymnol catalysed by liver microsomes isolated from normal and streptozotocin (STZ)-treated male Wistar rats were characterised by liquid chromatography-tandem mass spectroscopy (LC-MSMS). In order of increasing polarity relative to the reversed phase sorbent, structural assignments were made for four biotransformation products, namely 3-oxoscymnol (5ß-cholestan-3-one-7α,12α,24,26,27-pentol); 7-oxoscymnol (5ß-cholestan-7-one-3α,12α,24,26,27-pentol); 3ß-scymnol (5ß-cholestan-3ß,7α,12α,24,26,27-hexol) and 6ß-hydroxyscymnol (5ß-cholestan-3α,6ß,7α,12α,24,26,27-heptol). In addition, a total of eight biotransformation products were characterised from microsomal incubations of crude oxoscymnol compounds, namely 7ß-scymnol; 3,12-dioxoscymnol; 3,7-dioxoscymnol; 7,12-dioxoscymnol; 12-oxo-3ß-scymnol; 7-oxo-3ß-scymnol; 6ß-hydroxy-12-oxoscymnol and 6ß-hydroxy-7-oxoscymnol. Collectively, the results indicate hepatic enzyme-catalysed hydroxylation, dehydrogenation and epimerisation reactions on the steroid nucleus of scymnol, and provide an insight into biotransformation pathways for scymnol use as a therapeutic nutraceutical in higher vertebrates.

Elucidation of the hepatoprotective moiety of 5ß-scymnol that suppresses paracetamol toxicity in mice.

The shark bile alcohol, 5ß-scymnol, protects mice from the hepatotoxic effects of paracetamol (APAP) overdose. To elucidate the hepatoprotective structural moiety of scymnol, we compared its effect with that of its analogue and natural bile salt, sodium scymnol sulfate, in a clinically relevant model of APAP-induced toxicity. Exposure of healthy male Swiss mice to a toxic overdose of APAP (350 mg/kg, ip) significantly increased serum hepatocellular enzyme activities, decreased hepatocellular glutathione (GSH) levels, and induced severe centrilobular hepatocellular necrosis. Repeated low-dose scymnol (5 mg/kg/day for 7 days, ip) significantly reduced the extent of APAP-induced hepatotoxicity without preventing GSH depletion. Sodium scymnol sulfate, which lacks the tri-hydroxyl-substituted aliphatic side chain of scymnol, failed to reduce the APAP hepatotoxicity or prevent GSH depletion when tested under the same experimental conditions. We conclude that the tri-hydroxyl-substituted aliphatic side chain is the hepatoprotective structural moiety of 5ß-scymnol that suppresses APAP-induced cytotoxicity in mice.

Hydroxysteroid dehydrogenase transformations of 5ß-scymnol and identification of oxoscymnol transformation products by liquid chromatography-tandem mass spectroscopy.

A new and sensitive high performance liquid chromatography (HPLC) separation procedure coupled with tandem mass spectroscopy (MS and MS(2)) detection was developed to identify for the first time the oxidation products of 5ß-scymnol [(24R)-(+)-5ß-cholestan-3α,7α,12α,24,26,27-hexol] catalysed by bacterial hydroxysteroid dehydrogenase (HSD) reactions in vitro. The authentic scymnol (MW 468) standard yielded a protonated molecular ion [M+H](+) at m/z 469 Da, and higher mass adduct ions attributed to [M+NH(4)](+) (m/z 486), [M+H+CH(3)OH](+) (m/z 501) and [M+H+CH(3)COOH](+) (m/z 530). (24R)-(+)-5ß-Cholestan-3-one-7α,12α,24,26,27-pentol (3-oxoscymnol, m/z 467 Da, relative retention time (RRT)=0.89) was identified as the principle molecular species of scymnol in the reaction with 3α-HSD pure enzyme. [S](0.5) for the reaction of 3α-HSD with scymnol as substrate was 0.7292 mM. (24R)-(+)-5ß-cholestan-7-one-3α,12α,24,26,27-pentol (7-oxoscymnol, m/z 467 Da, RRT=0.79) and (24R)-(+)-5ß-cholestan-12-one-3α,7α,24,26,27-pentol (12-oxoscymnol, m/z 467 Da, RRT=0.81) were similarly identified as principle molecular species in the respective 7α-HSD and 12α-HSD reactions. Polarity of the oxoscymnol species was established as 7-oxoscymnol>12-oxoscymnol>3-oxoscymnol>scymnol (in order from most polar to least polar). Confirmation that 5ß-scymnol is an oxidative substrate for steroid-metabolising enzymes was made possible by the use of sophisticated liquid chromatography-mass spectrometry (LC-MS) techniques that will likely provide the basis for further exploration of scymnol as a therapeutic compound.

Prophylactic and therapeutic effects of Mytilus edulis fatty acids on adjuvant-induced arthritis in male Wistar rats.

Lipid-rich fractions from the flesh tissue of Mytilus edulis were obtained by solvent extraction and chromatographic separation, and tested for anti-inflammatory (AI) activity in vitro and in vivo. Inhibition of leukotriene production by isolated human neutrophils in response to calcium ionophore stimulation in the presence of exogenous arachidonic acid substrate was demonstrated for the hydrolysed triglyceride fraction of the crude lipid extract. This fraction was subsequently tested for in vivo AI activity using the mycobacterial adjuvant-induced polyarthritis rat model. The hydrolysed triglyceride fraction showed significant AI activity when dosed therapeutically (10 mg/kg BW/day, p.o., for 6 days from the onset of arthritis), decreasing body weight loss by 55% and hind paw swelling by 65% compared to the arthritic control. The (non-hydrolysed) crude lipid extract was effective when dosed prophylactically (30 mg/kg BW/day, p.o., for 16 days starting on day -2 of arthritigen inoculation). Structural analysis by GC and GC-MS revealed in the extracts an abundance of EPA (20:5n-3) and DHA (22:6n-3) (37% of total fatty acids), along with a small quantity of a rare anti-inflammatory n-3 analogue of arachidonic acid, namely 7, 11, 14, 17-eicosatetraenoic acid (20:4n-3).

Phytochemical analysis and biological screening of leaf and twig extracts from Kunzea ericoides.

Kunzea ericoides is a member of the Myrtle group of tea trees. Leaf and twig material of K. ericoides was extracted with different solvents to afford terpene (including the essential oil), flavonoid and lipid classes (but no alkaloid class), which were subsequently screened for antibacterial, antitumour, cytotoxic, antioxidant and antiinflammatory activity. Differences were observed in the biological activity for the chemical classes tested, and in general, the leaf extracts were comparatively more bioactive than the twig extracts. The leaf lipid extract was the most bioactive fraction, exhibiting antibacterial, antitumour and antiinflammatory activity. Thin layer chromatography and gas chromatography-mass spectroscopy analysis of each extract revealed previously identified phytochemicals that may be responsible for the observed bioactivities.