A low-toxicity method for the separation of lanosterol and dihydrolanosterol from commercial mixtures

Luciferase-based HMG-CoA reductase degradation assay for activity and selectivity profiling of oxy(lano)sterols

HMG-CoA reductase (HMGCR) is the rate-limiting enzyme in the cholesterol biosynthetic pathway, and is the target of cholesterol-lowering drugs, statins. Previous studies have demonstrated that the enzyme activity is regulated by sterol-induced degradation in addition to transcriptional regulation through sterol-regulatory-element-binding proteins (SREBPs). While 25-hydroxycholesterol induces both HMGCR degradation and SREBP inhibition in a nonselective manner, lanosterol selectively induces HMGCR degradation. Here, to clarify the structural determinants of selectivity for the two activities, we established a luciferase-based assay monitoring HMGCR degradation and used it to profile the structure-activity/selectivity relationships of oxysterols and (oxy)lanosterols. We identified several sterols that selectively induce HMGCR degradation and one sterol, 25-hydroxycholest-4-en-3-one, that selectively inhibits the SREBP pathway. These results should be helpful in designing more potent and selective HMGCR degraders.

Oxysterols in cosmetics-Determination by planar solid phase extraction and gas chromatography-mass spectrometry

Sterol oxidation products (SOPs) are linked to several toxicological effects. Therefore, investigation of potential dietary uptake sources particularly food of animal origin has been a key issue for these compounds. For the simultaneous determination of oxysterols from cholesterol, phytosterols, dihydrolanosterol and lanosterol in complex cosmetic matrices, planar solid phase extraction (pSPE) was applied as clean-up tool. SOPs were first separated from more non-polar and polar matrix constituents by normal phase thin-layer chromatography and then focussed into one target zone. Zone extraction was performed with the TLC-MS interface, followed by gas chromatography-mass spectrometry analysis. pSPE showed to be effective for cleaning up cosmetic samples as sample extracts were free of interferences, and gas chromatographic columns did not show any signs of overloading. Recoveries were between 86 and 113% with relative standard deviations of below 10% (n=6). Results of our market survey in 2016 showed that some cosmetics with ingredients of plant origin contained phytosterol oxidation products (POPs) in the low ppm range and therefore in line with levels reported for food. In lanolin containing products, total SOPs levels (cholesterol oxidation products (COPs), lanosterol oxidation products (LOPs), dihydrolanosterol oxidation products (DOPs)) being in the low percent range exceeded reported levels for food by several orders of magnitudes.

Synthesis of novel 24-amino-25,26,27-trinorlanost-8-enes: cytotoxic and apoptotic potential in U937 cells

In the present study, the synthesis of a range of novel 24-amino-25,26,27-trinorlanost-8-ene derivatives including 24-piperadino-trinorlanost-8-enes, 24-piperazino-trinorlanost-8-enes, 24-morpholino-trinorlanost-8-enes, and 24-diethylamino-trinorlanost-8-enes is reported and their cytotoxic and apoptotic potential evaluated in U937 cell lines. Excellent IC₅₀ results for piperidine and 1-(2-hydroxyethyl)piperazine derivatives have been observed (IC₅₀ values of 1.9 μM and 2.7 μM in U937 cells, respectively).

Steroids: partial synthesis in medicinal chemistry

This article reviews the progress in the chemistry of the steroids that was published between January and December 2004. The reactions and partial synthesis of estrogens, androgens, pregnanes, cholic acid derivatives, cholestanes and vitamin D analogues are covered. There are 127 references.