Campesterol formation

Microwave-assisted catalytic hydrogenation of steroid compounds, e. g. cholesterol, campesterol, sitosterol, etc., in the presence of Pd/C catalyst and ammonium formate in glycol solvent was fast and afforded the corresponding products in high yield (80-95%) and purity [42]. 

Unsaturated sterols such as cholesterol, campesterol, sitosterol and bile alcohols with unsaturated side chains can be transfer hydrogenated efficiently and with high yields under microwave irradiation, using ammonium formate and a Pd/C catalyst in methylene chloride/propylene glycol solvents (Scheme 4.3)17. 

The enzyme studied by Garcia and Mudd (1978d) did not distinguish between [ C]cholesterol and [ C]sitosterol in the formation of SE. Competition studies on sterols for [ C]cholesterol further indicated no specificity in the use of campesterol. The Km for cholesterol and sitosterol was estimated to be 57 pM. 

In D. tertiolecta, we were able to idenhfy the majority of enzymes responsible for the biosynthesis of stigmasterol and p-sitosterol. We have also identified the enzymes synthesizing episterol, a precursor of campesterol, which is an important phytosterol known to have potential antiosteoarthritic properties (Gabay et al., 2010). Episterol is also a precursor for ergosterol however, the biosynthetic pathway branches after (S)-squalene-2,3-epoxide formation and follows a different route. Due to the fact that we did not identify most of the... 

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