The ratio of cholesterol 5,6-secosterols formed from ozone and singlet oxygen offers insight into the oxidation of cholesterol in vivo

Ongoing efforts to unravel the origins of the cholesterol 5,6-secosterols (1a and 1b) in biological systems have revealed that the two known chemical routes to these oxysterols, ozonolysis of cholesterol (3) and Hock-cleavage of 5-alpha-hydroperoxycholesterol (4a), are distinguishable based upon the ratio of the hydrazone derivatives (2a and 2b) formed in each case and this ratio offers an insight into the chemical origin of the secosterols in vivo.