6-epidoxycycline (Crude)

6-epidoxycycline (Crude) is a tetracycline derivative featuring a 6β-hydroxy configuration, contrasting the 6α-hydroxy group in doxycycline. Its core structure includes a dimethylamino group at C4, a methylene bridge at C10a, and conjugated ketone systems across the tetracyclic ring. The compound arises via epimerization during doxycycline synthesis or degradation, retaining the 10-methyl substitution and 11a-hydroxy lactone moiety. This impurity exhibits distinct chromatographic behavior due to altered stereochemistry, serving as a critical HPLC reference standard for quantifying process-related impurities in doxycycline formulations.