Dienogest is a high potency progestin used in oral contraceptives to treat endometriosis. Dienone steroids, such as dienogest, can degrade via direct photolysis in sunlit surface waters. Dienogest undergoes rapid phototransformation (t<sub>1/2</sub>~ 1 min at pH 7) to produce mixtures of products, some with known biological activity. Of the numerous phototransformation products, the three major photoproducts are light-stable photohydrates. These photohydrates undergo a thermal dehydration reaction in the dark, regenerating the parent compound to nearly 40% of original mass at pH 7, thus increasing the environmental persistence of dienogest. One minor product of interest is dienogestenol, an unusual phenolic rearrangement product with a novel 6,5,8,5-ring system. The tetracylic unit of dienogestenol consists of an aromatic A ring, a cyclooctene C ring, and cyclopentane B and D rings. Literature suggests that the tricyclic unit (i.e., rings A-C) exists as a subunit of synthetic analogues of dibenzocyclooctenes, which are known to have biological activity that cause central nervous system effects. Although initially minor in yield (~5% of mass), the enrichment of dienogestenol through diurnal, light-dark cycling will likely dominate the long-term fate of dienogest in sunlit aquatic environments. This study involved a 6-hour photolysis (light) followed by an 18-hour regeneration (dark) cycle to enrich dienogestenol over a three-day period in order to examine its potential environmental persistence and accumulation. <br/>

Diurnal enrichment of an initially minor bioactive rearrangement product from the aqueous photolysis of dienogest

2019 Spring National Meeting

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