Environmental Photochemistry of Altrenogest: Photoisomerization to a Bioactive Product with Increased Environmental Persistence via Reversible Photohydration

Abstract

Despite its wide use as a veterinary pharmaceutical, environmental fate data is lacking for altrenogest, a potent synthetic progestin. Here, it is reported that direct photolysis of altrenogest under environmentally relevant conditions was extremely efficient and rapid (half-life ∼25 s). Photolysis rates (observed rate constant kobs = 2.7 ± 0.2 × 10(-2) s(-1)) were unaffected by changes in pH or temperature but were sensitive to oxygen concentrations (N2-saturated kobs = 9.10 ± 0.32 × 10(-2) s(-1); O2-saturated kobs = 1.38 ± 0.11 × 10(-2) s(-1)). The primary photoproduct was identified as an isomer formed via an internal 2 + 2 cycloaddition reaction; the triplet lifetime (8.4 ± 0.2 μs) and rate constant (8 × 10(4) s(-1)) of this reaction were measured using transient absorption spectroscopy. Subsequent characterization determined that this primary cycloaddition photoproduct undergoes photohydration. The resultant photostable secondary photoproducts are subject to thermal dehydration in dark conditions, leading to reversion to the primary cycloaddition photoproduct on a time scale of hours to days, with the photohydration and dehydration repeatable over several light/dark cycles. This dehydration reaction occurs more rapidly at higher temperatures and is also accelerated at both high and low pH values. In vitro androgen receptor (AR)-dependent gene transcriptional activation cell assays and in silico nuclear hormone receptor screening revealed that certain photoproducts retain significant androgenic activity, which has implications for exposure risks associated with the presence and cycling of altrenogest and its photoproducts in the environment.

An Eleven-Year Review of Congenital Pulmonary Lesions in a Referral Children’s Hospital in Tehran

“…Annual incidence of congenital thoracic malformation is 4.4/10,000 (1). A subdivision of these is categorized as cystic lesions (2).…”

“…A subdivision of these is categorized as cystic lesions (2). There have always been controversies about their origin, nomenclature, pathology, and even therapeutic approaches (1,2). Congenital pulmonary airway malformation (CPAM), previously called congenital cystic adenomatoid malformation (CCAM), with the incidence of 1/11,000 to 1/35,000, is subdivided into five types (1)(2)(3).…”

“…There have always been controversies about their origin, nomenclature, pathology, and even therapeutic approaches (1,2). Congenital pulmonary airway malformation (CPAM), previously called congenital cystic adenomatoid malformation (CCAM), with the incidence of 1/11,000 to 1/35,000, is subdivided into five types (1)(2)(3). It is known that this lesion has the potential for prenatal regression and that it may retain its primary size or grow and bring about pulmonary hypoplasia and hydrops (2,3).…”

“…Bronchopulmonary Sequestrations (BPSs), as nonfunctional pulmonary tissues, comprise up to 14% to 30% of congenital lung lesions (1)(2)(3). They are classified as extra lobar sequestration (ELS) and intra lobar sequestration (ILS).…”

“…ILS is often located in the posterior basal segment of the left lower lobe. ELS, in almost 50% of cases, has associated malformations, such as congenital diaphragmatic hernia (1)(2)(3). ELS is found more often in the left lower lobe and is more prevalent in males (3).…”