Naturally occurring progesterone in loblolly pine (Pinus taeda L.): a major steroid precursor of environmental androgens.

Progesterone, androstenedione, and androstadienedione were previously identified in the water and sediment of the Fenholloway River (Taylor County, FL, USA), a river that contains populations of masculinized female mosquitofish downstream of a paper mill, at levels higher than those in the nearby Spring Creek. Plant sterols, such as beta-sitosterol in mill effluent derived from pine tree pulp, were suggested to be metabolized by bacteria to progesterone and androgens to account for the masculinization phenomenon. The current study made use of standard solid-phase methanol extraction procedures, high-performance liquid chromatography, liquid chromatography-mass spectrometry, and a cell-based, androgen-receptor transcription assay to determine naturally occurring progesterone levels in mature pine trees.