Turkesterone

Turkesterone is a naturally occurring phytoecdysteroid, one of a family of roughly two hundred plant steroids built around the same skeleton as 20-hydroxyecdysone, the hormone that controls moulting in insects ^[1]. Structurally it is closely related to 20-hydroxyecdysone, differing by an extra hydroxyl group at the 11-alpha position, and it is one of the major ecdysteroids of the plants that make it ^[2]. Like other members of the class it is a polyhydroxylated steroid distinct from the androgens.

The compound takes its name from Ajuga turkestanica, a plant of the mint family used in traditional medicine and regarded as a rich source; ecdysteroid analysis of that species has identified turkesterone alongside 20-hydroxyecdysone and numerous minor ecdysteroids ^[2]. Phytoecdysteroids in general occur across many plant families, including species of Vitex and Rhaponticum and even common crops, where they are thought to help defend the plant against insects ^[1].

In recent years turkesterone has been marketed as a dietary supplement for muscle growth and athletic performance. The human evidence specific to turkesterone is essentially absent; its absorption, bioavailability and effects in people have not been established ^[1]. Most of what is claimed is extrapolated from animal studies and from research on the closely related ecdysteroid ecdysterone, for which a controlled trial in strength-training men reported increases in muscle mass and performance and proposed that the effect is mediated through estrogen receptor binding rather than the androgen receptor ^[3].

Because ecdysteroids do not appear to act on the androgen receptor, they are described as non-conventional or non-androgenic anabolics, and proposed mechanisms include estrogen-receptor-beta signalling and activation of protein-synthesis pathways. Older animal experiments with turkesterone reported anabolic, blood-sugar-lowering and red-blood-cell-stimulating effects broadly comparable in direction to a steroidal anabolic drug ^[4][5]. These findings, however, come from laboratory and animal work and have not been confirmed in controlled human studies.

Turkesterone is sold as a botanical supplement rather than an approved medicine, and product quality and ecdysteroid content vary between preparations. It is not a controlled substance, though anti-doping researchers have argued that the related ecdysterone should be added to prohibited lists for sport; safety data for concentrated turkesterone in humans are limited ^[3].

Appears well tolerated in the short term, with occasional GI upset or nausea reported. Because it does not act on androgen receptors, it lacks classic steroid side effects, but long-term human safety data are lacking. Product contamination and mislabeling are practical concerns.