Oleoyl‐estrone (OE) is a powerful slimming agent that is also present in plasma and adipose tissue, where it is synthesized. It acts through the formation of a derivative W. OE effects (and W levels) are proportional to the dose. OE reduces food intake but maintains energy expenditure (thermogenesis). The energy gap is fulfilled with adipose tissue fat, sparing body protein and maintaining glycemia (and glycogen) with lower insulin and leptin levels. OE (in fact W) acts through specific receptors, different from those of estrogen. OE increases cholesterol catabolism, reducing hypercholesterolemia in obese rats. The main metabolic effect on adipose tissue is lowering of lipid synthesis, maintaining unchanged the intracellular lipolytic processes; the imbalance favors the progressive loss of fat, which is largely used by the muscle. OE administration induces additive effects with other antiobesity agents, such as β3‐adrenergic agonists, forcing a massive loss of lipid. Corticosteroids markedly limit OE action by altering the liver control of lipogenesis. OE also inhibits the action of 17β‐hydroxysteroid dehydrogenase, decreasing the synthesis of β‐estradiol and testosterone. Discontinuous treatment allows for maximal efficacy both in rats and humans. OE has the advantage that the loss of fat is maintained and does not require additional dietary limitations.
Oleoyl‐3‐estrone (OE) is the ester of oleic acid (cis‐Δ9–10 octadecenoic) and estrone. It has a waxy consistence and high hydrophobicity. It is insoluble in water, but soluble in dimethyl‐sulfoxide and most organic solvents and vegetable oils. It is soluble in pure ethanol and methanol, but small portions of water rapidly decrease its solubility. OE chemical synthesis is relatively simple; it is formed by the reaction of oleoyl‐chloride with estrone in an organic medium containing an organic base (i.e. pyridine) to take away the protons and facilitate the coupling. The yield, even at ultramicroescale conditions, exceeds 60–70%. OE purification from estrone and remaining oleoyl‐chloride is slightly more difficult, but high degrees of purity up to 98% can be easily achieved if the purity of the initial reagents is also high. Impure oleic acid (i.e. containing the trans isomer, elaidic acid, other fatty acids or methyl‐esters) results in a softer product that keeps most of these impurities difficult to eliminate. (Med Res Rev. 2012 Nov;32(6):1263-91.)