Hordenine is a natural Phenethylamine compound that occurs in a number of different plants, but especially barley grass. It is structurally similar to the amino acid Tyramine. It antagonized D2-mediated beta-arrestin recruitment indicating functional selectivity. Hordenine inhibited melanogenesis by suppressing cAMP production, which is involved in the expression of melanogenesis-related proteins. Hordenine may be an effective inhibitor of hyperpigmentation. Hordenine is an indirectly acting adrenergic drug. It liberates norepinephrine from stores. In isolated organs and those structures with reduced epinephrine contents, the hordenine-effect is only very poor. Experiments in intact animals (rats, dogs) show that hordenine has a positive inotropic effect upon the heart, increases systolic and diastolic blood pressure, peripheral blood flow volume, inhibits gut movements but has no effect upon the psychomotorical behavior of mice. Hordenine is considered to be generally very safe and well-tolerated in healthy adults. Hordenine is a nootropic compound that works equally well for cognitive enhancement and athletic performance.

Emoxypine (ethylmethylhydroxypyridine) succinate (MEXIDOL®) is a 3-hydroxypyridine derivative which is quite similar in structure to Vitamin B6 (pyridoxine). The most important components of the mechanism of action of Mexidol® are its antioxidant and membranotropic effects, the ability to modulate functioning of receptors and membrane-bound enzymes, restore a neurotransmitter balance. Due to its mechanism of action Mexidol® has a wide range of pharmacological effects, realized on at least two levels – neuronal and vascular. It has antihypoxic, anti-ischemic, neuroprotective, nootropic, vegetotrophic, anti-stress, anxiolytic, anticonvulsant, anti-alcohol, cardioprotective, anti-atherogenic, geroprotective and other actions. Under the action of Mexidol®, it is observed an improvement in cerebral circulation and microcirculation. Emoxypine is distributed in Russia but it is widely unknown in other regions.

WAY-100635 is an achiral phenylpiperazine derivative that originally discovered as an antagotist of 5-HT1A receptor. Later WAY-100635 was described as a potent dopamine D4 receptor agonist. WAY-100635 was in preclinical studies for the treatment of Diabetes mellitus, Anxiety and Cognition disorders, howevere the development was discontinued. Isotope labeled WAY-100635 could be used for the study of central 5-HT 1A receptors with potential for application to the study of neuropsychiatric disorders and to the human pharmacology of psychoactive drugs.