Prof. Gregory Oxenkrug, MD (Pavlov Medical Academy, 1965), PhD (Bekhterev Psychoneurological Research Institute ,1970), St. Petersburg, Russia, is internationally recognized as one of the pioneers in the field of psychopharmacology for his studies of serotonin - melatonin and kynurenine (Kyn) – NADF+ pathways of tryptophan (Trp) catabolism in psychiatric disorders and aging. Major contributions to the field are: Serotonin-Kyn hypothesis of major depressive disorder [Lancet. 1969;1(7586):132–136]; Prolongation of life span of Drosophila by genetic or pharmacologic inhibition of Trp – Kyn pathway [J Neural Transm, 2009, 117: 23-26]; Anthranilic acid hypothesis of cognitive impairment in neurodegenerative disorders and aging [Int. J. Mol. Sci. 2024,25, 13269]; 4). Discovery of antidepressant and antiaging effects of N-acetyl-serotonin and anti-hypertensive effect of melatonin [Curr Drug Targets. 2013;14 :514-21]. Academic appointments: Professor of Psychiatry, Tufts University, Boston, MA (1994 – Emeritus Professor from July 2025 - present); Brown University, Providence, RI (1988 – 1994), Wayne State University, Detroit, MI (1982-1988). He was Chairman, Department of Psychiatry, St. Elizabeth's Medical Center, Boston, MA (1994-2005); and Chief, Psychiatry Service, VA Hospital, Providence, (1988-1994). He is Fellow Emeritus of American, Canadian and International Colleges of Neuropsychopharmacology and Life member, International Society for Tryptophan Research.