Natural products chemist Lester Mitscher, PhD, passed away on May 8, 2015, at the age of 83 after a battle with cancer. Throughout his lengthy and lauded career, Dr. Mitscher’s research and studies were devoted to naturally occurring antimicrobial and anticancer agents, including the untapped potential of herbal medicines. His work impacted scientists, researchers, students, and the natural products pharmaceutical industry. In particular, he focused on equipping and empowering laboratories in developing countries, holding training workshops at university chemistry departments.
While studying to earn his doctorate from Wayne State University in Detroit, Michigan, Dr. Mitscher had the opportunity to work under the late Carl Djerassi, PhD, on the structure of coffee (Coffea spp., Rubiaceae) oil diterpenes. Dr. Mitscher completed his PhD in 1958 and continued to pursue his interest in natural products chemistry, joining the staff of Lederle Laboratories in New York and eventually becoming a group leader in antibiotic discovery. He held the position until 1967, when he left New York to become an associate professor at the College of Pharmacy at Ohio State University. He gained full tenure before accepting a job in the department of medicinal chemistry at the University of Kansas School of Pharmacy in 1975. Though Dr. Mitscher would go on to pursue his interests in the industry and government sectors, he eventually returned to the University of Kansas in 1992. He remained a professor at the University until 2011, when he retired as a professor emeritus. He lent his name to the Lester A. Mitscher Faculty Fellowship in Medicinal Chemistry. During his tenure at Kansas, he also held academic appointments at the University of Missouri in Kansas City and the Victorian College of Pharmacy in Melbourne, Victoria, Australia.
In his work for the nonprofit International Organization for Chemical Sciences in Development (IOCD), Dr. Mitscher blended his research knowledge with a deep sense of philanthropy. “Les developed very simple antibacterial/anti-infective/antiviral assays which could be performed by chemists in typically poorly-equipped developing countries’ labs,” wrote Michael Tempesta, PhD, who worked closely with Dr. Mitscher at the IOCD (email, June 26, 2015). “[He] incorporated them into hands-on training workshops … in South America and Africa in the late 1980s and early 1990s.” This approach allowed scientists to conduct bioassays on various natural materials for active ingredients in their own facilities, negating the need to send samples abroad. “The foresight and cleverness of Les was apparent in this effort to provide powerful tools to chemists in developing countries,” added Dr. Tempesta. “Later, Les provided a complete electronic medicinal chemistry course via IOCD, which continues today and is quite popular.” Dr. Mitscher always included a session on intellectual property rights, allowing the scientists a better understanding of the patent process for natural products and more control over their own work.
Dr. Mitscher was published widely in the field of medicinal plants, with more than 270 research publications and seven technical books on natural product drug discovery and properties. He was on the editorial board of 20 journals, including the Journal of Medicinal Chemistry and the Journal of Natural Products, which published a special issue in his honor in 2013. He also consulted widely among industry pharmaceutical firms and for the National Institutes of Health, serving as senior advisory council member of firms such as Abbott Laboratories, Searle Laboratories, and DuPont-Merck, and as a member of the executive committee of the IOCD.
Dr. Mitscher was an active member of the scientific advisory board of Nu Skin Pharmanex, a global producer of natural consumer products based in Utah, for nearly 20 years, according to Mark Bartlett, PhD, vice president of global research and development at Nu Skin. “His expertise and experience as a natural products chemist contributed greatly to our ability to assess new ideas and innovate them into new products, especially in the area of nutrition and phytochemicals,” said Dr. Bartlett (email to M. Blumenthal, July 15, 2015). “Dr. Mitscher had a keen sense of humor and an infectious smile. He will certainly be missed by all of us at Nu Skin.”
Dr. Mitscher held 15 US and international patents, and his research and writing received numerous awards and recognitions throughout the industry, including the Research Achievement Award in Natural Products Chemistry from the American Pharmaceutical Association (now the American Pharmacists Association) in 1980, the Ernest H. Volwiler Award for Research Achievement from the American Association of Colleges of Pharmacy in 1985, the Higuchi-Simons Award in Biomedical Sciences at the University of Kansas in 1986, the Bristol-Myers Squibb/Edward E. Smissman Award in Medicinal Chemistry from the American Chemical Society in 1989, the Division of Medicinal Chemistry Award from the American Chemical Society in 2000, and the Norman R. Farnsworth Research Achievement Award from the American Society of Pharmacognosy in 2007.
Dr. Mitscher is survived by his wife of 62 years, Betty; sons, Kurt and Mark; three grandchildren; and five great-grandchildren. He was preceded in death by his daughter, Katrina Chapman, and his brother, Ronald. Services honoring his life were held in Lawrence, Kansas, on May 15, 2015. “Les was a very dedicated scientist,” concluded Dr. Tempesta, “with an excellent and dry sense of humor — a scientist’s scientist, and he will be missed by many.”
—Hannah Bauman