Karl August Folkers was an American biochemist who made major contributions to the isolation and identification of bioactivenatural products. Karl August Folkers was born on September 1, 1906, in Decatur, Illinois. Folkers’s search for the anti-pernicious-anemia factor, begun in 1938, ended in 1948 with the isolation of a red crystalline compound now called vitamin B12. His research team also discovered mevalonic acid, which is a key substance in the production of numerous important biochemical compounds, including carotenoids, steroids, and terpenes. In 1948 Folkers’s team isolated, synthesized, and determined the structure of numerous members of the streptomycin group of antibiotics. His work also encompassed the antibiotics penicillin, grisein, oxamycin, neomycin, and novobiocin. In recognition for his scientific contributions, he received the Perkin Medal in 1960, the Priestley Medal in 1986, and the National Medal of Science in 1990. Folkers died on December 7, 1997 in Sunapee, New Hampshire, United States.