Fruits and flowers are colorful, quite unlike leaves that have shades of gray. These natural colors, that are often shades of orange, yellow, and red come from carotenoids such as beta-carotene and xanthophylls. In addition, colors such as purple, blue and yellow come from flavinoids. Together, these bright and colorful compounds are a rich source of vitamins and anti-oxidants, that keep human body healthy and agile.
How did we discover chemistry behind these colorful natural substances
The person behind chemistry of carotenoids, structure of Vitamin A, and riboflavin is Paul Karrer. Born in 1889 to a dentist father, Paul started to study chemistry in 1908 at University of Zurich. He was initially trained under Alfred Warner in Zurich (who later got a Nobel Prize in chemistry in 1913), and later with Paul Ehrlich in Frankfurt (who had received a Nobel earlier in 1908). The two mentors, shaped his career. Ehrlich passed away in 1915, and Werner in 1918. Paul Karrer was eventually appointed to Werner’s chair at a young age of 29, in university of Zurich. He started working on organic chemistry, and isolating various substances, including carbohydrates, amino-acids, tannins and lecithin.
In 1927, Karrer started working on substances that give color to plant products. By next year, he and his team isolated a family of substances or carotenoids. By 1930, it was clear that all these compounds had similar chemical structures. As he discovered the structure of beta-carotene, he could also isolate its derivative – Vitamin A. Karrer went on to discover structures of Riboflavin, and energy generating co-enzymes we know as NAD and NADP. Thus he was awarded a 1937 Nobel Prize for these discoveries, along with WN Howarth, who discovered the structure of Vitamin C.
What do these discoveries mean ?
Discovery of structures of these vitamins, allowed these to be artificially produced. Today we know of more about 500 carotenoids, and can artificially produce beta-carotene as well as vitamin A. Beta-carotene is a precursor of Vitamin A or retinol. This in turn metabolizes to Retinoic acid, which is important for vision, reproductive as well as skin health. Knowing these structures helps us know the pathways of how these molecules work in human bodies. Today retinoids are also a family of useful compounds, that have diverse medicinal uses.
So the molecules, that give plant its colors are not only important nutrients, but are also an important physiological substance in humans. These colors after-all have a lot of lot of substance !!
