Vitamin C was long posited. Researchers Axel Holst and Alfred Frohlich,
for instance, had proposed its existence as early as 1907, but no definitive
agent emerged as the likely candidate. As researchers struggled to identify
the unique substance, one, Albert Szent-Györgyi, in the 1920s, was
making experimental connections others did not.
Born to a family that already included three generations of scientists,
Szent-Györgyi was interested in science from an early age. He enrolled
at the University of Budapest, but his studies were interrupted by the
outbreak of World War I. Fervently anti-war throughout his life, Szent-Györgyi
wounded himself to escape combat and returned to the university to finish
his studies in 1917. He was reputed to have said that he was "overcome
with such a mad desire to return to science that one day I grabbed my
revolver and in my despair put a shot through my upper arm."
Szent-Györgyi received a medical degree upon graduation, thereafter
studying at various European universities. He began his scientific career
by studying the chemical changes that occur when cells utilize foodstuffs,
such as carbohydrates, fats, and protein, a process sometimes known as
biological combustion. In the course of his studies Szent-Györgyi
isolated a molecule from adrenal glands that lost and regained hydrogen
atoms. This "hydrogen carrier," containing six carbon atoms,
had the properties of a sugar and an acid. Szent-Györgyi christened
it "hexuronic acid."
In the 1920s, he became interested in cell respiration and energy production
in plants, closely investigating the "browning" processes that
interrupted or impeded growth and normal functioning. Szent-Györgyi
discovered that as plants brown, they do so as a result of damage at the
cellular level: a breakdown in the mechanism that supplies enough hydrogen
to prevent excessive oxidation.
While conducting a series of experiments on citrus plants, he found that
browning could be induced with peroxidase, a plant enzyme active in oxidation.
Szent-Györgyi was then able to delay the browning with the addition
of citrus juice to the peroxidase. Further experiments allowed Szent-Györgyi
to isolate the protective hexuronic-acid agent he believed was active
in citrus juice.