Mar 8, 2008

Women scientists, sixty years ago

Microscopic image (200-fold magnification) of Candida albicansNew York City, 1949. During the last three years, Elizabeth Hazen had been isolating hundreds of microbes from dirt samples taken at different locations. Many microbiologists at the time were following a path open by Alexander Fleming, Selman Waksman and others, who discovered that some soil microbes produced certain substances—antibiotics—with powerful activities against bacteria. However, rather than looking for a new agent against prokaryotic microbes, Elizabeth searched for a medicine to fight fungal infections. For this purpose, she grew the soil microbes and tested the cultures against disease-causing fungi (Cryptococcus neoformans, Candida albicans [see image]). Whenever a culture showed an interesting activity, she put it in a glass Mason jar and mailed it to Albany, 250-km away. Here, Rachel Brown—a chemist—used the culture for purification and characterization of the active compound. Then, Rachel mailed the fruit of her efforts back to New York, where the microbiologist tested the sample again for fungicidal potency. Through this collaboration, the two scientists isolated several antifungal compounds that, unfortunately, were too toxic when tested in laboratory animals.

Chemical structure of Nystatin A1But, finally, Elizabeth and Rachel found a useful fungicidal agent with a lower toxicity. It was produced by a soil bacterium isolated from a sample that Elizabeth had collected, while on holiday, in Warranton, Virginia. She had taken a bit of soil at the edge of a cow pasture, near a dairy barn, at the farm of a certain Walter B. Nourse. Because the microbe appeared to be a new species of streptomycetes, it received the name Streptomyces noursei, in honor of Mr. Nourse. The fungicidal agent was initially named fungicidin, but it was soon renamed nystatin, as both Elizabeth and Rachel worked for the New York State Department of Health (although in different locations). Since then, nystatin has been widely used to treat candidiasis and other fungal infections.

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This post modestly celebrates March 8th, International Women's Day. The discovery of nystatin seems a good example of an important contribution of women scientists to microbiology, natural product chemistry, and medicine. A related story is that of Alma Whiffen, who discovered cycloheximide—also known as actidione—around the same time (1947). She isolated the compound from cultures of a soil microbe, Streptomyces griseus. Cycloheximide has antifungal activity, and was employed to treat fungal infections in plants; however, it is not useful for human treatment. The compound is better known as a general inhibitor of protein synthesis in eukaryotes, and it is widely used for research purposes. Read more here:

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Image credits: Wikipedia.

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