One is donated to the national herbarium or marine organism depository in the country of collection, and another is deposited with the Smithsonian Institution's Museum of Natural History in Washington, D.C. Plant products are dried and shipped by air freight. Marine products are shipped frozen. Once the plant specimen arrives at NPR, it is stored at -20 C for 48 hours to kill unwanted pests and pathogens. Frozen marine samples are ground in a large meat grinder, immersed in water, and centrifuged to separate the aqueous extract. Extracts showing significant selective cytotoxicity are provided to qualified research groups, including the NCI Laboratory for Drug Discovery Research and Development through the Active Repository Program.
Chemists isolate the active chemicals and determine their structures.
Novel active chemicals, which show sufficient activity against cancer, are advanced to preclinical development. One such collection is the American Type Culture Collection in Manassas, Virginia, which serves as a major repository for microbial cultures. Once the microorganism is cultivated, it goes through processing similar to that of plant and marine samples. The sample is extracted with water and organic solvents and is screened for cytotoxicity and anti-HIV activity. The extension of this program to organizations testing against all human diseases was implemented in 1999.