Chemistry
Pangamic acid is the name given to the chemical compound with the empirical formula C10H19O8N and a molecular weight of 281 which appeared to be an ester derived from -gluconic acid and dimethylglycine. In 1943, the Krebses applied for a patent for a process for extracting this chemical compound which they reported had been previously isolated from apricot seeds, and received the patent in 1949. A 1951 paper by the Krebses reported the first isolation of this compound using this patented process, but did not include enough information to confirm that this compound was actually isolated. In 1955, the Krebses received a patent for another synthesizing process for "N-substituted glycine esters of gluconic acid," but the patent contained no supporting data to confirm the process was able to synthesize compounds described by the patent, including pangamic acid.
Subsequent attempts at synthesizing this ester by other researchers found Krebs' purported methods of producing pangamic acid were not reproducible, and research into pangamic acid have focused on compounds of various chemical compositions. A review noted that of all the chemicals described in research about pangamic acid, "ot a single product labeled "pangamate" or "B15" has been established in a scientifically verifiable manner to conform to the empiric formula" described by the Krebses. Analysis of a sample of a compound called "pangamic acid" which was provided by a co-worker of the Krebses in the 1950s showed only lactose upon further evaluation by nuclear magnetic resonance spectroscopy. Thus, "pangamic acid" is more a label used to describe one of any number of chemical compounds rather than a particular substance.
Chemical compounds sold as "pangamic acid" for medicinal purposes have also had various chemical compositions, and suppliers of "pangamic acid" have regularly changed the chemical composition of the compounds sold under this label. One anecdote noted that the FDA has seized lots of calcium pangamate sold by General Nutrition Center (GNC), which agreed to stop selling the compound in those bottles after the FDA filed suit to stop sales. Afterwards, it was noted that GNC was still selling something in the same bottles with the same labels, likely a different compound. Due to ambiguity in situations like this, the Food and Drug Administration (FDA) considers it "not an identifiable substance."
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