title: Diurnal fluctuations of cocaine and potential precursors in leaves of Erythroxylum coca.
abstract: Cocaine is abundant in leaves of Erythroxylum coca var. coca Lam. Consequently, cocaine and two of its early biosynthetic precursors were monitored for 24 h to determine whether they fluctuated diurnally. E. coca was grown under controlled environmental conditions in a growth chamber in soil at pH 3.5. After 17.5 months of growth, leaves not less than 35 days old were harvested every 2 and 4 h for 24 h for arginine, phenylalanine and cocaine content, respectively. The content of cocaine was determined by GC/MS and amino acid content by HPLC. Diurnal fluctuation of cocaine occurred during the 24 h cycle. Cocaine was highest in leaves of E. coca at 8 and 16 h where its content was 7.67 and 9.45 mg.g-1 dry weight, respectively. Arginine and phenylalanine in leaves of E. coca also displayed diurnal rhythmic patterns of fluctuation. The content of arginine declined from hours 6 to 12 and increased to the highest content at 13 h (21.8 mg.g-1 dry weight). Overall, phenylalanine content was lower than arginine, but had two peak periods of accumulation during the 24 h cycle, occurring at 8 and 14 h. The content of phenylalanine in leaves of E. coca during the peak hours was 6.98 and 6.54 mg.g-1 dry weight, respectively.
authors.affiliation: United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705-2350.
authors.forename: E L
authors.initials: EL
authors.lastname: Johnson
mesh_terms: D000470:Alkaloids / Q000302:isolation & purification / Q000378:metabolism*; D000596:Amino Acids / Q000302:isolation & purification / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D002940:Circadian Rhythm; D003042:Cocaine / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D010944:Plants / Q000378:metabolism*
chemical_list: D000470:Alkaloids; D000596:Amino Acids; D003042:Cocaine