title: Rapid measurement and evaluation of the effect of drying conditions on harpagoside content in Harpagophytum procumbens (devil's claw) root.
abstract: The effect of drying conditions on harpagoside (HS) retention, as well as the use of near-infrared spectroscopy (NIRS) for rapid quantification of the iridoids, HS, and 8-rho-coumaroyl harpagide (8rhoCHG) and moisture, in dried Harpagophytum procumbens (devil's claw) root was investigated. HS retention was significantly (P < 0.05) lower in sun-dried samples as compared to tunnel-dried (60 degrees C, 30% relative humidity) and freeze-dried samples. The best retention of HS was obtained at 50 degrees C when evaluating tunnel drying at dry bulb temperatures of 40, 50, and 60 degrees C and 30% relative humidity. NIRS can effectively predict moisture content with a standard error of prediction (SEP) and correlation coefficient (r) of 0.24% and 0.99, respectively. The HS and 8rhoCHG NIRS calibration models established for both iridoid glucosides can be used for screening purposes to get a semiquantitative classification of devil's claw roots (for HS: SEP = 0.236%, r = 0.64; for 8rhoCHG: SEP = 0.048%, r = 0.73).
authors.affiliation: ARC Infruitec-Nietvoorbij, Private Bag X5026, Stellenbosch 7599, South Africa. mman@sun.ac.za
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Joubert
authors.forename: Marena
authors.initials: M
authors.lastname: Manley
authors.forename: Brian R
authors.initials: BR
authors.lastname: Gray
authors.forename: Hartwig
authors.initials: H
authors.lastname: Schulz
mesh_terms: D003890:Desiccation / Q000379:methods*; D005612:Freeze Drying; D006027:Glycosides / Q000032:analysis*; D031684:Harpagophytum / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry*; D011714:Pyrans / Q000032:analysis*; D013472:Sunlight; D013678:Technology, Pharmaceutical; D013696:Temperature
chemical_list: D006027:Glycosides; D011714:Pyrans; C033249:harpagoside