Table 3.
Analytical methods and methods of quality control.
| Topic | Year | Reference |
|---|---|---|
| Macroscopic and microscopic descriptions | 1964 | [58] |
| Macroscopic, microscopic, and chromatographic differentiation of commercial drug samples | 1973 | [218] |
| Macroscopic, microscopic, and chromatographic differentiation of commercial drug samples | 1974 | [219] |
| Simple TLC with Scrophularia nodosa as a reference standard | 1975 | [220] |
| Distribution of harpagoside within H. procumbens and H. zeyheri | 1977 | [221] |
| Standardization by determination of harpagoside, bitterness value, and dry residue | 1977 | [11] |
| Spectrometric method for the quantitative evaluation of the glycoiridoids | 1978 | [222] |
| Report of falsified, adulterated, and contaminated commercial products | 1978 | [214] |
| Quantitative determination of harpagoside via HPLC | 1980 | [223] |
| GLC method for the determination of harpagide and harpagoside | 1981 | [224] |
| Histological characteristics under scanning electron microscope | 1984 | [225] |
| Stability of iridoids during extraction | 1985 | [226] |
| Determination of harpagoside, luteolin, chlorogenic, caffeic, and cinnamic acid from extracts | 1986 | [227] |
| Analysis of permethylated iridoid glycosides by GC/MS | 1986 | [228] |
| Determination of harpagide, 8-p-coumaroyl harpagide (8-PCHG), and harpagoside by HPLC | 1994 | [229] |
| Analysis of the harpagoside content of commercial samples by HPLC | 1995 | [230] |
| TLC method for determination of harpagoside | 1995 | [231] |
| HPLC/UV for the determination of harpagoside in commercial powdered dry extracts | 1996 | [232] |
| HPLC/UV for the determination of harpagoside in commercial tea products | 1996 | [233] |
| HPLC/UV for the determination of harpagoside in commercial products (multiple dosage forms) | 1996 | [234] |
| HPTLC for quantitative determination of harpagoside | 1996 | [235] |
| HPLC determination of harpagide, 8-PCHG, and harpagoside in H. procumbens and H. zeyheri—ratio of harpagoside/8-PCHG can be used to distinguish species | 1997 | [19] |
| HPLC determination of ratio of harpagoside/8-PCHG, 8-PCHG < 8% proposed for H. procumbens | 1998 | [12] |
| Methods for quality control and stability testing of Harpagophytum homeopathic preparations | 1998 | [236] |
| HPLC/UV for the determination of harpagoside in commercial dry extract products | 1999 | [237] |
| Differentiation of H. procumbens (<9% 8-PCHG), mixtures (10–30% 8-PCHG), and H. zeyheri (>31 8-PCHG) proposed | 2000 | [13] |
| Biopharmaceutical quality, release of active ingredients in vitro, and disintegration tests | 2000 | [238] |
| Methods for detection of adulterations and contaminations | 2001 | [239] |
| Bioequivalence of Harpagophytum products | 2002 | [240] |
| Near infrared spectroscopy (NIRS) determination of harpagoside, 8-PCHG, and their ratio | 2003 | [241] |
| NIR-FT-Raman spectroscopy for identification and quantification of harpagoside | 2005 | [242] |
| Determination of harpagoside from CO2-extracts with HPLC and HPTLC-densitometry | 2005 | [243] |
| NIRS determination of harpagoside, 8-PCHG, and their ratio | 2005 | [244] |
| Fast HPLC determination of harpagoside using a monolithic silica column | 2005 | [245] |
| Validation of a fast-HPLC for separation of iridoid glycosides to distinguish between species | 2005 | [246] |
| LC-DAD-MS/SPE-NMR hyphenation for identification of isobaric iridoid glycoside regioisomers | 2005 | [247] |
| X-ray fluorescence spectrometry (SRTXRF) to determine trace elements | 2005 | [248] |
| Determination of aflatoxin B1 | 2006 | [249] |
| LC/MS determination of harpagoside, 8-PCHG, and their ratio | 2006 | [250] |
| Computational study to estimate the proton and sodium cation affinities of harpagide | 2006 | [251] |
| Quality parameters of finished products in the German market | 2006 | [252] |
| Proposal to revise the drug–extract ratio of aqueous/ethanolic extracts | 2006 | [253] |
| Methods for determination of minerals and heavy metals | 2007 | [254] |
| Analysis of iridoids in horse urine | 2008 | [255] |
| Solid-phase extraction for LC/MS analysis of harpagoside, 8-PCHG, and harpagide in equine plasma | 2008 | [256] |
| Validated HPTLC method for the determination of harpagoside | 2008 | [257] |
| High-Pressure Liquid Chromatography-Diode Array Detection (HPLC-DAD) for harpagoside and isoacteoside contents | 2009 | [258] |
| HPLC-DAD and HPLC–ESI-MS analyses of stability of the constituents | 2011 | [181] |
| Anatomical study of secondary tubers and quantification of harpagoside by HPLC | 2012 | [259] |
| Authenticity and contamination tests by DNA barcoding | 2013 | [260] |
| Exploring species substitution through chemometric modeling of 1H-NMR and UHPLC-MS | 2014 | [182] |
| Mid-infrared spectroscopy and short-wave infrared hyperspectral imaging for qualitative assessment of H. procumbens and H. zeyheri | 2014 | [85,88] |
| Morphology, histochemistry, and ultrastructure of foliar mucilage-producing trichomes | 2014 | [261] |
| NMR-based chemometric approach for species differentiation | 2014 | [262] |
| UPLC Q-TOF ESI determination of harpagosides in H. procumbens, H. zeyheri, and extracts | 2016 | [263] |
| Loss on drying and total ash | 2016 | [264] |
| Comparison of microwave and ultrasound-assisted with conventional solvent extraction methods for harpagoside determination | 2016 | [265] |
| Innovative micro-extraction techniques to determine harpagoside and phenolic patterns in H. procumbens and finished products | 2017 | [266] |
| Determination of suitable extraction solvent | 2017 | [267] |
| GC-MS determination of chemical constituents | 2017 | [268] |
| DNA barcoding to detect contamination and substitution | 2017 | [269] |
| HPLC and MS analyses of spagyric tinctures | 2019 | [270] |
| Validated RP-HPLC-PDA method for quantification of harpagoside in extracts and finished products | 2019 | [271] |
| UPLC–MS profiling of samples from different locations | 2019 | [90] |
| Determination of macro- and micro-elements in finished products using ICP OES | 2020 | [272] |
| HPLC method for harpagoside determination in finished product (tablet) | 2020 | [273] |