title: A modern approach to the authentication and quality assessment of thyme using UV spectroscopy and chemometric analysis.
abstract: BACKGROUND
  Recently, the fields of chemometrics and multivariate analysis have been widely implemented in the quality control of herbal drugs to produce precise results, which is crucial in the field of medicine. Thyme represents an essential medicinal herb that is constantly adulterated due to its resemblance to many other plants with similar organoleptic properties.
  
  
  OBJECTIVE
  To establish a simple model for the quality assessment of Thymus species using UV spectroscopy together with known chemometric techniques. The success of this model may also serve as a technique for the quality control of other herbal drugs.
  
  
  METHODS
  The model was constructed using 30 samples of authenticated Thymus vulgaris and challenged with 20 samples of different botanical origins. The methanolic extracts of all samples were assessed using UV spectroscopy together with chemometric techniques: principal component analysis (PCA), soft independent modeling of class analogy (SIMCA) and hierarchical cluster analysis (HCA).
  
  
  RESULTS
  The model was able to discriminate T. vulgaris from other Thymus, Satureja, Origanum, Plectranthus and Eriocephalus species, all traded in the Egyptian market as different types of thyme. The model was also able to classify closely related species in clusters using PCA and HCA. The model was finally used to classify 12 commercial thyme varieties into clusters of species incorporated in the model as thyme or non-thyme.
  
  
  CONCLUSIONS
  The model constructed is highly recommended as a simple and efficient method for distinguishing T. vulgaris from other related species as well as the classification of marketed herbs as thyme or non-thyme.
authors.affiliation: Faculty of Pharmacy, Ain Shams University - Department of Pharmacognosy, Cairo, Egypt.
authors.forename: Haidy A
authors.initials: HA
authors.lastname: Gad
authors.forename: Sherweit H
authors.initials: SH
authors.lastname: El-Ahmady
authors.forename: Mohamed I
authors.initials: MI
authors.lastname: Abou-Shoer
authors.forename: Mohamed M
authors.initials: MM
authors.lastname: Al-Azizi
mesh_terms: D004534:Egypt; D010936:Plant Extracts / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry*; D025341:Principal Component Analysis; D011786:Quality Control; D013057:Spectrum Analysis / Q000379:methods*; D046930:Thymus Plant / Q000737:chemistry*
chemical_list: D010936:Plant Extracts
keywords: Chemometrics; UV spectroscopy; multivariate analysis; thyme