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The merits of chemometrics in categorizing different Egyptian olive chemovarieties based on their compositional integrity were implemented in this study. Fingerprints of 9 different olive leaves varieties cultivated in Egypt were established using reversed-phase high-performance thin-layer chromatography (RP-HPTLC) prior to and after post-chromatographic derivatization with natural product-polyethylene glycol (NP/PEG) reagent and image analysis using ImageJ® software in order to build 2 separate data matrices. The chromatographic fingerprints were separately subjected to unsupervised pattern recognition multivariate analysis to build 2 separate models using principal component analysis (PCA) and hierarchical clustering analysis (HCA) algorithms to explore the distribution pattern of different chemovarieties. The second model which involved olive samples’ fingerprints after post-chromatographic derivatization exhibited greater ability to reveal a broader spectrum of phytoconstituents with enhanced sensitivity. Densitometric RP-HPTLC quantification of oleuropein marker was compared to image analysis approach using Sorbfil TLC Videodensitometer® by newly developed and validated methods. Densitometry exhibited better performance characteristics than image analysis method and therefore was executed for determination of oleuropein concentration in the 9 Egyptian olive varieties. Oleuropein marker solely was found to be inadequate for standardization of olive leaves varieties. This study demonstrated a comprehensive approach for the rapid classification of different Egyptian olive varieties, which is crucial to warranting their chemical-consistency and, thereafter, effective consistency.

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Effects of cultivation variety, collection time, and climate on amounts of oleuropein (OE), a strong antioxidant, in olive leaves were studied. A modified ultrasound-assisted method was used for efficient and quantitative extraction of OE from olive leaf samples before their analysis by a rapid HPLC method. Under the optimized conditions, the extraction was performed in two successive steps with an RSD better than 2.95% (n = 5) and a detection limit of 0.02 μg OE. The amount of OE was determined in twelve samples of olive leaves from Mary Zeitoon, Koroneiki, and Sevillana varieties cultivated in three different regions of Iran after collection in two different seasons. The results confirmed that the amounts of OE varied in different olive varieties with mean values of 127, 115, and 144 μg g−1, respectively, although statistical tests indicated a significant interaction of collection time and climate with olive variety. In general, the OE concentration was significantly higher in the cold season and in the tropical regions than in the hot season and the temperate region.

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Ciafardini, G., Marsilio, V., Lanza, B. & Pozzi, N. (1994): Hydrolysis of oleuropein by Lactobacillus plantarum strains associated with olive fermentation. Appl. environ. Microbiol

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Bisignano, G. , Tomaino, A. , Lo Cascio, R. , Crisafi, G. , Uccella, N. & Saija, A. (1999): On the in-vitro antimicrobial activity of oleuropein and hydroxytyrosol. J. Pharmacy Pharmacol , 51 , 971

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605 612 Ciafardini, G., Marsilio, V., Lanza, B. & Pozzi, N. (1994): Hydrolysis of oleuropein by Lactobacillus plantarum strains associated with olive

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