Principal Component and Hierarchical Cluster Analysis of Major Compound Variation in Essential Oil among Some Red Oregano Genotypes in Albania

Abstract

Red oregano (Origanum vulgare L. subsp. vulgare) is native to the mountainous slopes of Albania, thriving at altitudes ranging from 400 to 1300 m above sea level. The aerial components of oregano have been found to address a spectrum of health concerns. However, this subspecies presents intriguing characteristics that require comprehensive exploration and analysis. This study extensively analyzes the ex −situ collection of various genotype populations of red oregano in Albania. Essential oils were extracted by employing the hydrodistillation method. At the same time, their chemical analyses were carried out using gas chromatography coupled with a flame ionization detector (GC−FID) and gas chromatography coupled with a mass−spectrometer detector (GS−MS). We employed two statistical techniques, namely hierarchical cluster analysis (HCA) and principal component analysis (PCA), which allowed for a comprehensive examination of the relationships within the data set and more profound insights into the compositional patterns and interrelationships within the essential oils to be gained. The results revealed significant qualitative distinctions at the intraspecific level, particularly for sesquiterpenes, of populations originating from seven diverse geographic locations. The study’s findings enhance our understanding of the chemical composition of Albania’s red oregano and its chemical variation among different populations, which will potentially contribute to identifying the most suitable clones for breeding programs within red oregano populations.