Secondary metabolic profile of rose-scented geranium: A tool for characterization, distinction and quality control of Indian genotypes

Rose-scented geranium (Pelargonium graveolens L'Herit. ex Aiton), belonging to the family Geraniaceae, has gained considerable attention because of its fragrance and high economic value. The compositional complexity of rose-scented geranium essential oil (GEO) has been challenging for quality control. In this study, the chemical profiles of GEOs extracted from Indian cultivars/genotypes were developed using polarity-based fractionation, followed by characterization using a combination of gas chromatography (GC-FID), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance spectroscopy (NMR). The analysis led to the identification of 121 compounds. Major components of the GEOs were citronellol (22.4-42.2 %), geraniol (5.7-30.5 %), linalool (2.1-9.8 %), citronellyl formate (4.0-9.5 %), isomenthone (5.3-7.5 %), geranyl formate (2.0-5.1 %), 6,9-guaiadiene (0.0-4.3 %), 10-epi-gamma-eudesmol (0.2-6.4 %), 2-phenyl ethyl tiglate (1.0-2.1 %), geranyl tiglate (1.4-2.7 %), germacrene D (0.8-1.7 %) and geranial (0.4-1.6 %). This study identified effective markers which could help determine the authenticity of Indian cultivars/genotypes. Physical properties and chromatographic profiles of GEOs and terpeneless GEOs (TLOs) derived from Indian cultivar/genotype were compared. The twostep chromatographic separation coupled with principal component analysis allowed the identification of possible markers. The presence or absence of the sesquiterpenes, namely 10-epi-gamma-eudesmol, 6,9-guaiadiene, and some other minor constituents, physical, and organoleptic properties, could effectively distinguish and define the quality of Indian cultivars/genotypes. Besides, the GEOs and TLOs prepared from different cultivars exhibited significant antimicrobial activity against Staphylococcus aureus and Candida albicans.