Metabolite Variations in Lepidium sativum Seeds Among Different Germplasms: Unraveling the Link Between Environment...

This research investigated the intraspecific phytochemical diversity in garden cress by analyzing the seed essential oils, fatty acid composition, and antioxidant activity of seed oils in various cultivated populations. The goal was to understand how phytochemical variations occur across populations and how these variations affect their biological activities. To conduct this study, approximately 500 g of seeds were harvested from each population across ten different locations. Essential oils were extracted using the hydrodistillation method with a Cleavinger-type apparatus, while seed oils were obtained through solvent extraction using a Soxhlet apparatus. Antioxidant activity was determined using the DPPH method. The resulting essential oils and seed oils were then analyzed with an Agilent gas chromatograph (GC) and gas chromatography-mass spectrometry (GC/MS) to identify their chemical profiles. Appropriate internal standards were used to enhance the accuracy of the analyses. The examined populations were distributed across the Holarctic and Paleotropical kingdoms, encompassing several floristic districts, indicating wide ecological adaptability. Essential oil yield was low and showed no significant difference among populations; however, it was significantly influenced by environmental factors, with positive correlations to habitat humidity and northern distribution and a negative correlation with solar radiation. Chemical analysis revealed hydrocarbon dominance in all populations, with benzyl nitrile identified as the major constituent, although its concentration varied considerably. Secondary constituents such as benzyl isothiocyanate, benzaldehyde, and other minor compounds showed population-specific variation. Multivariate analyses indicated distinct chemotypic groupings, although these were only weakly associated with geographic or phytogeographic factors. Seed oil fatty acid profiles were dominated by unsaturated fatty acids, particularly α-linolenic acid, with minor variation among populations, indicating relative metabolic stability. Antioxidant activity assessed by the DPPH assay was weak across all populations, with no significant pairwise differences detected. Overall, the results suggest that while essential oil yield is environmentally sensitive, core chemical composition and fatty acid profiles remain relatively stable. These findings highlight the combined influence of ecological conditions and intrinsic regulation on phytochemical variability in L. sativum.