Comparative Phytochemical Analysis of the Aerial Parts of Pelargonium radula and Geranium macrorrhizum Cultivated in Bulgaria Using GC-MS and HPLC

Background: Geraniaceae species are widely used in traditional medicine. Pelargonium radula and Geranium macrorrhizum are aromatic medicinal plants traditionally used in Bulgaria for their antimicrobial, anti-inflammatory, and wound-healing properties. Comparative phytochemical data on Pelargonium radula and Geranium macrorrhizum cultivated in Bulgaria, however, remain limited. The present work aimed to characterize and compare the chemical composition of essential oils and main phenols, in support of future pharmacological evaluation. Methods: Essential oils from aerial parts of both species were obtained by hydrodistillation and analyzed by GC-MS. Through HPLC-UV, ethanol extracts were evaluated to quantify the major phenolic acids and flavonoids. Results: The yield of essential oils was 0.10% for P. radula and 0.03% for G. macrorrhizum, dominated by oxidized monoterpenes, mainly citronellol and geraniol-type compounds. HPLC analysis revealed marked differences in their phenolic profiles. P. radula showed a composition with six phenolic acids—primary protocatechuic and ferulic acids, and very low levels of flavonoids, with rutin being the only quantifiable glycoside. In contrast, G. macrorrhizum contained nine phenolic acids and four flavonoids, with remarkably high levels of salicylic, rosmarinic, and p-coumaric acids, as well as catechins, absent in P. radula. Conclusions: The two species showed different phytochemical characteristics in both their volatile and non-volatile fractions. P. radula is characterized by a citronellol/geraniol-rich essential oil and a moderate phenolic profile, while G. macrorrhizum exhibits significantly higher phenolic diversity and abundance. These findings expand the current phytochemical knowledge of both taxa and provide a solid basis for future chemotaxonomic and pharmacological studies. The obtained results suggest that Geranium macrorrhizum may be more promising for antioxidant and anti-inflammatory applications, while Pelargonium radula may be preferentially explored for ant-microbial purposes.