Towards Understanding the Bioactive Potential of Two Intriguing Nepeta Species: Metabolomic and Phylogenetic...

Nepeta govaniana and Nepeta subsessilis display metabolomes typical for the genus Nepeta L. (Lamiaceae), predominated by monoterpenoid iridoids and phenolic acids. Underexplored phytochemical composition and largely undefined biological potential are the main reasons for the underutilized status of these two intriguing species. This study fills some of the existing knowledge gaps by comprehensively analyzing the composition of methanol-soluble nonpolar, semi-polar, and polar metabolites in leaves, and providing the information about antimicrobial and antioxidant potential. Integration of comprehensive HPLC/MS and GC/MS metabolomics with plastid loci-derived (trnL-F, rbcL, and matK) phylogenetic data, revealed the phylogenetic relatedness of N. govaniana and N. subsessilis with congeneric species, and placed them within the Nepeta's chemotype A whose members produce both iridoid aglycones and glycosylated iridoids. Methanol extracts of these two phylogenetically related species displayed a notable antioxidant potential, but were less efficient as antimicrobial agents. Such results draw from the predominance of methanol-soluble polar compounds (polyphenolics and iridoid glycosides), exhibiting respectable antioxidant potential, and lower abundance of nepetalactone-type iridoids, known as potent antimicrobials. N. govaniana is here highlighted as a slightly more efficient antimicrobial and antioxidant agent than N. subsessilis, which can be ascribed to a higher content of methanol-soluble metabolites in leaves.