Lippia integrifolia: Are there morphological, anatomical and biochemical differences among chemotypes?

Abstract Lippia integrifolia, commonly known as “incayuyo”, is a traditional aromatic and medicinal plant that grows wild in northwestern Argentina. Aqueous extracts of this species exert beneficial effects against affections of the gastrointestinal tract, mainly gastric inflammations. Across the wide distribution of L. integrifolia, there is a high variability in the essential oil composition and four chemotypes have been characterized based on the dominant terpenoids in their essential oil composition: trans-nerolidol, lippiafolienone, spathulenol/byciclogermacrene and trans-davanone. In the present work, the morphology, anatomy, chemical constituents and biochemical properties of the aqueous extract of different chemotypes of L. integrifolia were evaluated comparatively. The chemotype whose essential oil is dominated by trans-nerolidol showed significantly higher density of trichomes on the leaves and higher yield in aqueous extractions. Only quantitative variations of dominant metabolites in the aqueous extracts were found among the different chemotypes; those compounds were characterized as 6-methoxyluteolin-O-hexoside, 6-methoxyscutellarein-hexoside, B ring-dimethoxylated flavone-hexoside I, II and lippidulcine-A. In spite of the higher phenolic and flavonoid content, trans-nerolidol chemotype sample presented similar antioxidant properties compared with the other chemotypes. Additionally, the histochemistry of leaves of the trans-nerolidol chemotype was analyzed. The trans-nerolidol chemotype, which grows naturally in the province of La Rioja (Puerto Alegre), presents the best qualities for the medicinal use of the species, due to its higher yield in aqueous extractions and higher phenolic and flavonoid content.