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Introduction: Catnip (Nepeta cataria L.) produces volatile iridoid terpenes, mainly nepetalactones, with strong repellent activity against species of arthropods with commercial and medical importance. Recently, new catnip cultivars CR3 and CR9 have been developed, both characterized by producing copious amounts of nepetalactones. Due to its perennial nature, multiple harvests can be obtained from this specialty crop and the effects of such practice on the phytochemical profile of the plants are not extensively studied. Methods: In this study we assessed the productivity of biomass, chemical composition of the essential oil and polyphenol accumulation of new catnip cultivars CR3 and CR9 and their hybrid, CR9×CR3, across four successive harvests. The essential oil was obtained by hydrodistillation and the chemical composition was obtained via gas chromatography-mass spectrometry (GC-MS). Individual polyphenols were quantified by Ultra-High-Performance Liquid Chromatography- diode-array detection (UHPLC-DAD). Results: Although the effects on biomass accumulation were independent of genotypes, the aromatic profile and the accumulation of polyphenols had a genotype-dependent response to successive harvests. While cultivar CR3 had its essential oil dominated by E,Z-nepetalactone in all four harvests, cultivar CR9 showed Z,E-nepetalactone as the main component of its aromatic profile during the 1st, 3rd and 4th harvests. At the second harvest, the essential oil of CR9 was mainly composed of caryophyllene oxide and (E)-ß-caryophyllene. The same sesquiterpenes represented the majority of the essential oil of the hybrid CR9×CR3 at the 1st and 2nd successive harvests, while Z,E-nepetalactone was the main component at the 3rd and 4th harvests. For CR9 and CR9×CR3, rosmarinic acid and luteolin diglucuronide were at the highest contents at the 1st and 2nd harvest, while for CR3 the peak occurred at the 3rd successive harvest. Discussion: The results emphasize that agronomic practices can significantly affect the accumulation of specialized metabolites in N. cataria and the genotype-specific interactions may indicate differential ecological adaptations of each cultivar. This is the first report on the effects of successive harvest on these novel catnip genotypes and highlights their potential for the supply of natural products for the pest control and other industries.
RESUMO
HIGHLIGHTS Essential oils from populations of B. dracunculifolia were investigated. β-pinene and (E)-nerolidol were the main compounds in B. dracunculifolia populations. The difference in the chemical profile of the essential oils is quantitative only. There is a negative correlation between the antioxidant activity and spathulenol.
Abstract Baccharis dracunculifolia DC. is a Brazilian native plant, presenting wide chemical diversity and numerous pharmaceutical and industrial applications. This research assessed the yield, antioxidant activity and the chemical similarity of essential oils from 10 populations of B. dracunculifolia in the state of Paraná, southern Brazil. The extraction of the volatile compounds was carried out by hydrodistillation, the chemical composition was determined by GC/FID and GC/MS and the antioxidant activity by the DPPH method. The essential oil yield of wild B. dracunculifolia populations ranged from 0.14 to 0.87%. The oils were predominantly composed of oxygenated sesquiterpenes (34.16 - 51.01%), monoterpene hydrocarbons (18.02 - 46.17%) and sesquiterpenes hydrocarbons (9.60 - 17.70%). The major compounds found in all populations were β-pinene (7.65 - 29.8%) and (E)-nerolidol (9.11 - 21.68%). Essential oil solutions (20%) from different populations presented antioxidant capacity ranging from 27.78 to 91.67%. A negative correlation was found between the antioxidant activity and spathulenol (r = -0.696). Multivariate analyses separated the populations into three groups: (1) low concentrations of α-pinene (2.02 - 2.06%), (2) high concentrations of α-pinene (4.17 - 4.61%) and β-pinene (22.54 - 29.80%), and (3) intermediate concentrations of α-pinene (2.38 - 3.31%), β-pinene (12.77 - 19.03%) and spathulenol (6.02 - 9.06%).