Sensory and instrumental evaluation of catnip (Nepeta cataria L.) aroma

Functional analysis of (E)-β-farnesene synthases involved in accumulation of (E)-β-farnesene in German chamomile (Matricaria chamomilla L.)

German chamomile (Matricaria chamomilla L.) is a traditional medicinal aromatic plant, and the sesquiterpenoids in its flowers have important medicinal value. The (E)-β-farnesene (EβF) is one of the active sesquiterpenoid components and is also a major component of aphid alarm pheromones. In this study, two EβF synthase (βFS) genes (McβFS1 and McβFS2), were cloned from German chamomile. Subcellular localization analysis showed that both McβFS1 and McβFS2 were localized in the cytoplasm and nucleus. Tissue-specific expression analysis revealed that McβFS1 and McβFS2 were expressed in all flower stages, with the highest levels observed during the tubular flower extension stage. Prokaryotic expression and enzyme activity results showed that McβFS1 and McβFS2 possess catalytic activity. Overexpression of McβFS1 and McβFS2 in the hairy roots of German chamomile led to the accumulation of EβF, demonstrating enzyme activity in vivo. The promoters of McβFS1 and McβFS2 were cloned and analyzed. After treating German chamomile with methyl jasmonate (MeJA) and methyl salicylate (MeSA), the transcription levels of McβFS1 and McβFS2 were found to be regulated by both hormones. In addition, feeding experiments showed that aphid infestation upregulated the expression levels of McβFS1 and McβFS2. Our study provides valuable insights into the biosynthesis of EβF, laying a foundation for further research into its metabolic pathways.

Investigation of Volatile Iridoid Terpenes in Nepeta cataria L. (Catnip) Genotypes

Catnip (Nepeta cataria L.) is of scientific interest largely due to the production of nepetalactones, volatile iridoid terpenes with strong arthropod repellent activity. However, the plant can also produce other bioactive volatile iridoids, such as nepetalic acid (NA), nepetalactam (NT) and dihydronepetalactone (DHNL) that have not been studied extensively. Germplasm studies on plants that can produce such compounds are scarce. The present study evaluated the chemical diversity of catnip genotypes with a focus on NA, NT and DHNL. A total of 34 genotypes were harvested at different times over two years. The ethanolic extract of the plants was screened for iridoids by ultra-high-performance liquid chromatography/triple quadrupole mass spectrometry. CR9 × CR3 genotype had the highest value for biomass yield, while cultivar CR9 had the highest value for accumulated NA. Genotype UK.2 had the highest value for accumulated NT yield and CR5 had the highest value for accumulated DHNL. Overall, patented cultivars and elite selections performed better than other less studied genotypes. Harvest time influenced the accumulation of secondary metabolites differentially for the genotypes. This is the first germplasm study with a focus on these iridoid compounds, yet more studies are necessary as genotype characterization is essential for breeding and standardization of products for industry.

Volatolomics of Sardinian and Spanish Bituminaria: Characterization of Different Accessions Using Chemometrics

The present study aims to determine the volatile compositions of 15 different accessions of native Sardinian populations of Bituminaria morisiana (Pignatti & Metlesics) Greuter, Bituminaria bituminosa (L.) C. H. Stirt. (B. b.), and Spanish native accessions of B. bituminosa. Furthermore, we particularly focused on the essential oil characterization of these accessions and discriminated within populations with low furocoumarin content useful for fodder production in Mediterranean environments or furocoumarin extraction for pharmaceutical utilization. The plant extracts were analyzed by GC/MS, showing great variability in the content and composition. No differences were found in Bituminaria bituminosa (L.) C.H. Stirt. var. bituminosa essential oils, while the varieties Bituminaria bituminosa (L.) C.H. Stirt. var. crassiuscula P. Méndez, Fern. Galván & A. Santos and Bituminaria bituminosa (L.) C.H. Stirt. var. albomarginata P. Méndez, Fern. Galván & A. Santos are characterized by the presence of a high concentration of long-chain alcohols and of salicylic acid benzylic ester. In B. bituminosa var. albomarginata, we observed a different profile with predominance of a large concentration of alcohols as dodecanol and tetradecanol. The endemic B. morisiana can be identified for the predominant presence of farnesene. In methanolic fractions, we detected the presence of maltol, methyl citrate, methyl cumarate, santonin, and methyl linoleate. B. morisiana showed a low content of psoralens, and the accession of B. morisiana, from Siliqua indicated the presence of apocynin.

Phytochemical and biological investigations on two Nepeta species: Nepeta heliotropifolia and N. congesta subsp. cryptantha

In the present study, the essential oil and aroma compositions of Nepeta heliotropifolia (NH) and N. congesta subsp. cryptantha (NC) were determined by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detector (GC/FID), and their phenolic compounds by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In addition, antioxidant, cytotoxic, anticholinesterase, urease, and tyrosinase activities of essential oils obtained from NH and NC aerial parts and ethanol extracts prepared from different parts of NH and NC were investigated. The major constituent of water-distilled essential oils was found to be germacrene D (36.7% and 38.5%, respectively), and their main aroma component was eucalyptol (48.0% and 24.7%, respectively). Among the studied parts of NH and NC, their flowers extracts were found to be the richest in phenolic compounds and in which the most abundant compound was rosmarinic acid (8,909.91 and 4,317.20 μg/g, respectively). NH and NC flower extracts exhibited also strong antioxidant activity in DPPH, ABTS, and CUPRAC assays. Among the tested samples, NH essential oil indicated the best cytotoxic effect against PDF, HT-29, and MCF-7 (IC₅₀ 52.34, 25.89, and 44.70 μg/ml, respectively), and the highest butyrylcholinesterase (77.21 ± 1.12% inhibition) and moderate acetylcholinesterase (41.36 ± 0.69% inhibition) inhibitory activities. PRACTICAL APPLICATIONS: This is the first report on the essential oil and aroma compositions, the phenolic compounds, the antioxidant with total phenolic and flavonoid contents, cytotoxic, anticholinesterase, urease, and tyrosinase activities of Nepeta heliotropifolia and N. congesta subsp. cryptantha, except for their essential oil compositions. The reported results suggested that Nepeta heliotropifolia and N. congesta subsp. cryptantha flowers being rich in rosmarinic acid and having strong antioxidant potential, and NH essential oil possessing significant cytotoxic and butyrylcholinesterase inhibitory effect could be source for nutraceutical, food, and drug industries.

Plants of Nepeta cataria var. citriodora Beck. and essential oils from them for food industry

Nepeta cataria var. citriodora Beck. (catmints) is a source industrial production of citral and attractive raw material for food industry and cooking. Aerial part of Nepeta are characterized by high antimicrobial activity and fungicidal action against mold fungi, used in folk medicine, as ingredient in recipes for sausages, liqueurs and soft drinks, vegetable and fruit canned food, in the manufacture of vermouth. Ukrainian variety 'Melody' was created specifically for growing in the Forest-Steppe zone, and variety 'Peremozhets' – in the Steppe zone. Data on the yield aerial part and essential oil Nepeta was determined. The dry aerial part of plants N. cataria we used to create a dry spicy mixture for sweet dessert dishes. Quantitative content and qualitative composition of essential oil of plants by organs and phases of vegetation are presented in the article. In our research we used essential oils obtained by hydro distillation procedure for 2 h using Clevendger-type apparatus from the flowering parts of plants N. cataria 'Peremozhets' and 'Melody'. Investigate of components was carried out by high effective gas chromatography with HP 6890 chromatograph coupled with HP 5972 mass selective detector. The most abundant components of Nepeta essential oil was citral, geraniol, as well as nerol, citronellol, citronellal, carvacrol, camphor, eugenol. We proposed fractional distillation of essential oils to obtain a line of flavors with stable sensory and physicochemical indicators for food industry. The separation of essential oils into fractions was carried out on a pilot installation of fractional distillation DFD (Device of Fractional Distillation). Calculations of parameters controlled dispersal of essential oils (residual pressure, temperature regimes, number of theoretical plates, reflux number) were carried out. During fractionation of essential oil of N. cataria four fractions were obtained with a content of 96 ±0.5% to the total mass of samples. Sensory and physicochemical analysis of aromatic fractions announced them as promising flavours for food industry.

Antibacterial and Cytotoxic Activity of Nepeta Cataria L., N. Cataria Var. Citriodora (Beck.) Balb. and Melissa Officinalis L. Essential Oils

The aim of the present study was to investigate the susceptibility of bacteria that play a role in respiratory tract and skin infections to the essential oils of catnip (Nepeta cataria), lemon catnip (N. cataria var. citriodora) and lemon balm (Melissa officinalis) with regard to their chemical composition. In addition, we wanted to assess whether antibiotic-resistant and -sensitive strains differ in their susceptibility to the oils and if there are cross resistances between standard antibiotics and essential oils. To evaluate the safety of topical application, cytotoxicity of the oils was studied in human keratinocyte and bronchial epithelial cell lines and irritation threshold concentrations were determined in ovo using the HET-CAM-test. The composition of the essential oils was analyzed by GC and GC-MS. Their MICs and MBCs were determined by a broth microdilution method against both reference strains from culture collections and clinical isolates with different susceptibility to standard antibiotics. Cytotoxicity was assessed by the MTT assay. Except for P. aeruginosa (MIC ≥2%), all reference strains tested were susceptible to catnip and lemon balm oils with MIC values ranging from 0.016 % to 0.25% (v/v). The clinical isolates were as susceptible to the oils (± 1 serial dilution) as the corresponding reference strains, regardless of their origin and resistance to standard antibiotics. The oils were cytotoxic to both keratinocytes and bronchial epithelial cells at CC50 values from 0.0012% to 0.015% (v/v). Lemon balm oil, whose main components were monoterpene aldehydes, exhibited the highest antibacterial and cytotoxic activity, followed by lemon catnip oil, which contained mainly monoterpene alcohols, and catnip oil, which was characterized by nepetalactones. Our results provide a rationale for the use of catnip, lemon catnip and lemon balm oils in the complementary topical treatment of respiratory tract infections, as the oils show a high antibacterial activity against respiratory tract pathogens, including clinical isolates with reduced susceptibility to standard antibiotics. However, cytotoxicity must be considered in topical therapy.

Insecticidal and repellent activities of the essential oil of Callistemon citrinus (Myrtaceae) against Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

The essential oil of Callistemon citrinus (Curtis) leaves was extracted by hydro distillation and tested on female and male adults of Callosobruchus macullatus (F.) for insecticidal and repellent effects. GC-MS analysis was used to identify and quantify the volatile composition of the essential oil. Results showed that 1,8-cineole (34.2%) and α-pinene (29.0%) were the major components of the oil. Callistemon citrinus oil was found to be toxic to adult insects when applied by fumigation. Responses varied according to the gender of the insect and exposure time. LC50 values were 12.88 and 84.4 μL. L(-1) for males and females, respectively. An increase in exposure time from 3 to 24 h caused an increase in mortality from 50% to 100% in males and from 15.5% to 85.2% in females, at the highest concentration (500 μL. L(-1)). The essential oil also had a repellent effect against C. macullatus in a filter paper arena test. After 2 and 4 h, 86% and 94%, respectively, repellent effects were demonstrated at the highest concentration of 0.4 μL .cm(-2). These observations suggest that C. citrinus essential oil may be usefully applied to control storage pests.

Chemical composition and mechanisms underlying the spasmolytic and bronchodilatory properties of the essential oil of Nepeta cataria L

AIM OF THE STUDY

The study was aimed to investigate the chemical composition and pharmacological basis for traditional use of essential oil of Nepeta cataria L. (Limiaceae) (Nc.Oil) in gastrointestinal and respiratory disorders.

MATERIALS AND METHODS

Chemical analysis was carried out through GC-EIMS, 13C NMR and Kovats Retention Indices while pharmacological study was carried out in isolated tissues preparations.

RESULTS

Four major components; 1,8-cineol (21.00%), alpha-humulene (14.44%), alpha-pinene (10.43%) and geranyl acetate (8.21%) were identified among the 27 compounds in Nc.Oil. In isolated rabbit jejunum, Nc.Oil, papaverine and verapamil inhibited spontaneous and high K+(80 mM) precontractions, as well as shifted the Ca++ concentration-response curves (CRCs) to right, indicating calcium channel blocking activity. In isolated guinea-pig trachea, Nc.Oil and papaverine inhibited carbachol (1 microM) and K+ precontractions with similar potency, while verapamil was more potent against K+. Nc.Oil also potentiated isoprenaline inhibitory CRCs, similar to papaverine, indicating papaverine-like PDE inhibitor activity. In isolated guinea-pig atria, Nc.Oil caused cardiodepression at around 25-80 times higher concentrations, similar to papaverine.

CONCLUSIONS

These data indicate that Nepeta cataria possesses spasmolytic and myorelaxant activities mediated possibly through dual inhibition of calcium channels and PDE, which may explain its traditional use in colic, diarrhea, cough and asthma.

Quantification of nepetalactones in catnip (Nepeta cataria L.) by HPLC coupled with ultraviolet and mass spectrometric detection

Nepetalactones, the major chemical components of catnip (Nepeta cataria L.), were analysed by reversed-phase HPLC coupled with UV and MS detection. Two major nepetalactones, Z,E-nepetalactone and E,Z-nepetalactone, were successfully identified and quantified. The linearity range for Z,E-nepetalactone was determined as 0.00655-0.655 mg/mL with a correlation coefficient of 0.9999, and the linearity range of E,Z-nepetalactone was found to be 0.00228-0.456 mg/mL with a correlation coefficient of 0.9999, under UV detection at 228 nm. The linearity ranges were from 0.00164 to 0.0328 mg/mL, with a correlation coefficient of 0.9999, for ZE-nepetalactone and 0.00114-0.0228 mg/mL, with a correlation coefficient of 0.9999, for E,Z-nepetalactone by MS detection with selected ion monitoring of ion peak m/z 167. The MS detection was found to be more sensitive than UV detection and this method was validated as simple, reliable and sensitive for catnip nepetalactone analysis. This method can be used for identification and fingerprinting of catnip products.

An evaluation of the allelopathic potential of selected perennial groundcovers: foliar volatiles of catmint (Nepeta x faassenii) inhibit seedling growth

Six perennial groundcovers including Alchemilla mollis, Nepeta x faassenii, Phlox subulata, Sedum acre, Solidago cutleri, and Thymus praecox were investigated for the allelopathic potential of their respective foliar tissues via evaluation of volatile constituents produced by foliage. These groundcovers were selected for further laboratory evaluation because of superior performance as weed-suppressive groundcovers in previous field experiments. Foliar volatile components of N. x faassenii exhibited the strongest inhibitory effects on seedling growth of curly cress (Lepidium sativum), but S. cutleri also showed allelopathic potential by reducing shoot growth of curly cress seedlings with extracted volatiles. Although A. mollis and P. subulata exhibited strong weed-suppressive traits in past field experiments, weed suppression is apparently associated with either competition for resources or other allelopathic mechanisms rather than an allelopathic effect caused by volatiles. Volatiles of N. x faassenii were further evaluated with gas chromatography coupled to mass spectrometry (GC-MS). A total of 21 chemical constituents were identified in the volatile cocktail; 17 components were identified from a direct crude leaf sample extraction, including sabinene, beta-pinene, beta-myrcene, 2-(2-ethoxyethoxy)-ethanol, 1,8-cineole, ocimene, neryl Acetate, 4aalpha,7alpha,7aalpha-nepetalactone, alpha-copaene, trans-caryophyllene, alloaromadendrene, 4abeta,7alpha,7abeta-nepetalactone, germacrene D, beta-farnesene, chi-cadinene, germacrene B, and beta-sesquiphellandrene. Five additional constituents were identified in a methanolic extract of dried of N. x faassenii foliage, but not the volatile cocktail collected from N. x faassenii foliage. These included methyl benzoate, 2,4-decadienal, neryl acetate, isodihydronepetalactone, and caryophyllene oxide. Three components, 2-(2-ethoxyethoxy)-ethanol, alloaromadendrene, and chi-cadinene, were not only detected in both the volatile mixture and the methanolic extract, but also in an aqueous foliar extract that exhibited potential allelopathic activity.