Essential oil ofNepetagenus (Lamiaceae) from Iran: a review

Essential oil content and composition of six Iranian Nepeta species (N. prostrata, N. saturejoides, N. sessilifolia, N. fissa, N. betonicifolia and N. ucranica)

The aerial parts essential oils of six Nepeta species (N. prostrata, N. saturejoides, N. sessilifolia, N. fissa, N. betonicifolia and N. ucranica) were analyzed by GC-FID and GC/MS. In the oils of two populations of N. prostrata, 1,8-cineole (49.8%-51.1%) was main constituent. Epoxy-alloaromadendrene (42.5%) was major compound in the oil of one population of N. saturejoides and α-humulene (25.4%), and caryophyllene oxide (19.7) were major components of the second population. In the oils of two populations of N. sessilifolia, n-octadecanol (17%-19%) and caryophyllene oxide (5.8%-16%) were main constituents, while α-pinene (32.5%) and spathulenol were major components of the third population. In the essential oils of three populations of N. fissa, caryophyllene oxide (16.1%-33.5%) was major compound, but each population had particular compound such as carvacrol, (E)-caryophyllene or spathulenol with remarkable amount. Tetradecanal (55.5%) and trans-muurola-4(14),5-diene (46.2%.) were main components in the oils of N. betonicifolia and N. ucranica, respectively.

Chemical Composition of Essential Oils from Nepeta transcaucasica Grossh. and Nepeta cataria L. Cultivated in Bulgaria and Their Antimicrobial and Antioxidant Activity

The genus Nepeta, belonging to the family Lamiaceae, includes about 300 species, most of which are used in folk medicine due to their pronounced biological properties. The aim of the present study was to evaluate the agrobiological characteristics of Nepeta transcaucasica (N. transcaucasica) Grossh. and Nepeta cataria (N. cataria) L., cultivated in Bulgaria, and obtain their essential oils and determine their antimicrobial and antioxidant activities. The agrobiological characteristics of the two species growing in Kazanlak were analyzed; therefore, high variability in the population of N. transcaucasica and comparative homogeneity in N. cataria was shown. The species N. transcaucasica contained 0.28% essential oil with main components β-citronellol (52.05%), eucalyptol (7.34%), β-citronellal (6.06%), germacrene D (5.45%), (Z)-β-ocimene (5.14%), and β-caryophyllene (3.06%). The species N. cataria consisted of 0.19% essential oil with main components β-citronellol (26.31%), geraniol (15.92%), neral (11.45%), nerol (9.56%), carvacrol (6.04%), and β-citronellal (5.35%). The antibacterial activity against Gram-positive bacteria Listeria monocytogenes and Staphylococcus aureus and Gram-negative bacteria Escherichia coli (E. coli) and Salmonella enterica subsp. enterica serovar Abony was determined. The essential oils showed antimicrobial activity only against E. coli. The diameters of the inhibition zones were found to be 26 mm for the species N. transcaucasica and 10 mm for the species N. cataria. The antioxidant activity of the two essential oils was also determined by four different methods, DPPH, ABTS, FRAP, and CUPRAC, with the highest values for the ABTS radical, for the species N. transcaucasica (48.72 μM TE/mL), and the species N. cataria (310 μM TE/mL).

Cytotoxicity against A549 Human Lung Cancer Cell Line via the Mitochondrial Membrane Potential and Nuclear Condensation Effects of Nepeta paulsenii Briq., a Perennial Herb

The genus Nepeta belongs to the largest Lamiaceae family, with 300 species, which are distributed throughout the various regions of Africa, Asia, India, and America. Along with other plant families distinguished by their medicinal and therapeutic values, the Nepeta genus of Lameaceae remains relatively valuable. Hence, the phytochemicals of N. paulsenii Briq. were extracted using different plant parts, i.e., leaves, stem, roots, flowers, and the whole plant by using various solvents (ethanol, water, and ethyl acetate), obtaining 15 fractions. Each extract of dried plant material was analyzed by FT-IR and GC-MS to identify the chemical constituents. The cytotoxicity of each fraction was analyzed by MTT assay and mitochondrial membrane potential and nuclear condensation assays against lung cancer cells. Among the ethyl acetate and ethanolic extracts, the flowers showed the best results, with IC₅₀ values of 51.57 μg/mL and 50.58 μg/mL, respectively. In contrast, among the water extracts of the various plant segments, the stem showed the best results, with an IC₅₀ value of 123.80 μg/mL. 5-flourouracil was used as the standard drug, providing an IC₅₀ value of 83.62 μg/mL. The Hoechst 33342 stain results indicated apoptotic features, i.e., chromatin dissolution and broken down, fragmented, and crescent-shaped nuclei. The ethanolic extracts of the flowers showed more pronounced apoptotic effects on the cells. The mitochondrial membrane potential indicated that rhodamine 123 fluorescence signals suppressed mitochondrial potential due to the treatment with the extracts. Again, the apoptotic index of the ethanolic extract of the flowers remained the highest. Hence it can be concluded that the flower part of N. paulsenii Briq. was found to be the most active against the A459 human lung cancer cell line.

Encapsulation of Nepeta hormozganica and Nepeta dschuprensis essential oils in shrimp chitosan NPs: Enhanced antifungal activity

This study investigated the encapsulation of Nepeta hormozganica (NHEO) and Nepeta Dschuprensis (NDEO) essential oils into chitosan nanoparticles (CSN) via a simple ionic gelation method with tripolyphosphate (TPP). Chitosan (CS) is prepared by demineralizing, deproteinizing, and deacetylating shrimp shells waste in high yield (70.2 %). SEM, TEM, FT-IR, TGA, and XRD techniques were employed to characterize the encapsulated essential oils ((NHEO-CSN) and (NDEO-CSN)). The prepared EOs-CSN and CSN are found with particle sizes of 100-150 nm and 400-500 nm, respectively, and regular distribution. The encapsulation efficiency of encapsulated Nepeta hormozganica and Dschuprensis essential oils were found to be 73.64 % and 75.91 %, respectively. The synthesized nanocapsules were evaluated for antifungal activity against Fusarium oxysporium, Sclerotinia sclerotiorum, Pythium aphanidermatum, Alternaria alternata, Rhizactonia Solani, and Botrytis cinerea. Antifungal studies show that encapsulated essential oils increased antifungal efficiency by up to 100 %.

Volatile metabolites from new cultivars of catnip and oregano as potential antibacterial and insect repellent agents

Plant based natural products have been widely used as antibacterial and insect repellent agents globally. Because of growing resistance in bacterial plant pathogens and urban pests to current methods of control, combined with the long- and short-term negative impact of certain chemical controls in humans, non-target organisms, and the environment, finding alternative methods is necessary to prevent and/or mitigate losses caused by these pathogens and pests. The antibacterial and insect repellent activities of essential oils of novel cultivars of catnip (Nepeta cataria L. cv. CR9) and oregano (Origanum vulgare L. cv. Pierre) rich in the terpenes nepetalactone and carvacrol, respectively, were evaluated using the agar well diffusion assay and petri dish repellency assay. The essential oils exhibit moderate to high antibacterial activity against three plant pathogens, Pseudomonas cichorii, Pseudomonas syringae and Xanthomonas perforans of economic interest and the individual essential oils, their mixtures and carvacrol possess strong insect repellent activity against the common bed bug (Cimex lectularius L.), an urban pest of major significance to public health. In this study, the essential oils of catnip and oregano were determined to be promising candidates for further evaluation and development as antibacterial agents and plant-based insect repellents with applications in agriculture and urban pest management.

Comparison of antibacterial and antioxidant potentials of pure and nanoemulsified Nepeta pogonosperma essential oil

The current study aimed to investigate the antiradical and antibacterial potential of pure and its nanoemulsified (NNE) Nepeta pogonosperma essential oil (PNE). Antimicrobial activity of the essential oil against two Gram-positive (E. faecalis and B. cereus) and two Gram-negative (M. catarrhalis and K. pneumonia) food-related pathogens during 60-day storage was investigated based on disc diffusion, minimum inhibition concentration (MIC), and minimum bactericidal concentration (MBC). The chemical compounds of Nepeta essential oil were estimated by GC/MS. The physical properties of the nanoemulsion including polydispersity index (PDI), mean particle diameter, and viscosity were also determined. 4aα,7α,7aβ-Nepetalactone (46.31%), 1,8-cineole (23.13%), and (Z)-α-bisabolene (4.01%) were the main compounds of this essential oil. The Nepeta nanoemulsion had a mean droplet diameter of 254.07 nm, PDI of 0.281, and viscosity of 0.887 cP. NNE had stability for up to 60 days. The PNE showed a higher IC₅₀ value than NNE (p < .05). During storage, the antiradical performance of both PNE and NNE was decreased (p < .05). However, emulsification was successful to control this decreasing trend. E. faecalis was the most susceptible bacteria to PNE and NNE, while the lowest inhibition zone was obtained for K. pneumoniae. At the first time, the antibacterial effect of PNE was more than NNE. However, over time nanoemulsion became more successful in maintaining its antibacterial effect. Overall, the incorporation of Nepeta pogonosperma essential oil into a nanoemulsion system can be a promising system to maintain the bioactivity of the essential oil for a longer time.

Diversity and Distribution Patterns of Endemic Medicinal and Aromatic Plants of Iran: Implications for Conservation and Habitat Management

Iran, with its unique climatic and topographic conditions, is home to about 8200 species of vascular plants. Approximately 2300 of the 8200 species are popularly characterized as medicinal or aromatic. Here, we compile information about the endemic medicinal and aromatic plants (MAPs) of Iran and map their distributions. Our survey found 180 endemic species of MAPs, belonging to 10 families and 30 genera. The majority of species are found in Lamiaceae, Fabaceae, and Apiaceae, with 86, 30, and 18 species, respectively. Approximately 70% of these plants have been recorded in the 10 provinces of Esfahan, Kerman, Fars, Tehran, Chaharmahal va Bakhtiari, East Azarbaijan, Lorestan, West Azarbaijan, Hamadan, and Mazandaran. These provinces are located in the Iran-o-Turanian region, one of the three major phytogeographic regions in Iran, which covers five areas of endemism (i.e., Azarbaijan, Zagros, Kopet Dagh-Khorassan, Alborz, and Central Alborz). So, Iran-o-Turanian region is the main center of diversity for the Iranian endemic MAPs. The north, center and western parts of Iran are rich in MAPs and could be considered as the dominant biodiversity hotspots of Iran more seemingly due to the diverse climatic and geographic assortment which generates the highest frequency and distribution of MAPs. Many of these MAPs are at the edge of extinction due to the unwise, unscientific harvesting and/or global climate change. Therefore, there is an urgent need to conserve and propagate some of these important MAPs to save them from extinction and also to ensure the availability of raw materials for their use and future research into their efficacy. Furthermore, identifying the areas of endemism (AEs) is an essential part of ongoing regional conservation management programs in Iran and worldwide.

Novel β-Cyclodextrin and Catnip Essential Oil Inclusion Complex and Its Tick Repellent Properties

Cyclodextrin inclusion complexes have been successfully used to encapsulate essential oils, improving their physicochemical properties and pharmacological effects. Besides being well-known for its effects on cats and other felines, catnip (Nepeta cataria) essential oil demonstrates repellency against blood-feeding pests such as mosquitoes. This study evaluates the tick repellency of catnip oil alone and encapsulated in β-cyclodextrin, prepared using the co-precipitation method at a 1:1 molar ratio. The physicochemical properties of this inclusion complex were characterized using GC-FID for encapsulation efficiency and yield and SPME/GC-MS for volatile emission. Qualitative assessment of complex formation was done by UV-Vis, FT-IR, ¹H NMR, and SEM analyses. Catnip oil at 5% (v/v) demonstrated significant tick repellency over time, being comparable to DEET as used in commercial products. The prepared [catnip: β-CD] inclusion complex exerted significant tick repellency at lower concentration of the essential oil (equivalent of 1% v/v). The inclusion complex showed that the release of the active ingredient was consistent after 6 h, which could improve the effective repellent duration. These results demonstrated the effective tick repellent activity of catnip essential oil and the successful synthesis of the inclusion complex, suggesting that β-CDs are promising carriers to improve catnip oil properties and to expand its use in repellent formulations for tick management.

Analysis of the essential oil composition of three cultivated Nepeta species from Iran

Essential oils (EOs) of three Iranian cultivated Nepeta species were investigated. The oils were obtained by hydrodistillation of air-dried plant materials at full flowering stage and analyzed by gas chromatography (GC) and gas chromatography coupled to mass spectroscopy (GC/MS). In total, 89 compounds were detected. In over 2 years, a number of constituents were identified in the EO of Nepeta binaloudensis first and second years (26 and 37, respectively), Nepeta cataria (25 and 32, respectively), and Nepeta assurgens (45 and 50, respectively). In the oils of N. binaloudensis, 4a-α,7-α,7a-α-nepetalactone (NL) 59.7% and 1,8-cineole (19.6%) during the first and second years, respectively, were the main constituents. The main components of N. cataria were 4a-α,7-α,7a-β-NL (72.8%) and 4a-α,7-β,7a-α-NL (73.9%) during the first and second years, respectively, and 4a-α,7-α,7a-α-NL (55.5%) and 1,8-cineole (24.1%) during the first and second years, respectively, were the main constituents of N. assurgens. The results showed that NLs isomers and 1,8-cineole were the main components of the oils of three cultivated Nepeta species.

Antiplatelet Aggregation, Cardiotonic, Anti-Inflammatory, Antioxidant, and Calcium Channel Antagonistic Potentials of Nepeta ruderalis Buch

The objective of this study was to authenticate the ethnobotanical claims of the Nepeta ruderalis Buch.-Ham. (N. ruderalis) extract in the traditional system of medicine. Crude extract was prepared via a simple maceration process. DPPH free radical scavenging and carrageenan-induced rat paw edema models were used to monitor antioxidant and anti-inflammatory responses of the N. ruderalis extract. Furthermore, it was tested for antiplatelet aggregation, cardioprotective, and calcium channel antagonistic activities via standard documented protocols. The N. ruderalis extract exhibited 80.82% antioxidant activity (IC₅₀ = 207.51 ± 4.36 μg) while the anti-inflammatory response was significant (p < 0.05 to p < 0.01) at 50 mg/kg (45.58%) and 100 mg/kg (60.90%) doses. Moreover, it was found to inhibit platelet aggregation (IC₅₀ = 1.06 and 0.91 mg/mL) and, in addition, to increase the force of contraction at the concentration of 3.0-10 mg/mL with a decrease in the heart rate on isolated paired atria (EC₅₀ = 11.78 mg/mL). Relaxant activity was observed on the isolated rabbit jejunum (EC₅₀ = 0.96 mg/mL) and trachea (EC₅₀ = 0.89 mg/mL). However, in a cumulative way, an 80-millimolar potassium-induced contraction was evaluated (EC₅₀ = 1.31 mg/mL). The N. ruderalis extract exhibited antioxidant, anti-inflammatory, platelet aggregating, cardiotonic, and calcium channel antagonistic activities, therefore proving scientifically its effectiveness in the traditional system of medicine.

Chemical composition and larvicidal activity of essential oils from Peganum harmala, Nepeta cataria and Phellodendron amurense against Aedes aegypti (Diptera: Culicidae)

Essential oils from aerial parts of the herbs Peganum harmala and Nepeta cataria, and leaves of the tree Phellodendron amurense were analyzed by GC-FID and GC-MS, and their larvicidal activities were assayed on the early fourth instar larvae of Aedes aegypti. The major constituents of the oils were limonene (14.5%) and thymol (11.5%) in P. harmala, thymol (46.5%), 4aα,7α,7aβ-nepetalactone (18.3%) and 4aα,7β,7aα-neptalactone (19.7%) in N. cataria, eugenol (14.5%) andγ-eudesmol (9.5%) in P. amurense.The oil of N. cataria had a strong larvicidal activity (LC50 < 50 µg/mL; LC90 < 86.8 µg/mL) on A. aegypti while the remaining oils showed a moderated killing effect. The larvicidal activity of N. cataria oil was associated to the contents of 1,8-cineol, camphor, 4aα,7α,7aβ-Nepetalactone, 4aα,7β,7aα-Nepetalactone and thymol. Our results indicate that the oil of N. catariadeserves to be used as a source of larvicidal agents against A. aegypti.

Comparing cytotoxicity of propoxur and Nepeta crispa (Lamiales: Lamiaceae) essential oil against invertebrate (Sf9) and vertebrate (L929) cell lines

Background and Aim:

Attempts to use the plant products are to be an appropriate option due to substantial concerns about human health and environmental problems of using synthetic pesticides. Therefore, the cytotoxicity of Nepeta crispa essential oil was compared with propoxur against invertebrate (Sf9) and vertebrate (L929) cell lines.

Materials and Methods:

The cell lines of Sf9 and L929 which were derived from the ovary glands of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) and mouse fibroblast cells, respectively, were obtained from the National Cell Bank of Pasteur Institute of Iran. About a number of 2 × 10³ cells were placed into the wells of 96-well plate experiments. Then, appropriate concentrations of essential oil of N. crispa plant and propoxur added to the wells. The cells were allowed to grow for 3-5 days and estimated the numbers of cells. The cells of control experiment wells contained only cells with dimethyl sulfoxide. All control and treatment experiments repeated at least four replicates.

Results:

Propoxur had negative effects on the viability of both invertebrate (Sf9) and vertebrate (L929) cell lines. The cytotoxicity of propoxur against invertebrate (Sf9) and vertebrate (L929) cell lines was gradually increased in accordance with propoxur concentrations. The cytotoxicity of N. crispa essential oil against vertebrate (L929) cell line was gradually decreased in accordance with plant concentrations, while the cytotoxicity of N. crispa essential oil against invertebrate (Sf9) cell line was strongly increased in accordance with plant concentrations.

Conclusion:

Plant essential oil not only had no negative effects but also had boosting effects on vertebrate cell viability. Essential oil of N. crispa plant had negative effects on invertebrate cell viability with the differences that the products derived from plants possessing of biodegradable and environmentally friendly derivatives, hydrolyzing rapidly in nature, and nearly having no destructive effects on environment, humans, or the mammals.

Nepeta menthoides Boiss. & Buhse, an endemic species in Iran: A review of traditional uses, phytochemistry and pharmacology

Nepeta menthoides Boiss & Buhse is one of the endemic species in Iran. Named Ostokhodus, it is almost used as substitute of the Lavandula stoechas –the original Ostokhodus- in traditional Persian medicine (TPM) over the time and widely used for the management of some ailments such as anxiety, depression, dementia and chronic pain. The aim of this study is to review the pharmacological and phytochemical evidence on Nepeta menthoides for the assessment of the recommended traditional indications of this herb. In this review, all the relevant articles that met our inclusion criteria [English or Persian articles, having full text, evaluating therapeutic effects of N. menthoides and dated mainly from the year 1980 to 2018] were included by searching studies in PubMed, Scopus, Google Scholar, Web of Science, and SID. The search terms were "Nepeta menthoides, "Ostokhodus". Triterpenes and monoterpenes were the most chemicals reported from essential oil of N. menthoides. Several pharmacological properties via in vitro, in vivo and clinical studies have been reported including antioxidant, anti-inflammatory, anti-nociceptive, antidepressant and anxiolytic, anticholinesterase, neuroprotective, memory enhancing, anti-Alzheimer’s disease, anticancer and effect on opioid dependence. Some proposed traditional indications of this herb in TPM books are in accordance with pharmacological evidence like anti-nociceptive, anti-seizure, anti-Alzheimer’s disease, memory enhancing, neuroprotective, antidepressant, anxiolytic activity and anti-infective properties. Although some properties in TPM, such as anti-tussive and gastrotonic effects are not supported by scientific evidence, they need more investigations.

Sustainable manufacture of insect repellents derived from Nepeta cataria

Malaria devastates sub-Saharan Africa; the World Health Organization (WHO) estimates that 212 million people contract malaria annually and that the plasmodium virus will kill 419 000 in 2017. The disease affects rural populations who have the least economic means to fight it. Impregnated mosquito nets have reduced the mortality rate but the Anopheles mosquitoes are changing their feeding patterns and have become more active at dusk and early morning rather than after 22h00 as an adaptation to the nets. Everyone is susceptible to the Anopheles at these times but infants and pregnant women are the most vulnerable to the disease. Plant-based mosquito repellents are as effective as synthetic repellents that protect people from bites. They are sustainable preventative measures against malaria not only because of their efficacy but because the local population can produce and distribute them, which represents a source of economic growth for rural areas. Here, we extract and test the essential oil nepetalactone from Nepeta cataria via steam distillation. Families in endemic areas of Burundi found them effective against bites but commented that the odor was pungent. An epidemiological study is required to establish its clinical efficacy.

Himalayan Aromatic Medicinal Plants: A Review of their Ethnopharmacology, Volatile Phytochemistry, and Biological Activities

Aromatic plants have played key roles in the lives of tribal peoples living in the Himalaya by providing products for both food and medicine. This review presents a summary of aromatic medicinal plants from the Indian Himalaya, Nepal, and Bhutan, focusing on plant species for which volatile compositions have been described. The review summarizes 116 aromatic plant species distributed over 26 families.

Chemoinformatics Approach to Antibacterial Studies of Essential Oils

The chemical composition and antibacterial activity of Nepeta nuda (Lamiaceae) essential oil were examined, as well as the association between it and standard antibiotics: tetracycline and streptomycin. The antibacterial activities of 1,8-cineole, the main constituent of N. nuda oil, individually and in combination with standard antibiotics were also determined. The interactions of the essential oil and 1,8-cineole with antibiotics toward five selected strains were evaluated using the microdilution checkerboard assay in combination with chemoinformatics methods. Oxygenated monoterpenes were the most abundant compound class in the oil (57.8%), with 1,8-cineole (46.0%) as the major compound. The essential oil exhibited in vitro antibacterial activity against all tested bacterial strains, but the activities were lower than those of the standard antibiotics. The combinations N. nuda oil-antibiotic and 1,8-cineole-antibiotic produced a predominantly antagonistic interactions. Chemoinformatics survey confirms the antagonistic interactions as a consequence of membrane potential/proton motive force dissipation. These data indicate cytochrome c oxidase as a target for 1.8-cineole toxicity action mechanisms.