Geranium Essential Oil Research Articles

Organic fertilization systems on the vegetative growth and essential oil production of Pelargonium graveolens

The aromatic plant Pelargonium graveolens L. 'Hérit, known as geranium, presents bioactive compounds of high economic interest. Since the secondary metabolism is affected by several factors such as the cultivation conditions, this work aimed to assess the impact of different fertilization systems on geranium vegetative growth and essential oil content and yield. The treatments were: T1) chemical fertilization (N-P-K); T2) no fertilization; T3) biodynamic fertilization; T4) organic fertilization; T5) biodynamic fertilization + plant growth-promoting bacteria (PGPB); T6) organic fertilization + PGPB; and T7) organic compost. The application of Azospirillum brasilense (PGPB) had no significant effect on geranium vegetative growth and essential oil production. Essential oil production was not observed in plants treated with chemical (T1) or biodynamic fertilizers (T3 and T5). Plants treated with organic fertilization (T4 and T6) showed greater agronomic development in addition to essential oil content and yield. Consequently, organic fertilization emerges as a promising approach for cultivating P. graveolens.

Antimicrobial and synergistic effects of lemongrass and geranium essential oils against Streptococcus mutans, Staphylococcus aureus, and Candida spp.

The oral cavity harbors more than 700 species of bacteria, which play crucial roles in the development of various oral diseases including caries, endodontic infection, periodontal infection, and diverse oral diseases. To investigate the antimicrobial action of Cymbopogon Schoenanthus and Pelargonium graveolens essential oils against Streptococcus mutans, Staphylococcus aureus, Candida albicans, Ca. dubliniensis, and Ca. krusei. Minimum microbicidal concentration was determined following Clinical and Laboratory Standards Institute documents. The synergistic antimicrobial activity was evaluated using the Broth microdilution checkerboard method, and the antibiofilm activity was evaluated with the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay. Data were analyzed by one-way analysis of variance followed by the Tukey post-hoc test (P ≤ 0.05). C. schoenanthus and P. graveolens essential oils were as effective as 0.12% chlorhexidine against S. mutans and St. aureus monotypic biofilms after 24 h. After 24 h P. graveolens essential oil at 0.25% was more effective than the nystatin group, and C. schoenanthus essential oil at 0.25% was as effective as the nystatin group. C. schoenanthus and P. graveolens essential oils are effective against S. mutans, St. aureus, Ca. albicans, Ca. dubliniensis, and Ca. krusei at different concentrations after 5 min and 24 h.

Study of genotype × environment interaction on the morphological and chemical features of geranium (Pelargonium graveleons L'Her Ex Ait.)

Geranium is a multi-harvest perennial plant in the Geraniaceae family grown for its sweet-scented herbs and essential oils. It is well-known for its imposing rose-like aroma. Geranium essential oil is commonly used in the soap, fragrance, and cosmetic industries to isolate rhodinol, an aromatic compound found in most high-grade perfumes. The current study evaluated a total of 5 geranium genotypes across three years, at two locations, to identify the superior and stable geranium genotypes. "The pooled ANOVA results showed substantial genotype × environment interactions for all the traits under study. The CIM-Bio 171 genotype had the highest essential oil production per plant (g) (X9), followed by Kelkar (rank II, 10.24), Algerian CIM-Pawan (rank III, 10.03), CIM-Pawan (rank IV, 7.63), and Bourbon (rank V, 7.24) g/plant. For the trait citronellol content (X10), the Algerian genotype ranked top (37.83%), followed by CIM-Pawan (rank II, 30.81%), CIM-Bio 171 (rank III, 28.33%), Bourbon (rank IV, 26.89%), and Kelkar (rank V, 12.58%). The Kelkar genotype ranked the highest (6.20%) in the trait 10-epi-γ-Eudesmol content (X16), followed by CIM-Pawan (rank II, 5.89%), Algerian (rank III, 4.56%), Bourbon (rank IV, 4.29%), and CIM-Bio 171 (rank V, 4.25%). The genotype CIM Bio 171 exhibited the highest mean value for essential oil yield, and cis-Rose oxide content (%). The following genotypes, such as CIM Bio 171, Algerian, and CIM Pawan, emerged as high-mean performers and exhibited stability across diverse environments. The genotype CIM Bio 171 is closer to the ideal genotype, followed by CIM Bio 171, Algerian, and CIM Pawan as the most desirable genotypes. Similarly, the year Y3 was determined to be the most desirable based on GGE-biplot environment evaluations at both locations. Therefore, CIM Bio 171 has been released for commercial cultivation because of its exceptional performance in essential oil yield and quality attributes across locations and years. Kew wordscis-Rose oxide; essential oil; environment ranking; GGE-biplot; genotype × environment interaction.

Isolation and identification of postharvest pathogenic bacteria of Syzygium samarangense and antibacterial test of essential oils

With Syzygium samarangense as the test subject，postharvest pathogenic bacteria were isolated，purified，and identified. Their pathogenicity was determined using Koch's postulates，and the antibacterial activity of 36 types of plant essential oils against highly pathogenic bacteria was assessed. The findings indicated that a highly pathogenic fungus was isolated and identified from naturally existing S. samarangense, labeled LW3-1. The pathogenicity rate of strain LW3-1 reached 100% within 2 days of inoculation, and molecular biology identified it as Colletotrichum gloeosporioides. Among the 36 essential oils, clove, geranium, myrrh, rose and sophora flavescens essential oils (1000 μl/L) had the most significant antibacterial effect on the LW3-1 strain, with an antibacterial rate of 100%. The antibacterial rate of 500 μl/L clove essential oil against the LW3-1 strain was still >85% after 12 days of treatment. In summary, it is determined that the pathogenic bacteria causing postharvest diseases of l S. samarangense is C. gloeosporioides, which is highly pathogenic. 500 μl/L clove essential oil has the best inhibitory effect on C. gloeosporioides.

The Influence of Physical Fields (Magnetic and Electric) and LASER Exposure on the Composition and Bioactivity of Cinnamon Bark, Patchouli, and Geranium Essential Oils.

In recent years, essential oils (EOs) have received increased attention from the research community, and the EOs of cinnamon, patchouli, and geranium have become highly recognized for their antibacterial, antifungal, antiviral, and antioxidant effects. Due to these properties, they have become valuable and promising candidates for addressing the worldwide threat of antimicrobial resistance and other diseases. Simultaneously, studies have revealed promising new results regarding the effects of physical fields (magnetic and electric) and LASER (MEL) exposure on seed germination, plant growth, biomass accumulation, and the yield and composition of EOs. In this frame, the present study aims to investigate the influence of MEL treatments on cinnamon, patchouli, and geranium EOs, by specifically examining their composition, antimicrobial properties, and antioxidant activities. Results showed that the magnetic influence has improved the potency of patchouli EO against L. monocytogenes, S. enteritidis, and P. aeruginosa, while the antimicrobial activity of cinnamon EO against L. monocytogenes was enhanced by the electric and laser treatments. All exposures have increased the antifungal effect of geranium EO against C. albicans. The antioxidant activity was not modified by any of the treatments. These findings could potentially pave the way for a deeper understanding of the efficiency, the mechanisms of action, and the utilization of EOs, offering new insights for further exploration and application.

Development of silanized bacterial cellulose aerogels for the incorporation of natural oils with healing properties: Copaiba (Copaifera officinalis), bourbon geranium (Pelargonium X ssp.) essential oils and buriti (Mauritia flexuosa) vegetable oil

Bacterial cellulose (BC) represents a promising biomaterial, due to its unique and versatile properties. We report, herein, on purposely-designed structural modifications of BC that enhance its application as a wound dressing material. Chemical modification of the functional groups of BC was performed initially to introduce a hydrophobic/oleophilic character to its surface. Specifically, silanization was carried out in an aqueous medium using methyltrimethoxisilane (MTMS) as the silanizing agent, and aerogels were subsequently prepared by freeze-drying. The BC-MTMS aerogel obtained displayed a highly porous (99 %) and lightweight structure with an oil absorption capacity of up to 52 times its dry weight. The XRD pattern indicated that the characteristic crystallographic planes of the native BC were maintained after the silanization process. Thermal analysis showed that the thermal stability of the BC-MTMS aerogel increased, as compared to the pure BC aerogel (pBC). Moreover, the BC-MTMS aerogel was not cytotoxic to fibroblasts and keratinocytes. In the second step of the study, the incorporation of natural oils into the aerogel's matrix was found to endow antimicrobial and/or healing properties to BC-MTMS. Bourbon geranium (Pelargonium X ssp.) essential oil (GEO) was the only oil that exhibited antimicrobial activity against the tested microorganisms, whereas buriti (Mauritia flexuosa) vegetable oil (BVO) was non-cytotoxic to the cells. This study demonstrates that the characteristics of the BC structure can be modified, while preserving its intrinsic features, offering new possibilities for the development of BC-derived materials for specific applications in the biomedical field.

Investigating the Effectiveness of Novel Repellent Labels Produced from Invasive Plant Species

Although N,N-diethyl-3-methylbenzamide (DEET) remains the most effective repellent against mosquitoes and ticks, concerns about skin irritation, rashes, and neurological problems in children have driven the search for natural alternatives. The aim of this research was to develop, manufacture, and test prototype stickers derived from invasive plant species in Europe. These labels contained a coating with encapsulated repellents made from essential oils to protect against mosquito bites and similar blood-sucking insects. Six samples of invasive plant species in Europe such as Japanese knotweed (Fallopia japonica), goldenrod (Solidago gigantea), and black locust (Robinia pseudoacacia) were coated with two essential oil mixtures (of geranium, lavender, and eucalyptus) and were encapsulated on solid carriers for prolonged evaporation. Analysis of the structural properties (weight, thickness, density, and specific volume) were carried out on the coated label samples. Analysis of surface properties (roughness and porosity), capillary absorption, and a comparison of time and evaporation of essential oils were also carried out. Scanning electron microscopy was performed on the samples and the solid carrier with different mixtures of essential oils. The Japanese knotweed sample, coated with a blend of geranium, lavender, and eucalyptus essential oils, showed the highest efficacy and stability.

Enhancing functional buffalo yogurt: Improving physicochemical properties, biological activities, and shelf life using marjoram and geranium essential oils

The use of essential oils (EO) has attracted interest in the food industry because of their wide range of beneficial properties. In this study, a new functional yogurt was developed using 2 EO, marjoram and geranium, at 3 different concentrations (0.2%, 0.4%, and 0.6% vol/vol). The physicochemical properties, including syneresis, viscosity, pH, and chemical composition; bioactivities, including antioxidant activity, anticancer and antibacterial effects, total phenolic content (TPC), and total flavonoid content (TFC); and sensory characteristics of the developed yogurt were evaluated. The findings indicated that the yogurts fortified with 0.6% marjoram or geranium exhibited higher viscosity and lower syneresis compared with other treatments. The yogurt supplemented with 0.6% marjoram displayed significant antibacterial activity against Listeria monocytogenes, Staphylococcus aureus, Salmonella typhimurium, and Escherichia coli. In addition, the yogurt enriched with geranium and marjoram oils at a concentration of 0.6% had notably significant (P < 0.05) higher TFC levels compared with the control sample and other concentrations. In the same context, in terms of TPC, yogurt supplemented with 0.6% marjoram displayed significantly (P < 0.05) elevated levels in comparison to the other samples tested. Yogurt enriched with marjoram oil exhibited noteworthy antioxidant activity, followed by geranium oil, compared with the control samples. The yogurt supplemented with 0.6% marjoram demonstrated strong radical scavenging activity, and the yogurt fortified with 0.6% geranium showed higher anticancer activity against HepG2 human liver carcinoma cells and oxidative stress enzyme activities. Among the various concentrations of EO tested, the yogurts fortified with 0.6% marjoram or geranium EO exhibited the most favorable outcomes, followed by 0.4% marjoram or geranium. To summarize, geranium and marjoram EO can be used as a potential nutritious ingredient and as a natural preservative for milk and related products.

Development of phytoactive essential oils-composed organogels against oral pathogens

Gingivitis, one of the most common periodontal diseases, is the inflammation of the gingival tissues that causes swelling, tenderness, redness and bleeding. The treatment should contain anti-inflammatory, antibacterial, and antioxidant agents to decrease the risk of dental plaque formation and periodontal tissue damage in the inflammatory process. In line with the antibacterial, antifungal, and antioxidant effects of the geranium (Pelargonium graveolens L'Hér.) herb, common sage (Salvia officinalis L.) herb, and mastic tree (Pistacia lentiscus L.) leaf, in this work we propose their use as active pharmaceutical ingredients of periodontal gels. The organogel formulations were produced either by microwave-assisted irradiation method or by the conventional approach (microwave-free), and further characterized for their physicochemical properties, antimicrobial efficacy and cell viability. Among them, the gel formulation containing 4 % geranium essential oil obtained by the conventional method was identified as the best candidate to be developed as an effective and safe alternative suitable for oromucosal applications.

Bacillus velezensis B63 and chitosan control root rot, improve growth and alter the rhizosphere microbiome of geranium

The root rot complex of geranium plants caused by Rhizoctonia solani and Macrophomina phaseolina is a major threat, and control of these pathogens predominantly relies on chemicals. This study explored multifaceted applications of Bacillus velezensis (strain B63) and chitosan, assessing their biocontrol efficacy against root rot, and their subsequent effects on rhizosphere communities. Strain B63 was antagonistic to R. solani and M. phaseolina. Under field conditions, greatest efficacy was obtained with strain B63 (36% and 33% disease reductions in, respectively, two growing seasons), chitosan soaking + foliar spray 0.2% (CSF 0.2%) (33 and 27% reductions), and 0.1% chitosan soaking + foliar spray (CSF 0.1%) (33 and 26% reductions). These treatments also changed rhizosphere microbiota, as shown by numbers of colony-forming units (CFU) and 16S rRNA gene microbiome analyses. Concomitant with rhizosphere shifts, essential oil yields and composition were positively affected, as shown by gas chromatography analyses. Chitosan soaking + foliar spray 0.2% increased concentrations of citronellol (1.36-fold), geraniol (1.37-fold), citronellyl formate (1.54-fold), and geranyl formate (1.94-fold) in geranium essential oil, compared with the experimental controls. Strain B63 also increased these essential oils by 1.04- to 1.27-fold. B63 also enhanced eugenol levels by 1.35-fold. Treatments with B63 were more effective than chitosan in improving the geranium plant morphological parameters (plant height, numbers of branches, biomass). These results show that B. velezensis strain B63 treatments have potential for enhancing yields and product quality from geranium plant under root rot infection.

Natural Sources of Therapeutic Agents Used in Skin Conditions.

Skin conditions are numerous and often have a major impact on patients' quality of life, and effective and safe treatment is very important. The conventional drugs used for skin diseases are usually corticosteroids and antimicrobial products that can induce various side effects, especially with long-term use, which is why researchers are studying alternatives, especially biologically active natural products. Three products caught our attention: bee venom (BV), due to reported experimental results showing anti-inflammatory, antibacterial, antiviral, antioxidant, antimycotic, and anticancer effects, Ficus carica (FC) due to its demonstrated antioxidant, antibacterial, and anti-inflammatory action, and finally Geranium essential oil (GEO), with proven antifungal, antibacterial, anti-inflammatory, and antioxidant effects. Following a review of the literature, we produced this paper, which presents a review of the potential therapeutic applications of the three products in combating various skin conditions and for skin care, because BV, FC, and GEO have common pharmacological actions (anti-inflammatory, antibacterial, and antioxidant). We also focused on studying the safety of the topical use of BV, FC, and GEO, and new approaches to this. This paper presents the use of these natural therapeutic agents to treat patients with conditions such as vitiligo, melasma, and melanoma, as well as their use in treating dermatological conditions in patients with diabetes.

Chemical variability and insect repellent effects of lemon catnip essential oil and related phytochemicals against Cimex lectularius L

Plants are sources of natural products that reflect the ecological interactions that shaped their secondary metabolism. Among those, phytochemicals with insect repellent activity have shown potential to be part of integrated pest management programs. In this study, we performed an initial screening of the repellent activities of five commercially available essential oils, as well as the essential oil of lemon catnip (Nepeta cataria var. citriodora Dumoulin ex Lej.) and related natural products against the common bed bug (Cimex lectularius L.). Additionally, we studied the effects of two different growing locations (Upper Deerfield and Pittstown, state of New Jersey, United States) on the chemical composition of three lemon catnip lines (commercial lemon catnips Richters and Jelitto, and lemon-scented catnip line CN5). The chemical composition of the essential oils was determined by gas chromatography-mass spectrometry (GC-MS) and the repellent activity was assessed by the petri dish method. Cinnamon bark, clove buds, citronella and geranium essential oils were as effective as N,N-diethyl-meta-toluamide (DEET), the gold standard of insect repellents, against bed bugs after one hour of exposure in vitro. The essential oil of lemon catnip and its major compounds citronellol and geraniol were also as repellent as DEET using the same test. Citral shows promising short-term repellency but is inferior to geraniol and citronellol for extended duration of repellency. As for the chemical variability of lemon catnip lines in different growing locations, CN5 line was not significantly affected by the different locations, while both commercial lines Richters and Jelitto had significantly higher proportions of geraniol when grown in Upper Deerfield. Richters lemon catnip produced more nepetalactone in its essential oil when cultivated in Pittstown. This study is the first report of the activity of lemon catnip essential oil as an insect repellent and emphasized the importance of ecological conditions for the production of natural products for pest control applications.

Antimicrobial activity of geranium (Pelargonium graveolens) essential oil and its encapsulation in carioca bean starch ultrafine fibers by electrospinning

Geranium (Pelargonium graveolens) is known for being an aromatic plant rich in bioactive compounds with antibacterial properties. In this study, geranium essential oil (GEO) was extracted and encapsulated in ultrafine bean starch fibers produced by electrospinning as an antibacterial agent. GEO revealed a composition rich in volatile compounds, including citronellol, cis-geraniol, β-linalool, citronellyl formate, and linalool formate. In its free form, GEO exhibited high antibacterial activity against pathogenic bacteria strains (L. monocytogenes, S. aureus, and E. coli). The bean starch fibers, produced with and without the addition of GEO, were uniform and continuous, with an average diameter ranging from 249 to 373 nm. Confocal analysis indicated a uniform distribution of GEO in the fibers, with a loading capacity of 54.0 %, 42.9 %, and 36.5 % for 20 %, 30 %, and 40 % GEO concentrations, respectively. Remarkably, fibers containing 40 % GEO showed a significant reduction in tested bacteria (L. monocytogenes, S. aureus, and E. coli), suggesting promising applications in preventing losses and extending the shelf life of food through active packaging.

Plant Essential Oils: Dual Action of Toxicity and Egg-Laying Inhibition on Tetranychus urticae (Acari: Tetranychidae), Unveiling Their Potential as Botanical Pesticides.

Tetranychus urticae, a prominent pest mite in strawberry and vegetable cultivation in China, has developed escalating resistance due to extensive chemical pesticide application. Consequently, there is an urgent need to identify safe and efficacious methods to reduce resistance development. In this study, 38 commercially available plant essential oils (EOs) were screened for their acaricidal potential and ability to inhibit oviposition. The findings revealed that 13 EOs exhibited notable acaricidal activity, with lemon EO demonstrating the highest toxicity, followed by sage, patchouli, frankincense, lemongrass, palmarosa, and oregano EOs. In addition, 18 EOs displayed significant inhibitory effects on oviposition, with lemon EO exhibiting the highest inhibition rate (99.15%) and inhibition index (0.98). Subsequently, sage, frankincense, clove, lemongrass, oregano, patchouli, myrrh, black pepper, palmarosa, and geranium EOs also showed inhibition rates exceeding 50%. Despite black pepper, clove, myrrh, and oregano EOs demonstrating relatively low toxicity against T. urticae, they exhibited heightened efficacy in inhibiting oviposition and suppressing population expansion. This study conducted a comparative assessment of the acaricidal and oviposition inhibition activities of EOs and their principal constituents, thus providing a theoretical basis for the development of botanical acaricides against T. urticae.

Antioxidant and antibacterial activities of geranium (pelargonium graveolens L’Hér.) essential oil as affected by the growing biotope

ABSTRACT This study investigated the variability of antioxidant and antibacterial activities of essential oil (EO) from geranium (Pelargonium graveolens) aerial parts, collected from four Tunisian regions. The highest EO yield was obtained in Korba, followed by Beja, Tozeur and Sfax. In all regions, geranium EO was rich in oxygenated monoterpenes mainly due to the predominance of citronellol and geraniol. Antioxidant potential of geranium EO was evaluated by DPPH, ABTS, iron reducing power and β-carotene bleaching assays. Independently of region, geranium EO showed a weak antioxidant potential as compared to the positive control BHT. However, geranium EO was endowed with important antibacterial properties. In fact, Escherichia coli and Staphylococcus aureus were the most sensitive strains than Serratia marcescens, Pseudomonas aeruginosa, Pseudomonas aeruginosa and Enterococcus hirae. These findings suggested that geranium EO could be used as new and rich potential sources of many future multipurpose products for food preservation, pharmaceutical, and industrial applications.

Silicone-geranium essential oil blend for long-term antifouling coatings

This study explores the potential of geranium essential oil as a natural solution for combating marine biofouling, addressing the environmental concerns associated with commercial antifouling coatings. Compounds with bactericidal activities were identified by 13Carbon nuclear magnetic resonance (13C NMR). Thermogravimetric analysis (TGA) revealed minimal impact on film thermal stability, maintaining suitability for antifouling applications. The addition of essential oil induced changes in the morphology of the film and Fourier transform infrared spectroscopy (FTIR) analysis indicated that oil remained within the film. Optical microscopy showed an increase in coating porosity after immersion in a marine environment. A total of 18 bacterial colonies were isolated, with Psychrobacter adeliensis and Shewanella algidipiscicola being the predominant biofilm-forming species. The geranium essential oil-based coating demonstrated the ability to reduce the formation of Psychrobacter adeliensis biofilms and effectively inhibit macrofouling adhesion for a duration of 11 months.

Effects of Inhaled Linalool on the Autonomic Nervous System in Awake Mice

Objective/background A previous study showed that geranium essential oil predominantly affects the parasympathetic nervous system. This article examined the effects on the autonomic nervous system of linalool, one of the main components of geranium essential oil. Methods Mice were placed on a narrow elevated open platform and pulse wave measurements were taken while they were awake, with behaviors restricted. Heart rate and heart rate variability were analyzed from the pulse waves obtained and the effects on the parasympathetic and sympathetic nerves were examined. Results The results showed that linalool (5 μL/L air, inhaled) resulted in parasympathetic dominance before and after administration. Conversely, a tendency toward sympathetic dominance was observed with fluoxetine (1 mg/kg, intraperitoneal) as the positive control in the elevated open-platform test. Conclusion These results suggest that linalool and essential oils containing linalool regulate the autonomic nervous system by promoting dominance of the parasympathetic nervous system.

In vitro acaricidal activity of essential oils and their binary mixtures against ixodes scapularis (Acari: Ixodidae)

Ixodes scapularis ticks are vectors of infectious agents that cause illness in humans, including Lyme disease. Recent years have seen a surge in tick-borne diseases (TBD) resulting in a high demand for tick management products. Plants offer a valuable source of active compounds for the development of novel, eco-friendly tick control products, reducing potential risks to human and animal health. Essential oils (EOs) have emerged as potential acaricides and repellents against ticks providing an alternative to synthetic chemicals and aiding in the prevention of TBD by lowering the risk of tick bites. We investigated the acaricidal activity of EOs from lemongrass (Cymbopogon citratus), geranium (Pelargonium x asperum), savory thyme (Thymus saturejoides), and white thyme (Thymus zygis) on I. scapularis. The interactions (i.e., synergistic, antagonistic, or additive) of their binary mixtures were also evaluated. EO samples were analyzed via gas chromatography-mass spectrometry to determine their chemical composition. The adult immersion test was used to determine the lethal concentration (LC50) of each EO alone and in mixtures. Quantitative assessment of synergistic, additive, or antagonistic effect of the binary mixtures was performed by calculating the combination index. Strong acaricidal activity was recorded for savory thyme and white thyme EOs, with LC50 values of 28.0 and 11.0 μg/μL, respectively. The LC50 of lemongrass and geranium EOs were 49.0 and 39.7 μg/μL, respectively. Among the tested EOs, savory thyme and white thyme had a strong acaricidal effect on I. scapularis, which might be linked to the presence of carvacrol (26.05 % ± 0.38) and thymol (53.6 % ± 2.31), main components present in savory thyme and white thyme EOs, respectively. The tick killing efficacy of lemongrass and geranium EOs was lower when mixed than when used separately (LC50 of 65.3 µg/µL). The same happened with savory thyme and white thyme EOs, except at 9.75 µg/µL where they had a synergistic effect (LC50 of 58.3 µg/µL). Lemongrass and savory thyme EOs had a synergistic effect at low concentrations, and an antagonistic effect at higher concentrations (LC50 of 95.4 µg/µL). Lemongrass and white thyme EOs had a synergistic effect against ticks from 15 to 120 µg/µL (LC50 of 18.5 µg/µL) similar to white thyme EO. Geranium and savory thyme EOs had an antagonistic effect at all concentrations, with an LC50 of 66.8 µg/µL. Geranium and white thyme EOs also had an antagonistic effect, except at 12.7 µg/µL where they had a synergistic effect (LC50 of 66.8 µg/µL). The interaction observed when combining selected essential oils suggests promising potential for developing acaricidal formulations aimed at controlling ticks and curbing the transmission of tick-borne disease agents.

Pelargonium graveolens L., (Geranium) essential oil from Northeast India: chemical composition, pharmacology and genotoxicity study

Pelargonium graveolens L., essential oil (EO) has various therapeutic properties, including aromatherapy. The present experiment was designed to investigate chemical makeup of the P. graveolens (Geranium) EO from Northeast India using gas chromatography-mass spectroscopy (GC-MS) and gas chromatography-flame ionization detection (GC-FID), and the pharmacological potential was determined using a range of assays along with Allium cepa assay for genotoxicity study. GC-MS analysis of the EO revealed the presence of 11 compounds with a total 97.43% identified area, with citronellol (32.84%), geraniol (23.62%), and citronellyl formate (12.14%) as the major compounds. The essential oil exhibited type-II anti-diabetic properties with an IC50 6.66 μL/mL and skin whitening potential IC50 of 1.89 μL/mL. P. graveolens EO (IC50 26.16 μL/mL) was found to possess comparatively weaker anti-inflammatory agent than the standard diclofenac (IC50 9.24 μL/mL) in the protease inhibitory test. The EO demonstrated moderate antioxidant activity with an IC50 value of 22.68 μL/mL than ascorbic acid IC50 12.53 μL/mL in the ABTS assay. The EO was found to moderately affect the mitotic index (15.32%) and induce chromosomal aberrations (11.40%) at a concentration of 1 μL/mL after 72 h of exposure. Based on the findings the Northeast Indian variety of P. graveolens EO exhibits promising type-II anti-diabetic and skin whitening properties, which could be further utilized in the formulation of anti-diabetic and skin whitening agents after validation through clinical trials.

Acaricidal activity of five essential oils against Rhipicephalus annulatus ticks and their GC-MS analyses

Rhipicephalus annulatus is regarded as the most common tick in transmitting cattle disease. Chemical acaricides resistance and toxicity have directed research on the use of essential plant oils which have great potential for pest management for safe food production. Therefore, the current study was designed to test the larvicidal activity of essential oils (EOs) of five medicinal plants; cilantro leaves, orange leaves, Tagetes flower, geranium herb, and sweet basil herb against R. annulatus larvae using the larval packet test. Analysis of EO chemical composition using gas chromatography-mass spectrometry (GC-MS) was also carried out to justify the assigned activities. Cilantro, orange, and Tagetes EOs showed 100.0% larval mortality with lethal concerntrations that kills 50% (LC50) of 1.46%, 0.88%, and 2.94%, respectively. Geranium and sweet basil herbs EOs showed 96.33% ± 3.18% and 92.33% ± 1.45% larval mortality with LC50 of 5.28% and 7.20%, respectively. Major compounds were identified by GC-MS as follows, [2(E)-decenal (49.72%), decanal (21.47%)] from cilantro EO, [methyl methanthranilate (63.45%), γ-terpinene (18.64%)] from orange EO, [trans-β-ocimene (24.93%) and isoartemisia ketone (8.84%)] in Tagetes EO, [β-citronellol (41.83%), citronellyl formate (10.41%), geraniol (9.47%)] from geranium EO, and [β-Linalool (55.63%), 1,8-cineole (9.66%)] from sweet basil. Our results showed the potential of EOs as eco-friendly and economic acaricides for tick control.