Citronella Essential Oil Research Articles

Biplot investigation for essential oil yield and chemical compositions under the Deccan Plateau region of southern India in cultivars of Java citronella (Cymbopogon winterianus Jowitt)

The aromatic grass Java Citronella (Cymbopogon winterianus Jowitt) belongs to the Poaceae family. Citronella essential oil is used to extract the aroma chemicals geraniol and citronellal, which can then be converted into citronellol, hydroxy citronellol, synthetic menthol, and geraniol esters. In the Deccan Plateau region of southern India, farmers have a tough time determining which kind would produce high-quality essential oil. As a result, the goal of this study was to evaluate five java citronella cultivars in the Deccan Plateau region of south India and choose the best variety (or varieties) for large-scale production in the Deccan Plateau region. For evaluation, scientists from CSIR-CIMAP, RC, Hyderabad, India, used a three-time replicated randomized complete block design with a plot size of 3.0 m2 from 2017 to 2018 and 2018–2019. In Java citronella Java I, Jc-5 was the most stable and high-yielding genotype, though Jc-3 >Jc-2 >Jc-1 in the order performed better in Java citronella Java II type. This is due to the high stability/strong consistency across the years. Based on average performance and stability for higher-quality essential oil yield, these Java citronella genotypes are recommended for large-scale cultivation in the Deccan Plateau region of southern India.

Antimicrobial and Toxic Activity of Citronella Essential Oil (Cymbopogon nardus), and Its Effect on the Growth and Metabolism of Gilthead Seabream (Sparus aurata L.)

Aquaculture procedures usually induce stress that affects the physiological status of fish. For this reason, the inclusion of additives in fish feeds to palliate stress might be a good alternative. This study aimed to assess the antimicrobial activity of citronella (Cymbopogon nardus) essential oil (CEO) against bacterial pathogens and to determine its dietary impact on the growth performance of Sparus aurata. In vitro tests confirmed that CEO possesses antimicrobial activity against several fish-specific pathogens. For the in vivo tests, three experimental groups were fed for 60 days with different concentrations of CEO: CTRL (0 mL kg−1 fish feed); CEO1 (1 mL kg−1 fish feed); and CEO2 (2 mL kg−1 fish feed). At the end of the experiment, the physiological status was characterized. Subsequently, the specimens of the CTRL and CEO2 groups were subjected to a challenge with an injection of Poly I:C for immune stimulation. Although S. aurata individuals tolerated CEO inclusion without compromising growth performance, it significantly reduced glycogen in the CEO2 group, concomitant to an increment of total peripheral leucocytes. Moreover, different hematological profiles’ responsive patterns against an inflammatory stimulus were observed. In conclusion, our results suggest that the use of CEO as a fish feed additive can prevent bacterial outbreaks and improve potential in vivo disease resistance in S. aurata without negatively affecting growth.

The aromatherapy formulation of essential oils in reducing stress and blood pressure on human

Unhealthy lifestyles such as low physical activity, unbalanced nutrition consumption, high workloads, and low emotional management make a person vulnerable to stress. The large-scale lockdowns to reduce COVID-19 transmission also exacerbate the stress level. Regarding organic and complementary therapeutic schemes, both increased relaxation and decreased hypertension are carried out using aromatherapy that involves essential oil formulations. This study aims to identify the characteristics and effects of aromatherapy formulations, including benzoin, nutmeg, and citronella essential oils on relaxation and human blood pressure. The study began by identifying local applications of essential oils through interviews with 20 local people who apply essential oil in their remedies. The method included initial and final measurements of blood pressure in aromatherapy application for three consecutive days. To evaluate aromatherapy profiles, forty respondents were selected purposively and asked about their expression after inhalation. The results showed that application of the aromatherapy formulation reduced systolic pressure by 8.5 mmHg and diastolic pressure by 1.2 mmHg. Most of the respondents considered that the aroma of formulated essential oils has a refreshing and calming effect on their mind. These antidepressant effects are obtained from combination of benzyl cinnamate, geraniol, linalool, myristicin, p-cymene etc in formulated essential oils. This research concluded that inhalation of essential oils formulation provided a relaxing effect and reduced hypertension, significantly.

Kajian Minyak Serai Wangi (Cymbopogon nardus L.) terhadap Aedes aegypti

The Aedes aegypti mosquito can develop an immune system against the insecticide used. Control efforts with the use of insecticides are no longer effective if the target insects have become resistant. So there needs to be an effort to overcome the insect resistance that is targeted. Citronella grass is an herbal plant that can be used as an ingredient in vegetable pesticides. The leaves and stems are distilled to produce essential oil known as citronella oil. This research is about studying the effects of citronella oil against the resistance of the vector carrier for dengue fever, namely Aedes aegypti. The detection of citronella essential oil (Cymbopogon nardus L.) by Thin Layer Chromatography showed a reduction in UV254 visualization (Rf 0,68). The resistance test showed that the mortality percentage of adult mosquitoes Aedes aegypti exposed to 0.03% alphacymethrin was 73,7% resistant criteria (<90%). The mortality percentage of adult mosquitoes Aedes aegypti exposed to Alphacypermethrin (0,03%) and citronella oil was 2,5% each; 5%; 7,5% and 10% with treatment time 15 respectively, namely 18,7%, 50,7%, 70,7% and 82,7%; the treatment time of 30 minutes consecutively is 62,7%, 89,3%, 96% and 97,3% and the treatment time is 60 minutes respectively, namely 93,3%, 98,7%, 98,7% and 100%. There was an increase in the percentage of mosquito deaths exposed to the combination of alphacypermethrin and citronella oil, compared to those without citronella oil, this indicates that mosquitoes are more susceptible and resistance has decreased due to exposure to citronella oil.Â

Uji In Vitro Aktivitas Imunomodulator Minyak Atsiri Serai Dapur (Cymbopogon citratus) terhadap Proliferasi Sel Limfosit Mencit

This study aims to determine the immunomodulatory activity of lemongrass essential oil on the proliferation of mouse lymphocyte cells in vitro. The method used is steam distillation to obtain citronella essential oil. Isolation of lymphocyte cells was obtained from the spleen organ of Swiss-Webster strain mice which was carried out aseptically. The lymphocyte cell proliferation test was carried out using the MTT Assay method and the absorbance was measured using an ELISA reader at 550 nm. The results showed that the lemongrass essential oil contained positive alkaloids, flavonoids, saponins, and steroids/triterpenoids with an essential oil yield of 0.043%. The higher the volatile oil concentration, the higher the Optical Density (OD) value obtained, but the OD increase at a 50 to 100 g/mL concentration was not significantly different. In conclusion, lemongrass essential oil has immunomodulatory activity against lymphocyte cell proliferation in mice tested in vitro.
 Keywords: Immunomodulator, Essential Oil, Lemongrass (Cymbopogon citratus), Immune System

Biodegradable Alginate Films with ZnO Nanoparticles and Citronella Essential Oil-A Novel Antimicrobial Structure.

The petroleum-based materials could be replaced, at least partially, by biodegradable packaging. Adding antimicrobial activity to the new packaging materials can also help improve the shelf life of food and diminish the spoilage. The objective of this research was to obtain a novel antibacterial packaging, based on alginate as biodegradable polymer. The antibacterial activity was induced to the alginate films by adding various amounts of ZnO nanoparticles loaded with citronella (lemongrass) essential oil (CEO). The obtained films were characterized, and antibacterial activity was tested against two Gram-negative (Escherichia coli and Salmonella Typhi) and two Gram-positive (Bacillus cereus and Staphylococcus aureus) bacterial strains. The results suggest the existence of synergy between antibacterial activities of ZnO and CEO against all tested bacterial strains. The obtained films have a good antibacterial coverage, being efficient against several pathogens, the best results being obtained against Bacillus cereus. In addition, the films presented better UV light barrier properties and lower water vapor permeability (WVP) when compared with a simple alginate film. The preliminary tests indicate that the alginate films with ZnO nanoparticles and CEO can be used to successfully preserve the cheese. Therefore, our research evidences the feasibility of using alginate/ZnO/CEO films as antibacterial packaging for cheese in order to extend its shelf life.

Chemical Composition and Antifungal Potential of Citronella (Cymbopogon nardus) Leaves Essential Oil and its Major Compounds

The present study aims for quantitative analysis of citronella essential oil followed by its antifungal evaluation on maize fungi. GC/MS analysis of Cymbopogon nardus essential oil indicated the presence of citronellal (22.15 %), citronellol (16.34 %), and geraniol (11.16 %) as major constituents. Saponification value, acid value and moisture content were 139.15 mg/g, 2.1 mg/g and 20 %, respectively. The essential oil and its isolated compounds were tested for their antifungal potential against Fusarium verticillioides and Dreschlera maydis using the Poisoned food technique. C. nardus essential oil markedly suppressed the growth of F. verticillioides and D. maydis with ED50 values 0.095 and 0.098 mg/ml, respectively and was comparable to synthetic fungicide. The essential oil provides a great scope to be used as a natural eco-friendly fungicide for the control of maize fungi.

Attenuated total reflectance–Fourier transform infrared (ATR–FTIR) spectroscopy coupled with chemometric analysis for detection and quantification of adulteration in lavender and citronella essential oils

The growing consumer interest in "naturals" led to an increased application of essential oils (EOs). The market outbreak induced the intensification of EO adulterations, which could affect their quality. Nowadays, little is known about the illegal practice of adulteration of EOs with vegetable oils. Therefore, the application of mid-infrared spectroscopy coupled with chemometrics was proposed for the detection of EO counterfeits. Two EOs, three seed oils, and their mixtures were selected to build the adulteration model. EO-adulterant mixtures for model calibration and validation were analyzed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The spectral data were analyzed with principal component analysis (PCA) and partial least-squares (PLS) regression. PCA allowed the discrimination of the EO and adulterant percentages by explaining 97.47% of the total spectral variance with two principal components. A PLS regression model was generated with three factors explaining 97.73% and 99.69% of the total variance in X and Y, respectively. The root mean square error of calibration and the root mean square error of cross-validation were 0.918 and 1.049, respectively. The root mean square error of prediction value obtained from the external validation set was 1.588 and the coefficients of determination R2 CAL and R2 CV were 0.997 and 0.996, respectively. The results highlighted the robustness of the developed method in quantifying counterfeits in the range from 0 to 50% of adulterants, disregarding the type of EO and adulterant employed. The present work offers a research advance and makes an important impact in phytochemistry, revealing an easily applicable method for EO quality assessment.

PREPARATION OF HYBRID POLYMERS AND USE AS CONTROLLED RELEASE DELIVERY VEHICLE FOR VOLATILE REPELLENT TO CONTROL Aedes aegypti

The Zika virus is a flavivirus spread by the Aedes aegypti mosquito, which also transmits dengue and chikungunya. Current forms of control include elimination of mosquito breeding sites, use of insecticides, repellents and other means. The present study developed new adsorbent materials based on silica and biomaterials capable of releasing an Aedes aegypti mosquito repellent. The materials synthesized were characterized by Fourier-Transform Infrared, thermogravimetric analysis, Scanning Electron Microscopy and Brunauer, Emmett and Teller analysis and tested with citronella, an essential oil widely recognized as a natural insect repellent. The materials presented type IV isotherms, with type H1 hysteresis, characteristic of mesoporous materials, with pore diameters of between 50 Å and 80 Å. Materials based on silica-chitosan-glutaraldehyde dried in an oven (SCGO) and silica-chitosan-glutaraldehyde dried under a vacuum (SCGV) were found to produce more controlled release of citronella essential oil. The bioassay test was performed using a horizontal double-choice olfactometer. The adsorbent SCGO remained stable for the four hours of the bioassay, while the commercial repellent became ineffective after two hours of release. The production of a prototype in the form of bracelets, stickers releasing a volatile repellent is therefore proposed as a method for the control of the mosquito in urban areas.

Innovative Antimicrobial Chitosan/ZnO/Ag NPs/Citronella Essential Oil Nanocomposite-Potential Coating for Grapes.

New packaging materials based on biopolymers are gaining increasing attention due to many advantages like biodegradability or existence of renewable sources. Grouping more antimicrobials agents in the same packaging can create a synergic effect, resulting in either a better antimicrobial activity against a wider spectrum of spoilage agents or a lower required quantity of antimicrobials. In the present work, we obtained a biodegradable antimicrobial film that can be used as packaging material for food. Films based on chitosan as biodegradable polymer, with ZnO and Ag nanoparticles as filler/antimicrobial agents were fabricated by a casting method. The nanoparticles were loaded with citronella essential oil (CEO) in order to enhance the antimicrobial activity of the nanocomposite films. The tests made on Gram-positive, Gram-negative, and fungal strains indicated a broad-spectrum antimicrobial activity, with inhibition diameters of over 30 mm for bacterial strains and over 20 mm for fungal strains. The synergic effect was evidenced by comparing the antimicrobial results with chitosan/ZnO/CEO or chitosan/Ag/CEO simple films. According to the literature and our preliminary studies, these formulations are suitable as coating for fruits. The obtained nanocomposite films presented lower water vapor permeability values when compared with the chitosan control film. The samples were characterized by SEM, fluorescence and UV-Vis spectroscopy, FTIR spectroscopy and microscopy, and thermal analysis.

Sanitary and physiological quality of corn seeds (Zea mays) treated with essential oil emulsion

The aim of the present studies were to evaluate the effects of treatments with essential oil emulsion on the sanitary and physiological quality of creole corn seeds. In the studies were evaluated the essential oils of neem (Azadirachta indica), citronella (Cymbopogon nardus), lemon balm (Cymbopogon citratus), melissa (Melissa officinalis L.), and the combinations neem-citronella, neem-lemon balm, neem-melissa, citronella-lemon balm, citronella-melissa and lemon balm-melissa. The tests carried out were germination, length of seedlings (aerial part and root), dry mass and pathology for Fusarium sp and Aspergillus sp, in seeds of creole corn produced without the use of synthetic pesticides. The studies were carried out in vitro and consisted of the preparation of water emulsion, 5,000 ppm of essential oil and 1% of triton X100 and direct application on the seeds of creole corn, following the protocol of Rules of Seed Analysis (RSA). The results showed a significant decrease in the occurrence of fungi Fusarium sp and Aspergillus sp with treatment with essential oils of citronella, lemon balm and melissa, while the oil of neither reduced the occurrence of Fusarium sp, but increased the occurrence of Aspergillus sp in almost four times. All binary combinations of essential oils reduced the occurrence of both fungi. On the other hand, the physiological quality was strongly affected by the death of creole corn seeds, except for the treatment with lemon balm essential oil. Therefore, these studies allow to affirm that essential oils can be efficient in the control of pathogens, however they can kill the seeds of creole corn.

Enhanced protective potential of novel citronella essential oil microsponge hydrogel against Anopheles stephensi mosquito

Abstract Citronella oil has been frequently used as an insect repellant and antibacterial agent for management of vector borne diseases. In this study, the fabrication of citronella oil microsponge loaded hydrogel (HG-COMS) was conceptualized in order to provide future insight for developing delayed release formulation. The hydrogel was characterized for drug content, drug interaction studies, spreadability, texture analysis and in vitro occlusive behaviour and results were found satisfactory. Further, in vitro antimicrobial studies were carried out to compare the antimicrobial inhibitory potential of the HG-COMS against citronella oil loaded hydrogel (HG-CO). HG-COMS formulation showed better antimicrobial efficacy than HG-CO (zone of inhibition of E. coli, P. aeruginosa and S. aureus; with P value less than 0.01, 0.001 and 0.05, respectively). In addition, the safety (irritation potential) of the oil loaded hydrogel formulation was assessed by Hen’s Egg Test Chorioallantoic Membrane (HAT-CAM) method. Mosquito repellent activity against Anopheles stephensi (malaria vector mosquito) was also performed in a net cage having blood starved female mosquitoes. The repellent potential of prepared HG-COMS (34% repellency for 6 h) was found dependent on release of CO from the microsponges as well as from the gel matrix. HET-CAM test revealed that HG-COMS (irritation score: 6.43 ± 0.77) was found very promising in comparison to HG-CO (irritation score: 12.77 ± 0.36), and was thus, considered safer for dermal use. HG-COMS showed reduced frequency of application, no skin irritation and potential for controlling A. stephensi for longer time periods. Hence, HG-COMS is found as a promising eco-friendly protective option, to minimize the burden of mosquito-transmitted diseases, especially malaria in future.

Essential oils control anthracnose in pepper seeds

Pepper (Capsicum annum) is one of the main vegetables consumed in the Brazilian market, however, an important fungal disease, anthracnose, caused by Colletotrichum gloeosporioides, can decimate all its fruits in the field. Chemical control is the most commonly used measure of control, but, some active ingredients are proving ineffective, and consumers appreciate healthier options such as organic foods. Therefore, studies with natural substances that may help in the management of diseases have been encouraged. Because it is transmitted via seed, seed treatment becomes an essential measure in the management and control of pepper anthracnose. The objective of this study was to evaluate the effect of basil (Ocimum basilicum), citronella (Cymbopogon winterianus), clove (Syzygium aromaticum), copaiba (Copaifera langsdorfii), eucalyptus (Eucalyptus citriodora), mint (Mentha arvensis), rosemary (Rosmarinus officinalis) and tea tree (Melaleuca alternifolia) essential oils on the development of C. gloeosporioides. Citronella, clove, eucalyptus, mint and basil essential oils totally inhibited the pathogen, regardless of the concentration used. These essential oils were then used to treat seeds infected with C. gloeosporioides, evaluating the physiological and health quality of these seeds. Clove essential oil reduced the incidence of fungi in seeds inoculated with the pathogen, without affecting their physiological quality.

Physiological potential and fungi control of Moringa oleifera Lamark seeds treated with essential oils

Moringa oleifera Lam. is a fast-growing, drought-resistant, rustic plant with high nutritive value. The aim of the present study was to determine the effectiveness of essential oils from citronella grass (Cymbopogon winterianus), lemongrass (Cymbopogon citratus) and thyme (Thymus vulgaris) on the reduction of the incidence of fungi associated with moringa seeds as well as the influence of these oils on the physiological quality of the seeds. Two experiments were conducted, both with an entirely randomized design. The seeds were treated with the citronella, lemongrass and thyme essential oils at concentrations of 250 and 500 µL (100 seeds per treatment). The fungicide Captan was used as the control treatment. The incidence of fungi on the treated seeds was evaluated in the first experiment. The germination percentage, shoot length, primary root length, shoot dry mass and root dry mass of the seedlings were evaluated in the second experiment. The most incident fungus was also isolated for the transmission test. The following fungi were identified on the moringa seeds: Fusarium spp., Nigrospora sp., Aspergillus sp., Penicillium sp., Alternaria sp., Phomopsis sp., Curvularia sp., Colletotrichum sp., Pestalotipsis sp., Lasiodiplodia sp. and Chaetomium sp. The essential oils significantly reduced the incidence of the fungi. However, changes in the physiological quality of the seeds were associated with the use of the oils. No transmission of Fusarium spp. from the seeds to the seedlings occurred, but this fungus caused the rotting of seeds in the germination phase.

Chemical composition and antimicrobial activity of Java citronella (Cymbopogon winterianus Jowitt ex Bor) essential oil extracted by different methods

ABSTRACT Citronella (Cymbopogon spp.) essential oil is an important component of various fragrances, cosmetics, and household products. In this study, comparative chemical composition and antimicrobial activity of Java citronella (Cymbopogon winterianus Jowitt ex Bor) essential oil, extracted by different methods, namely hydro-distillation and steam-distillation were determined by GC, GC-MS, and disc diffusion assay and microdilution broth assay. Major constituents of the essential oil were citronellal (2.2–55.4%), geraniol (14.2–53.0%), citronellol (8.2–16.4%), isopulegol (0.3–12.6%), elemol (0.8–8.2%), and limonene (0.2–5.0%). The essential oils showed inhibition of test bacteria with minimum inhibition concentration (MIC) in the range of 250–1000 µg/mL and showed anticandidal activity with MIC in the range of 125–500 µg/mL. In general, the oils were moderately active against Gram-positive and Gram-negative bacterial strains and also showed good activity against Candidal strains. The essential oils extracted from the herbage by different techniques exhibited variations in their yield, chemical composition, and antimicrobial activities.

Utilization of biodiesel waste in the development of botanical-based floating tablet formulation against early stages of mosquitoes

The current paper has elaborated the efficient utilization of liquid biodiesel waste in combination with dillapiole and citronella essential oil as active ingredients. Sawdust, cellulose and hydrophobic silica were used as inert ingredients, which make the tablet to float over the water surface. ATR-FTIR analysis of tablet confirmed the compatibility with citronella oil, dillapiole, liquid biodiesel waste in tablet composition after compression. Physico-chemical analysis studies show that tablet parameters are in standard limits. SEM analysis shows some porous structures in tablet composition which confirms the floating nature of the tablets. The specific ratio (2:2:1) of citronella oil, dillapiole and liquid biodiesel waste showed maximum mortality, i.e. 95% after 24 h. After application, the tablet is nontoxic towards the aquatic organisms and water quality remains unaffected. The better performance of the tablets has been evaluated in terms of characterization studies, viz. ATR-FTIR and SEM studies and bioefficacy trials which confirmed the presence of active ingredients responsible for insecticidal activity.

Sensitivity and Feasibility Analysis of Citronella Oil Business

Today, citronella essential oil business in Indonesia is fronting two major problems: a diverse range of product quality and fluctuated price. Meanwhile, the global market demand keeps increasing until 3–5% per year. This fact indicated that the citronella essential oil business was having a high chance of participating in the global market. This study aimed to analyze the citronella essential oil business feasibility as a “people-oriented-economy” activity and determine variables that affected the feasibility in implementing this business. Citronella essential oil is produced by a steam distillation process with a production capacity of 2,400 kg/year. The number of citronella essential oil international product sales was reaching 76% with the selling price of IDR 360,000/kg and reaching 24% on the local market with the selling price of IDR 180,000/kg, therefore the total of sales in 300 days/year was IDR 7,360,320,000. Based on this calculation the total of profit obtained in a year was IDR 99,463,383. An effort through managing the material and selling price sensitivity already done to maintain the BEP and B/C values. The increasing price was anticipated by managing the product selling price fraction, while the decreasing of the selling price anticipated by managing the market fraction.

Application of microemulsions as coating in fresh cut strawberries.

The objective of this study was to evaluate microemulsions as a protective coating for fresh cut (FC) strawberries. The effectiveness of the coating was evaluated by physicochemical, fungal deterioration, and sensorial analysis. The fruits were processed and submitted to different treatments: control (T1); microemulsion with citronella oil (T2); pure microemulsion (T3); microemulsion with avocado oil (T4), and emulsion containing Tween® 20 and avocado oil in water (T5). The loss of mass, deterioration by fungi, color, and anthocyanin content were evaluated. Sensory analysis was carried out for appearance, brightness, color, and odor. Of all the evaluated coatings, conservation of FC strawberries was the highest with T5, wherein the evaluated sample exhibited reduced loss of mass and deterioration by fungi, minimal changes in physical appearance, and highest anthocyanin content. The avocado oil-containing microemulsion reduced deterioration by fungi, while the microemulsion with citronella essential oil maintained tonality of the fruits and preserved anthocyanins. This study has significantly contributed to the limited literature-based information available about MEs in the food.

Synthesis, characterization and crystal structure of two polymorphs of trans N-benzyl-3,9,9-trimethyl-1,2,3,4,4a,9,9a,10-octahydroacridine

Two polymorphs of the new heterocyclic compound trans-N-benzyl-3,9,9-trimethyl-1,2,3,4,4a,9,9a,10-octahydroacridine have been efficiently prepared via a one-pot BiCl3-catalyzed cationic Povarov reaction of N-benzyl aniline with a) (±)-citronellal (Polymorph I) and b) citronella essential oil from C. nardus (Polymorph II), in a highly diastereoselective fashion. The polymorphs were characterized by ATR-FTIR spectroscopy, 1H/13C NMR spectroscopy, IE and ESI-IT mass spectrometry, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and by single crystal X-ray diffraction. Polymorph I is monoclinic, space group Cc (N° 9), with unit cell parameters a = 12.0555(9) Å, b = 17.4664(13) Å, c = 17.7337(13) Å, β = 99.134(7), V = 3686.8(5) Å3, Z = 8. Polymorph II is triclinic, P1¯ (No. 2), with a = 9.8528(10) Å, b = 10.5144(11) Å, c = 10.8845(10) Å, α = 103.211(9)°, β = 114.048(9)°, γ = 101.483(9)°, V = 946.78(18) Å3, Z = 2. In polymorph I, the two independent molecules interact via weak C–H⋯C contacts to form dimers which are further connected by C–H ⋯ π interactions. In contrast, in form II the molecules interact via the same contacts but form infinite chains along the a-axis. Hirshfeld surface analysis indicates that H⋯H interactions are more important than C⋯H interactions. Theoretical calculations indicated that PM6-D3 methods produced the best agreement between the experimental and the energy minimized structure.

Antimicrobial activities of citronella (Cymbopogon nardus) essential oil against several oral pathogens and its volatile compounds

Introduction: Cymbopogon nardus is a strong aromatic plant with relevant medicinal properties due to its essential chemical compounds and its potential therapeutic effects. This study was aimed to evaluate the antimicrobial activities of citronella essential oil against several oral pathogens and to identify the volatile compounds. Methods: The essential oil of C. nardus was purchased from Excellent Wisdom Sdn. Bhd., Malaysia. The source of raw material was collected from Malacca, the southern region of Malaysia, and the company made its taxonomic identification. An experimental in-vitro study was conducted on the essential oil processed from C. nardus genus Cymbopogon of Poaceae family. The in-vitro antimicrobial activities of C. nardus essential oil were evaluated against Streptococcus mutans (ATCC 25175), Streptococcus sobrinus (ATCC 33478), and Candida albicans (ATCC 10231) using agar well diffusion assay. The identification of the volatile compounds was performed using gas chromatography-mass spectrometry (GC-MS). Results: The C. nardus essential oil exhibited inhibitory activity against C. albicans at the concentration of 6.25%, whereby the inhibitory activity against S. mutans and S. sobrinus began at the concentration of 25%. The antimicrobial activity of C. nardus essential oil was statistically significant at the concentration of 50% in all tested pathogens. The GC-MS analysis of the C. nardus essential oil revealed the presence of few constituents, which include monoterpenes, diterpenes, sesquiterpenes and phenolic compounds. Monoterpenes were the major identified terpenoids and contributed to 54.45% of the total volatile composition. The main identified monoterpenes were citronellal (11.35%), z-Citral (11.34%), β-Myrcene (6.70%), and β-Trans-ocimene (6.03%), which was the first time β-Myrcene and β-Trans-ocimene was found in high percentage. Conclusion: C. nardus essential oil is an active antibacterial agent against several oral pathogens, and the percentages of active volatile compounds are different within different origins.