Cymbopogon Distans Research Articles

Cymbopogon distans: A source of essential oil with potential antibacterial, antifungal, and mosquito-repelling properties

The essential oils have become increasingly popular in recent years due to their potential as natural antimicrobial agents and a means of controlling mosquitoes. This study explored the chemical composition and antibacterial, antifungal, and mosquito-repellent properties of Cymbopogon distans (Nees ex Steud.) Wats (Poaceae) is a less explored aromatic plant distributed in the Himalayas. The fresh biomasses of C. distans and two commercially grown Cymbopogon species, namely C. flexuous and C. martini were submitted to hydrodistillation to extract their essential oils. Gas chromatography-flame ionisation detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS) analyses revealed the presence of citral, geraniol, and geranyl acetate as major constituents of C. distans. The essential oils of C. flexuous and C. martini were dominated by citral and geraniol, respectively. Antibacterial and antifungal activities of C. distans essential oil were evaluated using disc diffusion and micro-dilution methods and compared with the essential oils of C. flexuous and C. martini. C. distans essential oil showed a broader spectrum of potent antibacterial and antifungal activities (minimum inhibitory concentration: 0.41 mg/ml and minimum bactericidal concentration/minimum fungicidal concentration: 0.82 mg/ml) against the test strains. C. distans essential oil, in combination with norfloxacin and penicillin G showed synergistic interactions (fractional inhibitory concentration ≤0.5) against Staphylococcus aureus and Staphylococcus epidermidis. C. distans essential oil showed a repellent effect against Aedes aegypti (73.3 %) that was comparable to C. winterianus essential oil (75.6 %). This study suggests that C. distans essential oil may be a promising natural candidate for developing new herbal therapies for combating microbial infections and mosquito-borne diseases.

Neuroinflammation and acetylcholinesterase inhibition potentials of acyclic monoterpenoids isolated from Cymbopogon distans (Nees ex Steud.) Will. Watson

Cymbopogon distans (Nees ex Steud.) Will. Watson (Poaceae) is a promising aromatic plant distributed in the Himalayas. In this study, five acyclic monoterpenoids, namely geranyl acetate (RS1), neral (RS2), geranial (RS3), citral (RS4) and geraniol (RS5) were isolated from the essential oil of C. distans. The isolated compounds were tested for in-vitro neuroinflammation inhibitory potential in LPS-stimulated BV2 microglial cells. RS1-RS4 exhibited significant neuroinflammation inhibition without any cytotoxic effect at the dose of 10 μM. RS4, the most active anti-neuroinflammatory compound (TNF-α 31.48 ± 1.00%; IL-6 24.02 ± 0.63%; IL-1β 42.15 ± 1.76%) was also able to inhibit acetylcholinesterase (AChE) in a dose-dependent manner. The results showed that RS4 (an isomeric mixture of neral and geranial) has the potential to inhibit neuroinflammation and AChE, which are the biomarkers of neurodegenerative disorders.

Multilayer Ti3C2-CNTs-Au Loaded with Cyclodextrin-MOF for Enhanced Selective Detection of Rutin.

In this work, multi-layer Ti3C2 - carbon nanotubes - gold nanoparticles (Ti3C2-CNTs-Au) and cyclodextrin metal-organic framework - carbon nanotubes (CD-MOF-CNTs) have been prepared by in situ growth method and used to construct the ultra-sensitive rutin electrochemical sensor for the first time. Among them, the large number of metal active sites of Ti3C2, the high electron transfer efficiency of CNTS, and the good catalytic properties of AuNPs significantly enhance the electrochemical properties of the composite carbon nanomaterials. Interestingly, CD-MOF has a unique host-guest recognition and a large number of cavities, molecular gaps, and surface reactive groups, which gives the composite outstanding accumulation properties and selectivity for rutin. Under the optimized conditions, the constructed novel sensor has satisfactory detection performance for rutin in the range of 2 × 10-9 to 8 × 10-7M with a limit of detection of 6.5 × 10-10M. In addition, the sensor exhibits amazing anti-interference performance against rutin in some flavonoid compounds and can be used to test natural plant samples (buckwheat, Cymbopogon distans, and flos sophorae immaturus). This work has promising applications in the field of environmental and food analysis, and exploring new directions for the application of Mxene-based composites.

Response of Metabolites in Cymbopogon distans Leaves to Water Addition in Karst Areas during Different Seasons

Climate change could influence the plant response to drought stress in karst environments. However, fewer related studies have been reported. This study examined the impact of artificial water addition on the accumulation of metabolites of Cymbopogon distans with a non-targeted metabolomics approach during both the dry and wet seasons. Three water treatment gradients (CK, T1, and T2, indicating 0%, +20%, and +40% relative to the average monthly precipitation, respectively) were chosen. The findings of our study indicate that the levels of primary metabolites were higher in the leaves of C. distans during the dry season compared to the rainy season. In addition, the presence of water did not have a substantial impact on the composition and functionality of metabolites between the wet and drought seasons. The contents of some lipids were greater during the dry season, while others were greater during the wet season. During the dry season, the contents of FA, DG, MGDG, SQDG, TG, and PR decreased with water addition. Our findings demonstrated that artificial water addition might have a greater impact on metabolite accumulation during the dry season in drought-tolerant species in karst areas. Due to the buildup of certain metabolites, they exhibit clear drought resistance. At the same time, water addition during the dry season will also cause a certain stress, affecting the adaptability of plants. These findings have significant ramifications for the management and choice of species in various sea seasons in karst regions.

Acyclic monoterpenoid-rich essential oil of Cymbopogon distans mitigates skin inflammation: a chemico-pharmacological study.

The topical application of essential oils is considered an effective treatment for skin diseases. Cymbopogon distans (Nees ex Steud.) Wats (Poaceae) is a promising aromatic grass widespread in the Himalayan temperate zone. Therefore, using in-vitro and in-vivo bioassays, we examined the chemical and pharmacological characteristics of essential oil hydro-distilled from C. distans coded as CDA-01, specifically concerning skin inflammation. Characterization using GC-FID and GC-MS provided a chemical fingerprint for CDA-01, enabling the identification of 54 compounds; amongst them, citral (34.3%), geranyl acetate (21.2%), and geraniol (16.4%) were the most abundant. To examine the anti-inflammatory potential, CDA-01 treatment on LPS-stimulated macrophage cells in addition to 12-O-tetradecanoylphorbol-13-acetate (TPA) generated cutaneous inflammatory reaction in the mouse ear was assessed through quantification of the inflammatory markers. Consequently, CDA-01 demonstrated protection against inflammation caused by LPS by lowering the pro-inflammatory cytokines (IL-6 and TNF-α) level in HaCaT cells with negligible cytotoxicity. Consistent with the in-vitro findings, CDA-01 treatment reduced pro-inflammatory mediators (TNF-, IL-6, and NO) and lipid peroxidation in an in-vivo investigation. Subcutaneous inflammation in TPA-treated mice ears was similarly decreased, as evidenced by the histological and morphological studies. As a result of our findings, it is possible that CDA-01 could be an effective treatment for skin inflammation disorders.

Antifungal, Repellency, and Insecticidal Activities of Cymbopogon distans and Ruta graveolens Essential Oils and Their Main Chemical Constituents.

Essential oils produced by Cymbopogon distans and Ruta graveolens with a similar Chinese name could be explained as book fragrance in the Chinese idiom 'shu xiang men di', namely, a wealthy intellectual family according to ancient Chinese. Therefore, volatile oils from these two plants and their main compounds were tested to explore their antifungal, repellent, and insecticide actions. In this study, the essential olis (EO) of C. distans exhibited significant antifungal activity against Rhizopus stolonifera (97 %), Mucor racemosus (97 %), and Trichoderma viride (84 %); its main compounds exhibit interesting activity, such as methyleugenol (87 %) and elemicine (85 %) against T. viride and butyl hydroxytoluene against M. racemosus (90 %) and R. stolonifera (95 %). The EO of R. graveolens and other major chemical constituents showed weak inhibitory effects against other fungi (Aspergillus flavus and Fusarium oxysporum). Then, EO (C. distans and R. graveolens) and its main compounds exhibited obvious repellent activity (more than 85 %) at a concentration of 16 nL/cm2 , which was consistent with the repellency of the positive control (DEET). In terms of insecticidal activity, the mortality of C. distans volatile oil against R. padi (56.4 %) was lower than that of R. graveolens volatile oil (92.4 %), and all compounds showed weak lethal effects. These results provide a natural substance for controlling fungi and insects when storing books and that can be used as a biological pesticide for industrial production. Through our study, the book fragrance in the Chinese idiom 'shu xiang men di' was speculated to be the EO odor of C. distans.

Chemical Constituents of Essential Oils of Cymbopogon distans from Two Producing Areas during Different Storage Periods

Chemical Constituents of Essential Oils of Cymbopogon distans from Two Producing Areas during Different Storage Periods

Oxygenated Geosmins and Plant-like Eudesmanes from a Bacterial Mangrove Endophyte.

Geosmin (1) is a microbial terpene metabolite that is responsible for the typical smell of soil and causes an off-odor of food and water. Eudesmane sesquiterpenes are commonly found in plant essential oils. Here we describe the discovery of four geosmin-type metabolites, 7R-hydroxygeosmin (2), 3-oxogeosmin (3), 2R-hydroxy-7-oxogeosmin (4), 5-deoxy-7β,9β-dihydroxygeosmin (5), the plant-like eudesmanes 4β,10α-eudesmane-5β,11-diol (6) and (1S,5S,6S,7S,10S)-10α-eudesm-4(15)-ene-1α,6α-diol (7), and the known 1(10)E,5E-germacradiene-2,11-diol (8) from a bacterial endophyte (Streptomyces sp. JMRC:ST027706) of the mangrove plant Bruguiera gymnorrhiza. By means of NMR, MS, and ECD spectroscopy, all chemical structures as well as the absolute configurations for the new compounds were elucidated. Compounds 2-5 represent the first geosmin-related metabolites directly as bacterial natural products. The plant-derived eudesmane-5β,11-diol (6) and (1S,5S,6S,7S,10S)-10α-eudesm-4(15)-ene-1α,6α-diol (7) are also now reported as bacterial products. The broad antimicrobial activities of 6 against a suite of fungal and bacterial pathogens including methicillin-resistant Staphylococcus aureus suggest that this terpene could be an important active principle of the medicinal plant Cymbopogon distans. The discovery of geosmin metabolites from one actinomycete indicated that these bacteria could possess enzymes for modifying geosmin and offer a possibility for bioremediation.

Differential stoichiometric responses of shrubs and grasses to increased precipitation in a degraded karst ecosystem in Southwestern China

The elemental concentrations of both plants and soils are sensitive to variations in precipitation due to the limiting roles of water on soil processes and plant growth in karst ecosystems of Southwestern China; however, precipitation is predicted to increase in this region. Nevertheless, it is unclear how the elemental composition of soils and plants might respond to such increases in moisture. Particularly, how potassium (K) may behave as a key mediator in the regulation of the water potential of plants. For this study, the responses of the elemental composition of both soils and plants to the variable addition of water were investigated. Two grasses (Cymbopogon distans and Arundinella setosa) and two shrubs (Carissa spinarum and Bauhinia brachycarpa) were investigated under four levels of watering treatments 0%, +20%, +40%, and +60%, relative to the annual rainfall, respectively. Compared to the control (CK), the soil water content (SWC) increased to 3.75, 3.86, and 4.34 mg g−1 in T1, T2, and T3 groups, respectively (p < 0.05). Non-metal elements (C, H, N, S, and P, except for Si) in the soil were relatively stable with water addition; however, metal elements (Al, Na, Mg, Fe, and K, along with Si) increased significantly, whereas Zn and Ca decreased (p < 0.05). With water addition, leaf N and P remained unchanged in all four species, while K, Mg, and S decreased in both shrubs (higher C:K, N:K, and P:K). Increases in Fe, Si, and K were observed in both grasses (lower C:K, N:K, and P:K), which suggested that K played distinct roles for water regulation in shrubs and grasses. These findings implied that the elemental compositions of both soils and plants might be altered with increasing precipitation in the future, where different plant types may adopt distinct K-regulation strategies to cope with variable soil moisture.

Differential metabolic responses of shrubs and grasses to water additions in arid karst region, southwestern China

Increasing precipitation has been predicted to occur in the karst areas in southwestern regions of China. However, it is little known how various plants respond to increasing precipitation in this region. Here we determined the impacts of water addition on leaf metabolites of grasses (Cymbopogon distans and Arundinella sitosa) and shrubs (Carissa spinarum and Bauhinia brachycarpa) in this area. Four levels of water additions (CK, T1, T2 and T3 indicating 0%, +20%, +40% and +60% relative to the current monthly precipitation, respectively) were designed. Sphingolipids substantially increased in the leaves of all four species with increasing water supply which suggests that these plants adopted biochemical strategy to tolerate the wet stress. However, both shrubs showed decreases in valine and threonine (amino acids), threonate, succinate and ascorbic acid (organic acids), galactose and rhamnose (sugars) and epicatchin and oleamides (secondary metabolites) with increasing water supply. Both grasses increased in the total metabolites at T1, but the total metabolites in A. sitosa significantly decreased at T2 and T3 while remains unchanged in C. distans. Tri-carboxylic acid cycle and amino acid metabolism in shrubs and shikimate pathway in grasses were strongly affected with water supply. Overall, shrubs and grasses respond differentially to variation in water addition in terms of metabolomics, which is helpful in understanding how plants respond to climate change.

Types and species diversity of Cupressus communities in Southeast Tibet, China.

Cupressus communities are the important parts of natural forests in Southeast Tibet, with significance on plateau biodiversity conservation and ecological security. To clarify their types and plant species diversity, we analyzed species composition and diversity indices, diameter class pattern of constructive species in different communities in Milin County, Lang County and Bomi County, Southeast Tibet. The results showed that Cupressus communities could be classified into four types: C. torulosa-Lonicera lanceolate + Philadelphus tomentosus-Pteris cretica var. nervosa + Digitaria violascens community (Community1), C. gigantea-Desmodium elegans + Sophora moorcroftia-na-Tripogon filiformis + Cymbopogon distans + Orinus thoroldii community (Community2), C. gigantea-Leptodermis purdomii-Chenopodium hybridum + O. thoroldii community (Community 3), and C. gigantea-Ceratostigma minus-A. desertorum + O. thoroldii + Tribulus terrester community (Community 4). Across those four community types, Margalef index, Shannon index, Pielou index and interspecies encounter probability index all ranked with the decreasing order of Community1, Community2, Community 3 and Community 4. Diameter class pattern of the constructive species showed that many young and few middle/old individuals were within the four communities. High mortality rate occurred during the interim period from young to middle age classes. In general, populations of Cupressus plants showed a declining trend.

Molecular, Chemical and Microscopic Analysis of Medicinal Plant (&amp;lt;i&amp;gt;Cymbopogon distans&amp;lt;/i&amp;gt;) from Its Adulterants

Morphological resemblance among Cymbopogon distans species and their adulterants which are procured from different markets in the form of dried or fresh plant tissues represents a serious problem for quality and safety of medicinal plants, as it supports frauds for substitution. In order to assure the quality control of C. distans species, DNA barcode, microscopic identification and High Performance liquid chromatography (HPLC) fingerprint were synergistically used to discriminate C. distans from its adulterants. In this work, the internal transcribed spacer 2 (ITS2) was chosen for distinguishing C. distans from their usual adulterants from 5 provinces of China. Sequences were obtained after removal of the 5.8S and 28S sections. A multiple sequence alignment was finalized. Results exhibited that ITS2 performed well, with 100% of genera being accurately distinguished. Additionally, finding indicates that the upper epidermis in leaf of C. distans was composed of one layer of wide elongated cells called Bulliform cells whereas in C. distans the upper epidermis consist of one layer cell, thus these feactures are very important for the anatomy identification. The HPLC fingerprint method was also developed, the similarities of 6 batches of C. distans samples were all more than 0.93, indicating that the samples from different geographical origins shared similar HPLC fingerprints. And the similarities between C. distans, C. citratus, C. flexuosus and Imperata cylindrica were all less than 0.93, suggesting that there was significance difference between C. distans and its adulterants. Finally, it was concluded that the DNA barcode, HPLC fingerprint and microscopic methods could effectively authenticate the quality of C. distans from their adulterants and can provide accurate and reliable information to tackle the complex quality issue of C. distans in markets. This is the first report of detailed analysis of the C. distans for effective quality and safety.

P-Menthenols chemotype of Cymbopogon distans from India: composition, antibacterial and antifungal activity of the essential oil against pathogens

Cymbopogon distans (Nees. ex. Steud.) W. Watson (family: Poaceae) is a perennial aromatic grass widely distributed in tropical and subtropical zones of north-western Himalaya. The essential oil of C. distans has industrial potential for aromatherapy, fragrances and for natural aroma isolates. In view of chemotypic variations and industrial potential of the essential oil of C. distans, the present study was carried out to investigate the variability in chemical composition of p-menthenols chemotype of the C. distans harvested in different seasons during annual growth, and to evaluate the antimicrobial potential of its essential oil against pathogenic bacterial and fungal strains. The major constituents identified in essential oil of C. distans were cis-p-menth-2-en-1-ol (24.5–26.7%), δ-2-carene (19.9–28.2%), cis-piperitol (10.9–23.6%), trans-p-menth-2-en-1-ol (8.4–13.3%) and trans-piperitol (5.4–7.3%). The essential oil showed antagonist activity against nine bacterial strains (MIC: 250–1000 μg/mL) and three fungal strains (MIC: 130–530 μg/mL). Results revealed that the essential oil of C. distans possessed >50.0% of p-menthenols viz., cis-p-menth-2-en-1-ol, trans-p-menth-2-en-1-ol, cis-piperitol and trans-piperitol as major constituents, with a significant antimicrobial potential for pathogenic microbial strains.

Attraction behaviour of Anagrus nilaparvatae to remote lemongrass (Cymbopogon distans) oil and its volatile compounds

Utilisation of Anagrus nilaparvatae is a promising and effective method for planthoppers manipulation. Twenty-seven components of remote lemongrass (Cymbopogon distans) oil were identified by GC/MS and nine volatiles were selected for behavioural experiments. In this study, we noted that the remote lemongrass oil was attractive to female A. nilaparvatae at concentrations of 0.1 and 1 mg/L. α-Pinene, β-pinene, eucalyptol, carveol and D-carvone attracted female wasps in the dose-dependent bioassays. Blend 1 (a mixture of eucalyptol, D-carvone, carveol, α-pinene, and β-pinene with ratios of remote lemongrass oil volatiles of 625:80:11:5:3) attracted female wasps at 10 mg/L, while blend 2 (a mixture of the same five volatiles at the same loading ratio) attracted them at 0.1 and 1 mg/L. These results suggested that plant essential oils could be attractants for natural enemies to control pests. The ratios of volatiles in the mixtures affect the attractiveness of the synthetic mixtures.

Evaluation of essential oil of Cymbopogon distans and Cinnamomum tamala against plant pathogenic fungi

Resistance to conventional fungicides causes the poor disease control of agriculture plant essential oils have a great potential as novel fungicide sources for controlling pathogenic fungi. In this study antifungal activity of the essential oil of Cymbopogon distans and Cinnamomum tamala were evaluated in vitro against ten plants pathogenic fungal activity was evaluated with three replicates. The result showed C. distans and C. tamala essential oil with maximum zone of inhibition against Fusarium sp. (12.53 ± 0.97 mm) and P. aurantiogriseum (12.06 ± 0.52 mm) while minimum activity was seen against R. solani (6.83 ± 0.41, 6.16 ± 0.16 mm) zone of inhibition respectively. The highest efficacy was observed for C.distans essential oil where the MIC values 0.625 mg/ ml against A. flavus and Pythium sp. So, plant essential oils have the potential to replace the synthetic fungicides in the management of postharvest diseases of fruits and vegetables.

Post harvest storage effect on essential oil content and composition of Cymbopogon distans (Nees ex Steud.) Wats.

The members of Cymbopogon genus are of commercial importance owing to have essential oils, which are highly prized in flavor and fragrance industries. Cymbopogon distans (Nees ex Steud.) Wats. is an under-explored aromatic member of this genus which is found abundantly wild in western and central Himalayan region. The lemon-scented chemotype of C. distans, domesticated in foothills was studied for post harvest storage under shade and open field conditions. The results revealed that there were no losses in essential oil content up to 15 days of storage (0.46%) under shade conditions. However, in field conditions a loss of 6.52% and 10.87% of essential oil was observed over a fresh herb after 7 days and 15 days of storage, respectively. Major constituents of the essential oil, viz.geranial (20.3–25.9%), neral (13.2–17.5%), geraniol(15.3–18.6%), and geranyl acetate (17.2–23.0%) showed change under post harvest storage. In conclusion, C. distans should preferably be distilled a fresh or it may be stored in shade conditions up to 15 days without any loss of essential oil.

Chemical Composition and Antifungal Activity of Essential Oil of Cymbopogon distans (Nees ex Steud.) W. Watson, Eupatorium adenophorum Spreng and Lantana camara L. grown in Uttarakhand (India)

The volatile constituents of a naturally occurring aromatic grass, Cymbopogon distans (Nees ex Steud.) W. Watson (Family Poaceae) and two invasive weeds, Eupatorium adenophorum Spreng (Asteraceae) and Lantana camara L. (Verbenaceae) grown in Uttarakhand, India were analyzed by GC and GC-MS. The essential oil of C. distans was dominated by monoterpenoids (83.87 %) with camphene (15.26 %), limonene(14.21 %), α-terpinene (11.33 %), bornyl acetate (8.41 %), cis-p-menth-2-en-1-ol (5.76 %) and trans-p-menth-2-en-1-ol (3.29 %) in higher amounts. E. adenophorum oil was also dominated by monoterpenoids (59.77 %) having p-cymene (14.56 %), phellandrene (12.25 %), camphene (10.42 %) and bornyl acetate (9.76 %) as the major constituents, whereas the essential oil of L. camara was characterized by the presence of sesquiterpenes in higher portions (55.82 %), constituted of germacrene-D (19.55 %), trans-caryophyllene (17.53 %) and β-curcumene (10.22 %). All the three extracted essential oils were tested against the fungus Fusarium oxysporum at different concentrations. The results revealed that C. distans oil showed most prominent activity against Fusarium oxysporum.

Compositional Variation in Leaves and Inflorescence Essential Oils of Cymbopogon distans (Steud.) Wats. from India

Cymbopogon distans (Steud.) Wats., is a perennial aromatic grass wildly growing in xerophytic grasslands of upper Himalayan region. Hydrodistilled essential oils of the leaves and inflorescence of C. distans were analysed by capillary gas chromatography (GC–FID) and gas chromatography mass spectrometry (GC–MS). A total of 43 constitutes, representing 88.0–94.6 % of total oil compositions were identified. Leaves and inflorescence essential oils were dominated primarily by oxygenated monoterpenes (89.4 and 84.7 %, respectively), followed by small amount of monoterpene hydrocarbons (3.7 and 1.8 %, respectively). Major constituents of oils were geranial (26.3–38.2 %), geranyl acetate (22.6–25.6 %), neral (16.0–18.9 %), geraniol (4.8–12.3 %), limonene (1.0–1.7 %), linalool (0.8–1.3 %), and citronellal (1.0–1.2 %). The citral content (neral and geranial) was higher in leaf oil (57.1 %) as compared to inflorescence oil (42.3 %), while the amounts of geraniol and geranyl acetate were higher in inflorescence oil (12.3 and 25.6 %) as compared to leaf oil (4.8 and 22.6 %).

Introduction of Cymbopogon distans (Nees ex Steud.) Wats to the sub-tropical India: Evaluation of essential-oil yield and chemical composition during annual growth

Cymbopogon distans (Nees ex Steud.) Wats is a perennial aromatic grass growing wild in the temperate Himalayan region. In order to find new ecological areas for its commercial cultivation, an attempt has been made to introduce this plant to the sub-tropical region. In the present study, successfully domesticated lemon-scented strain of C. distans was evaluated for their essential-oil yield and chemical composition throughout the year. The essential-oil yields observed in the initial two years were 3.85±0.22mL/plant/year. The essential-oil content varied from 0.34±0.05 to 0.44±0.04% in different seasons. A total of thirty-eight constituents, representing 85.5–94.7% of the total oil compositions were identified using gas chromatography (GC) and GC–mass spectrometry (GC–MS) methods. Geraniol (10.7–20.8%), neral (15.0–18.0%), geranyl acetate (16.0–22.7%), geranial (19.7–24.7%), and limonene (1.9–6.1%) were identified as the major constituents of the essential-oil. Besides seasonal changes, variations in the essential-oil composition were also noticed between the first and second harvests of the plant.

Repellent Constituents of Essential Oil of Cymbopogon distans Aerial Parts against Two Stored-Product Insects

The screening for bioactive principles from several Chinese medicinal herbs showed that the essential oil of Cymbopogon distans aerial parts possessed strong repellency against the booklouse, Liposcelis bostrychophila , and the red flour beetle, Tribolium castaneum . A total of 36 components of the essential oil were identified by GC and GC-MS. trans-Geraniol (16.54%), (R)-citronellal (15.44%), (+)-citronellol (11.51%), and α-elemol (9.06%) were the main components of the essential oil followed by β-eudesmol (5.71%) and (+)-limonene (5.05%). From the essential oil, four monoterpenes were isolated by bioassay-guided fractionation. The compounds were identified as limonene, citronellol, citronellal, and trans-geraniol. Geraniol and citronellol were strongly repellent against the booklouse, L. bostrychophila, whereas citronellal and limonene exhibited weak repellency against the booklouse. Geraniol and citronellol exhibited comparable repellency against the booklouse relative to the positive control, DEET. Moreover, geraniol and citronellol exhibited stronger repellency against the red flour beetle than DEET, whereas the two other compounds showed the same level of repellency against the red flour beetle compared with DEET.