56 International Journal of Essential Oil Therapeutics (2009) 3, 56-65

e International Journal of rc Essential Oil Therapeutics EORC www.ijeot.com

Cymbopogon essential oils: Chemical compositions and bioactivities

D. Ganjewala

Plant Biotechnology Division, School of Biosciences and Technology, Vellore Institute of Technology (VIT) University, Vellore-632 014, Tamil Nadu, India

Abstract The genus () is most important from the point of view of their essential oils. Essential oils from these species are widely used in flavours, fragrances, cosmetics, soaps, detergents and perfumery owing to their typical lemon and -like aroma. Cymbopogon essential oils and constituents present therein e.g. citral, geraniol, citronellol, citronellal and piperitone, have been known to possess impressive antibacterial, antifungal, antiyeast, insecticidal and insect repellent activities for a long time. However, the biological and pharmacological significance of these essential oils has been rapidly expanded in the past ten years; anti-inflammatory, anticancer, allelopathic, free radical scavanging and other useful biological activities have now been demonstrated. Cymbopogon essential oils and constituents offer outstanding biological activities and therefore may be used in the treatment of several diseases, including cancers, and in applications of industrial importance particularly food packaging. The present review discusses the chemical compositions and biological activities essential oils from Cymbopogon species and emphasizing mechanisms of action. These details were gathered from reports on the bioactivities of essential oils of Cymbopogon species published during 1999-2009.

Keywords: allelopathic, anticancer, anti-inflammatory, antioxidant, Cymbopogon species, essential oil, isointermedeol

Introduction have been studied extensively, both previously and The genus Cymbopogon (Poaceae) is renowned for currently [1-9]. their essential oils of immense commercial significance The essential oils of Cymbopogon species mainly in flavours, fragrances, cosmetics, perfumery, soaps, consist of the monoterpene fractions. Several reports detergents and pharmaceuticals [1]. The genus comprises published earlier have revealed the presence of citral of about 140 species of which most are aromatic and yield (a mixture of geranial and neral), geraniol, citronellol, an essential oil upon the steam distillation of their aerial citronellal, linalool, elemol, 1,8-cineole, limonene, geraniol, parts [2]. β-caryophyllene, methyl heptenone, geranyl acetate and Some most important species of this genus are: geranyl formate in the essential oils of different species • Cymbopogon flexuosus Stapf. (East Indian lemongrass) with marked variations have been reported. Also, the • Cymbopogon citratus DC Stapf. (West Indian essential oil components are greatly influenced by genetic, lemongrass) environmental and geographical conditions [1-3]. The • Cymbopogon nardus (L) essential oils in Cymbopogon species are biosynthesized in • Cymbopogon winterianus Jowitt (citronella) the rapidly growing leaves and stored in specific oil cells in the parenchymal tissues [10,11]. • Cymbopogon martinii Roxb. (palmarosa) • C. nardus x C. jwarancusa (jamarosa hybrid ) [3]. For many years lemongrass (C. flexuosus) has been used as a culinary flavouring in Asia. The leaves are cooked with Essential oils from Cymbopogon species of diverse origin foods, especially curries, and the peeled stems are available in local markets. Fresh leaves crushed in water are used as * Corresponding author. hair wash and toilet water in India. Beside their traditional E-mail address: [email protected] uses, studies aimed to evaluate the biological activities of © Essential Oil Resource Consultants. All rights reserved. the essential oils and constituents of Cymbopogon species International Journal of Essential Oil Therapeutics (2009) 3, 56-65 57 have revealed their usefulness. Perhaps their significance extensively studied for their chemical composition by gas has been best realized in the past ten years. Studies have chromatography, GC-MS and NMR spectroscopy [1-9]. In revealed many useful biological activities of the essential recent years C. flexuosus, C. citratus, C. martinii, C. winterianus, oils and essential oil constituents of Cymbopogon species C. nardus, C. giganteus, C. schoenanthus and C. parkeri have in recent years such as anti-inflammatory, anticancer been investigated for their chemical compositions as well as and allelopathic activities [12-16]. There are few reports evaluated for biological activities The studies have revealed available describing other bioactivities of agricultural and that their essential oils mainly consist of monoterpenes ecological significance such as food packaging and insect (acyclic and acyclic), whilst those of C. flexuosus and C. repellent of essential oils of Cymbopogon species [17-20]. parkeri also consist of bicyclic monoterpenes, piperitone For example, C. martinii (palmarosa) essential oil is used as and sesquiterpenes such as isointermedeol [14, 21]. fumigation to control beetles like Callosobruchus chenesis Isointermedeol is a major component in the essential oil and Tribolium castaneum, which grow in stored grain [18]. of C. flexuosus that has anticancer properties [18]. Similarly, the insect repellent properties of C. winterianus (citronella) are used to protect cartons containing muesli and wheat germ from beetles [19]. It is also reported that the essential oils of Cymbopogon flexuosus, C. citratus, C. martinii, C. winterianus, C. nardus, C. khasianus, C. nervatus, C. schoenanthus, C. giganteus and C. densiflorus possess several useful bioactivities. In addition, individual chemical constituents such as citral, geraniol, citronellol, citronellal, linalool, limonene, piperitone, borneol, bisabolol and isointermedeol have demonstrated remarkable bioactivities, including anticancer activity [14]. The easy availability, pleasant olfactory properties and insignificant toxicity of the Cymbopogon essential oils make them most promising candidates for the treatment of chronic diseases [14]. In addition, their semio-chemical properties are useful as an alternative to synthetic chemical Figure 1. Mini Clevenger apparatus for extraction of essential oil. pesticides in an integrated pest management programme Figure 1. Mini Clevenger apparatus for essential oil [18]. extraction. Certainly, essential oils of the Cymbopogon species are Gas chromatographic analyses of essential oils of C. occupying increasingly and vastly varied significance in flexuosus cultivars OD-19 and GRL-1 has revealed the pharmaceuticals and medicine owing to their potential presence of several monoterpenes viz., citral (a and b), bioactivities. This trend, however, has been increased geraniol, borneol, isopulegol and 6-methyl hept-5-en-2- progressively in the past ten years. Despite the fact that one, geranyl acetate, γ-terpinene, α-thujene, α-pinene, the numbers of reports are increasing on the bioactivities sabinene, n-decanol, α-terpenyl acetate, β-caryophyllene, of Cymbopogon essential oils, these reports have not been α-humulene, germacrene D, β-bisabolene and γ-cadinene analyzed or reviewed at one place. In this review article, [1-9]. Structures of some of these monoterpenes are I have discussed chemical compositions and various presented in Figure 2. bioactivities of the essential oils of Cymbopogon species Our earlier study of essential oil compositions in eight from the collation of reports published in the past ten cultivars of C. flexuosus revealed that essential oils of the years. Also, the biosynthesis and accumulation of the seven cultivars consisted mainly of citral (75-85%), except essential oils has been briefly mentioned. that of cultivar GRL-1, which is mainly composed of Essential oil extraction from Cymbopogon species geraniol (90%) [1]. Citral is an isomeric mixture of geranial (citral a) and neral (citral b) and are major components Essential oils from members of the genus Cymbopogon are in the essential oils of several species of Cymbopogon usually extracted by steam or hydrodistillation of the aerial [10]. Both citral and geraniol have immense commercial parts, such as leaves and inflorescences in mini Clevenger significance due to their characteristic lemon and rose- apparatus (Figure 1). They yield an essential oil with a like smell in the flavour, fragrance, cosmetics, perfumery characteristic aroma due to the presence of the significant and pharmaceutical industries [1,22]. A study of essential monoterpene fractions. Cymbopogon flexuosus (East Indian oil composition and phylogenetic relationship in 19 lemongrass) oil is yellow to reddish-brown in colour and Cymbopogon taxa by Khanuja et al. 2005 [2] revealed marked the odour is powerful lemon like, while that of C. martinii variation in the essential oil content and compositions of (palmarosa) and C. flexuosus mutant cv. GRL-1 essential these taxa. Essential oils from C. confortiflorus and C. nardus oil has a rose-like aroma due to the higher proportion of var. confortiflorus were rich in geraniol with observed geraniol. values of 68% and 46%, respectively, whereas essential oils from C. nardus var. nardus and C. winterianus had very Chemical compositions of the essential oils little amount of geraniol. Essential oil extracted from C. Essential oils of a number of Cymbopogon species have been pendulus, C. flexuosus and C. citratus mainly consisted of 58 International Journal of Essential Oil Therapeutics (2009) 3, 56-65

1. 2. 3. 4.

5. 6. 7. 8.

9. 10. 11. 12. 13.

14. 15. 16. 17. 18.

Figure 2. Chemical structures of Cymbopogon essential oil constituents 1, citral a; 2, citral, b; 3, citronellol; 4, citronellal; 5, geraniol; 6, geranyl acetate; 7, limonene; 8, linalool; 9, nerol; 10, cis- ocimene; 11, piperitone; 12, α-terpineol, 13, thujane; 14, α-bisabolol, 15, isointermedeol; 16, borneol; 17, α-pinene; 18, β -pinene. citral that accounted for 80-84% [2]. the presence of cis- and trans-p-1(7),8-menthadien-2-ol The essential oil obtained from the roots of C. citratus (19.9% and 22.3%), cis- and trans-p-2,8-menthadien-1-ol consisted of ten components including longifolene-(V4) (10.1% and 14.3%) [13]. Like C. giganteus, the essential oil that accounted for 56.67% of the essential oil; also present of C. schoenanthus L. Spreng from Tunisia also had a very distinguished chemical composition, but characterised as a major constituent was selina-6-en-4-ol (20.03%) [16]. The chemical composition of the essential oil from the by different types of monoterpenes such as limonene shoots of C. citratus was completely different to that of (10.5–27.3%), β-phellandrene (8.2–16.3%), δ-terpinene the root essential oil, with the former consisting of 12 (4.3–21.2%) and α-terpineol (6.8–11.0%) [23]. So far, these components with citral (88%) as the major constituent essential oil compositions are unique. [16]. Cymbopogon giganteus essential oil has shown a very The essential oil of the C. martinii studied by GC-FTIR distinct composition, which is mainly characterised by indicated the presence of geraniol (65%) and geranyl International Journal of Essential Oil Therapeutics (2009) 3, 56-65 59 acetate (20%) as major components [24]. Similar cyclic terpenoids. Monoterpenes are colourless, lipophilic, composition of the leaf and flower essential oils of C. volatile substances responsible for the characteristic martinii with geraniol as dominating component (53.41% in odours of essential oils and scents of many [3]. leaf and 69.63% in flower oil) is reported [25]. In addition The monoterpenes are mainly derived from geranyl to geraniol, piperitone (6.0%) in flower and nerol (24.76%) diphosphate (GPP) through interconversions such as, and α-pinene (4.32%) in leaf essential oils have also been stereo specific isomerization, acetylation, deacetyaltion, identified [25]. Phytochemical analysis of the essential oil cyclisation and dehydrogenation [31,31]. Geranyl of C. winterianus Jowitt (java citronella) showed presence diphosphate (GPP) is believed to be biosynthesised by of geraniol (40.06%), citronellal (27.44%) and citronellol condensation of the isopentenyl diphosphate (IPP) with (10.45%) as major components [26]. The essential oil of dimethylallyl diphosphate (DMAPP) in a head to tail fashion. C. winterianus consisted of 23 compounds as revealed Isopentenyl pyrophosphate is the universal precursor of all by gas chromatographic analyses; major constituents isoprenoids including monoterpenes and sesquiterpenes identified were citronellal (27%), trans-geraniol (23%), and and is thought to be derived either from the cytoplasmic citronellol (10%) [27]. Earlier studies have shown similar acetate-MVA pathway or the newly discovered methyl- essential oil composition of C. winterianus with citronellol, erythritol-4-phosphate (MEP) pathway (Figure 3) [22, 32- citronellal, limonene and linalool as major components 34]. Incorporation studies in C. flexuosus (lemongrass) and [28]. The essential oil composition of C. nardus is almost C. martinii (palmarosa) using radiolabel substrates [2-14C]- 14 14 identical to that of C. winterianus, characterised by the acetate, CO2, [ C]-sucrose favoured acetate-MVA origin presence of geraniol, citronellal, and citronellol. However, of the essential oil [22,35,36]. The essential biosynthesis α-terpineol, cis-sabinene and carvone were identified as and accumulation is subjected to developmental regulation major constituents besides citronellal and geraniol in the in Cymbopogons [1]. Previous incorporation studies in essential oil of C. nardus harvested from India [29]. The lemongrass and palmarosa revealed only young and essential oil of C. parkeri Stapf. from Iran has piperitone rapidly growing leaves and inflorescences are most active (81%) as major component with some other minor in biogenesis as well as accumulation of essential oil [22, constituents including germacrene-D (5%), santolinyl 36,37]. acetate (2.1%) and α-eudesmol (2.1%) [21]. Histochemical methods using Schiff’s reagent have shown The study of the essential oil composition of various that Cymbopogon flexuosus cv. OD-19 and C. citratus Cymbopogon species presented here led to the conclusion accumulate essential oils in oil cells located in the adaxial that the monoterpene compositions of the essential oils side of the leaf mesophyll, commonly adjacent to non markedly varied among the species. Invariably, essential oil photosynthetic tissue and between vascular bundles content and compositions are greatly influenced by climate, [10,11]. season and diurnal effects. Additionally, developmental and ontogenic variations in the essential oil composition in Bioactivities of Cymbopogon essential oils Cymbopogon species have been reported [1,3]. The bioactive potential of Cymbopogon essential oils and their constituents have been rapidly recognised in the past Essential oil biosynthesis and accumulation ten years (Table 1), although the conventional bioactive Essential oils are complex mixture of acyclic and/ or properties against microbes have been known for much

Figure 3. Monoterpene biosynthesis via cytosolic acetate-MVA and plastidic MEP pathway. DMAPP, dimethylallyl diphosphate; G-3-P, glyceraldehyde-3-phosphate; GPP, geranyl diphosphate; IPP, isopentenyl diphosphate. Secondary transformations of GPP produce diverse monoterpenes structures. 60 International Journal of Essential Oil Therapeutics (2009) 3, 56-65 longer. Essential oils of Cymbopogon species are easily has demonstrated antibacterial activities against Shigella available, have a pleasant aroma, are non-toxic and safe; dysenteriae and Klebsiella pneumoniae [44], whilst that of the active principles are therefore becoming increasingly C. densiflorus has a wide spectrum of antibacterial activity popular in pharmaceuticals and medicines. Also, semio- against Gram positive and Gram negative bacteria [45]. chemical properties of the Cymbopogon essential oils De Billerbeck et al. [46] have studied the effect of the has been promising in integrated pest management essential oil of C. nardus on the growth of Aspergillus programme since this property may lead to development niger. The study revealed that the essential oil (800 mg/ of alternatives to synthetic chemical pesticides [18]. ml) had strong inhibitory action causing cytological While several research groups have investigated the modifications on growth of the mycelium. It was suggested bioactive potential of essential oils and their constituents that the essential oil damaged the plasma membrane and using animal models and cell systems, others have elucidated mitochondrial structural organization. Subsequently, Helal and proposed mechanisms underlying their actions. A et al. [47] described a very similar antifungal property of C. number of reports published in recent years have described citratus essential oil with negative effects on the growth, lipid several novel bioactivities viz., allelopathic, anthelmintic, content and morphogenesis in A. niger ML2-strain. The MIC anti-inflammatory, anticancer, antioxidant and insect and of the essential oil was 1.5-2.0 μ/ml. Observation of A. niger repellency of some Cymbopogon essential oils hyphae treated with essential oils under the light, scanning and the mechanisms of action. Among the various species, electron and transmission microscope demonstrated the C. citratus has been recognised most promising since the ultra structural alterations in the hyphae, which might be essential oil of this species has exhibited a variety of developed during treatment with essential oil. Fumigation fundamental and novel bioactivities (Table 1). Cymbopogon with essential oil also caused great loss in Ca2+, K+ and martinii and C. winterianus were other species that showed Mg2+ ions from the mycelium. Moreover, C. citratus essential outstanding bioactivities, particularly insect repellent and oil is reported to block aflatoxin B production in A. niger anthelmintic. In contrast, C. schoenanthus essential oil [48, 49]. The essential oil of C. martinii displayed remarkable demonstrated antioxidant activity. The bioactive potential antiyeast activity against Saccharomyces cerevisiae at of other species of Cymbopogon have not yet been fully a concentration as low as 0.1% [24]. Geraniol, which exploited. accounts for 90% of palmarosa essential oil, was found to Like essential oils, monoterpene constituent of the be responsible for this activity. essential oil have displayed useful bioactivities [12-16]. Two mechanisms of antiyeast activity have been suggested. For instance, citral, a major constituent in essential oils of Geraniol arrests the growth of yeast cells causing excessive many Cymbopogon species has shown strong antimicrobial K+ ion leakage from yeast cells and essential oil treatment properties against and human pathogens and induces alterations in the S. cerevisiae cell membrane insecticidal properties [38-41]. Similarly, limonene and composition by increasing the proportion of saturated fatty borneol present in the essential oil of C. flexuosus have acid and decreasing that of unsaturated fatty acid, resulting immunostimulatory, analgesic and anaesthetic properties, in growth inhibition. Besides the effects of palmarosa on respectively [42, 43]. Some other constituents such as S. cerevisiae, the oil has shown inhibitory effects on the geraniol, geranyl acetate, α-bisabolol and isointermedeol growth of dermatophytes and filamentous fungi [50]. This have also been correlated with different types of was studied by applying essential oil ointments against bioactivities. Isointermedeol, a major component in C. induced ringworm in a guinea pig model; hair samples flexuosus essential oil, possesses anticancer properties were collected after 7-21 days of the treatment and [14]. The number of reports describing the bioactivities examined for fungal growth [50]. The essential oil from C. of Cymbopogon essential oils is growing. Most of the citratus has been found to be useful in treatment of oral bioactivities shown by Cymbopogon essential oils are and vaginal candidiasis [51], with citral exhibiting powerful discussed in the following sections. inhibitory effects on growth of the yeast [51]. Other yeasts significantly affected include Candida oleophila, Antimicrobial activities Hansenula anomala, Saccharomyces cerevisiae, S. uvarum, Rapidly developing resistance of pathogenic microorganisms Schizosaccharomyces pombe and Metschnikowia fructicola. against currently available drugs/ treatment is a major Cymbopogon citratus essential oil has also shown significant concern in recent years. Essential oils of Cymbopogon inhibitory activities against a number of filamentous species have strong antimicrobial properties and thus could fungi, namely Alternaria alternata, Aspergillus niger, Fusarium produce alternative therapeutics to current antibiotic oxysporum and Penicillium roquefortii [52]. drugs. The antimicrobial properties of C. flexuosus, C. The essential oil and powder of C. citratus is used to citratus, C. martinii, C. winterianus, C. nardus, and C. parkeri control storage deterioration and aflatoxin contamination have been well documented (Table 1). Most of the studies of melon seeds caused by Aspergillus flavus, A. niger, A. have determined the antimicrobial activity of the essential tamarii and Penicillium citrinum [53]. The advantages of oil and its constituents in terms of minimum inhibitory this treatment are that the essential oil does not affect concentration (MIC), which is required for 50% inhibition the biochemical composition of the seeds and has strong of the growth of microorganisms. From these studies it has effects comparable to that of a commercial fungicide become clear that essential oils of Cymbopogon species have iprodione. Thus it is a better and safe natural control. outstanding antifungal activities and significant antibacterial Unlike essential oils of other Cymbopogon species, C. activities. Cymbopogon nervatus inflorescence essential oil parkeri essential oil has shown substantial activity against International Journal of Essential Oil Therapeutics (2009) 3, 56-65 61

Table 1. Bioactivities of Cymbopogon essential oils, constituents and extracts.

Cymbopogon species essential oil MIC/IC50 value biological activity ref. Cymbopogon citratus Stapf. Essential oil 126.5 and 15.5 μg/ml Anti-proliferative 12 Cymbopogon citratus Essential oil and N.D. Allelopathic 16 components Cymbopogon citratus Essential oil 1.0 - 1.5 μl/ml Antifungal 47 Cymbopogon citratus Essential oil 1.0- 3.0 μl/ml Antiyeast 48 Cymbopogon citratus Essential oil, citral 100 μg/ml Antifungal 51 Cymbopogon citratus Essential oil 1.0 - 1.5 μl/ml Antifungal 49 Cymbopogon citratus Essential oil and 1-10 g/100 g seeds and Antifungal 53 powder 0.1 to 1.0 ml/100 g seeds Cymbopogon citratus Lemon grass extract 100 mg/kg body weight Anticancer 55 Cymbopogon citratus Citral 22.25 μM Inducer of caspase-3 in 56 tumor cell lines Cymbopogon citratus Methanol, water 50-100 μg/ml Free radical scavenging 57 infusion & decoction and antioxidant Cymbopogon citratus Essential oil 50-200 mg/kg Antinociceptive effect 62 Cymbopogon citratus Essential oil N.D. Anxiolytic 63 Cymbopogon citratus Essential oil 0.5 - 1.0 g/kg Neurobehavioral effect 64 Cymbopogon citratus Fresh leaf aqueous 125-500 mg/kg Hypoglycemic and 65 extract hypolipidemic Cymbopogon citratus Citral 60 mg/kg body weight Anti-clastogenic 66 Cymbopogon citratus Lemongrass infusion N.D. In the treatment of oral 67 thrush in HIV/AIDS Cymbopogon flexuosus (Nees ex Essential oil 4.2 to 79 μg/ml Anticancer 15 Steud) Wats Cymbopogon flexuosus Essential oil, 30 and 20 μg/ml Anticancer 14 isointermedeol Cymbopogon martini Roxb. Essential oil 0.1% Antimicrobial 24 Cymbopogon martini Essential oil, geraniol 66.7 μg/ml Anthelmintic 60 Cymbopogon martini Oil extract N.D. Insecticidal 18 Cymbopogon martini Essential oils 150 and 500 ppm Antifungal activity 50 dermatophytes Cymbopogon martini Essential oil 150 and 500 ppm Antifungal activity 25 dermatophytes Cymbopogon martini Essential oil N.D. Anthelmintic activity 25 Cymbopogan martini var. sofia Essential oil 1 ml Repellent 20 Cymbopogon schoenanthus (L.) Essential oil 0.47 mg/ml Antioxidant 23 Spreng. Antiacetylcholineesterase Cymbopogon schoenanthus Essential oil, 1.6 μl/l and 2.7 μl/l Insecticidal 59 piperitone Cymbopogon schoenanthus Essential oil 33.3 μl/l Insecticidal 58 Cymbopogon winterianus Jowitt Essential oil 100- 400 mg/kg Anticonvulsant 26 Cymbopogon winterianus Essential oil N.D. Insecticidal/ repellent 60 Cymbopogon winterianus Essential oil 1-10 μl/ml Antimicrobial 27 Cymbopogon winterianus Citronella extract 0.2 g/m2 of carton board Insect repellent 19 Cymbopogon winterianus Citronellal 2.5 mM Phytotoxicity 17 Cymbopogon nardus Essential oil 800 mg/l Antifungal 46 Cymbopogon densiflorus Steud. Essential oil N.D. Antibacterial activity 45 Cymbopogon nervatus Stapf. Essential oil N.D. Antibacterial 44 N.D. = not detected 62 International Journal of Essential Oil Therapeutics (2009) 3, 56-65 phytopathogenic fungi, namely Rhizoctonia solani, Pyricularia oil of C. schoenanthus L. (Spreng.) has shown the ability orizea and Fusarium oxysporum [54] of scavenging of free radicals and also anti-acetylcholine esterase activity, hence believed to be a strong antioxidant Anticancer activity [23]. Cymbopogon schoenanthus is consumed in salads and Until recently, relatively little was known about the used to prepare traditional meat recipes in Tunisia. With anticancer properties of Cymbopogon essential oils and C. citratus, instead of essential oil, the methanol, methanol- their mechanism of actions; only few reports are available. water extract, infusion and decoction of leaves exhibited The first report on anticancer activity was the effects powerful antioxidant properties. The antioxidant activity of lemongrass on hepatocarcinogenesis in male Fischer of the essential oils of the above species were determined 344 rats administered with diethylnitrosamine [55]. using the DPPH assay [23,57]. Consequently, the anticancer activity of citral has been reported. Citral functions as a new inducer of caspase-3 in Allelopathic, repellent and anthelmint activities tumour cell lines, with the mechanism of action involving It is reported that Cymbopogon essential oils and their DNA fragmentation and enhancement of caspase-3 major constituents function as allelochemicals. Allelo- catalytic activity, eventually inducing apoptosis in several chemicals affect insect biology and behaviour and hence hematopoietic cell lines [56]. However, apoptotic effects are used in biocontrol. Cymbopogon schoenanthus essential were dependent on a- and b- unsaturated aldehyde groups. oil functions as an allelochemical and is used to control The most defined work on anticancer activity of Callosobruchus maculates development in cowpea stock Cymbopogon essential oil has been recently carried out [58, 59]. Piperitone, a major chemical constituent, was [14,15]. The two reports provided deeper insight in to more toxic than the essential oil to neonatal larvae. The anticancer principle of the essential oil and its mechanisms essential oil of C. citratus exhibited alleopathic activity and of action. Kumar et al. [14] have investigated the anticancer affects seed germination and seedling growth of corn and activity of C. flexuosus (CFO) essential oil and its major barnyard grass [16]. Very likely, C. winterianus essential oil constituent, isointermedeol (ISO) in human leukaemia has allelo-chemical property that affects the growth of HL-60 cells. This study revealed that C. flexuosus essential Spodoptera frugiperda larvae [60]. An extract of citronella oil and isointermedeol (ISO) induce apoptosis in human also has repellent activity [19] and it is for this reason that leukaemia HL-60 cells and anticancer activity of these citronella extract is used to prevent cartoons containing materials was correlated with down regulation of NF-κB muesli and wheat germ from beetles [19]. Similarly, C. expression and caspase activation. The caspase activation martinii var. sofia essential oil exhibited repellent action was through apical receptors and mitochondrial signaling against Anopheles sundaicus [20]. Palmarosa oil is safe pathways. As a part of the mechanism of action it was for human use and is thus recommended for protection suggested that significantly increased levels of cytochrome from malaria due to its potent repellent action against c in mitochondria after essential oil treatment, played a mosquitoes. Beside mosquito repellent activity, palmarosa role in triggering apoptosis. Sharma et al. [15] have studied essential oil also showed strong pesticidal activity against the anticancer activity of C. flexuosus essential oil in human insect infestation and is used to protect stored wheat and cancer cell lines HL-60, murine Ehrlich and Sarcoma-180 grain from the beetles Callosobruchus chenesis and Tribolium tumors in combination with electron microscopy. This castaneum [18]. indicated some morphological changes favouring induction Palmarosa essential oil demonstrated significant of apoptosis in cancer cells lines that were most probably anthelmintic activity against the Caenorhabditis triggered by the essential oil. Chromatin condensation and elegans induced apoptosis and fragmentation of the nuclei and [61]. and this was mainly due to geraniol (a major apoptosis were apparent morphological changes in HL-60 chemical constituent). Palmarosa oil has also showed and sarcoma-180 cell lines, respectively [15]. anthelmintic activity against the Indian earthworm Pheretima posthuma [25]where it causes paralysis and Antiproliferative, anti-inflammatory and death in a short time. antioxidant activities The antiproliferative effect of C. citratus essential oil against Other biological activities Trypanosoma cruzi was demonstrated to be due to citral. Essential oils of Cymbopogon species have some other Citral also showed significant trypanocidal activity against less studied bioactivities. Cymbopogon citratus is reported the parasite [12]. Cymbopogon giganteus is widely used in to possess additional properties such as antinociceptive, traditional medicine against several diseases. The chemical anxiolytic-type, and neurobehavioral activity [53, 62- constituents of this essential oil showed inhibitory effects in 65]. Aqueous extracts of C. citratus leaves have shown vitro on 5-lipoxygenase. The 1,1-diphenyl-2-picrylhydrazyl hypoglycaemic and hypolipidaemic effects in rats suggesting (DPPH) method was used for determination of the its possible therapeutic role in Type 2 diabetic mellitus [65]. antiradical scavenging activity of the essential oil [13]. Administration of aqueous extracts of leaves (125-500 mg/ Antioxidants are substances with the ability to scavenge free kg body weight) in normal male Wistar rates for 42 days radicals and the essential oils of Cymbopogon species have resulted in a significant decline in fasting plasma glucose, shown this ability and are thus considered as antioxidants. increase in plasma HDL-c level and no change in plasma However, the antioxidant properties of Cymbopogon species triglycerides level [65]. have not yet been sufficiently evaluated. The essential The essential oil of C. winterianus is used in Brazilian folk International Journal of Essential Oil Therapeutics (2009) 3, 56-65 63 medicine as an analgesic and anxiolytic [15]. A recent rapidly increased, shifting from their aromatic potential to study has revealed anticonvulsant and depressant activity bioactive potential. It is very timely to investigate bioactive of C. winterianus essential oil on central nervous system potential of this genus when the demand for natural (CNS) of rodents [26]. Citronella essential oil exhibited remedies from the public is escalating because of their significant inhibitory effects on the growth of several safe use with no side effects. Also, the growing resistance weed species like Ageratum conyzoides, Chenopodium album, of pathogenic microbes against current antibiotics has Parthenium hyterophorus, Malvastrum coromendelianum, prompted the search for plant-based new or alternative Cassia accidentalis and Phalaris minor [17]. It is suggested drugs. that a major component, citronellal, exerts multiple effects on the biochemistry and physiology of the weeds Acknowledgement and inhibits their emergence. Citronellal mainly impairs The author is grateful to the Chancellor, Vellore Institute the photosynthetic and respiratory metabolism, disrupts of Technology (VIT) University, Vellore, India for providing cuticular wax, clogs stomata, shrinks epidermal cells necessary support and facilities. This work is done under and causes rapid electrolyte leakage. Post-emergence the project “Metabolic fingerprinting of the monoterpenes application of citronella has been equally effective and in the genus Cymbopogon” financially supported by the cause chlorosis, necrosis, wilting and finally death of the Department of Science and Technology (DST), New Delhi, weeds [17]. government of India. Citral possesses many useful bioactivities and one of these is an anti-clastogenic effect in nickel chloride- References treated mouse micronucleus system [66]. The citral 1. Ganjewala D, Kumari Ambika, Khan KH. Ontogenic caused inhibition of micronuclei formation and enhanced and developmental changes in essential oil content and the superoxide scavenging activity. Elevated superoxide compositions in Cymbopogon flexuosus cultivars. In: Prasad scavenging activity was thought to be responsible for the BN, Lazer Mathew, editor. Recent Advance in Biotechnology. anti-clastogenic effects of the citral [66]. New Delhi, India: Excel India Publishers, 2008. p. 82-92. 2. Khanuja SPS, Shasany AK, Pawar A, Lal RK, Darokar MP, Recently, Wright et al. [67] have reported that lemon Naqvi AA, et al. Essential oil constituents and RAPD markers juice and C. citratus infusion is safe in and highly effective to establish species relationship in Cymbopogon Spreng. in the treatment of oral thrush in HIV/AIDS patients in (Poaceae). Biochem Syst Ecol. 2005;33:171-86. comparison to group using gentian violet aqueous solution 3. Ganjewala D. Biochemical and molecular characterization of (0.5%). This randomised controlled trial validated the geraniol rich lemongrass (Cymbopogon flexuosus Nees ex Steud) Wats. Mutant cv. GRL-1. 2002 Thesis. efficacy of lemon juice and lemongrass for the treatment 4. Sarma KK, Nath SC, Leclercq PA. The essential oil of a of oral candidiasis in an HIV population in South Africa. variant of Cymbopogon flexuosus (Nees ex Steud.) Wats from Northeast India. J Essent Oil Res. 1999;11:381-85. Conclusion 5. Nath SC, Sarma KK, Vajezikova I, Leclercq PA. Comparison Essential oils of Cymbopogon species that are diverse of volatile inflorescence oils and of certain in chemical composition possess many important and Cymbopogon taxa described as Cymbopogon flexuosus potential bioactivities of great pharmaceutical and medicinal (Nees ex Steud.) Wats. Biochem Syst Ecol. 2002;30:151-62. significance. Some of the novel bioactivities ofCymbopogon 6. Shahi AK, Sharma SN, Tava A. Composition of Cymbopogon essential oils and constituents include anti-inflammatory, pendulus (Nees ex Steud) Wats., an elemicin rich oil grass known in Jammu region of India. J Essent Oil Res. 1997; 9:561- anticancer, antioxidant and insect repellency. In addition, 64. they have a number of other activities of ecological and 7. Mathew S, Chittattu GJ, Thomas J. OD-468Fa lemongrass industrial significance. chemotype rich in geranyl acetate. Indian Perfumer. At present, the focus of several research laboratories is 1996;40:9-12. to investigate plausible mechanism/s of action underlying 8. Nath SC, Saha BN, Bordoloi DN, Mathur RK, Leclercq PA. The chemical composition of the essential oil of Cymbopogon the newer bioactivities of Cymbopogon essential oils. flexuosus (Steud.) Wats. growing in Northeast India.J Essent Despite the fact that Cymbopogon essential oils have Oil Res. 1994;6:85-87. offered immense biological, ecological and pharmaceutical 9. Sidibe L, Chalchat JC, Garry RP, Lacombe L. Aromatic plants properties, little efforts have been made to harvest the of Mali (IV): Chemical composition of essential oils of maximum bioactive potential of these species. Only C. Cymbopogon citratus (DC) Stalf and C. giganteus (Hochst.) citratus has been extensively investigated and it possesses a Chiov. J Essent Oil Res. 2001;13:110-13. range of outstanding bioactivities. 10. Lewinsohn E, Dudai N, Tadmor Y, Katzir I, Ravid U, Putievsky E, et al. Histochemical localization of citral accumulation One of the major concerns with regard to bioactivity in lemongrass leaves (Cymbopogon citratus (DC) stapf. screening is subsequent adequate clinical trials in human Poaceae). Anal Bot. 1998;81:35-39. subjects, which are often lacking in many cases. The absence 11. Luthra R, Luthra PM, Kumar S. Redefined role of mevalonate- of clinical trails severely impedes the development of the isoprenoid pathway in terpenoid biosynthesis in higher bioactive component identified as an alternative medicine plants. Curr Sci. 1999;76:133-35. or therapeutic agent. Thus the studies of Cymbopogon 12. Santoro GF, Cardoso MG, Guimarães LG, Freire JM, essential oils also need to be substantiated by clinical trials Soares MJ. Anti-proliferative effect of the essential oil of Cymbopogon citratus (DC) Stapf (lemongrass) on in human subjects. intracellular amastigotes, bloodstream trypomastigotes It is true that our interest in Cymbopogon essential oils has and culture epimastigotes of Trypanosoma cruzi (Protozoa: 64 International Journal of Essential Oil Therapeutics (2009) 3, 56-65

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