Molecules 2012, 17(10), 11447-11455; doi:10.3390/molecules171011447

Article
Chemical Characterization of Volatile Compounds of Lantana camara L. and L. radula Sw. and Their Antifungal Activity
Juliana Lanna Passos 1, Luiz Claudio Almeida Barbosa 1,*, Antonio Jacinto Demuner 1, Elson Santiago Alvarenga 1, Cleiton Moreira da Silva 1 and Robert Weingart Barreto 2
1
Department of Chemistry, Federal University of Vicosa, Av. P. H. Rolfs, s/n, 36570-000, Vicosa, MG, Brazil
2
Department of Phytopathology, Federal University of Vicosa, Av. P. H. Rolfs, s/n, 36570-000, Vicosa, MG, Brazil
*
Author to whom correspondence should be addressed; Email: lcab@ufv.br; Tel.: +55-31-3899-3068; Fax: +55-31-3899-3065.
Received: 10 August 2012; in revised form: 20 September 2012 / Accepted: 20 September 2012 /
Published: 27 September 2012

Abstract

: A comparative study of the chemical composition of essential oils of two very similar species of the Verbenaceae family (Lantana camara and L. radula) revealed that the main components of essential oil of L. camara were germacrene-D (19.8%) and E-caryophyllene (19.7%), while those of L. radula were E-caryophyllene (25.3%), phytol (29.2%) and E-nerolidol (19.0%). We have hypothesized that the observed differences could contribute to the differentiated reaction of the two species of Lantana to the attack of the phytopathogenic fungi Corynespora cassiicola. An experiment, involving C. cassiicola cultivation in culture media containing volatile oils of the two species demonstrated that the oils of L. radula were more fungistatic than the oils of L. camara, in accordance with the in vivo observations. It is likely that E-nerolidol and phytol, only found in the oil of L. radula, play a significant role in the effects of L. radula on C. cassiicola.
Keywords:
Verbenaceae; essential oils; Corynespora cassiicola; Lantana camara; L. radula

1. Introduction

Metabolites produced by plants are highly diverse, having distinct functions according to their structure and the places where they are secreted in the plant [1]. The Verbenaceae family includes numerous species that are rich in essential oils produced by secretor trichomes [2,3,4]. These essential oils can protect the plants against herbivore attacks and pathogens [5]. Many studies on the chemical composition of such essential oils have been published [6,7,8,9,10].

The Verbenaceae species Lantana camara L. is native to tropical and subtropical America and has been dispersed throughout the World as a popular ornamental plant, becoming one of the World’s worst weeds [11]. Corynespora cassiicola (Berk. & Curt.) is an anamorphic fungus, which causes foliar spots in more than 70 species of plants worldwide [12]. This is capable of causing a severe disease on L. camara and to provoke defoliation and debilitation of the attacked plants [13,14]. Conversely, the essential oils produced by L. camara may have defense properties against pathogens since Lantana species are known to produce essential oils with antimicrobial activity [15,16,17,18]. The effect of Lantana oils on C. cassiicola and related fungi has never been investigated. Lantana camara and L. radula are two closely related species, as reflected by their close morphological similarity [19]. However, when plants of the two species are maintained side by side, clear differences such as odor and foliar texture are easily noticed. The empirical observation made on differences of smell intensity suggested that the volatile substances produced by these two species might have a different composition leading to this comparative study.

The species L. camara presents secreting trichomes and idioblasts, both dispersed on the mesophyllum [19]. These structures are known to secrete lipidic substances [10], alkaloids, sesquiterpene lactones and flavonoids [20]. The chemical composition of essential oils produced by L. camara from various origins has been reported [6,9,15,21,22]. However, no report was found on the chemical composition of the essential oils produced by L. radula. As in a separate unpublished phytopathological study, inoculation of L. radula with C. cassiicola under controlled conditions resulted only in minor disease symptoms as compared to a significant impact on L. camara. Also, to the best of our knowledge, there is no published record of C. cassiicola as a pathogen of L. radula, contrary to L. camara. Based on such information, it was then conjectured that L. radula oil could be involved in the different response of this plant species to inoculation with C. cassiicola as compared with L. camara. This work represents an additional contribution to the studies on the composition of essential oils produced by aromatic and medicinal plants carried out by our research group [23,24,25,26,27,28,29,30,31,32,33,34,35,36] and the investigation of bioactive substances produced by microorganisms [31,32]. It includes information on the composition of essential oils produced by L. camara and L. radula, and their effect on mycelial growth in C. cassiicola.

2. Results and Discussion

2.1. Volatile Oils

It was found that both plant species produced a very small amount of oil, but L. camara produced nearly three times more (0.09 ± 0.005% w/w) than L. radula (0.03 ± 0.006% w/w). The moisture content for the leaves of L. camara was 79 ± 0.51% and for L. radula 67 ± 0.01%. Previous studies of L. camara reported oil content ranging from 0.06% w/w to 0.22% w/w [6,21]. The components found for the oils of L. camara (19 compounds) and L. radula (nine compounds) are presented in Table 1.

Table Table 1. Major components identified in the volatile oils of L. camara and L. radula.

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Table 1. Major components identified in the volatile oils of L. camara and L. radula.
Peak no.Constituent aRIL. camara (%)L. radula (%)
1α-Copaene13741.1 ± 0.12-
2β-Elemene13903.2 ± 0.51-
3Tetradecane13991.0 ± 0.551.8 ± 0.26
4E-Caryophyllene141819.7 ± 3.3225.3 ± 5.47
5β-Gurjunene14271.2 ± 0.15-
6α-Humulene14519.3 ± 0.301.2 ± 0.06
7β- E-Farnesene1458 1.3 ± 0.20Tr
8Germacrene-D1479 19.8 ± 1.4017.6 ± 1.21
9Bicyclogermacrene149311.7 ± 0.674.0 ± 0.10
10α-Muurolene14981.5 ± 0.15-
11Germacrene-A15012.5 ± 0.36-
12Cubeol15112.5 ± 1.14-
13δ-Cadinene15202.4 ± 0.35-
14E-Nerolidol 1562-19.0 ± 3.56
15Germacrene-D-4-ol15671.2 ± 0.30-
16Caryophyllene oxide 1579-1.7 ± 0.67
17Davanone15721.2 ± 0.58-
18Globulol15810.7 ± 0.40-
19Humuladyenone *15941.2 ± 0.36-
20Epi-α-Muurolol16384.8 ± 0.32-
21Phytol20924.0 ± 1.4529.2 ± 5.23
Identified (%) 86.399.8

Tr: component aspect < 0.1; * Identification with GC-MS; a Compounds listed in order of elution; Retention Index (RI): measurement relative to alkanes in a BD-5 column.

The empirical observation made previously of a clear smell difference between the two species of Lantana was confirmed by gas chromatography and mass spectrometry analyses that revealed different compositions for their volatile oils. The common constituents for the two species are: tetradecane, E-caryophyllene, α-humulene, β-E-farnesene, germacrene-D, bicyclogermacrene and phytol. The major components in the oil of L. camara are germacrene D (19.8%), E-caryophyllene (19.7%), bicyclogermacrene (11.7%) and α-humulene (9.3%). These compounds represent approximately 60.5% of the oil. The four major constituents of the oil of L. radula are E-caryophyllene (25.3%), germacrene-D (17.6%), E-nerolidol (19.0%) and phytol (29.2%), representing 91.1% of the oil.

The greater chemical diversity of the volatile oils of L. camara as compared to L. radula could be connected with the presence of secretor idioblasts in L. camara [19] which are absent in L. radula but further studies are required to confirm this hypothesis.

2.2. Bioassay

As observed on Figure 1, oils obtained from each of these species caused a significant inhibition on fungal growth, as compared to controls.

Molecules 17 11447 g001 200
Figure 1. Colonies of C. cassiicola after eight days of growth in medium containing increasing amounts of oil obtained from L. camara (A) and L. radula (B) as compared to control: (1) control; (2) 3,000 mg L−1; (3) 5,000 mg L−1; (4) 10,000 mg L−1.

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Figure 1. Colonies of C. cassiicola after eight days of growth in medium containing increasing amounts of oil obtained from L. camara (A) and L. radula (B) as compared to control: (1) control; (2) 3,000 mg L−1; (3) 5,000 mg L−1; (4) 10,000 mg L−1.
Molecules 17 11447 g001 1024

In the first two days of evaluation the oil of L. camara at a concentration of 1,000 mg L−1, caused a reduction in the growth of the fungal colonies of 25.0% and 19.6%, respectively. At higher concentrations the fungus growth was completely inhibited during the first day and for 10,000 mg L−1 a full inhibition was still observed during the second day (Figure 1A and Figure 2).

Molecules 17 11447 g002 200
Figure 2. Radial culture growth of C. cassiicola in culture media containing L. camara volatile oils (LC) at concentrations of 1,000, 3,000, 5,000 and 10,000 mg L−1.

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Figure 2. Radial culture growth of C. cassiicola in culture media containing L. camara volatile oils (LC) at concentrations of 1,000, 3,000, 5,000 and 10,000 mg L−1.
Molecules 17 11447 g002 1024

At the eighth day of evaluation the reduction of the development of the colonies was dependent on the oil concentration tested and the following results were found: 12% inhibition at 1,000 mg L−1; 17% at 3,000 mg L−1; 27% at 5,000 mg L−1 and 49% at 10,000 mg L−1. These results are similar to published results where inhibitory effect of the oil from L. camara on the growth of Aspergillus niger van Tiegh and Fusarium solani Mart. (Sacc) are reported [15].

For the oil of L. radula at the concentrations of 1,000 mg L−1 and 3,000 mg L−1, 17.2% and 40.6% inhibition were observed, respectively, on the first day of evaluation (Figure 1B and Figure 3). At higher concentrations (5,000 and 10,000 mg L−1) the oils caused complete inhibition of the fungus growth. Even after eight days of experiment the volatile oils of L. radula caused a significant reduction on fungus development (4.7% inhibition at 1,000 mg L−1; 23.2% at 3,000 mg L−1; 42.3% at 5,000 mg L−1 and 60.8% at 10,000 mg L−1).

Molecules 17 11447 g003 200
Figure 3. Radial culture growth of C. cassiicola in culture medium containing L. radula volatile oils (LR) at concentrations of 1,000, 3,000, 5,000 and 10,000 mg L−1.

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Figure 3. Radial culture growth of C. cassiicola in culture medium containing L. radula volatile oils (LR) at concentrations of 1,000, 3,000, 5,000 and 10,000 mg L−1.
Molecules 17 11447 g003 1024

The results demonstrated that the volatile oils from L. radula have a greater effect on the growth of C. cassiicola compared with the oils obtained from L. camara. Although bioassays with each individual component of oils from each plant species were not performed, it is likely that the greater activity of L. radula’s oil could be associated with its higher concentration of E-nerolidol, since this compound has already been shown highly active against Escherichia coli [37], to have larvicidal activity on Aedes aegypti larvae and anti-parasitic activity against a strain of Leishmania amazonensis [38]. Another significant difference between the oils is the higher concentration of phytol in L. radula oil, although there is no published report of any anti-fungal activity for this compound. Although caryophyllene is present in high concentration in both oils, previous investigation have demonstrated that it has no effect, at least against the basidiomycete species Laetiporus sulphureus, Lenzites betulina and Trametes versicolor [39]. The higher growth-inhibiting activity observed for L. radula oil on C. cassiicola may in part explain the observed resistance to attack by this fungus [19].

3. Experimental

3.1. Plant Material

Aerial parts of L. camara and L. radula, from plants grown in a greenhouse, were used. Voucher specimen of each plant species were deposited in the VIC Herbarium [registration numbers 30159 (L. camara) and 30160 (L. radula)] for reference.

3.2. Extraction and Analysis of the Essential Oils

Leaves of L. camara and L. radula were collected and each sample was subdivided into three portions of 40 g each and then subjected to 3 h of hydrodistillation in a Clevenger apparatus. The resulting oils were separated from the aqueous phase, weighed and the reported yields were calculated with respect to the mass of dry material. All distillations were repeated three times and the oils obtained were separated from the aqueous phase and stored under a nitrogen atmosphere, maintained at 0 °C, until they were chromatographically analyzed. Dry leaf weight was calculated by drying each sample (2 g, held at 103 ± 2 °C for 24 h) [40]. Each analysis was carried out in triplicate.

3.3. Essential Oil Gas Chromatography-Mass Spectrometry (GC-MS) Chemical Analysis

Qualitative analyses were conducted on a GC-MS-QP5050A system with a mass-selective detector (Shimadzu, Kyoto, Japan), equipped with a DB-5 (J & W Scientific, Albany, NY, US) fused silica column (30 m × 0.25 mm i.d., film thickness 0.25 µm). Column temperature was 40 °C (2 min), increased at 3 °C/min to 240 °C, and kept at this temperature for 10 min. Injector temperature was 220 °C. Helium was the carrier gas at a flow rate of 1.8 mL/min. An amount of 1 μL (1% w/v solution of the oil in dichloromethane) was injected and the split ratio was 1:10. The column pressure corresponded to 100 kPa. Mass detector conditions were as follows: temperature source 240 °C; electron impact (EI) mode at 70 eV; scan rate 1 scan/s; mass acquisition range 29–450 u.

The identification of the components was performed by comparison of their retention indexes (RI), relative to a standard alkane series (C9-C24), and comparison of the mass spectra with those on record in the Wiley library data base (Wiley 330000) or from the literature [41].

GC analyses were carried out in triplicate, and accomplished with a GC-17A series instrument (Shimadzu) equipped with a flame ionization detector (FID). Chromatographic conditions were as follows: Fused silica capillary column (30 m × 0.22 mm) with a DB-5 bonded phase (0.25 μm film thickness); carrier gas, N2 at a flow rate of 1.8 mL/min; injector temperature 220 °C, detector temperature 240 °C; column temperature was programmed to start at 55 °C (isothermal for 2 min), with an increase of 3 °C/min, to 240 °C, isothermal at 240 °C for 15 minutes; injection of 1.0 μL (1% w/v in dichloromethane); split ratio 1:10; column pressure of 115 kPa.

3.4. Effect of Volatile Oils on Mycelial Growth of C. Cassiicola

The oils obtained from each plant were dissolved in Tween 20 and tested in vitro for antifungal activity against C. cassiicola, using the “Poison Food Technique” [42]. Each oil was incorporated in the vegetable broth agar VBA [13] at 1,000, 3,000, 5,000 and 10,000 mg L−1 (Tween 0.1%), and were vigorously agitated and poured sterilized Petri dishes (60 mm in diameter). The plates were centrally seeded with culture disks (5 mm in diameter) obtained from the margin of actively growing cultures of C. casiicola f. ssp. lantanae (isolate JMP 17) from the culture collection of the Department of Plant Pathology at UFV and incubated at 25 ± 2 °C in the dark. Plates containing the fungus but without Lantana oil served as controls and were incubated under the same conditions. The incubation lasted 8 days in the dark. The effect of the oil on the mycelial growth (mm) was determined by measuring the radial growth of C. cassiicola in intervals from the 1st to the 8th day after the inoculation. The percentage of fungus growth inhibition was calculated in relation to the radial growth in control plates. Treatments were carried out in a completely randomized design with four replications and the data was analyzed by the Tukey’s test at 0.05 probability level.

4. Conclusions

The volatile oils obtained from the two species of Lantana had significantly different chemical composition and the oil produced by L. camara contained a greater diversity of compounds. Although chemical composition of L. camara oil has already been well investigated, no such data was found for L. radula. The greater effect of the volatile oil of L. radula compared with that produced by L. camara on the growth of C. cassiicola could in part explain its resistance to this fungal pathogen. The results of this study encourage further investigation on the effect of each of the major components of the oil from L. camara against plant pathogenic fungi, particularly against the dematiaceous species related to C. cassiicola.

Acknowledgments

We are grateful to the Conselho Nacional do Desenvolvimento Científico e Tecnológico (CNPq), Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) and Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG). We also thank Tânia Regina dos Santos Silva for helping with plant identification and Prof. Gráinne Hargaden (Dublin Institute of Technology) for her suggestions and corrections included in the manuscript.

References

  1. Fahn, A. Secretory Tissues in Plants; Academic Press: London, UK, 1979.
  2. Metcalfe, C.R.; Chalk, L. Anatomy of the Dicotyledons: Leaves, Stem and Wood in Relation to Taxonomy with Notes on Economic Uses; Clarendon Press: Oxford, UK, 1950.
  3. Gottlieb, O.R.; Salatino, A. Funções e evolução dos óleos essenciais e de suas estruturas secretoras (In Portuguese). Ciên. Cultura 1987, 39, 707–716.
  4. Combrinck, S.; Du Plooy, G.W.D.; McCrindle, R.I.; Botha, B.M. Morphology and histochemistry glandular trichomes of Lippia scaberrima (Verbenaceae). Ann. Bot. 2007, 99, 1111–1119, doi:10.1093/aob/mcm064.
  5. Werker, E. Function of essential oil-secreting glandular hairs in aromatic plants of the Lamiaceae—A review. Flavour. Fragr. J. 1993, 8, 249–255, doi:10.1002/ffj.2730080503.
  6. Alitonou, G.; Avlessi, F.; Bokossa, I.; Ahoussi, E.; Dangou, J.; Sohounhloué, D.C.K. Composition chimique et activités biologiques de l'huile essentielle de Lantana camara Linn. Comptes Rendus Chime 2004, 7, 1101–1105, doi:10.1016/j.crci.2003.11.017.
  7. Paré, P.W.; Tumlinson, J.H. Plant volatiles as a defense against insect herbivores. Plant Physiol. 1999, 121, 325–332, doi:10.1104/pp.121.2.325.
  8. Pichersky, E.; Gershenzon, J. The formation and function of plant volatiles: Perfumes for pollinator attraction and defense. Curr. Opin. Plant Biol. 2002, 5, 237–243, doi:10.1016/S1369-5266(02)00251-0.
  9. Randrianalijaona, J.; Ramanoelina, P.A.R.; Rasoarahona, J.R.E.; Gaydou, E.M. Seasonal and chemotype influences on the chemical composition of Lantana camara L.: Essential oils from Madagascar. Anal. Chim. Acta 2005, 545, 46–52.
  10. Moura, M.Z.D.; Isaias, R.M.S.; Soares, G.L.G. Ontogenesis of internal secretory cells in leaves of Lantana camara (Verbenaceae). Bot. J. Linn. Soc. 2005, 148, 427–431, doi:10.1111/j.1095-8339.2005.00426.x.
  11. Day, M.D.; Willey, C.J.; Playford, J.; Zalucki, M.P. Lantana: Current Management Status and Future Prospects; Australian Centre for International Agricultural Research: Canberra, Australian, 2003.
  12. Silva, W.P.K.; Deverall, B.J.; Lyon, B.R. Molecular, physiological and pathological characterization of Corynespora leaf spot fungi rubber plantations in Sri Lanka. Plant Pathol. 1998, 47, 267–277, doi:10.1046/j.1365-3059.1998.00245.x.
  13. Pereira, J.M.; Barreto, R.W.; Ellison, C.A.; Maffia, L.A. Corynespora cassiicola f. sp. lantanae: A potential biocontrol agent from Brazil for Lantana camara. Biol. Control 2003, 26, 21–31.
  14. Passos, J.L.; Barbosa, L.C.A.; Demuner, A.J.; King-Diaz, B.; Lotina-Hennsen, B. Effects of Corynespora cassiicola on Lantana camara. Planta Daninha 2010, 28, 229–237.
  15. Deena, M.J.; Thoppil, J.E. Antimicrobial activity of the essential oil of Lantana camara. Fitoterapia 2000, 71, 453–455, doi:10.1016/S0367-326X(00)00140-4.
  16. Hernandez, T.; Canales, M.; Ávila, J.G.; Garcıa, A.M. Composition and antibacterial activity of essential oil of Lantana achyranthifolia Desf. (Verbenaceae). J. Ethnopharm. 2005, 96, 551–544.
  17. Verdeguer, M.; Blazquez, M.A.; Boira, H. Phytotoxic effects of Lantana camara, Eucalyptus camaldulensis and Eriocephalus africanus essential oils in weeds of Mediterranean summer crops. Biochem. Syst. Ecol. 2009, 37, 362–369, doi:10.1016/j.bse.2009.06.003.
  18. Moura, M.Z.D.; Soares, G.L.G.; Isaias, R.M.S. Species-specific changes in tissue morphogenesis induced by two arthropod leaf gallers in Lantana camara L. (Verbenaceae). Aust. J. Bot. 2008, 56, 153–160.
  19. Passos, J.L.; Meira, R.M.S.A.; Barbosa, L.C.A.; Barreto, R.W. Foliar anatomy of the species Lantana camara and L. radula (Verbenaceae). Planta Daninha 2009, 27, 689.
  20. Ascensão, L.; Mota, L.; Castro, M.M. Glandular trichomes on the leaves and flowers of Plectranthus ornatus: morphology, distribution and histochemistry. Ann. Bot. 1999, 84, 437–447, doi:10.1006/anbo.1999.0937.
  21. Misra, L.; Laatsch, H. Triterpenoids, essential oil and photo-oxidative 28-13-lactonization of oleanolic acid from Lantana camara. Phytochemistry 2000, 54, 969–974, doi:10.1016/S0031-9422(00)00131-X.
  22. Andrade, E.H.A.; Zoghbi, M.G.B.; Luz, A.I.R.; Silva, J.D.; Maia, J.G.S. The essential oils of Lantana camara L. occurring in North Brazil. Flav. Fragr. J. 1999, 14, 208–210, doi:10.1002/(SICI)1099-1026(199907/08)14:4<208::AID-FFJ811>3.0.CO;2-F.
  23. Barbosa, L.C.A.; Demuner, A.J.; Teixeira, R.R.; Madruga, M.S. Chemical constituents of the bark of Gallesia gorazema. Fitoterapia 1999, 70, 152–156, doi:10.1016/S0367-326X(99)00014-3.
  24. Barbosa, L.C.A.; Demuner, A.J.; Maltha, C.R.A.; Silva, P.S.; Silva, A.A. Sintese e avaliação da atividade fitotóxica de novos análogos oxigenados do ácido helmintospórico (in Portuguese). Quím. Nova 2003, 26, 655–660.
  25. Barbosa, L.C.A.; Paula, V.F.; Azevedo, A.S.; Silva, E.A.M.; Nascimento, E.A. Essential oil composition from some plant parts of Conyza bonariensis (L.) Cronquist. Flav. Fragr. J. 2005, 20, 39–45, doi:10.1002/ffj.1392.
  26. Martins, E.R.; Casali, V.W.D.; Barbosa, L.C.A.; Carazza, F. Essential oil in the taxonomy of Ocimum selloi Benth. J. Braz. Chem. Soc. 1997, 8, 29–32.
  27. Silva, M.H.L.; Silva, A.F.; Barbosa, L.C.A.; Nascimento, E.A.; Casali, V.W.D. Chemical composition of the essential oil of Hyptis glomerata mart. ex Schrank (Lamiaceae). J. Essent. Oil. Res. 2000, 12, 725–727, doi:10.1080/10412905.2000.9712201.
  28. Barbosa, L.C.A.; Demuner, A.J.; Dumont, A.C.; Paula, V.F.; Ismail, F.M.D. Seasonal variation in the composition of volatile oils from Schinus terebinthifolius Raddi. Quím. Nova 2007, 30, 1959–1965, doi:10.1590/S0100-40422007000800030.
  29. Martins, F.T.; Santos, M.H.; Polo, M.; Barbosa, L.C.A. Variação química do óleo essencial de Hyptis suaveolens (L.) Poit, sob condições de cultivo (in Portuguese). Quím. Nova 2006, 29, 1203–1209, doi:10.1590/S0100-40422006000600011.
  30. Martins, F.T.; Santos, M.H.; Polo, M.; Barbosa, L.C.A. Effects of the interactions among macronutrients, plant age and photoperiod in the composition of Hyptis suaveolens (L.) Poit essential oil from Alfenas (MG), Brazil. Flav. Fragr. J. 2007, 22, 123–127, doi:10.1002/ffj.1769.
  31. Carvalho, M.R.; Barbosa, L.C.A.; Queiroz, J.H.; Howarth, O.W. Novel Lactones from Aspergillus versicolor. Tetrahedron Lett. 2001, 42, 809–810.
  32. Demuner, A.J.; Barbosa, L.C.A.; Veiga, T.A.M.; Barreto, R.W.; King-Diaz, B.; Henssen, B.L. Phytotoxic constituents from Nimbya alternantherae. Biochem. Syst. Ecol. 2006, 34, 790–795, doi:10.1016/j.bse.2006.06.008.
  33. Nascimento, J.C.; Barbosa, L.C.A.; Paula, V.F.; David, J.M.; Fontana, R.; Silva, L.A.M.; França, R.S. Chemical Composition and antimicrobial activity of essential oils of Ocimum canum Sims. and Ocimum selloi Benth. An. Acad. Bras. Ciências 2011, 83, 787–799, doi:10.1590/S0001-37652011005000019.
  34. Montanari, R.M.; Barbosa, L.C.A.; Demuner, A.J.; Silva, C.J.; Carvalho, L.S.; Andrade, N.J. Chemical composition and antibacterial activity of essential oils from Verbenaceae species: Alternative sources of (E)-caryophyllene and germacrene-D. Química Nova 2011, 34, 1550–1555, doi:10.1590/S0100-40422011000900013.
  35. Demuner, A.J.; Barbosa, L.C.A.; Gonçalves, M.C.; Silva, C.J.; Maltha, C.R.A.; Pinheiro, A.L. Seasonal variation in the chemical composition and antimicrobial activity of volatile oils of three species of Leptospermum (myrtaceae) grown in Brazil. Molecules 2011, 16, 1181–1191, doi:10.3390/molecules16021181.
  36. Castro, H.G.; Oliveira, L.O.; Barbosa, L.C.A.; Ferreira, F.A.; Silva, D.J.H.; Mosquim, P.R.; Nascimento, E.A. Teor e composição do óleo essencial de cinco acessos de mentrasto (in Portuguese). Quím. Nova 2004, 27, 55–57, doi:10.1590/S0100-40422004000100011.
  37. Roussis, V.; Chinou, I.B.; Tsitsimpikou, C.; Vagias, C.; Petrakis, P.V. Antibacterial activity of volatile secondary metabolites from caribbean soft corals of the genus Gorgonia. Flavour Fragr. J. 2001, 16, 364–366, doi:10.1002/ffj.1013.
  38. Marques, A.M.; Barreto, A.L.; Batista, E.M.; Curvelo, J.A.; Velozo, L.S.; Moreira, D.L.; Guimarães, E.F.; Soares, R.M.; Kaplan, M.A. Chemistry and biological activity of essential oils from Piper claussenianum (Piperaceae). Nat. Prod. Commun. 2010, 5, 1837–1840.
  39. Cheng, S.S.; Liu, J.K.; Hsui, Y.R.; Chang, S.T. Chemical polymorphism and antifungal activity of essential oils from leaves of different provenances of indigenous cinnamon (Cinnamomum osmophloeum). Bioresour. Technol. 2006, 97, 306–312, doi:10.1016/j.biortech.2005.02.030.
  40. Standards Engineering Practices Data, Moisture Measurement-Forages, ASAE S358.2 DEC99; American Society of Agricultural Engineers: St. Joseph, MS, USA, 2000.
  41. Adams, R.P. Identification of Essential Oil Components by Gas Chromatography/Mass Spectroscopy; Allured Publishing Corporation: Carol Stream, IL, USA, 1995.
  42. Dhingra, O.D. Sinclair, J.B.; Sinclair, J.B. Basic Plant Pathology Methods, 2nd ed.; Lewis Publishers: London, UK, 1995.
  • Sample Availability: Samples of the essential oils are available from the authors.
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