DSpace at VNU: Study of the Essential Oil of Limnophila Rugosa (Roth.) Merr. in the South of Vietnam

in the South of Vietnam Nguyen Truc Linh 1 , Le Ngoc Thach 2 * 1 Faculty of Chemical Technology, University of Cantho, 3/2 Street, Ninhkieu Dist., Cantho City, Vietnam University of Scie

This article was downloaded by: [New York University]

On: 01 December 2013, At: 19:31

Publisher: Taylor & Francis

Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH, UK

Journal of Essential Oil Bearing Plants

Publication details, including instructions for authors and subscription information:

http://www.tandfonline.com/loi/teop20

Study of the Essential Oil of Limnophila Rugosa (Roth.) Merr in the South of Vietnam

Nguyen Truc Linh a & Le Ngoc Thach b a

Faculty of Chemical Technology, University of Cantho , 3/2 Street, Ninhkieu Dist., Cantho City , Vietnam

b Department of Organic Chemistry, Faculty of Chemistry , University of Science, Vietnam National University-HCM City , 227 Nguyen Van Cu Street, Dist 5., Hochiminh City , Vietnam Published online: 12 Mar 2013

To cite this article: Nguyen Truc Linh & Le Ngoc Thach (2011) Study of the Essential Oil of Limnophila Rugosa (Roth.) Merr in

the South of Vietnam, Journal of Essential Oil Bearing Plants, 14:3, 366-372, DOI: 10.1080/0972060X.2011.10643947

To link to this article: http://dx.doi.org/10.1080/0972060X.2011.10643947

PLEASE SCROLL DOWN FOR ARTICLE

Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained

in the publications on our platform However, Taylor & Francis, our agents, and our licensors make no

representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever

or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content

This article may be used for research, teaching, and private study purposes Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any

form to anyone is expressly forbidden Terms & Conditions of access and use can be found at http://

www.tandfonline.com/page/terms-and-conditions

Study of the Essential Oil of Limnophila Rugosa

(Roth.) Merr in the South of Vietnam Nguyen Truc Linh 1 , Le Ngoc Thach 2 *

1 Faculty of Chemical Technology, University of Cantho, 3/2 Street, Ninhkieu Dist., Cantho City, Vietnam

University of Science, Vietnam National University-HCM City,

227 Nguyen Van Cu Street, Dist 5., Hochiminh City, Vietnam

Abstract: The essential oils of Limnophila rugosa (Roth.) Merr (Scrophulariaceae) in the south of

Vietnam obtained by hydrodistillation under conventional heating or microwave irradiation showed a slight

difference in chemical compositions The main constituents of these oils are trans-anethole (24.96-27.12 %)

and methyl chavicol (70.79-71.00 %) In addition, microwave method gave a higher extraction yield in a considerably shorter time than conventional heating protocol The physical, chemical and antimicrobial properties of the oils were also determined

Key words: Limnophila rugosa, Scrophulariaceae, chemical composition, trans-anethole, methyl

chavicol, microwave hydrodistillation

Introduction: Limnophila rugosa (Roth.) Merr., an annual herb native to wetlands in Vietnam,

belongs to the Scrophulariaceae family 1,2 It is widely cultivated and used as food flavoring, seasoning

or culinary herb In addition, the plant is also employed as a traditional medicine for colds, cough, laxative, diarrhoea, gonorrhea and anaprodisia 3,18 The chemical composition of Limnophila rugosa

(Roth.) Merr essential oil, obtained by hydrodistillation (steam distillation) with conventional heating, from several regions including the north of Vietnam, 4,5 China, 6,7 Hungary, 8 and India 9,10,11,18 had been studied However, only some of these reports mention the antimicrobial activity of the oils Moreover, the essential oil of Limnophila rugosa (Roth.) Merr from the south of Vietnam has not been studied yet Therefore, we decided to investigate this oil in term of both chemical and antimicrobial properties Recently, microwave-assisted extraction technique has been applied as a new and efficient method

to isolate essential oils from plant materials 12 In 1996, we reported that a modified domestic microwave oven could be used as a heating source for fast hydrodistillation of essential oils from plant materials.13

Unfortunately, this system was subsequently proved to be not applicable for long hydrodistillation because water is quickly evaporated out of the distillation flask after several minutes

In this paper, we report the first systematic study of essential oils from the aerial parts of

Limnophila rugosa in the south of Vietnam obtained by hydrodistillation using both conventional

Journal of Essential Oil Bearing Plants ISSN Print: 0972-060X Online: 0976-5026

www.jeobp.com

Received 14 February 2010; accepted in revised form 10 December 2010

heating (HDCH) and microwave irradiation (HDMW) We also introduce a newly-modified Clevenger type apparatus 14 designed for long hydrodistillation Oil contents in different parts of the plant and

versus age of material were also studied The chemical compositions of oil products were analyzed by

GC-MS The physical, chemical and antimicrobial properties of oils were also investigated

Experimental

Materials: All Limnophila rugosa samples were collected in the morning in Trang Bang Dist.,

Tay Ninh Province The plant was identified by the Department of Botany, School of Biology, University

Gas chromatography: GC analyses were performed on an Aglient 6890N GC equipped with

an FID and DB-5 capillary column (30 m x 0.32 mm x 0.25 μm) Nitrogen was used as the carrier at

a flow rate of 1.74 ml/min The constant pressure mode at 9.32 psi was chosen on GC program The oven temperature was programmed from 60°C to 240°C at 3°C/min The injector and detector

composition of the constituents of the oils was determined by area normalization

Gas chromatography-mass spectrometry (GC/MS): An Agilent 7890 GC coupled to a 5973A

Network Mass Selective Detector using HP-5MS capillary non-polar column (30.0 m x 0.25 mm x

at 10.604 psi was chosen on GC program The injection temperature was 250°C; the injection volume was 1.0 μl; the split ratio was 10:1, and the ionization voltage was 70 eV The oven temperature was programmed from 60°C to 240°C at 3°C/min The retention indices (arithemetic indices) of the oil components were calculated relative to the homologous series of C9-C17 n-alkanes by using the equation

propounded by van den Dool and Kratz in 1963 Identification of constituents was based on comparing their mass spectra with those of standard compounds registered in the NIST 2008 library Moreover, the identification was also confirmed by the retention indices of each individual constituent relative to those reported in the literature compiled by Adams 15

Density of oil products was determined by using glass densitometer, and their [α]27

Typical hydrodistillation procedure: Fresh aerial parts of the plant (300 g) were cut into small pieces, loaded onto a Clevenger type apparatus with distilled water (600 ml), and hydrodistilled using

Anti microorganism test: The oil is diluted in dimethyl sulphoxide (DMSO) The concentration can be calculated as following equations:

C0 = 100 μl-1: concentration of original oil

C1 = 1μl C0 + 9μl DMSO = 10-1 μl-1

C2 = 1μl C1 + 9μl DMSO = 10-2μl-1

C3 = 1μl C2 + 9μl DMSO = 10-3μl-1

C4 = 1μl C3 + 9μl DMSO = 10-4μl-1

The antimicrobial activity of Limnophila rugosa aerial part oil was tested by paper disc method (standard diameter of 6 mm) on Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa,

Staphylococcus aureus, and Candida albicans.

Results and discussion: The extraction yields in correspondence with extraction methods are

shown in Figure 1 The conventional method requires longer time (5 hours) but provides lower yield (0.1347 %) in comparison with the microwave method (0.1560 % yield in 9 minutes) This result is consistent with the fact that microwave heating accelerates the evaporation of volatile compounds from plant materials Therefore, microwave-assisted extraction has been recently considered as a

“green” technique due to its time and energy efficiency. 17 It should be noted that our newly-designed apparatus for microwave-assisted hydrodistillation allows water to return to the distillation flask, thus, providing enough water for long distillation processes. 13

The distribution of essential oils in different parts of plant materials was also investigated As illustrated in Figure 2, the leaf of the plant contains the highest amount of essential oil (0.2740 %), followed by the aerial part after flowering (AF) (0.1994 %),aerial part before flowering (BF) (0.1347

%) and stem (0.0151 %).It was also found that the oil content in the plant is dependent on the age of plant (nearly peak value observed at four months and slightly leveled off afterwards)

Figure 1 Oil yield vs the hydrodistillation time of HDMW (left) and HDCH (right)

Figure 2 The oil yields vs the plant part (left), and changes in oil yield

vs the age of the plant (right) investigated by HDCH method

The chemical compositions of the aerial part oil were identified by both GC-FID and GC-MSD technique as shown in Table 1 Generally, oil products isolated by the two techniques show a slight difference in oil compositions For example, the oil obtained by HDCH method indicates the presence

of limonene, coumarin, pentadecane… while these minor components were not found in the oil produced

by HDMW method In addition, the percentages of major components, trans-anethole and methyl

chavicol, are also variable with the heating methods On the other hand, these values are considerably

different with that of the oil from China and the north of Vietnam For example, only 24.96 % of

trans-anethole was found in the oil from the south of Vietnam while the figures for the oil from the north of Vietnam and China are 89.40 % and 76.39 %, respectively In contrast, methyl chavicol, the major component in the oil from the south of Vietnam (70.79 %), occurs as the minor one in the oil from the north of Vietnam (0.41%) (Table 2)

The chemical constituents of the aerial part after flowering oil (AF) were also identified by

GC-MS technique The result indicates a transformation between two major components after flowering

This can be easily observed by an increasing of trans-anethole (from 24.96 to 30.35 %) and decreasing

of methyl chavicol (from 70.79 to 64.20 %) while the total percentage of these two components remains unchanged (Table 1) In general, oils isolated by using different techniques show a slight difference in

compositions and abundance Besides, the oil constituents of the aerial part of Limnophila rugosa

(Roth.) Merr vary with the geographic position of the herbs The percentage of each component is variable with the periods of plant growth

Physical and chemical properties of aerial part oils isolated by both HDCH and HDMW methods were also determined (Table 3). 15 In general, the difference between two oils is negligible However, if compared with the oils from China and India, the difference becomes significant (Table 4)

The anti-microbial activity of Limnophila rugosa aerial part oil was tested by paper disc method (standard diameter of 6 mm) on Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa,

Staphylococcus aureus, and Candida albicans In addition, a typical fungi (Candida albicans) was

also used to test the antifungal activity of this essential oil.Interestingly, oil obtained from the microwave method exhibits stronger antimicrobial activity than the one from conventional method (Table 5) The antibacterial activity of the oil arises from the two main components The higher antimicrobial activity

of the oil obtained from HDMW method can be attributed to the larger amounts of the two main components Previous studies also demonstrated significant anti-bacterial and anti-fungal activities of this oil. 18,19 Infusion of leaves is used as diuretic and stomachic treatment in the Philippines and

genital infection in human 20 Further in vitro and in vivo tests are needed to confirm this finding The antifungal activity promises a broader usage of L rugosa’s oil.

Conclusions: Two different techniques (HDMW and HDCH) were used to extract essential oil

from Limnophila rugosa (Roth.) Merr HDMW method is more efficient to extract main components (trans-anethole and methyl chavicol) Therefore, HDMW is a suitable technique for extracting essential

oil from plant material containing a large amount of water HDCH method was applied to investigate the change in composition of oil versus period of growth The aerial parts can provide optimal oil yield

after 4 months Interestingly, a transformation between trans-anethole and methyl chavicol was observed

in the oil of aerial part after flowering In addition, the leaves were found to give the highest oil yield

Besides, the essential oil from Limnophila rugosa (Roth.) Merr indicates significant antibacterial

and fungal activities Although further testing is needed, it is believed that these results would lead to

a wider application for Limnophila rugosa oil.

References:

1 Pham, H.H (2000) Plants in Vietnam Youth Ed HCM City pp 480.

2 Ministry of Science, Technology and Enviroment (1996) The Red Book of Vietnam, Botanical

Part Science and Technology Hanoi pp 170

3 Do, H.B (2003) Medicinal Plants and Animals in Vietnam Science and Technology Hanoi.

pp 993-994

4 Vu, N.L., Nguyen, D T and Nguyen, T T (1988) Limnophila rugosa (Roth.) Merr - A rich

sources of anethole Journal of Pharmacy (4,5) 12-20

5 Tran, H.T (2003) Study of the essential oil of aerial part of Limnophila rugosa (Roth.) Merr.

in Vietnam Journal of Pharmacy (8) 14-15

6 Cheng, B., Yu, X and Tao, G (1986) Cultivation of caobajiao (Limnophila rugosa) and

assay of the chemical components of its essential oil Zhongcaoyao 17(4), 175-181

7 Yu, X and Cheng, B (1986) Chemical constituents of the essential oil from Limnophila

rugosa Yunnan Zhiwu Yanjiu 8(1), 103-106.

8 Kumar, V and Kapil, V B (1983) Essential oil of Limnophila rugosa (Roth.) Merr Herba

Hungarica 22(2), 77-81

9 Gulati, B.C and Duhan, S.B.S (1965) Essential oil of Limnophila rugosa Indian Oil and

Soap Journal 30(8), 233-236

10 Baslas, R.K and Baslas, K.K (1968) Essential oil from some exotic plants in Kumaon II.

Perfumery and Essential Oil Research 59(3), 180-182

11 Agarwal, S.G., Thappa, R.K., Vashist, V N., Atal, C.K and Gupta, R (1975) Chemical

examination of the volatile oil of Limnophila rugosa Indian Journal of Pharmacy 37(4),

99-100

D.(2007) Microwave-assisted isolation of essential oil of Cinnamomum iners Reinw ex Bl.:

Comparison with conventional hydrodistillation Molecules 12, 868-877

(b) Iriti, M.,Colnaghi, G.,Chemat, F.,Smadja, J.,Faoro,F and Visinoni, F A (2006).

Histo-cytochemistry and scanning electron microscopy of lavender glandular trichomes following conventional and microwave-assisted hydrodistillation of essential oils: A comparative study Flavour Fragrance Journal 21, 704-712

(c) Kosar, M., Tunalier, Z., Oezek, T., Kuerkcueoglu, M., Baser, K and Huesnue, C (2005).

A simple method to obtain essential oils from Salvia triloba L and Laurus nobilis L by using

microwave-assisted hydrodistillation Zeitschrift fuer Naturforschung, C: J Biosci 60, 501-504

(d) Elamrani, A., Zrira, S., Benjilali, B and Benaissa, M (2003) Isolation of Moroccan

Rosmarinus eriocalix oil: comparison between hydrodistillation and microwave extraction.

J Essent Oil Bearing Plants 6, 1-8

(1996) Microwave-assisted extraction process of the basil oil (South Vietnam) Journal of

Chemistry 34(2), 94-99

(b) Le, T.N., Tran, A.H and Vuong, V.M (1998) Contribution in investigation of the

essential oil of Cinnamomum parthenoxylon Meissn rooten wood Journal of Chemistry 36(4),

91-93

(c) Bui, P.M.N., Nguyen, L.T., Le, T.N., Tran, A.H and Luu, T.T (2004) Effect of

microwave irradiation on the composition of essential oil of Piper betel L Journal of Chemistry

42(2), 139-144

T T (2006) Award of “Innovation in Science and Technology” Ministry of Science and

Technology, Vietnam

(b) Nguyen, D.T.T., Tran, H A and Le, N.T (2008) The essential oil composition of

Eryngium foetidum L in South Vietnam extracted by hydrodistillation under conventionnal

heating and microwave irradiation Journal of Essential Oil Bearing Plants 11(2), 154-161.

the analysis of essential oils, Journal of Chromatography A, , 936, 1-22.

(b) Zellner, B.d’A., Bicchi, C., Dugo, P., Rubiolo, P.,Dugo, G and Mondello, L (2008).

Linear retention indices in gas chromatographic analysis: a review, Flavour and Fragrance

Journal, , 23, 297-314.

(c) Adams, R P (2007) Identification of Essential Oil Components by Gas Chromatography/

Mass Spectrometry Allured Carol Stream

(d) Baser, K H C and Buchbauer G (2010) Handbook of Essential Oils -Science, Technology,

and Applications CRC Press Boca Raton

16 AFNOR, (1992) Huiles Essentielles Paris pp 37-156.

17 Chemat, F and Lucchesi, M.-E (2006) Microwave-assisted Extraction of Essential Oils, in:

Microwaves in Organic Synthesis Loupy, A (Eds) VCH, Weinheim pp 959-983

18 Goutam Brahmachari, (2008) Limnophila (Scrophulariacea): Chemical and pharmaceutical

aspects The Open Natural Product Journal 1, 34-43

19 Kapil, V.P., Sinha, A.K., Sinha, G.K (1983) Antibacteria and antifungal study of some

essentials oils & their constituents from the plants of Kumaon and its Tarai tract Bulletin

of Medico-Ethno-Botanical Research IV (3, 4), 124-129

20 Ryan, K.J., Ray, C.G (2004) Sherris Medical Microbiology (4th Ed.) McGraw Hill.

New York

Table 1 Chemical composition (%) of the aerial parts

(BF and AF) of Limnophila rugosa (Roth.) Merr.

% Oil composition

Table 2 Comparison of the main constituents of aerial part oils in the south of Vietnam and other regions

% Oil composition Main constituents Southern Vietnam Northern Vietnam 5 China 7

Table 3 Physical and chemical properties of oil products

obtained by HDCH and HDMW methods

IA : Index of Acide ; IE : Index of Ester

Table 4 Comparison of physical and chemical properties of aerial

part oils in the south of Vietnam and other regions

[α]25

Table 5 Anti microorganism properties of Limnophila rugosa (Roth.) Merr volatile oil

Zone of inhibition (mm)

C* = 10 0 10 -1 10 -2 10 -3 10 0 10 -1 10 -2

*C : oil’s concentration (μl-1)