Essential oil composition of Melissa officinalis L. in vitro produced under the influence of growth regulators

ARTICLE

Essential oil composition of Melissa officinalis L. in vitro produced under the influence of growth regulators

Simone da Silva^I; Alice Sato^{*, II}; Celso Luiz Salgueiro Lage^II; Rosane Aguiar da Silva San Gil^III; Débora de Almeida Azevedo^III; Maria Apparecida Esquibel^I

^IInstituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS, Bloco G, Cidade Universitária, Ilha do Fundão, 21952-590 Rio de Janeiro - RJ, Brazil

^IIDepartamento de Ciências Naturais, Universidade Federal do Estado do Rio de Janeiro - UNIRIO, CCBS, Avenida Pasteur 458, 22290-040 Rio de Janeiro - RJ, Brazil

^IIIDepartamento de Química Orgânica, Instituto de Química, Universidade Federal do Rio de Janeiro, CT, Bl. A, Cidade Universitária, Ilha do Fundão, 21949-900 Rio de Janeiro - RJ, Brazil

ABSTRACT

It was investigated the effects of indole-3-acetic acid (11.42 µmol L^-1), benzylaminopurine (8.87 µmol L^-1) on essential oil composition and on the growth of Melissa officinalis in vitro plants. In vitro plantlets developed on MS media, showed 1.4 times in the proportion of nerol and 4.1 of geraniol, when compared with ex vitro plants. Treatments with 11.42 µmol L^-1 indole-3-acetic acid plus 8.87 µmol L^-1 benzylaminopurine led to 1.7 and 2.2 fold in proportion of nerol and geraniol, respectively in 60-day-old whole plants. These increases might be associated with the action of growth regulators wich stimulate plant growth (shoot organogenesis and elongation) and delaying the alcohol oxidation to aldehydes.

Keywords:Melissa officinalis, essential oil composition, VOCs, GC/MS, growth regulators, tissue culture

RESUMO

Foram investigados os efeitos de ácido indol acético (11,42 µmol L^-1) e benzilaminopurina (8,87 µmol L^-1) sobre o crescimento e composição do óleo essencial de plantas in vitro de Melissa officinalis. Plantas desenvolvidas em meio de Murashige e Skoog (MS) apresentaram o incremento de 1,4 vezes na proporção de nerol e de 4,1vezes de geraniol, quando comparadas às plantas ex vitro. Tratamentos com 11,42 µmol L^-1 de ácido indol acético mais 8,87 µmol L^-1 de benzilaminopurina resultaram em aumentos de 1,7 e 2,2 vezes na proporção de nerol e geraniol, respectivamente, em plantas de 60 dias. Estes aumentos podem estar associados à ação dos reguladores de crescimento, por estimularem o desenvolvimento vegetal (na organogênese e alongamento de brotos) e retardarem a oxidação de álcoois em aldeídos.

Introduction

Melissa officinalis Lam. (Lamiaceae) also known as lemon balm, is a perennial herb that presents a lemon flavor. The infusion of its leaves is used in folk medicine due to its sedative and antispasmodic properties. The chemical composition of the essential oil of the M. officinalis leaf (0.02-0.3% dry weight) has been previously studied, being the major compounds citronellal (2-40%) and citral (mixture of neral and geranial: 10-30%), followed by b-caryophyllene, germacrene D, ocimene and citronellol.¹

The growth of sprouts and roots and the composition of the essential leaf oil can be altered by addition of selected phytohormones into the nutrition medium.² Culture media supplemented with high concentrations of BA induced Melissa officinalis plants to accumulate more than 10% alloaromadendrene.³

In order to identify possible factors affecting the oil production and its quality, M. officinalis was cultured in vitro and the effect of growth regulators on the essential oil yield and composition were evaluated by gas chromatography and gas chromatography/mass spectrometry.

Experimental

Plant material

Seeds acquired from ISLAR, batch Nº 8250 were used to obtain the plant material. Erika Von Sohsten Medeiros and Angela Vaz (Jardim Botânico do Rio de Janeiro– RB, Brazil) undertook the taxonomic identification of this plant. A voucher nº RB – 365926 is deposited at the Herbarium of Jardim Botânico do Rio de Janeiro. The cultures were established according Silva.⁴ The nodal segments were inoculated in the basal media Murashige and Skoog (MS),⁵ MS without growth regulators (MS0) and were maintained under white light illumination (Sylvania fluorescent tubs) under 1.6 W m^-2, 30 mmol m^-2 s^-1 daily photoperiod of 16 hours at 25 ± 1 °C. Those plantlets were used as explants donors for growth regulators test effects. The methodology used follows Kreis and Mosandl.¹

Treatment with growth regulators

Nodal segments of in vitro plantlets were cultured in four different media composition: MS0; MS plus 11.42 µmol L^-1 Indole-3-acetic acid (IAA); MS plus 8.87 µmol L^-1 Benzylaminopurine (BA) and MS + 11.42 µmol L^-1 IAA plus 8.87 µmol L^-1 BA (n = 100 per treatment) during 60 days.

Acclimatization

Plantlets grown in MS medium were transferred to small pots filled with soil. The in vitro raised plants were hardened in a greenhouse and transplanted to the field after 90 days. The acclimatized plants were maintained in the soil during one year (complete vegetative cycle).

Extraction

The ex vitro and in vitro plantlets fresh aerial parts, 100 g each, were submitted to hydrodistillation for 1.40 hour, in a Clevenger-type apparatus⁶ in replicate (n = 2). The time between the isolation and analysis was the same in all experiments to preclude differences in composition due to external factors.⁷

Gas Chromatographic and Gas Chromatography-Mass Spectrometric analyses

Gas chromatography with flame ionization detection (GC/FID) was carried out on a Varian Star Model 3350 instrument using a capillary column coated with DB-5 (30 m x 0.25 mm i d , 0.25 µm film thickness; J & W Scientific, Folsom, CA, USA). The GC oven was heated using the following program: 40 ºC to 220 ºC at 4 ºC min^-1 with an initial isothermal period of 1 min, splitless. The detector and injector temperatures were held at 280 ºC. Hydrogen was used as carrier gas. The injection consisted of 1.0 µL of distilled oil diluted with hexane. The GC/MS analyses were carried out on a Hewlett-Packard (Agilent Technologies, Avondale, USA) Model 5972 MSD coupled to a HP 5890 GC. The GC conditions were the same as above, except that helium was used as carrier gas. The mass spectrometer was operated on electron impact mode at 70 eV. Molecular assignments were performed with the help of the Wiley 275 standard library of mass spectra, literature data,⁸ authentic geraniol standard (Sigma, Part Number: G5135) and mass spectra interpretation besides the comparison with previously published elution order.¹ Quantification was performed from GC profiles using area percent, since in the literature the FID response factor for most of monoterpenes is determined as 1.⁹

Results and Discussion

Data from development in different culture media were compared with those obtained from plantlets treated with MS0.

The addition of 8.87 µmol L^-1 BA or 11.42 µmol L^-1 of IAA plus 8.87 µmol L^-1 of BA to the MS medium resulted in a significant increase of shoot number per explant. When 11.42 µmol L^-1 IAA was used as unique growth regulator, there was a significant increase in the number of shoots and in the number of new nodes per plantlet (Table 1); all other parameters were not significantly affected.

According to GC essential oil analyses there is a direct dependence on the composition content of growth regulators in culture media (Table 2). The principal components of essential oil of the aerial parts of M. officinalis are presented on Table 2: geranial (38.1; 43.6; 43.1; 35.5 and 30.6%), neral (26.7; 31.7; 29.9; 27.4 and 23.3%), geraniol (3.3; 15.3; 17.9; 18.3 and 18.0%) and nerol (1.2; 1.9; 3.1; 3.3 and 3.1%) in plants cultured ex vitro and on the media MS0; MS+IAA; MS+BA and MS+IAA+BA, respectively (Figure 3). Plantlets developed in vitro, on MS media, showed an increase of 1.4 fold in the proportion of nerol and 4.1 of geraniol, when compared with ex vitro cultured plants. Comparative analysis of the chromatographic profiles showed high percentage of neral and geranial in relation to nerol and geraniol in ex vitro plantlets and in MS0 (Figure 2), while in plantlets submitted to the growth regulators it was observed a decrease of these levels. However, when the medium was supplemented with MS+IAA, it was observed an increase in the percentage of neral and geranial, when compared with other treatments.

Due to growth conditions employed in this work, the amount of light, temperature, mineral composition of growth regulators, pH and age of the explants could be completely controlled.

In this way, the results obtained show that the addition of these regulators in the culture medium induced the delay of alcohol oxidation to aldehydes.

Comparison between in vitro plantlets cultivated in MS medium without growth regulators (control) and in MS medium plus different growth regulators shows that the presence of 8.87 µmol L^-1 BA and 11.42 µmol L^-1 IAA in the medium resulted in a significant increase of geraniol level (Table 2 and Figures 1 and 2).

Growth of sprouts and roots, and the composition of the essential leaf oil of M. officinalis can be altered by addition of selected phytohormones to the nutrition medium. The essential oil is normally dominated by sesquiterpene hydrocarbons. By addition of appropriate amounts of napthalene acetic acid (NAA), the composition changes to a specific essential oil, dominated by oxygenated monoterpenes. The accumulation of monoterpenes is reduced; sesquiterpene accumulation can also be enhanced by abscisic acid (ABA).³

The effects of auxin on gene activity, especially in the epidermis, explains the quantitative variation promoted by addition of auxin.¹² Auxins may affect the kind of proteins formed in a plant cell before or as soon as growth promotion starts, which could explain changes in the level of some substances through the modification of the cell enzymatic pattern.¹³

The effect of cytokinins on the levels of secondary metabolites was already observed. Cytokinins are able to stimulate the synthesis of betacyanins ¹² and indole alkaloids.¹³

Field plants are exposed to considerable more stressful conditions, such as lower relative humidity, higher light levels, and herbivory those are the more stressful. The latter conditions tend to favor a greater essential oil accumulation.¹¹ On the other hand plantlets grown in vitro have been continuously exposed to a unique microenvironment that has been selected to provide minimal stress and nearly optimal conditions for plant multiplication.

The results obtained in the present study suggest that growth regulators (IAA and BA) influence on M. officinalis oil composition promote the delaying of the alcohol oxidation to aldehydes. It is very interesting, since geraniol has a great commercial value and is mainly utilized as fragrance fixative in the flavor industry.

Acknowledgment

S. Silva acknowledges the Master fellowship from Conselho Nacional de Desenvolvimento Científico e Tecnológico and fundação de Amparo à Pesquisa do stdo do Rio de Janeiro/RECOPE.

References

1. Kreis, P.; Mosandl, A.; Flavour Frag. J. 1994, 9, 249.

2. Binder, G.; Vandenberg, T.; Aboumandour, A.A.; Czygan, F.C.; Angew. Bot. 1996, 70, 181.

3. Binder, G.; Vandenberg, T.; Aboumandour, A.A.; Czygan, F.C., Angew. Bot. 1999, 74, 26.

4. Silva, S.; Monography, Universidade Federal do Estado do Rio de Janeiro, Brazil, 2000.

5. Murashige, T.; Skoog, F.; Physiol. Plantarum 1962, 15, 473.

6. Rezende, C.M.; Correa, V.F.S.; Costa, A.V.M.; Castro, B.C.S.; Alves, R.J.V.; Quim. Nova 2004, 27, 414.

7. Silva, S.; MSc. Dissertation, Universidade Federal do Rio de Janeiro, Brazil, 2003; Silva, S.; Sato, A.; Esquibel, M. A.; Lage, C.L.S.; Azevedo, D.A.; San Gil, R.A.S.; Br PI 0307136-7, 2004.

8. Adams, R.P.; Identification of Essential Oil Components by Gas Chromatography/Mass Spectroscopy, Allured Publishing Corporation: USA, 1995.

9. Carnat, A., Carnat, A. P.; Fraisse, D., Lamaison, J.D.; Fitoterapia 1999, 70, 44.

10. Salisbury, F. B.; Ross, S.; Plant Physiology, 4^th ed.; Wadsworth Publishing Company: New York, 1992.

11. Tavares, E. S.; Ph.D Thesis, Universidade Federal do Rio de Janeiro, Brazil, 2003; Tavares, E.S.; Lopes, D.; Bizzo, H.R.; Lage, C.L.S.; Leitão, S.G.; J. Essent. Oil Res., 2004, 16, 405.

12. Biddington, N. L.; Thomas, T. H.; Planta Med. 1973, 111, 183.

13. Mérillon, J. M.; Liu, D.; Huguet, F.; Chénieux, J.C.; Rideau, M.; Plant Physiology and Biochemistry 1991, 29, 289.

Received: August 23, 2004

Published on the web: October 24, 2005

Publication Dates

• Publication in this collection
  20 Jan 2006
• Date of issue
  Nov 2005

History

• Received
  23 Aug 2004