Volatile Constituents of Raphanus sativus L. var. niger Seeds

Volatile Constituents of Raphanus sativus L. var. niger Seeds

Afsharypuor, Suleiman

Abstract

Volatile constituents of Raphanus sativus L. var. niger seeds were analyzed by GC, GC/MS and retention indices. Ten isothiocyanates, seven aliphatic hydrocarbons and some other volatile substances were characterized. The main isothiocyanates were hexyl isothiocyanate (18.4%), 4-methylthiobutyl isothiocyanate (17%), 4-methylpentyl isothiocyanate (8.4%), 4-methylthio-(3E)-butenyl isothiocyanate (5.2%), 4-methylthio-(3Z)-butenyl isothiocyanate (4.7%) and isoamyl isothiocyanate (2.4%).

Key Word Index

Raphanus sativus var. niger, Cruciferae, black radish seed, volatiles, hexyl isothiocyanate, 4-methylthiobutyl isothiocyanate.

Introduction

Raphanus sativus L. var. niger (black radish) is a cruciferous plant cultivated in different parts of Iran (1). seeds of the plant are used as a diuretic, carminative, antifever, antitussive and stomach tonic in the Iranian traditional medicine (2,3).

Investigation of the glucosinolate composition of seeds of R. sativus L. (common cultivated radish) and R. sativus var. caudatus has been carried out by Daxenbichler et al.(4). This is the first report on the volatile constituents of seeds of R. sativus LJ. var. niger plant growing in Iran.

Experimental

Plant material: seeds of R. sativus var. niger (black radish) were obtained from a commercial market in Isfahan, Iran, in 1999. For proper authentication of the seeds, they were cultivated and the fully developed plants were characterized by the Botany Department of the Research Center of Natural Resources in Isfahan. A voucher specimen of the developed plant was deposited in the Herbarium of the Pharmacognosy Department, Faculty of Pharmacy and Pharmaceutical Sciences at the Isfahan University of Medical Sciences (Iran).

Autolysis and collection of the volatile constituents: seeds of the plant (30 g) were crushed and then immediately mixed with distilled water (450 mL), covered by a layer of cyclohexane (100 mL) and left for autolysis at 25°C overnight (17h). Then the mixture was shaken for 30 min and the volatile constituents were collected by distillation (5). The distillate was then concentrated in vacuum.

GC/MS analysis: Analysis of the volatile constituents was performed on a Hewlett Packard 6890 GC/MS instrument under the following conditions: injection of 0.1 pL sample, HP-5 MS capillary column (30 m x 0.25 mm, coating thickness 0.25 µm); carrier gas He, flow rate 2 mL/min, injector temperature 250°C, temperature program: 60°-275°C at 4°C/min; mass spectra: electronic impact, ionization potential 70 eV, ion source temperature 250°C, ionization current 1000 µA, resolution 1000, and mass range 30-300 amu.

Identification of the constituents was based on computer matching against the library spectra (Library Database Wiley 275), their retention indices with reference to an n-alkane series in a temperature programmed run, interpreting their fragmentation pattern and comparison of the mass spectra with the literature data (6-9).

GC analysis: Gas chromatographic determinations were run on a Perkin Elmer 8500 instrument using a BPl capillary column (30 m x 0.25 mm, film thickness 0.25 µm). The carrier gas was nitrogen with a flow rate of 2 mL/min. The oven temperature was programmed from 60°-275°C at 4°C/min. Injector and detector temperatures were 275°C and 28O°C, respectively. Quantitative data were derived from the integrator (Perkin Elmer GP-IOO ) data obtained from the GC-FID chromatograms recorded during routine GC.

Results and Discussion

The constituents of the concentrated distillate, the relative percentage of each component and the retention indices are presented in Table I. The distillate was consisted of a mixture of 10 glucosinolate autolysis products (i.e. the isothiocyanates), seven aliphatic hydrocarbons and some other volatiles.

The isothiocyanates represent a relatively high proportion of the volatiles (58.3%) and they are important contributes to characteristic flavor in the cruciferous plants.

In all, 31.6% of the total volatile isothiocyanates of the examined seeds was derived from hexyl glucosinolate; while 29.2% of the isothiocyanates derived from 4-methylthiobutyl glucosinolate, 14.4% from 4-methylpentyl glucosinolate, 8.9% from 4-methylthio-(SE)-butenyl glucosinolate, 8.1% from 4-methylthio-(3Z)-butenyl glucosinolate and 4.1% from isoamyl glucosinolate. Other volatile isothiocyanates, which were detected in lower amounts were the autolysis products of heptyl-, benzyl-, 2-phenylethyl- and 5-methylthiopentyl glucosinolates. Thus hexyl glucosinolate is the major glucosinolate of R. sativus L. niger seeds followed by 4-methylthiobutyl-, 4-methylpentyl-, 4-methylthio-(3E)-butenyl-, 4-methylthio-(3Zj-butenyl-and isoamyl glucosinolates. However, Daxenbichler et al. (4) analyzed the methanolic extracts of seeds of R. sativus (common cultivated radish) and R. sativus var. caudatus and reported the occurrence of 4-methylsulphinyl-3-butenyl glucosinolate as the major glucosinolate, followed by 4-methylsulphinylbutyl glucosinolate.

References

1. V. Mozaffarian, A Dictionary of Iranian Plant Names, p. 453. Farhang Mo’aser, Tehran (1996)

2. A.A. Bin Sina, AL-QANUN FI’-TIBB. Book II, p. 300, Institute of History of Medicine and Medical Research, New Delhi (1987).

3. H. Mirhaydar, Plants Used for Prevention and Treatment of Diseases. Vol. 1, p. 33, Daftare Nashre Eslamy, Tehran (1995).

4. M.E. Daxenbichler, G.F. Spencer, D.G. Carlson, G.B. Rose, A.M. Brinker and R.G. Powell, Glucosinolate Composition of seeds from 297 species of Wild Plants. Phytochemistry, 30, 2623-2638 (1991).

5. G.B. Lockwood and S. Afsharypuor, Comparative Study of the Volatile Aglucones of Glucosinolates from in vivo and in vitro grown Descurainia sophia and Alyssum minimum using Gas Chromatography-Mass Spectrometry. J. Chromatogr., 356, 438-440 (1986).

6. R.P. Adams, Identification of Essential oil Components by Gas Chromatography. Allured Publishing, Carol Stream, IL (1995).

7. H. Budzikiewicz, C. Djerassi and D.H. Williams, Interpretation of Mass Spectra of Organic Compounds. Holden-Day, San Francisco (1964).

8. FW. McLafferty, Mass Spectrometric Analysis. Anal. Chem., 34, 26-30 (1962).

9. The Mass Spectroscopy Data Centre, Eight Peak Index of Mass Spectra. Vol.1 -3. Mass Spectroscopy Data Centre, The Royal Society of Chemistry, The University, Nottingham, UK (1983).

Suleiman Afsharypuor* and Maryam Hoseiny Balam

Faculty of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, LR. Iran

* Address for correspondence

Received: February 2002

Revised: September 2002

Accepted: September 2002

10410 -2905/05/00040 -0440$6.00/00 -© 2005 Allured Publishing Corp.

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