Chemical Constituents of Gynura cusimbua Aerial Parts

Journal of Essential Oil Research: JEOR, Jan/Feb 2007 by Rana, Virendra S, Blazquez, M Amparo

Abstract

The essential oil isolated from the aerial parts of Gynura cusimbua was analyzed by GC and GC/MS. Forty-seven constituents totaling 91.92% of the oil were identified. The major constituents of the oil are myrcene (31.0%), β-phellandrene (12.43%), eugenol (6.34%), α-humulene (6.20%), dodecyl acrylate (6.09%), α-copaene (5.61%), phytol (3.21%), germacrene D (3.0%), cryptone (2.04%), 2,4-ditertbutylphenol (1.62%), α-pinene (1.33%), α-cadinene (1.26%), caryophyllene oxide (1.24%) and β-caryophyllene (1.08%).

Key Word Index

Gynura cusimbua, Asteraceae, volatile oil, myrcene, β-phellandrene.

Introduction

Gynura (Family: Asteraceae), a genus of herb, rarely under shrubs, widely distributed in the warmer parts of the world. Out of 14 species reported so far, seven species are growing in India (1). Gynura cusimbua is a large herb commonly found in roadsides, fields and grassy slopes in Imphal and other places of Manipur. The juice of stem and leaves are applied to fresh wounds for stopping bleeding and fast healing in traditional medicines. The leaf paste is also applied to forehead to relive headache and used as sedative drug by the local people (2,3).

Literature survey revealed that no phytochemical work has been done on this plant. Thus, it was thought worthwhile to carry out a detailed chemical analysis of the volatile components of its aerial parts by GC/MS.

Experimental

The aerial parts of G. cusimbua were collected from Imphal, Manipur (North-East) India in March 2004. Avoucherspecimen has been deposited (HN803) in the Herbarium of Institute.

Fresh aerial parts (500 g) of G. cusimbua were cut in to small pieces, air dried and subjected to hydrodistillation for 3 h in a Clevenger-type apparatus. The distillate was extracted with diethyl ether, the ethereal layer was dried over anhydrous sodium sulfate and ether distilled of on gently heated water bath. The yield of the oil obtained was found to be 0.18% and was stored at 4°C. The oil isolated from the leaves has the following physico-chemical properties, n^sup 25^^sub D^: 1.4300; [α]^sup 30^^sub D^ : 6.8 (c.0.1 in petroleum ether ).

GCIMSs Gas chromatography/mass spectrometry analysis of the volatile oil was carried out on a GCVMS (Model Agilent 19091S-433) equipped with a HP-5MS capillary column 30 m x 0.25 mm, film thickness 0.25 µm. The oven temperature was held at 60°C for 6 min, programmed at 5°C/min to 180°C, 10°C/min to 280°C and then held for 10 min. The carrier gas was He at a flow-rate of 2 mL/min (split mode). The injector and detector temperatures were 250°C and 280°C. The quadrupole mass spectrometer was scanned over the 30-500 a.m.u., range at 1 scan/s with an ionizing voltage of 70 eV. Retention indices were calculated using co-chromatographed standard hydrocarbons. The individual compounds were identify by MS and their identity was confirmed by comparing their retention indices relatives to C^sub 8^-C^sub 32^ n-alkanes and by comparing their mass spectra and retention times with those of authentic samples or with data already available in the NIST library and literature(4,5).

Results and Discussion

Cynura cusimbua is a potent medicinal plant used for curing many diseases in traditional medicine ( 1-3). The volatile oil of the aerial parts G. cusimbua was obtained by conventional hydrodistillation method using a Clevenger-type apparatus and the yield of the oil was found to be 0.18% (w/w), based on dry weight.

The results indicated (Table I) that 47 components, accounting for 91.92% of the oil were identified, while unidentified compounds constituted 8.08%. The main components of the oil were myrcene (31.0%), β-phellandrene (12.43%), eugenol (6.34%), α-humulene (6.20%), dodecyl acrylate (6.09%), α-copaene (5.61%), phytol (3.21%), germacrene D (3.0%), cryptone (2.04%), 2,4-ditertbutylphenol (1.62%), α-pinene (1.33%), α-cadinene (1.26%), caryophyllene oxide (1.24%) and β-caryophyllene (1.08%), respectively besides 23 other minor compounds.

Results also showed that the monoterpene hydrocarbons constituted the major portion (46.29%) of the oil and myrcene (31.0%), β-phellandrene( 12.43%) and α-pinene (1.33%) were the main components, while oxygenated monoterpene hydrocarbons (10.87%) contained eugenol (6.34%) and cryptone (2.04%) as major constituents.

GC/MS analysis further showed that sesquiterpene hydrocarbons (20.25%) were found to contain cc-humulene (6.20%), α-copaene (5.61%), germacrene D (3.0%), α-cadinene (1.26%) and β-caryophyllene (1.08%), as major compounds while dodecyl acrylate (6.09%), phytol (3.21%), 2,4-ditertbutylphenol (1.62%) and caryophyllene oxide (1.24%) were identified as major oxygenated sesquiterpenes in the oil.

It may therefore be concluded that G. eusimba used in traditional medicine in Manipur can also be utilized as a new source of myrcene. This is the first report of GC/MS analysis of its aerial parts oil.

References

1. Anon, Wealth of India: Raw Materials, pp. 280-281 .CSIR, New Delhi (1956).

2. S.C. Sinha, Medicinal plants of Manlpur. p. 84. Mass and Slnha Pub., Manipur(1996).