Variations in essential oil constituents at different growth stages of Ruta chalepensis on cultivation at North Indian plains

Journal of Essential Oil Research: JEOR, Jul/Aug 2003 by Bagchi, G D, Dwivedi, P D, Singh, Amrita, Haider, Flora, Naqvi, A A

Received: March 2001

Revised: June 2001

Accepted: July 2001

Abstract

Aerial parts of Ruta chalepensis L. plant grown under North Indian plain conditions were hydrodistilled to obtain essential oils from plants harvested at different stages of growth and were analyzed by GC and GC/MS. Nineteen compounds were identified representing 85.4-93.3% of the oil. 2-Undecanone (41.3-67.8%) was found to be the major compound followed by 2-nonanone (5.2-33.6%), 2-nonyl acetate (2.8-15.3%) and 2-dodecanone (

Key Word Index

Ruta chalepensis, Rutaceae, essential oil composition, 2-undecanone, 2-nonanone, 2-nonyl acetate, 2-dodecanone.

Plant Name

Ruta chalepensis L. (Rutaceae); local name: sadab.

Source

Ruta chalepensis plants were collected during different growth periods from field trials at CIMAP farm Lucknow for the cultivation of this species under North Indian plain conditions.

Plants

Ruta chalepensis seedlings were sown in the field in January 1999. Leaf materials were collected at vegetative stage (25th August 1999, plant height 60 cm, temp. min. 26.4[degrees]C, max. 35.6[degrees]C) and at budding stage (25th February 1999, plant height 115 cm, temp. min. 9.6[degrees]C, max. 26.2[degrees]C). At flowering stage (25th March 2000, plant height 118 cm, temp, min. 14.3[degrees]C, max. 29.7[degrees]C), both leaves and flowers were collected; at fruiting stage (25th April 2000, plant height 119 cm, temp. min. 21.5[degrees]C, max. 39.1[degrees]C), leaves and fruits were again collected for oil isolation and analysis.

Previous Work

Essential oils of R. chalepensis plants grown at different locations have shown wide range of variations even in their major constituents (1-6). 2-Undecanone has been reported to be the major constituent of an oil (38-66%) from Turkey (1,4) and Argentina (2), while an oil from Saudi Arabia was low (4.5%) in this constituent (3). A comparative study between the leaf oils of R. chalepensis and R. graveolens showed that 2-undecanone and 2-nonanone were the major constituents of oil in these species, respectively (6). However, on the contrary, R. chalepensis leaf oil from Sicily (5) showed a higher percentage of 2-nonanone (49.9%) than 2-undecanone (30.0%).

Present Work

Fresh plant parts (100 g each) collected as above were hydrodistilled using a Clevenger-type system for 5 h. GC analyses of the oils were performed using Varian GC, model CX-3400 with AIMIL chromatography data station. Supelcowax-10 capillary column (Supelco, USA) of dimension 30 m x 0.30 mm, film thickness 0.25 [mu]m was used in this study. Oven temperature was programmed from 50[degrees]-220[degrees]C at 6[degrees]C/min with initial and final hold of 2 min and 5 min, respectively. Injector and detector temperatures were maintained at 220[degrees]C and 240[degrees]C, respectively. Hydrogen was used as carrier gas (1 mL/m) with a split ratio of 1:50.

GC/MS analysis was carried out in EI mode using a Perkin Elmer Turbomass instrument fitted with PE-Wax capillary column of dimension 60 m x 0.32 mm, film thickness 0.32 [mu]m. Oven temperature was programmed from 70[degrees]-240[degrees]C at 3[degrees]C/min with an initial hold of 5 min. Helium was used as a carrier gas with split ratio 1:26. Mass spectral data were analyzed by NIST library search and comparison with standard published data. Constituents identified in the oil of R. chalepensis from different growth stages, plant parts and temperature conditions are given in Table I.

Analysis of the oils from R. chalepensis showed that the major constituents of oils were 2-undecanone, 2-nonanone, 2-nonyl-acetate and 2-dodecanone. 2-Undecanone was found to reach a maximum in the flower oil followed by fruit and leaf oils. The quantity of 2-undecanone was highest in the leaves when the plants were young and in the vegetative stage, and it gradually decreased when the plants started flowering and fruiting. 2-Nonanone, on the other hand, was at its maximum in the leaf oil followed by flower and fruit oils. The quantity of 2- nonanone in the leaves gradually increased from the vegetative stage to the flowering stage and was highest during fruiting stage. The concentration of 2-nonyl acetate was observed to be highest in the leaves during the vegetative stage, while 2-dodecanone was at its maximum in the fruits. Linalool, an important aromatic compound, has been found to be highest in flowers. [gamma]-Terpinene and 6-methyl-5-hepten-2-one were observed only in vegetative stage of the plants. During the flowering and fruiting stages they could not be detected. Pregeijerene was observed during flowering only, while geijerene was observed both during flowering and fruiting; however, this compound was found in leaves. On the other hand, camphor has been identified from Lucknow-grown R. chalepensis plants, but not from R. chalepensis grown elsewhere. In comparison with the R. graveolens oils, it has been observed that although linalool, thymol and carvacrol were constituents of R. chalepensis they have so far not been detected in the former species (7).