Essential Oil Composition from Duguetia Species (Annonaceae)

Journal of Essential Oil Research: JEOR, Jan/Feb 2006 by Maia, José Guilherme S, Andrade, Eloisa Helena A, Carreira, Léa Maria M, Oliveira, Jorge

Abstract

The leaf and fine stems and the bark oils of Duguetia eximia, D. flagellaris, D. pycnastera, D. riparia and D. trunciflora were obtained by hydrodistillation and analyzed by GC and GC/MS. The main constituents found in the leaf and fine stems oil of D. eximia were α-eudesmol (80.3%) and spathulenol (5.0%). The leaf and fine stems oil of D. flagellaris was dominated by spathulenol (58.7%) and α-muurolol (6.2%); the bark oil was dominated by germacrene D (16.5%), cyperene (10.6%), α-muurolol (8.6%), humulene epoxide II (5.3%) and spathulenol (5.0%). The major components identified in the leaf and fine stems oil of D. pycnastera were spathulenol (52.2%), allo-aromadendrene (9.1%), germacrene D (7.1%) and elemol (5.1%). The leaf and fine stems oil of D. riparia contained spathulenol (46.5%), caryophyllene oxide (28.9%) and α-pinene (6.1%) as their main compounds. The leaf and fine stems oil of D. trunciflora was dominated by α-pinene (21.1%), bicyclogermacrene (17.6%), bulnesol (10.6%), spathulenol (10.5%), guaiol (8.1%), globulol (5.7%) and humulene epoxide II (5.0%); the bark oil was dominated by β-phellandrene (45.7%), guaiol (8.3%) and α-cadinol (7.4%).

Key Word Index

Duguetia eximia, Duguetia flagellaris, Duguetia picnastera, Duguetia riparia, Duguetia trunciflora, Annonaceae, essential oil composition, α-eudesmol, spathulenol, caryophyllene oxide, α-pinene.

Introduction

The Annonaceae comprises tropical and sub-tropical species that are widespread in South and Central America, Africa, Asia and Australia. An early phytochemical review estimated 120 genera and more than 2000 species in this family (1). Economically, it is of appreciable importance as a source of edible fruits, raw material for cosmetics and perfumery and medicinal plants. The genus Duguetia has about 70 species of shrubs and small trees whose majority is distributed throughout Central and Tropical America and the West Indies.

As part an ongoing survey of the Amazon aromatic plants we are reporting the volatile composition of the species Ouguetia eximia Diels, D. flagellaris Huber, D. picnastera Sandwith, D, riparia Huber and D. trunciflora Maas et Gentry occurring wild in lowland rain forest areas.

The trunk wood of D. eximia and the trunk bark of D. panamensis have been shown to contain 2,4,5-trimethoxystyrene (2,3). The high content of the sesquiterpene spadiulenol existing in the trunk wood and leaves of D. flagellaris was previously reported by us (4). Aromadendrane sesquiterpenoids have been identified in the leaf essential oil of D. glabriuscula (5).

Experimental

Material and isolation of volatile constituents: The leaf and fine stems and the bark (250 g each) were collected at different places of Para State, Brazil, dried at room temperature for 3-5 days and submitted to hydrodistillation for 4 h, using a Clevenger-type apparatus. The oils were dried over anhydrous sodium sulfate and their percentage contents were calculated on basis of the dry weight of plant material. All specimens were obtained from flowering plants. Data of plant collection, voucher specimen and oil yield of the Duguetia samples are showed in Table I. The voucher specimens were deposited in the Herbarium of Museu Emilio Goeldi, city of Belém, Brazil.

Analysis of the volatile constituents: The qualitative analysis of the volatile compounds was performed on a Finnigan Mat INCOS XL GC/MS instrument, with the following conditions: a WCOT DB-5ms (30 m x 0.25 mm, 0.25 µm film thickness) fused silica capillary column; temperature programmed: 60°-240°C (3°C/min); injector temperature: 220°C; carrier gas: helium, adjusted to a linear velocity of 32 cm/sec (measured at 100°C); injection type: splitless (1 µL, of a 1:1000 hexane solution); split flow was adjusted to give a 20:1 ratio; septum sweep was a constant 10 mL/min; EIMS: electron energy, 70 eV; ion source temperature and connection parts: 180°C.

The quantitative data of volatile constituents was obtained by peak area integration using a HP 5890 GC/FID instrument, operated under the same GC/MS conditions, except for the carrier gas, hydrogen, which was produced by a Packard hydrogen generator.

Individual components were identified by comparison of both mass spectrum and their GC retention data with those of authentic compounds previously analyzed and stored in the data system. Other identifications were made by comparison of mass spectra with those existing in the data system libraries and cited in the literature (6). The retention indices were calculated for all volatile constituents using a n-alkanes homologous series.

Results and Discussion

In these Duguetia oils 76 volatile constituents were identified, as listed in Table II. The main constituents found in the leaves and fine stems oil of D. eximia were α-eudesmol (80.3%) and sphatulenol (5.0%). The leaves and fine steins oil of D. flagellaris was dominated by spathulenol (58.7%) and α-muurolol (6.2%); the bark oil was dominated by germacrene D (16.5%), cyperene (10.6%), α-muurolol (8.6%), humulene epoxide II (5.3%) and spathulenol (5.0%). The major components identified in the leaves and fine stems oil of D. pycnastera were spathulenol (52.2%), allo-aromadendrene (9.1%), germacrene D (7.1%) and elemol (5.1%). The leaf and fine stems oil of D. riparia contained spathulenol (46.5%), caryophyllene oxide (28.9%) and α-pinene (6.1%) as theirmain compounds. The leaf and fine stems oil of D. trunciflora was dominated by α-pinene (21.1%), bicyclogermacrene (17.6%), bulnesol (10.6%), spathulenol (10.5%), guaiol (8.1%), globulol (5.7%) and humulene epoxide II (5.0%); the bark oil was dominated by β-phellandrene (45.7%), guaiol (8.3%) and α-cadinol (7.4%).