Constituents of Essential Oil from Bauhinia forficata Link

Abstract

The essential oil of Bauhinia forficata was obtained from leaves by steam distillation. The oil was analyzed by GC and GC/MS. In total, 15 components were identified being 14 sesquiterpenes and one hydrocarbon. The main component found was γ-elemene (38.4%) followed by α-bulnesene (17.3%), cariophyllene oxide (9.4%) and (Z)-β-farnesene (9.1%).

Key Word Index

Bauhinia forficata, essential oil composition, γ-elemene, α-bulnesene.

Introduction

The genus Bauhunia belongs to Leguminosae family, subfamily Caessalpinioideae and comprising about 300 species distributed in tropical and subtropical regions (1). Several therapeutic properties are attributed to Bauhinia genus including anti-ameboic, anti-diabetic, analgesic, anti-rheumatic and hypocholesteromic (2,3). Bauhinia forficata is a tree which grows in Brazd from Rio de Janeiro to Rio Grande do Sul states. This species, commonly know as "Pata-de-Vaca" due to the form of its leaves, has been used in popular medicine to treat diabetes showing a significant hypoglycemic effect in diabetic rats (4,5). This species has been described in the literature as accumulating free and glycosides flavonoids, like kaempferol and quercetin, beside steroids like β-sitosterol (6). Essential oils have been described in Leguminosae famdy rarely, being the genus Bauhinia an exception. This paper reports the chemical composition of die essential oil in Bauhinia forficata coUected in São Paulo state - Brazd.

Experimental

Plant Material: Leaves of Bauhiniaforficata were collected at the Santana do Parnaíba city, São Paulo state, Brazil in October 2005. The identification was performed by comparison to a specimen kept at the Herbarium of Instituto Florestal de São Paulo, Brazd (A. Furdan 1519 SP, ISPF).

Extraction: The fresh leaves (80 g) were cut in small pieces and submitted to a hydrodistiUation for 8 h in modified Clevenger-type apparatus according to the Farmacopea Brasileira (7). The minimum amount (0.02% yield) of od was dissolved in diethyl ether, dried with anhydrous sodium sulphate and immediately analyzed by GC.

Analysis: Quantitative and qualitative data were determined by GC and GC/MS respectively. GC analysis was performed in a gas Chromatograph (Perkin-Elmer Claras 500) equipped widi a Total Chrom Navigatior software, using Elite 5 column (30 m x 0.53 pm), and a flame ionization detector. Injector and detectortemperatureswere set at 220°C and250°C, respectively. The oven temperature was programmed from 60°-300°C at 10°C/min and He was employed as carrier gas (3 mL/min) . The percentage composition was obtained from electronic integration measurements using flame ionization detection. GC/MS analysis was carried out on Hewlett-Packard HP5890/5988 A spectrometer, operating at 70 eV, at the same conditions as described above. The identification of the substances was performed by comparison of retention indexes on DB-5 column (determined relatively to the retention times of a series of nalkanes) and mass spectra with die available in die literature (8). The mass spectra of the constituents were also compared to those contained in the mass spectra data bank (NIST107. LIB, NIST21.LIB e WILEY229.LIB). Relative amounts of constituents in the od were assumed to be proportional to die areas under corresponding chromatogram peaks.

Results and Discussion

The composition of the od from leaves of B. forficata is summarized in Table I. Constituents are fisted in order of their elution from DB-5 apolar type phase column and were identified by GC/MS analysis and retention indexes. This analysis showed the presence of 15 components co rrespondingto 93.8% of the oil. Fourteen components were sesquiterpenes, the major components γ-elemene (38.4%), α-bulnesene (17.3%), caryophyUene oxide (9.4%) and (Z)-β-farnesene (9.1%). The single constituent identified in the od, which doesn't belong to sesquiterpene class, was the hydrocarbon eicosane (0.2%). Previous report with other species oí Bauhinia described only die identification of die sesquiterpenes ß-caryophyllene, germacrene D and spathulenol as die compounds more frequendy found in high concentrations in some species (9). Since only sesquiterpenes have been described in essential ods from other Bauhinia species, this observation might be characteristic of Bauhinia species. Altliough the composition of the od from B. forficata previously reported in literature recontain α-copaene and ß-caryophyUene as major components (9), these components were not found in the present analysis.

Acknowledgments

The authors are indebted to Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for financial support (01/05023-1).

References

1. A.B. Joly, Botànica: introdução à taxonomia vegetal. 12. edn., Companhia Editerai Nacional São Paulo (1998).

2. H. Achenbach, M. Stocker and M.A. Constenla, Flavonoid and others constituents of Bauhinia manca. Phytochemistry, 27, 1835-1841 (1988).

3. E.P. Viana, R. S. Santa-Rosa, S.S.M.S. Almeida and LS. Santos, Constituents of the stem bark of Bauhinia guianensis. Fitoterapia, 70, 111-112(1999).