Volatile Constituents and Insecticidal Activity of Essential Oil of Margaritaria discoidea (Baill.) G. L. Webster

Abstract

The volatile constituents and insecticidal activity of essential oil obtained by hydrodistillation of air-dried and pulverized leaves of Magaritaria discoidea (Baill.) G. L. Webster growing in Nigeria was studied. The constituents of the oil were analysed by means of gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS). The percentage yield of oil was 0.10% (v/w), calculated on a dry weight basis. A total of fifteen compounds, representing 99.99% of the total component of the essential oil of M. discoidea were characterized. The major compounds identified in the oil were geranyl acetone (33.0%), phytol (12.7%) and (E)-α-ionone (11.6%). The result of insecticidal activity indicated that M. discoideaessential oil at a concentration of 120 mg/mL displayed 100% mortality against Sitophilus zeamais, at 72 h. This is the first report on the chemical constituents and insecticidal activity of essential oil of M. discoidea. Aims: The aim of this study was to isolate essential oils from the leaf of Magaritaria discoidea (Baill.) G. L. Webster (Euphorbiaceae) and investigate the volatile constituents present therein as well as insecticidal potential. Study Design: The study involves the hydrodisitillation of essential oils from the air-dried plant materials, analysis of their chemical composition and evaluation of biological activity. Place and Duration of Study: Fresh leaves of M. discoidea were harvested from trees growing at Tipper Garage, Kolobo, Abeokuta, Ogun State, Nigeria, in March 2016. The study was coonducted over 3 months period. Methodology: About 500 g of air-dried plant samples was shredded and their oils were obtained by separate hydrodistillation for 4 h at normal pressure, according to the British Pharmacopoeia. The chemical constituents of the distilled oils were analyzed by means of gas chromatography-flame ionization detector (GC-FID) and gas chromatography coupled with mass spectrometry (GC-MS), while the insecticidal assay was conducted by established procedure. Results: The main compounds of the leaf essential oil geranyl acetone (33.0%), phytol (12.7%) and (E)-α-ionone (11.6%). The result of biological activities indicated that M. discoidea essential, oil at a concentration of 120 mg/mL displayed 100% mortality against Sitophilus zeamais, at 72 h. Conclusion: The present oil compositions were reported for the first for this species and for any member of Magaritaria family of plant.