Chemical composition and antimicrobial activity of the essential oils from New Caledonian Citrus macroptera and Citrus hystrix

Abstract

The essential oils from the leaves of Citrus macroptera and C. hystrix, collected in New Caledonia, have been analyzed by gas chromatography/mass spectrometry (GC/MS) and evaluated for their antimicrobial activity. A total of 35 and 38 constituents were identified, representing 99.1 and 89.0% of the essential oils, respectively. Both essential oils were rich in monoterpenes (96.1 and 87.0%, resp.), with beta-pinene as major component (33.3 and 10.9%, resp.), and poor in limonene (2.4 and 4.7%, resp.). Other main components of C. macroptera oil were alpha-pinene (25.3%), p-cimene (17.6%), (E)-beta-ocimene (6.7%), and sabinene (4.8%). The essential oil of C. hystrix was characterized by high contents of terpinen-4-ol (13.0%), alpha-terpineol (7.6%), 1,8-cineole (6.4%), and citronellol (6.0%). The antimicrobial activity was evaluated against five bacteria and five fungi strains. Both oils were inactive against bacteria. However, the C. macroptera leaf oil exhibited a pronounced activity against Trichophyton mentagrophytes var. interdigitale, with a minimal-inhibitory concentration (MIC) of 12.5 microg/ml.