Constituents and biological activity of Citrus aurantium amara L. essential oil

Citrus aurantium amara L. belongs to the order Geraniales and family Rutaceae. It is native to South East Asia, and it is a wild crop in Venezuela. It is a tree 6 to 8 m high bearing fruits with a thick, rugged and easily detachable cortex. The essential oil obtained from the cortex of C. aurantium amara has been used to add aroma to beverages and liquors and as an ingredient to give fragrance to soaps, detergents, cosmetics and perfumes. The fruits were collected in several sites of Tachira State, Venezuela. The oil was extracted from the cortex by cold pressing. Its components were analyzed by gas chromatography with flame ionization detector and gas chromatography-mass spectrometry. The main constituents found were the following: monoterpenes (limonene, 77.90%; beta-pinene, 3.40%; myrcene, 1.81%; and trans-ocimene, 1.16%), sesquiterpenes (valencene, 0.52%), aldehydes (decanal, 3.51%; dodecanal, 0.36% and geranial, 0.29%), alcohols (beta-nerolidol, 0.85% and linalool, 0.89%), and nootkatone as the only ketone. The extraction procedure can be considered as adequate since the oil obtained does not contain p-cimene, which is an indicator of oxidation of monoterpenes in citrus essential oils. Terpinene-4-ol, a product of limonene degradation, was found in traces and thus no unpleasant odor was present. The biological activity of C. aurantium amara essential oil against Escherichia coli, Stapylococcus aureus and Pseudomonas was determined using filter paper disks impregnated with 20 mul of essential oil placed on agar plates inoculated with these bacteria (10(7) UFC). The biological activity was evaluated after 48 hours, being inactive against E. coli and Pseudomonas and moderately active (17 mm) against S. aureus. The results obtained confirmed the traditional properties of the essential oil studied as savoring, odor, and a perfume base, as well as a natural antiseptic to inhibit S. aureus growth.