Study Of The Essential Oil Of Eucalyptus Citriodora Hooker Cultivated In Kenya

Abstract

The yield of essential oil from leaves of Eucalyptus citriodora Hooker varied considerably but was always within the range 2.2 to 8.3%. The physico-chemical properties of the oil from leaves collected from different places and at different times were as follows: d20 = 0.8623 to 0.8867; n 20 ~20 D = 1.4515 to 1.4582; ~ D :::-1.0to + 4.0; acid value 2.8 to 5.5; ester value 5.2 to 30.7 and ester value after acetylation 290 to 330. The oil was soluble in 1.5 to 4.0 volumes of 70% alcohol. The Principal components identified in the leaf oil from Kenyan plants were citronellal (65-88%), citronellol (2-25%) and isopulegol (1:.5~19%). Other components isolated from leaf oil were: C><. - pi.nerie, f3 -pinene, camphene, 0( - phellandrene, B-phellandrene, limonene, p-cymene, citronellyl acetate, geraniol, eugenol, carvone and 11 unidentified terpenoid compounds. The oil components were identified by ir spectroscopy, glc, tlc and other chemical methods. Investigations performed indicate presence of 2 intraspecific varieties of E. citriodora in Kenya differing from the normal, "Type", only in the composition of leaf oil. The variability of oil content and its composition depended on individual trees, age of leaves and the collection time. Other parts of the plant namely flower buds, flowers, fruits, branchlets, pedicels and peduncles show much lower oil content. The oil from these parts contained mainly hydrocarbons with 0<- pinene as the main constituent (23-86.6%) .

The leaf oil was found to increase bile secretion in rats by 50% at a dosage of 50 mg/kg body weight. The antispasmodic effect of the oil against acetylcholine and histamine induced spasms in isolated rabbit ileum and isolated guinea pig trachea was demonstrated. The insecticidal action of the oil on termites was compared with that of malathion. The oil was found to exhibit a weak larvicidal action. The antimicrobial action of the oil was also confirmed.