The leaf oils of eight Cinnamomum species (C. rhyncophyllum Miq., C. microphyllum Ridl., C. pubescens Kochummen, C. mollissimum Hook. f., C. impressicostatum Kosterm, C. scortechinii Gamb., C. sintoc Bl., and C. cordatum Kosterm) were investigated for their larvicidal and adulticidal activities against Aedes aegypti (Aedes aegypti Lynn) and Aedes albopictus (Aedes albopictus Skuse). Acute mortalities of the fourth instar larvae and the adult mosquitoes were determined according to the standard WHO methods. Among the essential oils studied, the leaf oils of C. rhyncophyllum, C. microphyllum, C. pubescens, C. mollissimum, and C. impressicostatum showed significant effects against the larvae of Ae. aegypti and Ae. albopictus with concentrations that caused 50% mortality (LC 50 ) values of less than 12.8 and 11.8 mg ml À1 , respectively. The essential oils that showed strong larvicidal effects also demonstrated relatively strong adulticidal effects on the mosquitoes after 3 h exposure with LC 50 values ranging from 133.0 to 243.0 mg ml À1 against Ae. aegypti and from 118.0 to 194.0 mg ml À1 against Ae. albopictus. The efficacy of the oils toward the larvae and adult mosquitoes of both species was nonselective as the LC 50 values showed little variation. The chemical composition of the oils was investigated by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). This study suggested that the essential oils containing high levels of benzyl benzoate and benzyl salicylate exhibited strong insecticidal activities against the larvae and adult mosquitoes.

The leaf, twig, bark and wood oils of Cinnamomum sintoc Blume from a mountain forest of peninsular Malaysia were analysed by GC and GC-MS. Safrole (23.4%) and γ γ γ γ γ-muurolene (13.5%) were the major components of the leaf oil. Other compounds present in appreciable amounts in the oil were eugenol, linalool, terpinen-4-ol, α α α α α-cadinol, germacrene D, α α α α α-terpineol and δ δ δ δ δ-cadinene. The most abundant component of the bark oil was linalool (23.8%). Sesquiterpenes accounted for 25.2% of the oil with α α α α α-copaene, allo-aromadendrene, γ γ γ γ γ-muurolene and cubenol present in appreciable amounts. The bark oil was also rich in aldehydes where tetradecanal (16.4%) was the major representative. The wood oil was similar to the bark oil in the content of aldehydes but the concentration of each component was different. The oil also contained appreciable amount of acids (27.9%), represented by octadecanoic acid, pentadecanoic acid, hexadecanoic acid and tetradecanoic acid. The twig oil could be a natural source of linalool as it constituted 52.9% of the oil. Other major components of the oil were methyl (Z)-cinnamate and its E-isomer, which were both present at 6.0% concentration. The chemical composition of the oils in the present study was markedly different from those previously reported on C. sintoc collected from two different locations, suggesting the existence of intraspecific chemical races within the species.

The leaf, bark and wood oils of Cinnamomum rhyncophyllum Miq. were investigated by gas chromatography on two columns of different polarity, retention indices and GC-MS. The oils were composed mainly of phenylpropanoids and benzylic compounds. The leaf oil may be a potential natural source of benzyl benzoate, since it constituted up to 77% of the oil. Other compounds present in appreciable amounts in the oil were β-phellandrene (6.3%) and methyl (E)-cinnamate (4.2%). The bark and wood oils were found to possess compositional similarities with little variation in the levels of each component. Safrole (43.3-51.0%) and methyl (E)-cinnamate (40.5-43.1%) were the major constituents in these oils. However, the bark oil could be distinguished from the wood oil by containing a higher concentration of benzyl benzoate.

The chemical composition of the leaf oil of Cinnamomum pubescens Kochummen was examined by GC with authentic samples on two columns of different polarity, GC/MS and retention indices. Oils hydrodistilled from samples collected from two different sites at different periods were found to possess minor compositional differences but considerable variation in the levels of some components. The oils were rich in benzyl benzoate (46.1-47.1%) and β-phellandrene (14.9-16.4%). The samples could be differentiated from each other in which one sample contained a significantly higher concentration of benzyl salicylate and relatively lower concentrations of pinenes and (E)-methyl cinnamate.