The tree
Canarium luzonicum is a large evergreen tree growing to a maximum height of about 30 m (100 ft). It is native to the Philippines. The elemi tree is related to frankincense, myrrh and opoponax, all belonging to the Burseraceae family. Clusters of flowers, which are pollinated by insects, are followed by thick-shelled nuts with edible kernels. The leaves are alternate and pinnate, about 30 centimeters long, commonly with three opposite pairs and a terminal leaflet. The leaflets are smooth and oblong-ovate, 12 to 20 centimeters long and 3 to 7 centimeters wide. The ovoid fruit is 4 to 5 centimeters long and holds a single seed. The tree is common in primary forests at low and medium altitudes from northern Luzon (Cagayan) to Mindoro, Ticao, and Masbate. Both Canarium luzonicum and C. ovatum are locally known as pili, and the Manila elemi of commerce is derived from both species.
The resin
When fresh, Manila elemi is oily and pale yellow or greenish, resembling crystallized honey in consistency. On exposure to air it loses some of its volatile constituents and hardens. Manila elemi is completely soluble in alcohol and ether. Manila elemi consists primarily of resenes together with some resin acids and volatile terpenes. Its approximate composition is 0.4-1% insoluble matter, 17-25% volatile terpenes, 1-2% non-volatile terpenes, 56-61% resenes, 15-18% resin acids and 1-3% moisture. One of the resin components is called amyrin.
Resins called elemi are obtained from members of the Burseraceae, particularly Canarium, Dacryodes and Protium. Elemis are more viscous than oleoresins, semisolid and very fragrant, and their soft, malleable nature comes from liquid sesquiterpenes. When the bark is lacerated it yields a sharp, green and pungent white or yellow oleoresin. Manila elemi has a spicy, rather bitter taste.
Soft elemi is aromatic and soft, while the hard elemis are only slightly aromatic and darker in colour. Three classes of Manila elemi exist for the domestic Philippine market and for export trade, although the designations are not always adhered to. Class 1 is the palest material, class 2 is the more yellowish material, and class 3 is a mixture of classes 1 and 2.
The oil and its constituents
The chemical composition of Manila elemi oil is approximately 56% limonene, 18% α-phellandrene, 6% elemol, 6% sabinene, 3% terpinolene, 2% elemicin and 3% β-phellandrene. The composition can vary a great deal. α-Pinene, β-pinene, myrcene, δ-carene, δ-terpinene and geraniol have also been demonstrated in the oil. The major components of elemi oil are limonene (40-72%), phellandrene (10-24%), and the sesquiterpene alcohol elemol (1-25%). Analysis of the oil by GC-MS found 39 compounds making up 99.2% of the oil, with limonene the most abundant. Terpineol, carvone, p-cymene and 1,8-cineole are also reported among its constituents. Water distillation of the oleoresin gave an average yield of 30% essential oil in one study.
Elemicin is a phenylpropene and a constituent of the oleoresin and the essential oil of Canarium luzonicum. Elemicin is named after this tree. Elemicin has the formula C₁₂H₁₆O₃. Elemicin was first isolated from elemi oil using vacuum distillation. In high doses, elemicin can cause irritation, so its concentration in cosmetics does not exceed 1%.
The oil is not stable because of the oxidation of terpenes, and freshly distilled oils should be preferred for use in flavour and perfume applications. Its high content of unstable monoterpenes tends to form peroxides and may present a hazard of explosion after heating the oil. Upon storage, the oil tends to resinify and polymerize, and the odor can become disagreeable.
Uses and trade
Elemi resin is chiefly used commercially in varnishes and lacquers, and certain printing inks. It is used as a herbal medicine to treat bronchitis, catarrh, extreme coughing, mature skin, scars, stress, and wounds. The resin has traditionally been used as incense in religious ceremonies and as caulking material for boats. Its industrial uses also include oil and spirit varnishes and paints, patent leather, sealing wax, soaps, plastics, linoleum, shoe polish and floor wax. On an experimental scale, Manila elemi oil at 5% concentration has proved capable of eliminating a number of wood-destroying fungi. At 20% the oil caused 88% mortality in drywood termites and 25% in powder post beetles. It shows significant antibacterial activities against Escherichia coli and Staphylococcus aureus.
The seed kernels are used for food, both raw and cooked. The young shoots can be boiled and eaten as a vegetable. In a 1985 review of 138 medicinal plant preparations used in the Philippines, 12, including Canarium luzonicum, exhibited detectable genotoxicity. The oleoresin of Canarium luzonicum has also been identified in studies as mutagenic.
The free-on-board (FOB) export prices were US$ 1.67-2.08 per kg for the period 1990-1993. By mid-1995, London-based importers reported a doubling of the price compared with the previous year and quoted prices of US$ 4.20-4.50 per kg. The FOB export price in 1996 was US$ 2.68/kg. France has been the largest single market, followed by Germany, and increasingly by Japan.
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Related: Amberwood · Amyris · Andiroba · Bakhoor · Balsamic Notes · Benzoin · Benzoin Resinoid · Benzyl Benzoate
