The oil of Dysoxylum spectabile has been examined and found to be similar to that of Trichilia hirta also in the Meliaceae.
Dysoxylum spectabile Hook., known to the Maoris as “Kohekohe” and to the early settlers as Maori cedar is a handsome tree up to 50 feet in height. It is largely confined to the North Island. The wood provides useful fencing posts, particularly for use in sandy situations. There are numerous indications of the use of this plant in Maori medicine (Brooker and Cooper, 1960), but the oil is not mentioned in this connection.
The fruits of the Kohekohe are about an inch in diameter, and each contains four seed with brilliant scarlet covering. The seeds for this investigation were obtained from the property of Sir Carrick Robertson, on the slopes of Mt. Eden, Auckland. Though collected in the late autumn, no ripe fruit could be found on any of the trees, so the work has been done on oil from unripe fruits. Changes in the fatty oils of plants as the fruits ripen have been reviewed by Kartha and Naryaranan (1956); see also Ruthowski and Makus (1959). In general the oil content increases, but the proportion of unsaturated fatty acids may rise, fall, or remain stationary.
After air drying the seeds had a moisture content of 8.0 per cent, and on extraction with petroleum ether yielded 29.2 per cent of greenish yellow oil with the following analytical values:—
|Iodine value (Wijs)||82.0|
|Refractive index nd20||1.470|
|Unsaponifiable matter||1.5 per cent|
Some of the oil was converted to methyl esters and analysed by gas liquid chromatography at the Fats Research Laboratory, Wellington, by the courtesy of the Director, Dr. F. B. Shorland, with the following results:—
|Moles per cent|
Ignoring the minor constituents this gives the following percentages of the principal fatty acids by weight:—
The oil has some affinity with that of Trichilia hirta or Napahuite, a Mexican tree of the Meliaceae family, having similar saponification and iodine values. The seeds are also covered with a reddish skin. Eckey (1954) reports that a small quantity of the oil is produced in Mexico and used as a hair dressing.
The author wishes to thank Sir Carrick and Lady Robertson and Dr. R. C. Cooper for assistance in collecting and identifying the fruit, and Dr. J. C. Hawke, who carried out the gas-liquid chromatographic analysis.,