Бульнезія

The tree

Bulnesia sarmientoi is a tree that inhabits a part of the Gran Chaco area in South America, around the Argentina-Bolivia-Paraguay border. It has recently been reclassified as Gonopterodendron sarmientoi. The tree is up to 20 m high and grows wild in the Gran Chaco region of South America.

Its wood is often traded as "Paraguay lignum vitae". Another common but rather ambiguous name is palo santo, a name it shares with the species Bursera graveolens. The heartwood is brown, black and green, varying in color from light olive green to chocolate brown, with streaks. The basic specific gravity of this wood is between 0.92 and 1.1 g/cm³.

The oil

Oil of guaiac does not come from the Guaiacum tree, despite its name, but from the palo santo tree (Bulnesia sarmientoi). It is sometimes incorrectly called guaiac wood concrete. The oil solidifies at room temperature to a yellow-white to light amber mass that melts at 40–50 °C. Once melted, it can be cooled back to room temperature yet remain liquid for a long time. In recent years, Paraguay has produced more than 150 t of the oil per year. It is considered non-irritating, non-sensitizing, and non-phototoxic to human skin. Oil of guaiac was a pre-Renaissance remedy for syphilis.

Chemistry

The main constituents of the oil are the sesquiterpene alcohols guaiol and bulnesol. Oil of guaiac is primarily composed of guaiol, bulnesol, δ-bulnesene, β-bulnesene, α-guaiene, guaioxide and β-patchoulene. The oil may be used as a starting material for the synthesis of guaiazulene and for the production of guaiyl acetate.

Uses of the wood

Palo santo wood is employed for engraving work and for the making of durable wooden posts. Its resin can be obtained by means of organic solvents, and is employed to make varnishes and dark paints. Small pieces of the wood are also used as a form of natural incense in spiritual rituals. It ignites easily despite being so dense, and produces a fragrant smoke.

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