Hydnocarpus wightianus

In India: It grows in tropical forests along western Ghats, along the coast from Maharashtra to Kerala, Assam, Tripura, often planted on road sides in hilly areas.

Other countries: The tree is found in South East Asia, chiefly in the Indo-Malayan region, and cultivated in Sri Lanka, Nigeria and Uganda.[6]

The oil is semi-solid at room temperature with no odor. Gas–liquid chromatography analysis has shown the oil to contain the following fatty acids – hydnocarpic acid, chaulmoogric acid, gorlic acid, lower cyclic homologues, myristic acid, palmitic acid, stearic acid, palmitoleic acid, oleic acid, linoleic acid and linolenic acid.[10] The oil is unusual in not being made up of straight chain fatty acids but acids with a cyclic group at the end of the chain.[11] The oil also contains 5′-methoxyhydnocarpin, an amphipathic weak acid, and isohydnocarpin.[12]

The crude oil has a pale greenish-brown color, and can be easily purified into a white, watery oil containing three cyclopentene fatty acids.

Table: fatty acid composition of oil[13]

Table of physical properties of oil[14]

Seeds are ovoid, irregular and angular, 1 to 1 1/4 inches long, 1 inch wide, skin smooth, grey, brittle; kernel oily and dark brown. A fatty oil is obtained by expression, known officially as gynocardia oil in Britain, as oleum chaulmoograe in the United States.[15]

Fruits are plucked by climbing the tree or using long sticks with a sickle tied to it. The fruits are peeled by knife and the seeds are washed in water and then dried in sun. Seeds are decorticated (dehusked) by mallet, hand hammer, or decorticator. They may also be crushed in an expeller and rotary. The kernels yield 43% oil. The extracted oil is stored in zinc barrels until exported.[6]

The Molokai island in Hawaii once the "Land of the Living Death," where lepers were treated with remarkable success by the then new chaulmoogra oil. Photo from 1922.

Chaulmoogra oil was commonly used in the early 20th century for the treatment of leprosy. It was applied topically (which was ineffective) or taken internally (more effective but nauseating and often rejected by people as worse than leprosy).[8][16][17] The ingredient that appears to produce antimicrobial activity is hydnocarpic acid, a lipophilic compound. It may act by being an antagonist of biotin.[18] American researcher Victor Heiser worked on developing a method of using the oil against leprosy by intravenous or intramuscular injection.[8][19]

An ethyl ester of the oil (the "Ball method") was developed by Alice Ball in 1916,[20][21] who died suddenly before publishing the technique. Her work was stolen by Arthur L. Dean who began producing large quantities of the treatment and named it after himself.[22]

It was then produced and marketed by Burroughs Wellcome (modern GlaxoSmithKline) in the early 1920s. The oil preparations were used intravenously for lepers. The oil was often obtained directly from trees in India, Sri Lanka or Africa. Doctors would locally prepare ethyl esters for treatments. In June 1927, Burroughs Wellcome released the commercial preparation – sodium hydnocarpate marketed as Alepol – which produced few unpleasant side effects. In May 1928, doctors reported cure of leprosy in some people treated with Alepol.[23] In the 1940s, chaulmoogra oil was replaced by the more effective sulfones.[20]