Jatropha seed oil is the predominant biodiesel in use today. The plant has achieved international reputation for its industrial and biotechnical applications. However, its cultivation raises some environmental issues which need to be addressed, taking into account the burgeoning global energy needs. Besides its ubiquitous use in manufacturing biodiesel, the seeds of jatropha plant, its oil and other parts of the plant are increasingly being researched for developing medicines and other therapeutical applications. As we shall see, a compound extracted from the oil of jatropha has shown promise in HIV trials and may turn out to be a solution to one of the biggest viral diseases on the planet.
The seeds which yield jatropha oil are born by a plant known as Jatropha curcas. Although it is native to Central America, now it is found in many tropical regions of the world naturally. Growing interest in harvesting biodiesel from it has led many organizations and entire countries to incentivize jatropha cultivation in wastelands, arid lands and some purely desert areas.
The jatropha plant resembles the castor oil plant remarkably. That is because they belong to the same biological family, although they are in different sub families. The seeds are brownish with yellowish striations. They are pressed to yield the preliminary jatropha seed oil (which is toxic too), which is then sent for further chemical processing to yield jatropha biodiesel.
It has been well known since historical times that the jatropha plants (most of its sub-species) are toxic to humans. They can cause itches, rashes and even severe inflammatory reactions, which is mainly because of 2 specific toxic compounds – phorbol esters and curcin. These are also present in the seed oil, so that means even handling the oil would lead to unwelcome reactions. Surprisingly, it is the toxic part of the oil, the phorbol esters, that are processed to create a compound called prostratin, which is being used to treat HIV in clinical trials. Strange are the ways of nature and remarkable the ways in which it helps us.
Jatropha seed oil is quite pale yellow in color. It does not have any tinge of redness to it.
Suitability for Use as a Bio-Fuel in Our Vehicles
It has been proven that jatropha diesel can be directly used in most standard diesel engines. It is less polluting because it has lower sulphur concentrations than in regular diesel. This seemingly minor difference can help us to reduce massive ambient air pollution in our cities which often manifests as particulate matter pollution (your PM 10 and PM2.5 particulates) and poisonous sulphur-laden gases.
Secondly, it is much easier to store than diesel because it flashes at a much higher temperature than diesel. Thirdly, it has lower viscosity than diesel, making it lighter on the engines. 
Chemical Composition and Medicinal Properties
Jatropha seeds are quite oily. They can yield anything between 25% to 40% of its weight as oil. This vegetable oil is rich in oleic acid (MUFA) and linoleic acid (PUFA), both of them unsaturated fats. The in-depth composition of fatty acids is mentioned in the table below.
|Fatty acid||Composition (as percent of total oil)|
The sum of oleic and linoleic acid itself amounts to 80% of the oil. If not for the toxic compounds that make it unsuitable for human consumption (neither as edible oil nor as topical oil), it would have made a fine addition to our edible vegetable oils.
The physico-chemical properties of jatropha oil are of significance.
|Relative density||0.850 to 0.950|
The very low viscosity at room temperatures makes it flow very easily. Combined with high linoleic acid, this makes jatropha oil an ideal candidate for industrial lubrication applications. Secondly, its high saponification value means it is suitable for use in making soaps. In fact, it is a key ingredient in the manufacture of Turkey red oil which was an earlier form of detergent.
Medicinal uses of jatropha seed oil components
A promising study has found that application of jatropha oil while applying small amounts of currents (micro-currents) to the skin of rats has shown increased effectiveness in faster wound healing. 
The HIV virus is a master at hiding inside the body and compromising the immune response, thus leading to the acquired immuno-deficiency syndrome (AIDS). A much-cited study has noted that a compound called prostatin has the capability to reactivate the virus lying latent (dormant) within our body cells. Such viruses are not recognized even by our immune system and as a consequence, the infection persists. Prostatin is being considered for an adjunctive (additional therapy) to aid the existing anti-viral treatments. Since the phorbol esters contain prostatin, it makes the jatropha oil an oil of immense medicinal value. 
Jatropha plant and its oil has demonstrated potent insecticidal and fungicidal property against a host of major agricultural crops (cow peas, maize, mung lentils).  However, it has not been able to achieve a major commercial success for use as a natural pesticide. That is because there are still concerns about toxicity of jatropha constituents and also its danger to other beneficial pests that kill the harmful pests in the fields. Plus, there is also the matter of economic feasibility.
Therefore, it is best to avoid using jatropha oil or its plant as a natural manure for household gardens and family owned fields.
For an unbiased analysis of the oil of jatropha, it is essential to be fully aware of its negative effects. Although the plant itself contains many toxic compounds, we shall focus only on those that are present in the oil.
The phorbol esters have been recorded to promote tumors, although not directly. The Curcin present in the oil affects the ribosomes of our cells. Basic biology tells us that ribosomes are a functional unit of each of our body’s cells and they are involved in the task of making proteins for the body. 
There have been some instances where people who have drunk very small quantity of jatropha oil had to suffer powerful vomiting and even diarrhea.
- Kamrun Nahar and Monica Ozores Hampton. Jatropha an alternative substitute to fossil fuel. University of Florida.
- Physical and Chemical Properties Analysis of Jatropha curcasSeed Oil for Industrial Applications. Abdullah et al.
- Application of Jatropha curcas L. seed oil (Euphorbiaceae) and microcurrent on the healing of experimental wounds in Wistar rats. Passarini Junior JR et al. Acta Circ Bra.
- Effects of Prostratin on T-Cell Activation and Human Immunodeficiency Virus Latency. Korin et al. Journal of Virology.
- Insecticidal Effect of Jatropha curcas oil on the Aphid Aphis fabae and on the main insect pests associated with cow peas in Niger. Habou et al. Tropicultura 2011.
- Ethnobotany, ethnopharmacology and toxicity of Jatropha curcas L. (Euphorbiaceae): A review. Abdelgadir H.A. and Staden J. Van. South African Journal of Botany.