CASTOR OIL PLANT
Euphorbiaceae are plants of varied appearance, from grasses to large trees, distributed all over the world but numerous in warm countries.
They often contain latex, white or colorless, which is sometimes irritating.
The flower is most frequently without petals, with an ovary with 3 cells giving, after fertilization, a fruit (capsular) with 3 lobes, hence the old name "tricoque" which was given to euphorbiaceae.
Among the more than 10,000 species that make up this large plant family, there are
3 important genera:
The euphorbiaceae include food plants (cassava), industrial (hevea) or decorative (croton, poinsettia).
Castor oil plant is native to northeastern Africa and the Middle East, the Egyptians cultivated it and used its oil at least for lighting 6000 years ago.
It was spread a very long time ago to India and China and in the 16th century to America.
This hardy plant has become acclimatized in the tropics and subtropics around the world, it can become invasive.
In the wild, it becomes a small tree but it is generally cultivated (including in Europe and the USA) as an annual plant for its oil seeds and incidentally its stems, it is also an ornamental plant with many horticultural varieties.
The hollow stem bears large leaves cut into 5 to 10 hand-shaped lobes (hence the Spanish name palma-christi), the underside of which is often colored red-purple.
The terminal panicle inflorescence shows the male flowers at the base topped by the female flowers;
the capsular fruit is bristling with small spikes, but there are smooth varieties.
Ricinus communis, the CASTOR,OIL PLANT is more of a TOXIC PLANT than a medicinal plant. The (poisonous) seed is oleaginous. Castor oil is not edible but interesting for skin care and is important in synthetic chemistry.
CHEMICAL COMPOSITION AND PROPERTIES
The whole plant and mainly the leaves contain an alkaloid, RICININE, which can cause poisoning in livestock.
Ricinine is thermostable (cooking does not destroy it), it is an alkaloid toxic to animals (including humans) and which has insecticidal and antioxidant properties.
The whole plant is allergenic, by contact with the sap, the flowers or seeds.
Castor oil plant pollen is also allergenic, the very light pollen when inhaled may trigger allergic reaction (asthma).
CASTOR BEANS (SEEDS)
The seeds are rich in oil and protein:
40 to 60% oil,
15 to 20% protein
and contain a very dangerous toxalbumin: RICIN.
The oil consists mainly of triacylglycerol including the C18 fatty acid (unsaturated and hydroxylated): ricinoleic acid.
It is a drastic PURGATIVE long used as a laxative, but it is above all an industrial oil: lubricant for engines running at very high speed, raw material in the polymer industry (RILSAN = polyamide 11) and source of undecylenic acid ( antifungal substance by local route and used in industrial synthetic chemistry).
CASTOR OIL CAKE PROTEINS (after oil extraction) are feed for cattle, but toxalbumin (ricin) must first be destroyed.
It is composed of two polypeptide chains (A and B chain)), the B chain is just used to fix the toxin to the surface of the cells, the A chain is the toxic part, it interferes in the synthesis of cellular proteins, modifying (at enzymatic level) the activity of part of the ribosomes and quickly causing the death of the cell.
Ricin is soluble in water but not in fatty substances, it is destroyed by heat.
Its dangerousness is impressive, lethal dose in rats: 0.4 microgram by intraperitoneal injection, the equivalent of 0.03 mg for a man weighing 75 kg !!
The accidental or deliberate ingestion (suicide) of castor seeds is not always fatal, it depends on the degree of chewing, and some of the ricin toxin is probably inactivated in the stomach or duodenum.
Injection or respiratory penetration of pure ricin is fatal and there is no antidote drug, but several scientific organizations (sometimes linked to the military) have filed for patents for the manufacture and use of monoclonal antibodies against ricin.
Intoxication manifests itself first by nausea, vomiting and rapidly bloody diarrhea; all the organs are progressively affected and irreversible cardiac and neurological disorders appear.
Castor leaves are traditionally used as a plaster against rheumatic pain and as an "external wash" by the Palikour Indians of French Guyana, to get back "in shape" after a prolonged feverish attack.
Castor oil is hardly used anymore as a purgative, too brutal, too dangerous, nevertheless many populations still prepare a domestic oil : the seeds are pounded and this more or less homogeneous paste is heated and placed on a sieve that allows the oil to drip off, the oil is then heated for an hour or two, this removes the water, destroys the residual ricin and colors this household castor oil in brown.
Cold-extracted industrial castor oil is clear, a little yellow, sometimes a little viscous (it depends on the outside temperature).
The toxin (ricin) is not soluble in oil and on the other hand very sensitive to heat.
- for EXTERNAL USE, it is a cosmetic oil which, associated with massage, calms pain or muscle contractures.
It is used for the care of the skin, nails and hair in particular in the West Indies under the name CARAPATE OIL or KARAPAT.
- In INTERNAL USE, the laxative effect is achieved with 1 teaspoonful, the "drastic" purgative effect with 1 to 2 tablespoons, but this use is strongly discouraged.
Castor oil is used as a base to produce polymers that are not derived from petroleum. POLYAMIDE 11 (discovered in France during the Second World War) is marketed under the name "RILSAN", it has physical properties and resistance (in particular to water, to high temperatures) which make it used in many industrial applications.
Fatty acid derivatives are also used in the food industry such as polyglycerol polyricinoleate (E 476), a yellow and viscous liquid composed of polyglycerol esters of fatty acids condensed from castor oil.
It is used in very low doses to make preparations, especially chocolate-based preparations, more fluid (eg: spread).
The glycoprotein character of the toxin and its capacities as a cellular poison made it possible to consider its use coupled with monoclonal antibodies to thus create an immunotoxin directed specifically at an antigen.
This "biological torpedo" would make it possible to reach metastasized cancer cells or to penetrate the interior of solid tumors.
Complex therapeutic protocols associating this immunotoxin (of ricin) with cytostatic drugs or radioisotopes are envisaged, but, to my knowledge, there is no use in oncology yet.
RICIN is one of the substances prohibited in armed conflict and is classified as potentially usable by bioterrorism.
As such, it is closely watched.
As we saw a little above, there are now anti-ricin monoclonal antibodies, but they are not marketed (reserved for the military or the fight against terrorism).
An oleaginous plant dangerous by its seed
Castor oil plant is very widespread in hot regions and has long been used for its oil
with cosmetic and laxative properties.
Castor bean contains a water-soluble, heat-sensitive substance which is very toxic, but which may be effective in destroying certain metastasized cancer..
Copyright 2021 : Dr Jean-Michel Hurtel