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CASTOR OIL
Source: Ricinus communis L. (Family
Euphorbiaceae).
Common/vernacular names: Castor bean,
palma christi, and ricinus.
GENERAL DESCRIPTION
An annual herb (up to 5 m high) when grown
in temperate zones and a perennial shrub or
tree (up to about 15 m high) in warmer cli-
mates. Castor bean is composed of many
varieties. It is generally believed to be a native
of Africa or India and is extensively cultivated
worldwide. Parts used are the ripe seeds from
which a colorless to pale oil is obtained by
cold pressing; yield, 25–35%; hot pressing
and solvent extraction yield darker grades
of oil, which are of lower quality. Castor oil
is remarkably stable and does not easily turn
rancid. Major castor oil-producing countries
include Brazil, China, and India.1,2
CHEMICAL COMPOSITION
Castor oil contains fatty acid glycerides of
linoleic,oleic,dihydrostearic,andstearicacids,
with ricinoleic acid comprising 80–90% of the
total fatty acid glyceride content. Ricinoleic
acid is a hydroxy acid, and as a result of
hydrogen bonding of its hydroxyl groups, cas-
toroil has acharacteristically highviscosity.1–3
Castor bean (seed) contains a highly poi-
sonous protein (ricin), which remains in the
seed cake (pomace) after the expression
of castor oil. Ricin is reported to contain
18 different amino acids and to have a molec-
ular weight of 53,000–54,000. Steam or moist
cooking of the pomace destroys the ricin. The
seed also contains ricinine (an alkaloid), lec-
tins, and a very powerful heat-stable allergen
(MARTINDALE).1,4
PHARMACOLOGY AND BIOLOGICAL
ACTIVITIES
Due to the content of ricinoleic acid, castor oil
has cathartic properties, acting on the small
intestine and producing purgation 2–8 h after
ingestion; its usual dose is about 15 mL. Large
doses may produce, besides purgation, nau-
sea, vomiting, and colic. It also has emollient
properties on the skin and is soothing to the
eyes.
TOXICOLOGY
Castor oil facilitates the absorption of oil-
soluble anthelmintics and should not be used
with them.
Castor seed is extremely toxic due to its
content of ricin, which is not present in the oil;
chewing a single seed may be fatal to a child
(MARTINDALE), and whereas seven or eight
seeds are believed to be sufficient to kill an
adult, as few as three seeds can cause fatal
gastroenteritis.^5
Glycoprotein allergens present in the seed
pulp can cause serious symptoms (asthma,
eye irritations, hay fever, skin rashes, etc.) in
certain individuals (MARTINDALE).^5 Allergic
reactions are also reported from wearing or-
namental necklaces made of the seeds.^6
A feeding study in chicks found that at
concentrations of 0.5–5% of the diet, castor
seed produced toxicity characterized by
154 Castor oil
