Allspice
pimenta dioicapimento officinalis, (LINDL.)
Myrtaceae
CONSTITUENTS
Chief constituent of Pimento
is from 3 to 4.5 per cent of a volatile oil,
contained in glands in the pericarp
of the seeds and obtained
by distillation from the fruit.
Occurs as a yellow or yellowish-red liquid,
becoming gradually darker on keeping and having
a pleasant aromatic odor, somewhat similar to that
of oil of cloves, and a pungent, spicy taste.
It has a slightly acid reaction.
It is soluble in all proportions of alcohol.
The specific gravity is 1.030 to 1.050.
Its chief constituent is the phenol Eugenol, which is present
to the extent of 60 to 75 per cent, and a sesquiterpene,
the exact nature of which has not yet been ascertained.
The specific gravity to some extent indicates the amount present;
if lower than 1.030, it may be assumed that some eugenol
has been removed, or that the oil has been adulterated
with substitutes having a lower specific gravity than that of eugenol.
The eugenol can be determined by shaking the oil
with a solution of potassium hydroxide and measuring
the residual oily layer.
The United States Pharmacopoeia
specifies that at least 65 per cent
by volume of eugenol should be present.
On shaking the oil with an equal volume
of strong solution of ammonia,
it should be converted into a semisolid
mass of eugenol-ammonium.
The clove-like odor of the oil is doubtless
due to the eugenol, but the characteristic odor
is due to some other substance
or substances as yet unknown.
A certain amount of resin is present,
but the oil has not yet
been fully investigated.
Bonastre obtained from the fruit,
a volatile oil, a green fixed oil,
a fatty substance in yellowish flakes,
tannin, gum, resin, uncrystallizable sugar,
coloring matter, malic and gallic acids,
saline matter and lignin.
The green fixed oil has a burning, aromatic
taste of Pimento and is supposed
to be the acrid principle.
Upon this, together with the volatile oil,
the medicinal properties of the berries
depend, and as these two principles
exist most in the shell, this part
is the most efficient.
According to Bonastre, the shell contains
1O per cent of the volatile and 8 per cent of the fixed oil;
the seeds only 5 per cent
of the former and 2.5 of the latter.
Berzelius considered the green fixed oil
of Bonastre to be a mixture of the volatile oil, resin,
fixed oil and perhaps a little chlorophyll.
