Page 38 - phytochemistry I - PharmD Clinical

"VOLATILE OILS"

"Essential Oils" "Ethereal Oils"

Definition:
The volatile oil is obtained by the steam distillation of plants or by other
means then by direct steam distillation. ex:
Bitter almond and mustard oils are obtained by enzymatic action, followed
by steam distillation.
Lemon and orange oil are obtained by simple pressing.
All volatile oils are obtained from plant source except oil of Musk, from
Male deer and Amber, from whale.

Points of differentiation exist between volatile oil and fixed oils:

Fixed oils Volatile oils

Cannot be distilled (Capable of volatilization) can
from their natural sources. be distilled from their natural sources.
Leave a permanent grease spot Do not leave a permanent grease
on paper. spot on paper.
Consist of glyceryl esters of Do not consist of glyceryl esters
fatty acids. of fatty acids.
Can be saponified with alkalis. Cannot be saponified with alkalis.
Become rancid upon long storage. Do not become rancid upon long
storage. Instead on exposure
to light and air, they become oxidized
and resinified.

Occurrence of V.O. in plant tissues:

- Widely distributed in certain plant families e.g., Pinaceae,

Lauraceae, Rutaceae, Myrtaceae, UmbelIiferae, Labiatae and

Compositae.

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