Apiol, as found in commerce, is usually prepared by extracting the bruised fresh fruits of parsley, Carum Petroselinum (Benth. et Hook.), (N.O. Umbelliferae), with ether, and distilling off the solvent. The residue is commercial liquid apiol, a green, non-viscous, oily liquid (specific gravity, 1.095 to 1.107), from which yellow apiol (specific gravity, 1.125) can be prepared by the removal of fatty and waxy substances. Liquid apiol has a peculiar odour and a disagreeable, acrid taste. So-called crystallised apiol or parsley camphor may be obtained from the volatile oil by cooling to a low temperature. In oil from German fruit it is present in such abundance as to render the oil semi-solid at ordinary temperatures (see Oleum Petroselini). It occurs in the form of white acicular crystals, having the formula C12H14O4. It has a slight parsley-like odour and an aromatic burning taste. Insoluble, or only very slightly soluble, in water; readily soluble in alcohol, ether, and oils. Melting-point, 30°; boiling-point, 294°. Not easily volatilised in aqueous vapour. It dissolves in strong sulphuric acid with a characteristic blood-red colour. Treatment with potassium permanganate yields apiolic acid (C10H10O6), melting-point, 175°. Boiling alcoholic solution of potassium hydroxide converts true apiol into an isomeric substance, isoapiol, melting at 55° to 56°, and boiling at 304°. The dose of crystallised apiol is from 2 to 3 decigrams (3 to 5 grains). Another apiol is that obtained from oil of Indian dill (Peucedanum Sowa, Kurz.), (N.O. Umbelliferae), and known as dill-apiol. It is an oily liquid, not crystallisable, boiling at 285° with slight decomposition. It has the same composition as that obtained from parsley-viz., C12H14O4, and yields crystalline dill-isoapiol when heated with sodium ethylate; dill-isoapiol melts at 44° and boils at 296°. Apiolin (white apioline) is prepared from yellow apiol by eliminating all traces of fats and wax, and represents the purest form of liquid apiol. Specific gravity, 1.124 to 1.135.
Insoluble in water, liquid apiol is quite soluble in alcohol, ether, acetone, glacial acetic acid, and benzene.
Action and Uses.—Liquid apiol has an action like that of essential oils generally. It is chiefly used in dysmenorrhoea and amenorrhoea, and, no doubt, acts by local reflex irritation during excretion by the urinary tract; it is also a diuretic. In large doses apiol sometimes produces effects like those of cinchonism, such as ringing in the ears, headache, and vertigo, and was at one time employed as an antiperiodic in ague. It is usually administered in capsules or perles.
Dose.—2 to 6 decimils (0.2 to 0.6 milliliters) (3 to 10 minims).