Lupulus, B.P., Hops.
Related entry: Lupulin
Hops (Humulus, U.S.P.) are the dried fruits (strobiles) of Humulus Lupulus, Linn. (N.O. Urticaceae), collected from cultivated plants. The hop is a climbing plant growing in Europe generally, but largely cultivated in England, Germany, Russia, California, etc. It is dioecious, but the pistillate plant only is cultivated. The hops are picked when they are fully developed, dried in kilns, and frequently exposed to the fumes of burning sulphur. They are then packed into bales known as "pockets." The strobiles are about 3 centimetres long, ovoid in shape, and consist of a number of imbricated yellowish-green membranous bracts and stipules attached to a hairy zigzag axis. Each of the bracts enfolds at the base a small fruit (achene), both fruit and bract being sprinkled with yellow, translucent glands. Fresh hops possess a bitter, aromatic taste, and a strong, characteristic aromatic odour. The latter, however, changes and becomes distinctly unpleasant as the hops are kept. This change is ascribed to oxidation of the soft resin with production of valerianic acid. On account of the rapid change in the odour of hops, the recently dried fruits should alone be used; these may be recognised by the characteristic odour and distinctly greenish colour. Hops yield about 7 per cent. of ash.
Constituents.—The aromatic odour of hops is due to volatile oil, of which they yield about 0.3 to 1.0 per cent.; it appears to consist chiefly of the sesquiterpene humulene. Petroleum spirit extracts a soft resin (7 to 14 per cent.), and ether a hard resin. The petroleum spirit extract contains the two crystalline bitter principles, α-lupamaric acid (humulone), and β-lupamaric acid (lupulinic acid). These bodies are chiefly contained in the glands. The leafy organs contain about 5 per cent. of tannin, which is not a constituent of the glands.
Action and Uses.—Hops have the action of the aromatic bitters. The infusion is employed as a vehicle especially for bitters and tonics; the tincture is stomachic and is used to improve the appetite and digestion. Both preparations were formerly believed to be sedative and were given in nervousness and hysteria, and at bedtime to induce sleep. Hops are also made up into pillows on the supposition that they induce sleep; any such action must be attributed to suggestion rather than to any effect of the volatile principles. Hop poultices are sometimes used for application to inflammatory swellings. Preparations of hops are incompatible with mineral acids and metallic salts.
Dose.—1 to 2 grammes (15 to 30 grains).
- Extractum Lupuli, B.P., 1885.—EXTRACT OF HOPS.
- Hops, 1 pound; rectified spirit, 1 ½ pints; distilled water, 1 gallon. Macerate the hops with the spirit for seven days; then press, filter, and distil off the spirit, leaving a soft extract. Boil the marc with the water for one hour; then press, strain, and evaporate on a water-bath until a soft extract is obtained. Finally, mix the two extracts, and evaporate at a temperature not exceeding 60°, until a mass of pilular consistence is obtained. Extract of hops is used in pills as a tonic and bitter, in a similar manner to extract of gentian. Dose.—3 to 10 decigrams (5 to 15 grains).
- Infusum Lupuli, B.P.—INFUSION OF HOPS.
- Hops, freshly broken, 5; distilled water, boiling, 100. Infuse the drug in the water for fifteen minutes, in a covered vessel, and strain. infusion of hops is used as an aromatic bitter and vehicle for tonics; also as a mild sedative. Dose.—30 to 60 mils (1 to 2 fluid ounces).
- Infusum Lupuli Concentratum, B.P.C.—CONCENTRATED INFUSION OF HOPS.
- A product closely resembling infusion of hops is obtained by diluting 1 part of this preparation with 7 parts of distilled water. Dose.—4 to 8 mils (1 to 2 fluid drachms).
- Tinctura Lupuli, B.P.—TINCTURE OF HOPS.
- Hops, 20; alcohol (60 per cent.), 100. Macerate for seven days, and complete the maceration process. Dose.—2 to 4 mils (½ to 1 fluid drachm).