"Betel consists of the dried leaves of Piper Betle, Linn." Br.
Betel, Betle, Pawn, or Pinang are popular Oriental names for Piper Betle L. and P. Siriboa L., the leaves of which are used by the Malays as a masticatory. The leaves are usually admixed with scrapings of the Areca nut and shell lime. The Betel plants are indigenous throughout the entire Indian-Malay region and cultivated in Madagascar, Bourbon and West Indies. The plants are climbing shrubs and trained upon trellises and poles in shady but hot places. The leaves are picked while green, pressed together by means of stones and dried. The Betel leaves of the British Pharmacopoeia are described as follows: "About fifteen centimetres long, broadly ovate, acuminate, obliquely cordate at base; thin and brittle, upper surface glossy, five or seven conspicuous lateral veins. Mesophyll contains abundant oil-cells filled with brown oleo-resin. Taste warm, aromatic, bitter. As found in commerce the leaves are frequently tied up or stitched together into packets." Br.
The warm aromatic taste of the betel leaves is due to an essential oil known as betel oil. This is of a color varying from clear yellow to dark brown and of aromatic, somewhat creosote-like, odor and burning sharp taste. The specific gravity ranges from 0.958 to 1.044, the lighter oil being that obtained from the fresh leaves. The alcoholic solution of the oil gives a greenish to bluish-green color with ferric chloride.
The betel oil from Siam contains cadinene and a characteristic phenol named betelphenol, isomeric with eugenol; the oil from Java contains in addition to the betelphenol, chavicol and a sesquiterpene; while the Manila oil contains betelphenol as the sole phenolic constituent. (Gildemeister and Hoffmann, Die Aetherische Oele, Berlin, 1899.)
Uses.—The essential oil of betel is an active local stimulant and has been used in doses of one to two minims (0.06-0.12 mil) in the treatment of various respiratory catarrhs, and as a local application, either by gargle or inhalation, in diphtheria. It is said that the juice of four leaves is equivalent in power to one drop of the oil. In India betel leaves are used locally to a considerable extent for the purpose of counter-irritation and applied to the mammary glands for the purpose of suppressing the secretion of milk in mammary abscesses. The essential oil has been given internally in doses of from one to two minims (0.06-0.12 mil).