This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
The term ' kino ' or ' kano ' was first applied to a red astringent substance imported from West Africa about the middle of the eighteenth century. This was obtained from Pterocarpus erinaceus, Poiret. It was, however, soon replaced by other similar astringent drugs, and the term; kino ' became a generic one. The official drug, although often spoken of as ' kino,' is better termed Malabar or Cochin kino. Malabar kino is the juice obtained from incisions in the trunk of Pterocarpus Marsupium, Roxburgh (N.O. Leguminosoe), evaporated to dryness. The bast of the tree, which grows in southern India and Ceylon, contains, according to v. Hohnel, numerous comparatively wide and short tubular cells arranged in axial rows; these cells are filled with a red astringent liquid, which flows from them when they are wounded. Vertical incisions, with oblique lateral ones running into them, are accordingly made in the bark; the juice that flows is collected in small cups made of leaves, or in other convenient receptacles, and soon dries in the sun to a dark mass that readily breaks up into small angular grains. It is sometimes boiled before it is evaporated, an operation that modifies the subsequent behaviour of the drug. Kino is occasionally imported as a treacly liquid which can easily be dried.
Kino occurs in small, glistening, angular grains that appear quite black and are remarkably free from dust. When thin lamina3 or the edges of the grains are examined they are seen to be transparent and of a dark ruby-red colour. They are hard and brittle, breaking with a vitreous fracture and yielding a brownish red powder. The drug is odourless, but has, when chewed, an astringent taste, and adheres to the teeth, colouring the saliva red.
In cold water kino is only partially (from 80 to 90 per cent.) soluble; it dissolves to a greater extent in hot water, and is almost entirely soluble in alcohol. The aqueous solution turns green on the addition of a ferrous salt, violet with an alkali, and throws down a precipitate (kinotannic acid) when acidified with a mineral acid.
The student should particularly observe
(a) The brilliant, apparently black, colour,
(b) The absence of any dust; and should compare the drug with red gum.
The principal constituent of kino is kinotannic acid, of which it contains from 70 to 82 per cent. The published assays vary from 50 to 96 per cent., but this variation is probably due partly to variation in the drug, partly to variation in the process adopted for the assay, and partly to the gradual production of oxidation products intermediate between the soluble kinotannic acid and the insoluble kino-red. This change from kinotannic acid to kino-red commences immediately the juice is exposed to the air, as evinced by a darkening in colour; it is continued slowly in the dry drug which becomes duller and less soluble, and proceeds rapidly in solutions of the drug, which may gelatinise owing to the formation of insoluble kino-red. It is caused by the presence of an oxydase enzyme, and may be prevented by destroying the activity of the enzyme by boiling the juice or the solution of the drug. Hence the boiling of the juice before evaporation, as required by the British Pharmacopoeia, is a rational procedure.
In addition to kinotannic acid and kino-red the drug contains about 10 to 15 per cent, of moisture, and small quantities of pyrocatechin (catechol), gallic acid, and mineral constituents (ash 1.5 per cent.).
Kino is a powerful astringent; it is given internally for diarrhoea and dysentery and is also used externally.
Kinos have been obtained from numerous plants belonging to various natural orders, including Legumincsoe, Myrtaceoe, Polygonaceoe, Myristicaceoe, and Saxifragaceoe. Of these kinos the following may be briefly mentioned: -
1. Red gum (see below).
2. Butea gum (see below).
3. Eucalyptus or Botany Bay kino from various species of Eucalyptus (Australia), the most suitable being E. calophylla, R. Brown, the tannin of which does not gelatinise. The drug occurs in irregular dark red pieces.
4. African kino from Pterocarpus trinaceus, Poiret, in West Africa. It closely resembles the official drug.