Chrysarobin

CHRYSAROBIN, Chrysarobinum, Araroba depurata, Pulvis Goa, Goa powder; the main constituent of araroba powder, which accumulates in the hollows and internal cavities of the tree Andira araroba (Leguminosae), growing in Brazil and India. Chrysarobin is obtained by extracting araroba with boiling benzene. Chrysarobin is a mixture of emodin (see), chrysophanic acid, emodin methyl ether, and their reduction products. The main constituent of chrysarobin consists of the reduction products of emodin and chrysophanic acid—anthranols and the ketone anthrone corresponding to anthranol (up to 60%).

Chrysarobin is a golden-yellow powder, tasteless and odorless, soluble in chloroform and benzene, slightly soluble in ether, and partially soluble in 200 parts of boiling water with a neutral reaction. The melting point is not sharp; according to observations by various authors, it ranges from 147° to 204°. In its physiological action, chrysarobin resembles pyrogallol, being related in this respect to other reducing agents of the phenol series used in the treatment of certain skin diseases, mainly psoriasis.

Chrysarobin acts as an irritant on the skin and mucous membranes, causing erythema and sometimes even a pustular rash. If it gets into the eye, it causes acute conjunctivitis, sometimes leading to persistent clouding of the cornea. When taken internally (for therapeutic purposes, chrysarobin is used only externally!), even a few centigrams of chrysarobin cause vomiting and enteritis.

Chrysarobin finds therapeutic application in dermatological practice in the form of a 5–25% ointment for psoriasis, herpes tonsurans, eczema marginatum, etc. The disadvantages of chrysarobin include the brown-violet staining of skin and linen, its caustic effect on the eyes, and frequent complications (see Dermatitis). When applied to large areas of the skin, chrysarobin, upon absorption, produces a picture of general poisoning: nephritis, albuminuria.

Chrysarobin preparations such as Eurobin (triacetyl-chrysarobin) and Lenirobin (tetra-acetyl-chrysarobin), which were proposed as substitutes for chrysarobin, are not very reliable. Of greater importance is anthrarobin (1,2-dioxyanthranol), obtained synthetically by the reduction of alizarin, with the formula C14H10O3; it is a yellowish-brown powder, odorless and tasteless, very difficult to dissolve in water, and easier in alcohol. Possessing therapeutic properties slightly less pronounced than chrysarobin, anthrarobin irritates the skin and mucous membranes significantly less, etc. The form of application is a 10–20% alcoholic solution.

Cignolin, Cignolin, an isomer of the previous preparation: 1,8-dioxyanthranol. Its properties and action are similar to the previous one.

S. Shubin. CHRYSOIDIN, chrysoidin, a basic azo dye with the formula C6H5N=NC6H3(NH2)2HCl (diamidoazobenzene hydrochloride), is a brown-red powder or shiny crystals; it dissolves easily in water with an orange-red color; the solution gives a red precipitate with hydrochloric acid and a yellowish one with caustic soda; reducing agents decolorize the solution.

In microscopic technique, chrysoidin finds limited application due to the low selectivity of the staining and is recommended only by Martinotti for the staining and fixation of fat. Sections from formalin-fixed objects on a freezing microtome are treated with a 1% aqueous solution of chrysoidin, quickly washed with water, and transferred to a 2% aqueous solution of potassium dichromate for 2 minutes or to a 10% solution of chromic acid in 95° alcohol for 1 minute; followed by quick washing with water, alcohol, xylene, and balsam. The fat is stained an intense brown color. A mixture of 1% chrysoidin and safranin T in equal parts, followed by treatment with 10% chromic acid, reveals red inclusions in the brown fat.