Powder

Br. Vouacapoua Araroba, (Aquiar) Druce. A mixture of neutral principles obtained from Goa Powder, a substance deposited in the wood of this plant.

Habitat. Brazil, Bahia; in damp forests.

Syn. Araroba or Arariba Tree, Po(h)de Bahia, Crude Chrysarobin; Chrysarob.; Fr. Poudre de Goa, Chrysarobine; Ger. Goa Pulvre, Chrysarobin.

Vou-a-ca-pou'a. L. fr. Native C. American name (nomen caribaeum), voicapou.

Ar-a-ro'ba. L. fr. E. India name, ar(ar)oba, as applied to the bark.

Chrys-ar-o-bi'num. L. for Chry-sar' o-bin, fr. Gr...., gold, + ar(ar)oba.

Go'a. After Portuguese colony of Goa, on the Malabar coast of India, to which it was imported from Bahia, in Brazil, 1852.

Plant

Large tree 24-30 M. (80-100 degrees) high; trunk smooth, spheroidal, head not very bushy; leaves paripinnate, with long petioles; flowers purple, paniculate racemes; wood yellow, with numerous longitudinal canals and many irregular transverse interspaces or lacunae in which the Goa Powder is found -- a result of decay or chemical changes in the cell-walls of the trunk-wood (medullary rays), being possibly an antiseptic preservative of the plant; yields much chrysophanic acid by oxidation.

Commercial

Tree resembles the copaiba, and is called natively Angelim Amargoso; the oldest yield most powder, which is obtained by felling, splitting the tree, and then scraping the powder from the clefts, those doing this often suffering with irritated eyes and face; occurs as a light yellow powder when fresh, but brownish on exposure, slightly crystalline, rough, mixed with wood fibers, inodorous, bitter; 7 p.c. soluble in water, 80 p.c., in benzene, 50 p.c. in hot chloroform.

Constituents

Goa Powder

Chrysarobin 65-85 p.c., gum 7 p.c., resin 2 p.c., bitter extractive 7 p.c, woody fiber 5 p.c., ash .3-3 p.c.

Chrysarobinum. Chrysarobin. -- Obtained by treating Goa Powder with hot benzene (hot chloroform), evaporating to dryness, powdering. It is a brownish, orange-yellow, microcrystalline powder, tasteless, odorless, irritating mucous membrane, soluble in alcohol (385), chloroform (13), ether (160), benzene (30), carbon disulphide (180), solutions of fixed alkali hydroxides (red), slightly in water and boiling water--neutral; contains methyl chrysarobin in varying percentage, and is a reduced quinone. Tests: 1. Dissolve in sulphuric acid -- deep red solution, which poured into water deposits chrysarobin unchanged. 2. Incinerate -- ash .25 p.c.; shake 1 Gm. with potassium hydroxide T.S. (10) -- yellow, yellowish-red, deep red, due to absorbing oxygen from the air, producing chrysophanic acid -- CHO+ O  = 2CHO + 3HO, or inversely -- 2CHO + H = CHO + HO.  3. Mix .002 Gm. with 2 drops of fuming nitric acid -- red mixture, turning violet-red with a few drops of ammonia T.S. (dif. from chrysophanic acid -- yellow liquid).  Should be kept dark, in well-closed containers.  Dose, gr. 1/8 (.008 Gm.).

Preparation

1. Unguentum Chrysarobini.  Chrysarobin Ointment.  (Syn., Ung. Chrysarob.; Fr. Pommade de Chrysarobine; Ger. Chrysarobinsalbe.)

Manufacture

6 p.c.  Triturate chrysarobin 6 G. with hydrous wool fat 94 Gm. previously melted, heat on water-bath for 20 minutes, stirring occasionally, strain (thereby removing about 1 p.c.), stir until congealed.

Properties

Irritant, in doses of gr. 20 (1.3 Gm.) gastro-intestinal irritant, causing large watery, bilious stools, vomiting, nausea.  Externally--produces diffuse dermatitis, followed by follicular and furuncular inflammation; stains skin dark brown, removed by chlorinated lime.

Uses

Parasitic skin diseases of vegetable origin, ringworm, acne, favus, psoriasis, chronic eczema, hemorrhoids -- ointment; solution in water, vinegar, or chloroform -- allowed to dry then cover with collodion; suppositories, 1 gr. (.06 Gm.) -- hemorrhoids.

Allied Compounds

1. Anthrarobin (Desoxyalizarin), CHO. -- Obtained from the coal-tar product alizarin by action of nascent hydrogen; it is a strong deoxidizing agent, miscible with fats, weaker, less irritating and toxic than chrysarobin, soluble in alcohol, glycerin.

2. Hydroxylamine Hydrochloride, NHOHHCl. -- This does not stain the skin, hence is preferred often to the other reducing agents (chrysarobin, pyrogallol, anthrarobin, etc.) in skin diseases, but being a poison, care should be exercised not to allow too much to be absorbed by the system.