Source, Etc

The greenheart tree, Nectandra Rodioei, Hooker (N.O. Laurineoe), is a large forest tree growing abundantly on the hills in British Guiana. Its tall, straight stem yields a hard and resistant wood that is highly valued for shipbuilding; the bark was recommended early in the present century as a substitute for cinchona bark, and the alkaloid obtained from it in 1835 by Rodie as a substitute for quinine. It aroused some interest at first, but now neither the bark nor the alkaloid obtained from it is much used.

Description

Bebeeru bark occurs in flat, heavy pieces, frequently 10 to 15 cm. long, 5 to 8 cm. wide, and 3 to 10 mm. thick. It is of a more or less uniform greyish brown colour, and frequently marked on the outer surface with broad shallow depressions left by the exfoliation of the outer portions by the formation of bands of cork; these exfoliating portions are occasionally but not often found adhering to the bark. The outer layer is usually a very thin greyish brown, often warty cork, which can easily be scraped off, disclosing a darker inner portion. The inner surface is walnut-brown, bears shallow, rather broad longitudinal depressions, and is coarsely longitudinally striated by strands of sclerenchymatous tissue, which, under the lens, can be seen slightly projecting beyond the remaining parenchymatous tissue.

The bark is extremely hard, and breaks with a short granular fracture. The transverse section, smoothed and moistened, exhibits under the lens a very narrow, pale grey cork; the remainder of the bark is completely traversed by closely approximated, yellowish, wavy medullary rays, showing that in the majority of cases the drug consists (with the exception of the cork) of bast tissue. Between the medullary rays numerous minute groups of sclerenchymatous cells can be distinguished, arranged in radial lines.

The bark has no odour, but a bitter taste.

The student should observe

(a) The flat heavy pieces,

(b) The thin grey cork,

(c) The structure of the transverse section; and should compare this bark with

(i) Sassy bark, which is seldom flat, is often nearly black on the inner surface, and exhibits in transverse section large conspicuous groups of sclerenchymatous cells;

(ii) Coto bark, which has a reddish brown colour, is usually much thicker, and has a characteristic odour and taste;

(iii) Elm bark, which is much paler in colour and fibrous.

Constituents

The chief constituents of bebeeru bark are the alkaloids beberine and siperine and probably others that have not yet been isolated.

Beberine, C19H11N03, crystallises in colourless prisms melting at 214°. It has a bitter taste, and forms colourless crystalline salts. It is identical with pelosine (see ' Pareira brava'), but distinct from buxine, a similar alkaloid occurring in box.

Siperine has been obtained in the form of dark scales of very doubtful purity.

The commercial sulphate of beberine in dark brown scales, which was official in the British Pharmacopoeia of 1885, is not a pure sulphate of the alkaloid. It contains about 30 per cent, of beberine associated with siperine and probably other alkaloids, as well as with much colouring matter.

Uses

Bebeeru bark is a bitter stomachic and tonic; the alkaloid is, to a small extent, antipyretic, but these effects being insignificant, its use in fever and ague has now been abandoned.