_Cortex Nectandræ_; _Greenheart Bark_, _Bibiru_ or _Bebeeru Bark_.
=Botanical Origin=—_Nectandra Rodiæi_ Schomburgk—The Bibiru or
Greenheart is a large forest tree,[1984] growing on rocky soils
in British Guiana, twenty to fifty miles inland. It is found in
abundance on the hill sides which skirt the rivers Essequibo, Cuyuni,
Demerara, Pomeroon and Berbice. The tree attains a height of 80 to 90
feet, with an undivided erect trunk, furnishing an excellent timber
which is ranked in England as one of the eight first-class woods for
shipbuilding, and is to be had in beams of from 60 to 70 feet long.
=History=—In 1769 Bancroft, in his _History of Guiana_, called
attention to the excellent timber afforded by the _Greenheart_ or
_Sipeira_. About the year 1835 it became known that Hugh Rodie, a navy
surgeon who had settled in Demerara some twenty years previously, had
discovered an alkaloid of considerable efficacy as a febrifuge, in the
bark of this tree.[1985] In 1843 this alkaloid, to which Rodie had
given the name _Bebeerine_, was examined by Dr. Douglas Maclagan; and
the following year the tree was described by Schomburgk under the name
of _Nectandra Rodiæi_.[1986]
=Description=—Greenheart bark occurs in long heavy flat pieces, not
unfrequently 4 inches broad and ³/₁₀ of an inch thick, externally of a
light greyish brown, with the inner surface of a more uniform cinnamon
hue and with strong longitudinal striæ. It is hard and brittle; the
fracture coarse-grained, slightly foliaceous, and only fibrous in the
inner layer. The grey suberous coat is always thin, often forming small
warts, and leaving when removed longitudinal depressions analogous
to the _digital furrows_ of Flat Calisaya Bark (p. 353), but mostly
longer. Greenheart bark has a strong bitter taste, but is not aromatic.
Its watery infusion is of a very pale cinnamon brown.
=Microscopic Structure=—The general features of this bark are very
uniform, almost the whole tissue having been changed into thick-walled
cells. Even the cells of the corky layer show secondary deposits; the
primary envelope has entirely disappeared, and no transition from the
suberous coat to liber is obvious.
The prevalent forms of the tissue are the stone-cells and very
short liber-fibres, intersected by small medullary rays and crossed
transversely by parenchyme or small prosenchyme cells with walls a
little less thickened, so as to appear in a transverse section as
irregular squares or groups. The only cells of a peculiar character
are the sharp-pointed fibres of the inner liber, which are curiously
saw-shaped, being provided with numerous protuberances and sinuosities.
[1984] Fig. in Bentley and Trimen’s _Medic. Plants_, part 26 (1877).
[1985] Halliday, _On the Bebeeru tree of British Guiana, and Sulphate
of Bebeerine, the former a substitute for Cinchona, the latter for
Sulphate of Quinine_.—_Edinburgh Med. and Surg. Journ._ vol. xl. 1835.
[1986] _Hooker’s Journ. of Bot._ 1844. 624.
The very small lumen of the thick-walled cells contains a dark brown
mass which is coloured greenish-black by sulphate of iron; the same
coloration takes place throughout the less dense tissue surrounding
the groups of stone-cells, and may in each case be due to tannic
matter.
=Chemical Composition=—Greenheart bark contains an alkaloid which
has long been regarded as peculiar, under the name of _Bibirine_ or
_Bebirine_. It was however shown by Walz in 1860 to be apparently
identical with _Buxine_, a substance discovered as early as 1830 in the
bark and leaves of the Common Box, _Buxus sempervirens_ L. In 1869 the
observation of Walz was to some extent confirmed by one of us,[1987]
who further demonstrated that _Pelosine_, an alkaloid occurring in
the stems and roots of _Cissampelos Pareira_ L. and _Chondodendron
tomentosum_ Ruiz et Pavon (p. 28), is undistinguishable from the
alkaloids of greenheart and box.
The alkaloid of bibiru bark, which may be conveniently prepared from
the crude sulphate used in medicine under the name of _Sulphate of
Bibirine_, is a colourless amorphous substance, the composition of
which is indicated by the formula C₁₈H₂₁NO₃. It is soluble in 5 parts
of absolute alcohol, in 13 of ether, and in 1400 (1800, Walz) of
boiling water, the solution in each case having a decidedly alkaline
reaction on litmus. It dissolves readily in bisulphide of carbon, as
well as in dilute acids. The salts hitherto known are uncrystallizable.
The solution of a neutral acetate affords an abundant white precipitate
on the addition of an alkaline phosphate, nitrate or iodide, of
iodohydrargyrate or platino-cyanide of potassium, perchloride of
mercury, or of nitric or iodic acid.
Maclagan, one of the earliest investigators of greenheart, has
obtained in co-operation with Gamgee[1988] certain alkaloids from the
_wood_ of the tree, to one of which these chemists have assigned the
formula C₂₀H₂₃NO₄ and the name _Nectandria_. Two other alkaloids, the
characters of which have not yet been fully investigated, are stated to
have been obtained from the same source.
_Bibiric Acid_, which Maclagan obtained from the _seeds_, is described
as a colourless, crystalline, deliquescent substance, fusing at 150° C.
and volatile at 200° C., then forming needle-shaped groups.
=Commerce=—The supplies of greenheart bark are extremely uncertain, and
the drug is scarcely to be found in the market. It has been imported in
barrels containing 80 to 84 lb. each, or in bags holding ½ to ¾ cwt.
=Uses=—The bark has been recommended as a bitter tonic and febrifuge,
but is hardly ever employed except in the form of what is called
_Sulphate of Bibirine_, which, as we have said, is _crude Sulphate of
Buxine_.[1989] It is a dark amorphous substance which, having while
in a syrupy state been spread out on glazed plates, is obtained in
thin translucent laminæ. We find it to yield scarcely one-third of its
weight of the pure alkaloid.
[1987] Flückiger, _Neues Jahrbuch für Pharmacie_, xxxi. (1869) 257;
_Pharm. Journ._ xi. (1870) 192.
[1988] _Pharm. Journ._ xi. (1870) 19.
[1989] Mr. W. H. Campbell, of Georgetown, Demerara, has assured me that
neither the bark nor its alkaloid is held in esteem in the colony.—D.
H.