Agriculture Reference
In-Depth Information
Ethnomedicinal Uses —
In North Africa, the plant is used mainly as a cough remedy and to
prevent extreme thirst in desert areas. In southern and eastern Africa, it is used as a remedy for
appendicitis and pulmonary tuberculosis and as a lotion for eye diseases.
79
Constituents —
The principal constituents of liquorice are glycyrrhizin and oleanane triter-
pene glycosides, also known as glycyrrhizinic or glycyrrhizic acid. The aglycone is glycyrrgetinic
acid (or glycyrrhitic acid). Co-occurring with glycyrrhizin are the terpenes liquiritic acid, glyc-
yrrhetol, glabrolide, and 28-hydroxyglycyrrhizinic acid.
595,596
The plant also contains flavonoids,
including liquiritin, rhamnoliquiritin, licoflavone, licoisoflavones A and B, licoisoflavonone, gla-
brol, glyzarin, formononetin, and liquiritigenin.
597,598
Chalcones, such as lichochalcones A and B,
liquiritigenin, licuraside, and echinatin, have been isolated from liquorice.
599
Other constituents
include glucose, amino acids, and volatile oil consisting of fenchone, linalone, furfuryl alcohol,
and benzaldehyde.
123
Pharmacological Studies —
Liquorice has been employed in the treatment of a variety of ill-
nesses and the pharmacological properties ascribed to the drug reflect the varied uses and heteroge-
neous nature of the constituents. The plant drug is an effective anti-inflammatory agent, demulcent,
expectorant, antitussive, spasmolytic, antiviral, immunostimulant, and therapeutic agent in the
treatment of adrenocortical insufficiency. It is difficult to select any of these actions as the most
important property of liquorice, although the focus in this section is on the anti-inflammatory activ-
ity of the drug; references are made to some of its other pharmacological and biochemical proper-
ties. Its potential use for treatment of human acquired immune deficiency syndrome (AIDS) and its
antiviral properties are subjects of ongoing research.
Glycyrrhizin and its aglycone, glycyrrhetinic acid, have been shown to possess remarkable anti-
inflammatory activity.
600,601
It inhibited edema induced by formaldehyde and carrageenan, as well
as activity against cotton pellet granuloma, granuloma pouch, and tuberculin reaction in BCG-
sensitized guinea pig.
600
In the carrageenan-induced edema model, an ED
25
of 30 mg/kg for glycyr-
rhetic acid was reported. It was also found to have an inhibitory effect on mononuclear leukocyte
migration in dextran shown to inhibit both the COX and 5-LOX pathways in AA metabolism.
602
In AA-induced mouse ear edema, it was found that the hemiphthalate derivatives were more active
than the parent compound, and the effect appears to be due to a direct anti-inflammatory action
rather than modulation of steroid-mediated antiphlogistic activity through secondary formation of
a reactive protein.
603
Inoue and his colleagues have demonstrated a similar effect on 12-0-tetra-
deconoylphorbol-13-acetate (TPA)-induced ear edema.
604
Glycyrrhizin is also an effective antial-
lergic agent. The aglycone has been shown to inhibit almost completely the dexamethasone-induced
increase in both the histamine content and histidine decarboxylase activity of cultured mastocy-
toma P-815 cells at a dose of [
3
H]dexamethasone binding to the cytoplasmic receptor, but it inhib-
ited the release of histamine from antigen-stimulated rat mast cells and intensified the inhibitory
activity induced by dexamethasone. It also inhibited antigen-induced release and incorporation of
[
3
H]dexamethasone AA in immunized rat mast cells.
605
The anti-inflammatory activity of
Glycyrrhiza
is not due to the triterpenoid constituents alone.
The chalcones licochalcone A (2-methoxy-4,4-dihydroxy-5-,7-dimethylallylchalcone) and licochal-
cone B (2-methoxy-3,4,4-tri-hydroxychalcone) at concentrations of 10
-3
to 10
-6
M
,
inhibited cal-
cium ionophore A23187-induced LTB4 and LTC
4
formation in human PMN leukocytes.
606
It has
previously been shown that the nonglycyrrhetinic acid-containing (but flavonoid-rich) fraction of
liquorice had anti-inflammatory activity, especially AN antigastric effect that is independent of
that attributed to the terpenoids.
607
An IC
50
of 4.6 × 10
-7
was reported for licochalcone A in the
leukotriene inhibition assay, and 4.2 × 10
-6
M
of licochalcone was required for the same purpose.
The two chalcones also increased the cyclic AMP level in human PMNs at concentrations of 10
-4
to 10
-3
M
and induced by calcium ion ionomycine dose dependently, in the presence of 1 mM
Ca
2+
or 1 mM
EGTA
(ethylenglycol-bis(β-aminoethylether)-
N
,
N
′-tetraacetic acid).
229
In addition to the
anti-inflammatory activity of glycyrrhiza, most of the other therapeutic applications associated with
