Agriculture Reference
In-Depth Information
The analysis of the relative concentrations of the mesembrine alkaloids has been useful in the qual-
ity control of commercial samples of the plant.
938
Both reversed-phase ultra high-performance liquid
chromatography with photodiode array detector (RP-UHPLC PDA) and GC/MS methods have been
used for quantitative assessment of mesembrine-type alkaloids in
S. tortuosum
raw materials and prod-
ucts.
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The use of nonaqueous capillary electrophoresis coupled to mass spectrometry (NACE-MS) was
also found efficient for the separation of complex alkaloid mixtures found in commercial kanna teas.
940
Pharmacological Studies —
Sceletium tortuosum
has been investigated by many groups to vali-
date its application in the treatment of depression, neurological disorders, and neurodegenerative dis-
eases.
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The extract has been shown to be a potent blocker in 5-HT transporter binding assays (IC
50
4.3 µg/ml) and had powerful inhibitory effects on phosphodiesterase 4 (PDE4) (IC
50
8.5 µg/ml), but
not other PDEs. No cytotoxic effects were observed. Mesembrine was the most active alkaloid against
the 5-HT transporter (K
i
1.4 nM), while mesembrenone was active against the 5-HT transporter and
PDE4 (IC
50
s < 1 µM). The activity of the
Sceletium tortuosum
extract on the 5-HT transporter and
PDE4 provides a probable explanation for the clinical effects of preparations made from this plant. The
activities were related to the presence of alkaloids, particularly mesembrine and mesembrenone.
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A
remarkable feature of the activity of
S. tortuosum
tested is the selectivity of action. Considering that
the plant extract will have several components, it is perhaps surprising that the
Sceletium
extract
affected so few sites in the extensive panel of receptors, ion channels, transporters, and enzymes used
in the study. Selective serotonin reuptake inhibitors are well known as antidepressants, and PDE4
inhibitors have also attracted considerable attention as potential antidepressants, although the phar-
maceutical compounds tested clinically have had dose-limiting side effects of nausea and emesis.
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Toxicity —
Sceletium
seems well tolerated in feeding experiments on dogs and cats. In the canine
evaluation, milled dry
Sceletium tortuosum
was given at a dose of 10 mg/kg twice a day to seven healthy
beagle dogs as well as one dog with dementia for 6 days. The plant material was mixed into the ani-
mals' food. Pre- and postfeeding observations and blood tests were made, including those for red cell
count, hemaglobin, hematocrit, white cell count, platelet count, blood urea nitrogen, creatinine, glucose,
glutamic pyruvic transaminase, total cholesterol, and total protein. Holter monitoring of the electrocar-
diogram (ECG) was done for the duration of the study. No changes in behavior or adverse effects were
noted in the healthy dogs. The blood tests showed no abnormality in the hematology, liver and kidney
functions, glucose, or lipid metabolism over the 6-day period. No adverse effects were noted in the dog
suffering from dementia. Similar results were obtained from the experiments on cats. However, a slight
increase in daytime sleep was noted, and in the blood chemistry, a slight decrease of GOT (glutamic oxa-
loacetic transaminase) and increase of ALP were observed, which were still within normal limits.
944,948
Commerce —
The use of
S. tortousum
alkaloids is the subject of U.S. Patent 6,288,104 by Gericke
and Van Wyk,
142
which discloses the use of mesembrine and related compounds, including novel
compounds, as serotonin uptake inhibitors and the use of standardized amounts of these compounds
in pharmaceutical formulations for use in the management of psychiatric and psychological condi-
tions, including depression, anxiety, drug dependence, bulimia, and obsessive-compulsive disorder. A
proprietary product, Zemberin, which contains the standard extract, is being evaluated for use as an
antidepressant agent.
SCHUMANNIOPHYTON MAGNIFICUM
Botanical Name —
Schumanniophyton magnificum
(K.Schum) Harms
Synonyms —
Tetrastigma magnificum
K.Schum
Family —
Rubiacea
African Names —
Cameroon: abamoto, titimoto; Igbo: akito
Description —
Schumanniophyton magnificum
is a shrub or tree 4-5 m high with a soft,
wooded stem and very large, simple leaves. The leaves are larger at the upper half than at the lower
