WHO monographs on selected medicinal plants - travolekar.ru

<strong>WHO</strong> <strong>monographs</strong> on selected medicinal plants
an active component. The MIC range of protolichesterinic acid, in free as
well as salt form, was 16.0–64.0 μg/ml (14).
Protolichesterinic acid, isolated from the thalli, inhibited the DNA
polymerase activity of human immunodeficiency virus-1 reverse transcriptase,
with a median inhibitory concentration (IC 50
) of 24.0 μM (22).
Antioxidant activity
The antioxidant activity, reducing power, superoxide anion radical scavenging
and free radical scavenging activities of an aqueous extract of the
thalli were investigated in vitro. The antioxidant activity increased with
increasing amount of extract (from 50.0 to 500.0 μg) added to linoleic acid
emulsion. About 50.0, 100.0, 250.0 and 500.0 μg of aqueous extract of the
thalli exhibited higher antioxidant activity than 500.0 μg of -tocopherol.
The samples showed 96, 99, 100 and 100% inhibition of peroxidation of
linoleic acid, respectively. On the other hand, 500.0 μg of -tocopherol
showed 77% inhibition of peroxidation of linoleic acid emulsion (23).
Antiproliferative effects
The effects of protolichesterinic acid, isolated from the thalli, on three malignant
cell-lines (T-47D and ZR-75-1 from breast carcinomas and K-562
from erythroleukaemia), as well as normal skin fibroblasts and peripheral
blood lymphocytes were assessed in vitro. Protolichesterinic acid caused a
significant reduction in DNA synthesis, as measured by thymidine uptake,
in all three malignant cell lines. The IC 50
was between 1.1 and 24.6 μg/ml
for protolichesterinic acid. The breast cancer cell-lines were more sensitive
than K-562. The proliferative response of mitogen-stimulated lymphocytes
was inhibited with an IC 50
of 24.5 μg/ml for protolichesterinic acid. These
concentrations are of the same order of magnitude as the MICs in the 5-
lipoxygenase assay. Significant cell death (assessed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium
assay and trypan blue exclusion) occurred in the three malignant
cell-lines at concentrations of protolichesterinic acid greater than 30.0 μg/
ml. In K-562, morphological changes consistent with apoptosis were detected.
At a concentration of protolichesterinic acid of 20 μg/ml, up to 38%
cell death was observed in mitogen-stimulated lymphocytes, but unstimulated
lymphocytes were clearly less sensitive. In contrast, the DNA synthesis,
proliferation and survival of normal skin fibroblasts were unaffected
at doses of protolichesterinic acid of up to 20 μg/ml (24).
Immune effects
A polysaccharide, isolated from the lichen, and described as a branched
galactomannan, with a backbone composed of two structural elements;
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