Stability of Extracts
Because extracts retained activity for several months we investigated the stability of
the antibacterial activity of dried leaves of herbarium samples of Combretum erythrophyllum
growing in the Pretoria area and collected between 92 and 12 years ago
on the one hand, and freshly collected dried leaves on the other. Staphylococcus
aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa were used
as test organisms. There were no differences in the MIC values of the different
samples. There were only minor differences in chromatograms separating steroids
and flavonoids. Light fungal infection indicated by small spots on herbarium
leaves did not influence the MIC value or the chromatographic profile, but heavy
fungal attack decreased the biological activity of the extracts. If biologically active
components in other plants are stable, the examination of herbarium material may
be a useful first step in establishing a scientific base for the use of plants in tradi-
tional medicine
Because extracts retained activity for several months we investigated the stability of
the antibacterial activity of dried leaves of herbarium samples of Combretum erythrophyllum
growing in the Pretoria area and collected between 92 and 12 years ago
on the one hand, and freshly collected dried leaves on the other. Staphylococcus
aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa were used
as test organisms. There were no differences in the MIC values of the different
samples. There were only minor differences in chromatograms separating steroids
and flavonoids. Light fungal infection indicated by small spots on herbarium
leaves did not influence the MIC value or the chromatographic profile, but heavy
fungal attack decreased the biological activity of the extracts. If biologically active
components in other plants are stable, the examination of herbarium material may
be a useful first step in establishing a scientific base for the use of plants in tradi-
tional medicine
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