Selective Extraction
We set out to investigate whether it is possible to simplify extracts to facilitate the
isolation of antibacterial compounds from the complex mixture of chemicals in the
plant by using different extractants [25]. Intact dried ground leaves of Combretum
microphyllum were extracted with a series of extractants of varying polarity (i.e. hex-
ane, carbon tetrachloride, di-isopropylether, ethyl ether, methylene dichloride, tet-
rahydrofuran, acetone, ethanol, ethyl acetate, methanol and water). Thin-layer
chromatography (TLC) was used to determine chemical composition, and antibac-
terial activity of extracts was determined by a microplate serial dilution method.
The different solvents extracted from 2.6 to 17.4% of the dry weight. Methanol,
methylene dichloride, and tetrahydrofuran extracted the most components. The
chemical composition of the nonpolar components of the different extracts was re-
markably similar. The minimum inhibitory concentration for the different extrac-
tants varied from 0.01 to 1.25 mg mL–1 with the four test organisms used (Staphy-
lococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis).
The extracts had similar activity towards Gram-negative and Gram-positive bacte-
ria. Di-isopropyl ether, ethanol, ethyl ether, acetone, and ethyl acetate extracted
high antibacterial activity with a lower quantity of other nonactive compounds and
appear to be useful for isolating bioactive compounds.
In another application of simplifying plant extracts using selective extraction,
there is rationale for using extracts to treat infectious diseases in preference to sin-
gle compounds. It is likely that interactions between various compounds present
in an extract result in synergistic effects which lead to heightened activity [35].
There is a distinct possibility that active principles with differing mechanisms of
action may be present in a crude extract, thus slowing the onset of antibiotic resis-
tance. Therefore, it may be worthwhile to seek to potentize plant extracts for anti-
infectivity in preference to solely aiming for isolation of active compounds. En-
hancing the activity of plant extracts by selectively removing bulky nonactive com-
ponents is a relatively simple process. These potentized preparations may find ap-
104 5 Plant Extracts Used to Manage Bacterial, Fungal, and Parasitic Infections in Southern Africa
plication chiefly in the arena of primary health care for humans and animals in de-
veloping countries. An example is the selective extraction of plant material from
Combretum woodii which resulted in an extract with high antibacterial and antioxi-
dant activity
We set out to investigate whether it is possible to simplify extracts to facilitate the
isolation of antibacterial compounds from the complex mixture of chemicals in the
plant by using different extractants [25]. Intact dried ground leaves of Combretum
microphyllum were extracted with a series of extractants of varying polarity (i.e. hex-
ane, carbon tetrachloride, di-isopropylether, ethyl ether, methylene dichloride, tet-
rahydrofuran, acetone, ethanol, ethyl acetate, methanol and water). Thin-layer
chromatography (TLC) was used to determine chemical composition, and antibac-
terial activity of extracts was determined by a microplate serial dilution method.
The different solvents extracted from 2.6 to 17.4% of the dry weight. Methanol,
methylene dichloride, and tetrahydrofuran extracted the most components. The
chemical composition of the nonpolar components of the different extracts was re-
markably similar. The minimum inhibitory concentration for the different extrac-
tants varied from 0.01 to 1.25 mg mL–1 with the four test organisms used (Staphy-
lococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Enterococcus faecalis).
The extracts had similar activity towards Gram-negative and Gram-positive bacte-
ria. Di-isopropyl ether, ethanol, ethyl ether, acetone, and ethyl acetate extracted
high antibacterial activity with a lower quantity of other nonactive compounds and
appear to be useful for isolating bioactive compounds.
In another application of simplifying plant extracts using selective extraction,
there is rationale for using extracts to treat infectious diseases in preference to sin-
gle compounds. It is likely that interactions between various compounds present
in an extract result in synergistic effects which lead to heightened activity [35].
There is a distinct possibility that active principles with differing mechanisms of
action may be present in a crude extract, thus slowing the onset of antibiotic resis-
tance. Therefore, it may be worthwhile to seek to potentize plant extracts for anti-
infectivity in preference to solely aiming for isolation of active compounds. En-
hancing the activity of plant extracts by selectively removing bulky nonactive com-
ponents is a relatively simple process. These potentized preparations may find ap-
104 5 Plant Extracts Used to Manage Bacterial, Fungal, and Parasitic Infections in Southern Africa
plication chiefly in the arena of primary health care for humans and animals in de-
veloping countries. An example is the selective extraction of plant material from
Combretum woodii which resulted in an extract with high antibacterial and antioxi-
dant activity
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