Results on Antibacterial Activity Obtained with Members of the Combretaceae
Introduction
When we began this work we decided to select a plant family for focused investiga-
tion. Some of the parameters considered were: ethnobotanical leads and condi-
tions when ethnobotanical leads are valuable, the quantity of material used in the
natural medicine trade, the use of the plant, pharmacological activity in related
taxa, availability of plant material and co-operators. Analysis of available data [57]
indicated that the Combretaceae was one of the main plant families used in Kwa-
Zulu-Natal with an average of 20.2 tonnes consumed per year. We decided to start
investigating this family especially since Noristan found indications of antibacteri-
al activity with Combretum erythrophyllum extracts (B Fourie, personal communica-
tion). In addition, preliminary studies had reported on the antimicrobial testing of
selected Combretum plant extracts [58].
Combretum erythrophyllum
In a preliminary investigation on the antibacterial activity of Combretum erythrophyllum
acetone leaf extracts, liquid/liquid extraction gave better group separation
of compounds than solid phase extraction on normal or reversed phase silica gel.
The six fractions obtained inhibited the four test organisms to different degrees.
Staphylococcus aureus was the most sensitive (100%) followed by Enterococcus faecalis
(36%), Escherichia coli (11%), and Pseudomonas aeruginosa (3%). With S. aureus as
test organism, the chloroform-soluble fraction contained by far the largest quantity
of inhibiting components (100%), followed by the fractions soluble in water (23%),
35% methanol in water (18%), butanol (5%), carbon tetrachloride (2%), and hexane
(traces). The lowest MIC value for S. aureus was 0.05 mg mL–1 at this stage of pur-
ification, compared with MIC values of 0.08 and 0.16 mg mL–1 for ampicillin and
chloramphenicol respectively. There were at least 14 different inhibitors with a
wide range of polarities present in the different fractions. The polar components
apparently did not contain polysaccharides and were probably basic according to
their chromatographic behavior
Introduction
When we began this work we decided to select a plant family for focused investiga-
tion. Some of the parameters considered were: ethnobotanical leads and condi-
tions when ethnobotanical leads are valuable, the quantity of material used in the
natural medicine trade, the use of the plant, pharmacological activity in related
taxa, availability of plant material and co-operators. Analysis of available data [57]
indicated that the Combretaceae was one of the main plant families used in Kwa-
Zulu-Natal with an average of 20.2 tonnes consumed per year. We decided to start
investigating this family especially since Noristan found indications of antibacteri-
al activity with Combretum erythrophyllum extracts (B Fourie, personal communica-
tion). In addition, preliminary studies had reported on the antimicrobial testing of
selected Combretum plant extracts [58].
Combretum erythrophyllum
In a preliminary investigation on the antibacterial activity of Combretum erythrophyllum
acetone leaf extracts, liquid/liquid extraction gave better group separation
of compounds than solid phase extraction on normal or reversed phase silica gel.
The six fractions obtained inhibited the four test organisms to different degrees.
Staphylococcus aureus was the most sensitive (100%) followed by Enterococcus faecalis
(36%), Escherichia coli (11%), and Pseudomonas aeruginosa (3%). With S. aureus as
test organism, the chloroform-soluble fraction contained by far the largest quantity
of inhibiting components (100%), followed by the fractions soluble in water (23%),
35% methanol in water (18%), butanol (5%), carbon tetrachloride (2%), and hexane
(traces). The lowest MIC value for S. aureus was 0.05 mg mL–1 at this stage of pur-
ification, compared with MIC values of 0.08 and 0.16 mg mL–1 for ampicillin and
chloramphenicol respectively. There were at least 14 different inhibitors with a
wide range of polarities present in the different fractions. The polar components
apparently did not contain polysaccharides and were probably basic according to
their chromatographic behavior
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