university of kwazulu-natal faculty of science and agriculture school ...

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cytotoxic activity against monkey kidney Vero cell lines, having IC50 values ranging
between 4.52µg/mL and 19.21µg/mL (Mujovo, 2010).
4.1 Antibacterial testing
Compounds I to IV (7β-acetoxy-6β-hydroxyroyleanone (I), 7β,6β-dihydroxyroyleanone
(II), ent-pimara-8(14),15-diene-3β,11α-diol (III) and 2α,3α,19α-trihydroxyurs-12-en-28-
oic acid (IV)) were sent to the Council for Science and Industrial Research (CSIR) in
Pretoria, South Africa to be assessed for their antibacterial activity. The bacterial strains
used were the Gram-negative Pseudomonas aeruginosa (ATCC25922) and the Gram-
positive Enterococcus faecalis (ATCC29212).
O
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5
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6 7
OH
OH
12
14
8
R
R
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16
(I) OC(O)CH3
(II) OH
15
O
17
4.1.1 Experimental
HO
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3
1
HO
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9
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10 8
18 19
12
The samples were dissolved in acetone to a known concentration (1.0 mg/mL) prior to
being tested, with the exception of compound IV which was prepared to a concentration
of 0.8 mg/mL due to there being insufficient sample. The antibacterial assays followed
the format of the serial microdilution assay (Eloff, 1998). In brief, two-fold serial
dilutions of the samples were carried out and made up to 100µL in 96-well microtitre
plates. Bacteria (100µL of an overnight culture) was then added to each well before
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HO
HO
1
4
25 26
9
5
10
6 7
8
23 24
(III) (IV)
2
12
29
27
18
14
OH
15
17
30
21
22
COOH