Student Number : 0000127R -
MPharm dissertation -
School of Pharmacy and Pharmacology -
Faculty of Health Sciences / Traditional medicines form a significant part of the lives of many people around the world
and in South Africa almost 60 % of people consult traditional healers in addition to the
modern medical services available. Plants form a significant part of traditional healing and
hence, selected species of a traditionally used plant genus, Hermannia, were chosen for
biological and chemical investigation to determine a scientific basis for the traditional use
of these plants.
A phytochemical investigation was carried out, firstly using thin layer chromatography
(TLC) and high performance liquid chromatography (HPLC) and then isolation and
identification of compounds from various Hermannia species. TLC analysis indicated
significant similarities between the various species with only H. saccifera displaying
chemical anomalies. This was further corroborated by the HPLC analysis although very
conservative profiles were produced. Isolation of compounds from H. saccifera yielded a
novel labdane compound, E-17, 19-diacetoxy - 15 - hydroxylabda - 7,13 - diene, as well as
two flavones, 5,8- dihydroxy-6,7,4’- trimethoxyflavone and cirsimaritin which have
previously been isolated. In addition, two commonly found compounds, lupeol and β-
sitosterol were isolated from H. cuneifolia and H. salviifolia respectively. This is the first
report on the isolation and identification of all five compounds from Hermannia species.
Antimicrobial activity was assessed using two methods i.e. minimum inhibitory
concentrations as well as the death kinetics assay. Minimum inhibitory concentrations were
determined using four Gram-positive and two Gram-negative bacteria as well as two
yeasts. All species investigated indicated antimicrobial activity with H. saccifera showing
good activity against S. aureus and B. cereus. E-17, 19-diacetoxy - 15 - hydroxylabda -
7,13 - diene isolated from H. saccifera indicated activity (MIC = 23.6 μg/ml against S.aureus) although the activity was less than that of the crude extract (MIC = 19.5 μg/ml),
thus, demonstrating that there are a number of compound contributing to the promising
activity of the crude extract. This was further corroborated by the bioautograms developed
of the H. saccifera extract. Time-kill studies on H. saccifera against S. aureus indicated
that at concentrations of 0.1, 0.25 and 0.5 % bacteriostatic activity was observed while at
0.75% the extract achieved complete bactericidal activity after 240min.
Free radical scavenging activity was assessed using the 2,2-diphenyl-1-picrylhydrazy
(DPPH) and 2,2′-azino-bis(3-ethyl-benzthiazoline-6-sulfonic acid) (ABTS) assays. Ten of
the twelve species indicated good activity with H. cuneifolia demonstrating the most
promising activity (IC50 = 10.26 μg/ml for DPPH and 10.32 μg/ml for ABTS). Two of the
isolated compound, 5,8- dihydroxy-6,7,4’- trimethoxyflavone and cirsimaritin displayed
insignificant activity.
The 5-lipoxygenase assay was used to assess the anti-inflammatory activity of Hermannia
species. All species exhibited intermediate activity with the exception of H. cuneifolia
(IC50 = 15.32 μg/ml). In addition, four isolated compounds, 5,8- dihydroxy-6,7,4’-
trimethoxyflavone, cirsimaritin, lupeol and β-sitosterol showed moderate inhibition of the
enzyme indicating that while these compounds do contribute to the activity of the extracts
they are not individually responsible for any significant activity.
Antimalarial activity was assessed using the titrated hypoxanthine incorporation assay
while toxicity was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl
tetrazolium bromide (MTT) cell proliferation assay. Only three species indicated any good
antimalarial activity i.e. H. saccifera, H. muricata and mostly H. trifurca (IC50 = 25.30,
28.17 and 18.80 μg/ml respectively). However, the activity of H. saccifera and H. trifurca are probably due to a general cytotoxicity as these species exhibited a low safety index. All
other species appear safe for use.
Several Hermannia species have indicated in vitro biological activity in a number of assays
which is related to their use in traditional medicines to treat a number of disease states.
Hence, a scientific basis, albeit in vitro, has been established for the use Hermannia
species in traditional healing.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/1535 |
| Date | 31 October 2006 |
| Creators | Essop, Ayesha Bibi |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 25597558 bytes, application/pdf, application/pdf |
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