2 research outputs found
The biological activity and phytochemistry of selected Hermannia species
Student Number : 0000127R -
MPharm dissertation -
School of Pharmacy and Pharmacology -
Faculty of Health SciencesTraditional 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
Safety of tenofovir gel, a vaginal microbicide, in South African women: results of the CAPRISA 004 Trial.
Background: Tenofovir gel, used vaginally before and after coitus, reduced women’s acquisition of HIV by 39%. This is a safety assessment of tenofovir gel, including renal, bone, gastrointestinal, genital and haematological parameters.
Methods: In the Centre for the AIDS Programme of Research in South Africa (CAPRISA) 004, a double-blind, randomized placebo-controlled trial, 445 of the 889 eligibly enrolled women were assigned to tenofovir gel. All participants were advised to use the gel vaginally only, with one dose of gel within 12 h before and a second dose as soon as possible after sex, with no more than two doses in 24 h. Clinical and laboratory safety data were collected at monthly and quarterly visits, respectively. Genital assessments were undertaken at enrolment and quarterly thereafter, or as indicated.
Results: Women assigned to tenofovir gel were exposed to an average monthly vaginal dose of 240 mg of tenofovir (six applications). In total, six women, three in each group, had mild creatinine elevations, all of which occurred in July/August 2008. The incidence of anaemia was 3.5 and 3.8 per 100 women-years in tenofovir and placebo groups, respectively (P=0.80). Of the six women (four tenofovir and two placebo) experiencing bone fractures, none were associated with abnormal phosphate or calcium values. The proportion of women with diarrhoea was higher in the tenofovir gel group (17% versus 11%; P=0.026). There was no significant increase of any genital adverse event in the tenofovir group.
Conclusions: No significant renal, haematological, genital or bone effects were associated with the use of tenofovir gel. Aside from a puzzling increase in diarrhoea, tenofovir gel has an excellent safety profile