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The pharmaceutical potential of compounds from Tasmanian Clematis species

Jin, F (2012) The pharmaceutical potential of compounds from Tasmanian Clematis species. PhD thesis, University of Tasmania.

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Abstract

Aims
The aim of the study was to investigate the antitumour, antibacterial and antiinflammatory
activities of some Tasmanian native Clematis spp. and to isolate and
identify the potential pharmaceutical constituents.
Methods
The antitumour activities, antibacterial activities and anti-inflammatory effects of
leaf material of Clematis spp. were screened by P388 cytotoxic assay, minimum
inhibition concentrations (MICs) and inhibitory NO production by
lipopolysaccharides (LPS) stimulated Raw 264.7 cells, respectively. The bioactiveguided
fractionation methodologies, including cartridge fractionation, HPLC
columns fractionation and Sephadex LH-20 column purification, were employed to
isolate active constituents. The chemical profiles of active constituents were
determined by ELSD, UV, LC-MS and GC-MS.
Scanning electron microscopy (SEM), Gram stain, antibiotic interaction with
chequerboard, deoxycholate-induced lysis and the antibiotic resistant mechanism
study of P. aeruginosa were employed to study the antibacterial mechanism of the
active constituent. The anti-inflammatory activity was also investigated by basal
(unstimulated) and LPS- and phytohaemagglutinin A (PHA)-stimulated cytokine
release from peripheral blood mononuclear cells (PBMC). Some novel compounds in Tasmanian native Clematis spp. were determined by
HPLC, LC-MS and LTQ-Orbitrap-MS.
Results and discussion
Ten out of eleven investigated Clematis spp. showed cytotoxic activities against
P388 cells with different IC50 values (0.084-3.106 mg/ml). Ranunculin and its
isomer were determined as the antitumour constituents. These compounds could be
hydrolysed by the cell medium to produce protoanemonin. The antitumour study
determined that ranunculin was a pro-cytotoxin with the antitumour activity derived
from protoanemonin.
Eight investigated Clematis spp. showed different antibacterial effects against E.
coli (MIC=0.39-3.13 mg/ml) and P. aeruginosa (MIC=0.31-6.25 mg/ml).
Ranunculin, the antibacterial constituent in Clematis spp., was selective against
Gram negative bacteria. In particular, it had a stronger antibacterial effect than
gentamicin against clinically isolated multi-drug resistant P. aeruginosa. The
change in ranunculin treated sensitive P. aeruginosa was elongation and cell lysis in
multi-drug resistant P. aeruginosa observed by SEM and obtained by deoxycholateinduced
lysis study. These results imply that the antibacterial mechanism of
ranunculin against sensitive and multi-drug resistance P. aeruginosa may be
different. The antibacterial effect of ranunculin might be still contributed to by
protoanemonin. Eleven investigated Clematis spp. showed varied inhibition of NO production.
Ranunculin and its isomers were determined as one of the anti-inflammatory
constituents in Tasmanian Clematis spp. For the cytokine study, in the presence of
LPS and PHA, C. aristata-L leaf at 10 μg/ml significantly decreased the release of
IL-1 (P<0.01) and TNF- (P<0.05) compared with LPS and PHA alone. These
results provide experimental data of the anti-inflammatory activities of Tasmanian
Clematis spp.
Flavonoids and hydroxycinnamate esters were obtained in these investigated
Clematis spp. The amounts of nine hydroxycinnamate esters were varied in each
Clematis leaf material. This would be the first time to discover these
hydroxycinnamte esters in Tasmanian Clematis spp.
Conclusion
The study demonstrated the antitumour, antibacterial and anti-inflammatory
activities of Tasmanian native Clematis spp. Ranunculin was discovered to be a
pro-cytotoxin of protoanemonin, which was one of the active constituents. This
study was the first to investigate the therapeutic value of Tasmanian native Clematis
spp. and discover the antibacterial value of protoanemonin in multi-drug resistant P.
aeruginosa and its complicated antibacterial mechanism against sensitive and
multidrug resistant P. aeruginosa. The anti-inflammatory activities may be the most
distinguishing therapeutic value of Tasmanian Clematis spp. Furthermore, study of
the chemical constituents suggested that Tasmanian Clematis spp. contained phenolic compounds. Although this study only provided the basic and preliminary
experimental data on the biological, potential pharmaceutical constituents and some
novel compounds of Tasmanian Clematis spp., further investigation into usage and
identification of effective pharmaceutical constituents would be worthy.

Item Type: Thesis (PhD)
Keywords: Tasmanian Clematis species, antibacterial, antitumor, anti-inflammatory, Ranuculin
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Date Deposited: 17 Aug 2012 04:42
Last Modified: 11 Mar 2016 05:53
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