Sylvia Urban - Academia.edu (original) (raw)
Papers by Sylvia Urban
Journal of Natural Products, 1996
Australian Journal of Chemistry, 2020
Chemistry in Australia, 2006
Publisher's details for: Anticancer Agents from Natural Products Cragg G. M., Kingston D. G. ... more Publisher's details for: Anticancer Agents from Natural Products Cragg G. M., Kingston D. G. I., Newan D. J. (eds), CRC Press Taylor & Francis Group, 2005, hardback, 577 pp., ISBN 0849318637, $241. 17 (ex. GST).
Chemical investigation of the dichloromethane extract of Gracilaria tenuistipitata var. liui Zhan... more Chemical investigation of the dichloromethane extract of Gracilaria tenuistipitata var. liui Zhang and Xia has led to the isolation of monogalactosyl diacylglycerol (1), β-sitosterol (2), linoleic acid (3), and 2-hydroxyethyl benzoate (4). The structures of 1-4 were identified by NMR spectroscopy.
Modern NMR Techniques for Synthetic Chemistry
Chemical investigation of the dichloromethane extra ct of the fruiting bodies of Pleurotus florid... more Chemical investigation of the dichloromethane extra ct of the fruiting bodies of Pleurotus floridaled t o the isolation of ergosterol ( 1 ), ergosterol peroxide ( 2 ), cerevisterol( 3 ), a mixture of palmitic acid and stearic acid, lin oleic acid, and oleic acid in about 1.5:1:0.5 ratio, and dilino leoyloleoylglycerol. The structures of these compou nds were identified by comparison of their NMR data with lit erature data.
Marine Drugs
This study provides a review of all isolated natural products (NPs) reported for sponges within t... more This study provides a review of all isolated natural products (NPs) reported for sponges within the order Verongiida (1960 to May 2020) and includes a comprehensive compilation of their geographic and physico-chemical parameters. Physico-chemical parameters were used in this study to infer pharmacokinetic properties as well as the potential pharmaceutical potential of NPs from this order of marine sponge. In addition, a network analysis for the NPs produced by the Verongiida sponges was applied to systematically explore the chemical space relationships between taxonomy, secondary metabolite and drug score variables, allowing for the identification of differences and correlations within a dataset. The use of scaffold networks as well as bipartite relationship networks provided a platform to explore chemical diversity as well as the use of chemical similarity networks to link pharmacokinetic properties with structural similarity. This study paves the way for future applications of net...
Pathogens
Eight secondary metabolites (1 to 8) were isolated from a marine sponge, a marine alga and three ... more Eight secondary metabolites (1 to 8) were isolated from a marine sponge, a marine alga and three terrestrial plants collected in Australia and subsequently chemically characterised. Here, these natural product-derived compounds were screened for in vitro-anthelmintic activity against the larvae and adult stages of Haemonchus contortus (barber’s pole worm)—a highly pathogenic parasitic nematode of ruminants. Using an optimised, whole-organism screening system, compounds were tested on exsheathed third-stage larvae (xL3s) and fourth-stage larvae (L4s). Anthelmintic activity was initially evaluated on these stages based on the inhibition of motility, development and/or changes in morphology (phenotype). We identified two compounds, 6-undecylsalicylic acid (3) and 6-tridecylsalicylic acid (4) isolated from the marine brown alga, Caulocystis cephalornithos, with inhibitory effects on xL3 and L4 motility and larval development, and the induction of a “skinny-straight” phenotype. Subsequen...
Marine Drugs
Marine macroalgae occurring in the south eastern region of Victoria, Australia, consisting of Por... more Marine macroalgae occurring in the south eastern region of Victoria, Australia, consisting of Port Phillip Bay and the heads entering the bay, is the focus of this review. This area is home to approximately 200 different species of macroalgae, representing the three major phyla of the green algae (Chlorophyta), brown algae (Ochrophyta) and the red algae (Rhodophyta), respectively. Over almost 50 years, the species of macroalgae associated and occurring within this area have resulted in the identification of a number of different types of secondary metabolites including terpenoids, sterols/steroids, phenolic acids, phenols, lipids/polyenes, pheromones, xanthophylls and phloroglucinols. Many of these compounds have subsequently displayed a variety of bioactivities. A systematic description of the compound classes and their associated bioactivities from marine macroalgae found within this region is presented.
Marine Drugs
The absolute configuration of retroflexanone (1) and a closely related phlorogluinol (2) was esta... more The absolute configuration of retroflexanone (1) and a closely related phlorogluinol (2) was established using the advanced Mosher method and by application of HPLC-NMR. HPLC-NMR permitted a small scale Mosher method analysis to be carried out on these unstable phloroglucinols.
Natural Product Communications
Six compounds previously isolated and reported from Macropidia fuliginosa were evaluated for anti... more Six compounds previously isolated and reported from Macropidia fuliginosa were evaluated for antimicrobial activity against 11 different microbial strains, with all compounds displaying broad spectrum activity. In addition, the compounds were also assessed for their antiproliferative activity and cytotoxicity. Further investigation of M. fuliginosa has led to the discovery of a previously described acenaphthylenediol from the bulbs of the plant.
Marine Drugs
The isolation and the structure determination of a new bromophenolic compound, polysiphonol (10),... more The isolation and the structure determination of a new bromophenolic compound, polysiphonol (10), as well as five previously reported compounds, (4–8), from the red alga Polysiphonia decipiens is reported. In addition, the absolute configuration of the natural product rhodomelol (8) could be unequivocally confirmed for the first time, and on biosynthetic grounds, the absolute configuration of polysiphonol (10) was tentatively suggested. Compounds 4–8 were evaluated for their antibacterial activity against both Gram-positive and Gram-negative bacteria, but none of the compounds showed any appreciable activity.
Journal of Herbal Medicine
Abstract The leaves of Clinacanthus nutans have been increasingly used as an adjuvant treatment f... more Abstract The leaves of Clinacanthus nutans have been increasingly used as an adjuvant treatment for cancers. Infusion of the dried leaves in water is the traditional and preferred method of preparation by cancer patients for consumption. Traditionally, this medicinal plant is brewed in boiling water before consumption as a tea but little is known about the effect of preparation temperature for optimal anticancer activity. Therefore, the present study assessed the effect of preparation temperature (hot or cold) of crude aqueous extracts of C. nutans leaves on the cytotoxicity of D24 melanoma cells using a colorimetric WST-8 assay. Apoptotic cell death was detected by a cytofluorometric double staining method. Biochemical and morphological changes in the treated cells were examined by fluorescence and transmission electron microscopy techniques, respectively, to further verify the type of cell death. The cold aqueous extract was the most cytotoxic against D24 melanoma cells with an EC50 of 163 μg/mL at 72 h. The extract also predominantly induced apoptosis in these cells according to cytofluorimteric, confocal and transmission electron microscopic analyses. This study provides important information on the preparation of C. nutans and its effectiveness as an anticancer concoction for regular consumption.
Natural Product Communications
NMR spectroscopic methodologies used to characterize and elucidate the structure of the marine na... more NMR spectroscopic methodologies used to characterize and elucidate the structure of the marine natural product elatenyne were also applied to the characterization of a new triazole structural derivative of elatenyne, obtained by “Click” chemistry. The two most probable relative configurations assigned to naturally occurring elatenyne were concluded on the basis of key single irradiation nOe NMR enhancements, in combination with the use of a variant of the HSQC NMR experiment that permitted NMR coupling constants to be measured for the overlapped ring junction protons. This study represents the first application of “Click” chemistry to chemically derivatize an unmodified natural product.
Natural Product Communications
The dichloromethane extract of the air-dried leaves and freeze-dried tubers of Smallanthus sonchi... more The dichloromethane extract of the air-dried leaves and freeze-dried tubers of Smallanthus sonchifolius afforded ent-kaurenoic acid (1). The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy and was found to exhibit significant analgesic and anti-inflammatory activities. Ent-kaurenoic acid (1), dissolved in dimethylsulfoxide, also displayed potential anti-diabetes and anti-toxicity activity. In addition, 1 showed low antimicrobial activities against E. coli, P. aeruginosa, S. aureus, C. albicans and T. mentagrophytes, but was found to be inactive against B. subtilis and A. niger.
Natural Product Communications
A chemical profiling/dereplication exercise, involving the use of HPLC-NMR and mass spectrometry ... more A chemical profiling/dereplication exercise, involving the use of HPLC-NMR and mass spectrometry in combination with the MarinLit database, was conducted on the crude dichloromethane extract of the southern Australian marine brown alga Cystophora torulosa. This strategy was successful in identifying a total of nine secondary metabolites representing two principle structure classes, including seven resorcinol (1–7) and two polyene derivatives (8 and 9). Validation of this on-line dereplication strategy was supported by the isolation and complete 2D NMR assignment of the major secondary metabolite (1). This methodology was concluded to be suitable for the rapid on-line identification of the resorcinol and polyene structure classes that are frequently encountered in the genus Cystophora.
Natural Product Reports
This review provides a summary of the current state of research concerning the unique specialised... more This review provides a summary of the current state of research concerning the unique specialised metabolites from Haemodoraceae.
International Journal of Pharmacognosy and Phytochemical Research
Chemical investigation of the dichloromethane extract of Rheum ribes has led to the isolation of ... more Chemical investigation of the dichloromethane extract of Rheum ribes has led to the isolation of β-sitosteryl-3β- glucopyranoside-6'-O-fatty acid esters (1), β-sitosterol (2), phytyl fatty acid esters (3), triacylgly c e r o l s (4) and chlorophyllide a (5). The structures of 1-5 were identified by comparison of their NMR data with literature data.
Journal of Chemical Education
First-year undergraduate classes present challenges in teaching as they usually have high student... more First-year undergraduate classes present challenges in teaching as they usually have high student enrolment numbers and students studying across a range of higher education programs that require a fundamental understanding of knowledge that is not perceived in their area of study. This provides a challenge in terms of engaging and maintaining student interest, primarily because students do not recognize the application of knowledge to their field of study. The challenge is to contextualize the content for the range of student cohorts within the one course. This is a common issue within many of the programs offered at
Journal of Natural Products, 1996
Australian Journal of Chemistry, 2020
Chemistry in Australia, 2006
Publisher's details for: Anticancer Agents from Natural Products Cragg G. M., Kingston D. G. ... more Publisher's details for: Anticancer Agents from Natural Products Cragg G. M., Kingston D. G. I., Newan D. J. (eds), CRC Press Taylor & Francis Group, 2005, hardback, 577 pp., ISBN 0849318637, $241. 17 (ex. GST).
Chemical investigation of the dichloromethane extract of Gracilaria tenuistipitata var. liui Zhan... more Chemical investigation of the dichloromethane extract of Gracilaria tenuistipitata var. liui Zhang and Xia has led to the isolation of monogalactosyl diacylglycerol (1), β-sitosterol (2), linoleic acid (3), and 2-hydroxyethyl benzoate (4). The structures of 1-4 were identified by NMR spectroscopy.
Modern NMR Techniques for Synthetic Chemistry
Chemical investigation of the dichloromethane extra ct of the fruiting bodies of Pleurotus florid... more Chemical investigation of the dichloromethane extra ct of the fruiting bodies of Pleurotus floridaled t o the isolation of ergosterol ( 1 ), ergosterol peroxide ( 2 ), cerevisterol( 3 ), a mixture of palmitic acid and stearic acid, lin oleic acid, and oleic acid in about 1.5:1:0.5 ratio, and dilino leoyloleoylglycerol. The structures of these compou nds were identified by comparison of their NMR data with lit erature data.
Marine Drugs
This study provides a review of all isolated natural products (NPs) reported for sponges within t... more This study provides a review of all isolated natural products (NPs) reported for sponges within the order Verongiida (1960 to May 2020) and includes a comprehensive compilation of their geographic and physico-chemical parameters. Physico-chemical parameters were used in this study to infer pharmacokinetic properties as well as the potential pharmaceutical potential of NPs from this order of marine sponge. In addition, a network analysis for the NPs produced by the Verongiida sponges was applied to systematically explore the chemical space relationships between taxonomy, secondary metabolite and drug score variables, allowing for the identification of differences and correlations within a dataset. The use of scaffold networks as well as bipartite relationship networks provided a platform to explore chemical diversity as well as the use of chemical similarity networks to link pharmacokinetic properties with structural similarity. This study paves the way for future applications of net...
Pathogens
Eight secondary metabolites (1 to 8) were isolated from a marine sponge, a marine alga and three ... more Eight secondary metabolites (1 to 8) were isolated from a marine sponge, a marine alga and three terrestrial plants collected in Australia and subsequently chemically characterised. Here, these natural product-derived compounds were screened for in vitro-anthelmintic activity against the larvae and adult stages of Haemonchus contortus (barber’s pole worm)—a highly pathogenic parasitic nematode of ruminants. Using an optimised, whole-organism screening system, compounds were tested on exsheathed third-stage larvae (xL3s) and fourth-stage larvae (L4s). Anthelmintic activity was initially evaluated on these stages based on the inhibition of motility, development and/or changes in morphology (phenotype). We identified two compounds, 6-undecylsalicylic acid (3) and 6-tridecylsalicylic acid (4) isolated from the marine brown alga, Caulocystis cephalornithos, with inhibitory effects on xL3 and L4 motility and larval development, and the induction of a “skinny-straight” phenotype. Subsequen...
Marine Drugs
Marine macroalgae occurring in the south eastern region of Victoria, Australia, consisting of Por... more Marine macroalgae occurring in the south eastern region of Victoria, Australia, consisting of Port Phillip Bay and the heads entering the bay, is the focus of this review. This area is home to approximately 200 different species of macroalgae, representing the three major phyla of the green algae (Chlorophyta), brown algae (Ochrophyta) and the red algae (Rhodophyta), respectively. Over almost 50 years, the species of macroalgae associated and occurring within this area have resulted in the identification of a number of different types of secondary metabolites including terpenoids, sterols/steroids, phenolic acids, phenols, lipids/polyenes, pheromones, xanthophylls and phloroglucinols. Many of these compounds have subsequently displayed a variety of bioactivities. A systematic description of the compound classes and their associated bioactivities from marine macroalgae found within this region is presented.
Marine Drugs
The absolute configuration of retroflexanone (1) and a closely related phlorogluinol (2) was esta... more The absolute configuration of retroflexanone (1) and a closely related phlorogluinol (2) was established using the advanced Mosher method and by application of HPLC-NMR. HPLC-NMR permitted a small scale Mosher method analysis to be carried out on these unstable phloroglucinols.
Natural Product Communications
Six compounds previously isolated and reported from Macropidia fuliginosa were evaluated for anti... more Six compounds previously isolated and reported from Macropidia fuliginosa were evaluated for antimicrobial activity against 11 different microbial strains, with all compounds displaying broad spectrum activity. In addition, the compounds were also assessed for their antiproliferative activity and cytotoxicity. Further investigation of M. fuliginosa has led to the discovery of a previously described acenaphthylenediol from the bulbs of the plant.
Marine Drugs
The isolation and the structure determination of a new bromophenolic compound, polysiphonol (10),... more The isolation and the structure determination of a new bromophenolic compound, polysiphonol (10), as well as five previously reported compounds, (4–8), from the red alga Polysiphonia decipiens is reported. In addition, the absolute configuration of the natural product rhodomelol (8) could be unequivocally confirmed for the first time, and on biosynthetic grounds, the absolute configuration of polysiphonol (10) was tentatively suggested. Compounds 4–8 were evaluated for their antibacterial activity against both Gram-positive and Gram-negative bacteria, but none of the compounds showed any appreciable activity.
Journal of Herbal Medicine
Abstract The leaves of Clinacanthus nutans have been increasingly used as an adjuvant treatment f... more Abstract The leaves of Clinacanthus nutans have been increasingly used as an adjuvant treatment for cancers. Infusion of the dried leaves in water is the traditional and preferred method of preparation by cancer patients for consumption. Traditionally, this medicinal plant is brewed in boiling water before consumption as a tea but little is known about the effect of preparation temperature for optimal anticancer activity. Therefore, the present study assessed the effect of preparation temperature (hot or cold) of crude aqueous extracts of C. nutans leaves on the cytotoxicity of D24 melanoma cells using a colorimetric WST-8 assay. Apoptotic cell death was detected by a cytofluorometric double staining method. Biochemical and morphological changes in the treated cells were examined by fluorescence and transmission electron microscopy techniques, respectively, to further verify the type of cell death. The cold aqueous extract was the most cytotoxic against D24 melanoma cells with an EC50 of 163 μg/mL at 72 h. The extract also predominantly induced apoptosis in these cells according to cytofluorimteric, confocal and transmission electron microscopic analyses. This study provides important information on the preparation of C. nutans and its effectiveness as an anticancer concoction for regular consumption.
Natural Product Communications
NMR spectroscopic methodologies used to characterize and elucidate the structure of the marine na... more NMR spectroscopic methodologies used to characterize and elucidate the structure of the marine natural product elatenyne were also applied to the characterization of a new triazole structural derivative of elatenyne, obtained by “Click” chemistry. The two most probable relative configurations assigned to naturally occurring elatenyne were concluded on the basis of key single irradiation nOe NMR enhancements, in combination with the use of a variant of the HSQC NMR experiment that permitted NMR coupling constants to be measured for the overlapped ring junction protons. This study represents the first application of “Click” chemistry to chemically derivatize an unmodified natural product.
Natural Product Communications
The dichloromethane extract of the air-dried leaves and freeze-dried tubers of Smallanthus sonchi... more The dichloromethane extract of the air-dried leaves and freeze-dried tubers of Smallanthus sonchifolius afforded ent-kaurenoic acid (1). The structure of 1 was elucidated by extensive 1D and 2D NMR spectroscopy and was found to exhibit significant analgesic and anti-inflammatory activities. Ent-kaurenoic acid (1), dissolved in dimethylsulfoxide, also displayed potential anti-diabetes and anti-toxicity activity. In addition, 1 showed low antimicrobial activities against E. coli, P. aeruginosa, S. aureus, C. albicans and T. mentagrophytes, but was found to be inactive against B. subtilis and A. niger.
Natural Product Communications
A chemical profiling/dereplication exercise, involving the use of HPLC-NMR and mass spectrometry ... more A chemical profiling/dereplication exercise, involving the use of HPLC-NMR and mass spectrometry in combination with the MarinLit database, was conducted on the crude dichloromethane extract of the southern Australian marine brown alga Cystophora torulosa. This strategy was successful in identifying a total of nine secondary metabolites representing two principle structure classes, including seven resorcinol (1–7) and two polyene derivatives (8 and 9). Validation of this on-line dereplication strategy was supported by the isolation and complete 2D NMR assignment of the major secondary metabolite (1). This methodology was concluded to be suitable for the rapid on-line identification of the resorcinol and polyene structure classes that are frequently encountered in the genus Cystophora.
Natural Product Reports
This review provides a summary of the current state of research concerning the unique specialised... more This review provides a summary of the current state of research concerning the unique specialised metabolites from Haemodoraceae.
International Journal of Pharmacognosy and Phytochemical Research
Chemical investigation of the dichloromethane extract of Rheum ribes has led to the isolation of ... more Chemical investigation of the dichloromethane extract of Rheum ribes has led to the isolation of β-sitosteryl-3β- glucopyranoside-6'-O-fatty acid esters (1), β-sitosterol (2), phytyl fatty acid esters (3), triacylgly c e r o l s (4) and chlorophyllide a (5). The structures of 1-5 were identified by comparison of their NMR data with literature data.
Journal of Chemical Education
First-year undergraduate classes present challenges in teaching as they usually have high student... more First-year undergraduate classes present challenges in teaching as they usually have high student enrolment numbers and students studying across a range of higher education programs that require a fundamental understanding of knowledge that is not perceived in their area of study. This provides a challenge in terms of engaging and maintaining student interest, primarily because students do not recognize the application of knowledge to their field of study. The challenge is to contextualize the content for the range of student cohorts within the one course. This is a common issue within many of the programs offered at