Wilfred T Mabusela - Academia.edu (original) (raw)
Papers by Wilfred T Mabusela
The University of Cepe Town has been given the right to reprocluc9 this thesis In whole
Natural products chemistry & research, Nov 30, 2015
Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summerblooming, deciduous... more Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summerblooming, deciduous and bulbous geophytes that grow naturally in the semi-arid succulent Karoo biome of South Africa. Both species grow under full sun conditions and have four distinctive growth phases: a winter (cold and wet) growing phase, leaf senescence phase towards spring, flowering phase during the hot and dry summer months, and fruit and leaf formation phase in autumn. The medicinal uses of this genus (including G. multifolia "Kukumakranka" and G. villosa "hairy kukumakranka") range from cures for colic, digestive disturbances, teething problems, fatigue, boils, bruises and insect bites, to being used as an aphrodisiac. Gethyllis multifolia is threatened in its natural habitat and is listed in the 'Vulnerable' category of the 'Red Data List of Southern African Plants' and the 'IUCN-World Conservation Union List of Plants'. The literature indicate that the habitats of both species are being exposed to drier conditions and is further xii
Tuberculosis, 2009
Artemisia afra [Jacq] (Asteraceae) phytotherapy is widely used for its medicinal properties in tr... more Artemisia afra [Jacq] (Asteraceae) phytotherapy is widely used for its medicinal properties in traditional practices. In this study we investigated whether extracts of A. afra are capable of controlling mycobacterial replication. For Mycobacterium aurum cultured in the presence of aqueous-, methanol-and dichloromethane (DCM) extracts of A. afra we found that bacterial replication was inhibited by the dichloromethane extract only. Activity of the DCM extract was confirmed in dose-dependent studies against both M. aurum and M. tuberculosis with an IC 50 = 270 μg/ml and IC 50 = 290 μg/ml, respectively. Fractionation of the DCM extract and evaluation of its efficacy in vitro found that most of the antimycobacterial activity was associated with isolate fraction C8 that contained several sesquiterpene lactones, the most prominent of which are Artemin and Arsubin. Evaluation of the bactericidal efficacy in vitro showed that isolate fraction C8 reduced replication of M. aurum and M. tuberculosis in a dose-dependent manner with IC 50 = 1.9 μg/ml and IC 50 = 2.0 μg/ml, respectively, and an MIC = 10 μg/ml. Further, isolate fraction C8 and the DCM extract was administered to M. tuberculosis-infected mice at a tolerated dose of 1000 mg/kg for up to 26 weeks and mycobacterial burdens compared to untreated-, INH/RIF treated-and aqueous-extract-treated animals to assess its bactericidal activity in vivo. Bacterial replication remained unaffected during treatment with either isolate fraction C8 or the DCM extract resulting in pulmonary and splenic bacilli burdens comparable to that of untreated mice. In contrast, INH/RIF treatment cleared M. tuberculosis infection after only 8 weeks to undetectable levels. Interestingly, treatment of M. tuberculosis-infected mice with aqueous extract of A. afra regulated pulmonary inflammation during early infection notwithstanding its inability to inhibit
Global and Planetary Change, 2005
The effects of elevated atmospheric CO 2 concentrations on plant polyphenolic, tannin, nitrogen, ... more The effects of elevated atmospheric CO 2 concentrations on plant polyphenolic, tannin, nitrogen, phosphorus and total nonstructural carbohydrate concentrations were investigated in leaves of subtropical grass and fynbos shrub species. The hypothesis tested was that carbon-based secondary compounds would increase when carbon gain is in excess of growth requirements. This premise was tested in two ecosystems involving plants with different photosynthetic mechanisms and growth strategies. The first ecosystem comprised grasses from a C 4-dominated, subtropical grassland, where three plots were subjected to three different free air CO 2 enrichment treatments, i.e., elevated (600 to 800 Amol mol À1), intermediate (400 Amol mol À1) and ambient atmospheric CO 2. One of the seven grass species, Alloteropsis semialata, had a C 3 photosynthetic pathway while the other grasses were all C 4. The second ecosystem was simulated in a microcosm experiment where three fynbos species were grown in open-top chambers at ambient and 700 Amol mol À1 atmospheric CO 2 in low nutrient acid sands typical of south western coastal and mountain fynbos ecosystems. Results showed that polyphenolics and tannins did not increase in the grass species under elevated CO 2 and only in Leucadendron laureolum among the fynbos species. Similarly, foliar nitrogen content of grasses was largely unaffected by elevated CO 2 , and among the fynbos species, only L. laureolum and Leucadendron xanthoconus showed changes in foliar nitrogen content under elevated CO 2 , but these were of different magnitude. The overall decrease in nitrogen and phosphorus and consequent increase in C:N and C:P ratio in both ecosystems, along with the increase in polyphenolics and tannins in L. laureolum in the fynbos ecosystem, may negatively affect forage quality and decomposition rates. It is concluded that fast growing grasses do not experience sink limitation and invest extra carbon into growth rather than polyphenolics and
Food Hydrocolloids, 1991
Abstract A comparison is made between the molecular structures of three polysaccharides of plant ... more Abstract A comparison is made between the molecular structures of three polysaccharides of plant origin, all of which contain alternating sequences of D -glucuronic acid and D -mannose. They vary considerably in the degree of substitution of OH groups in the core structure, O-3 of both the uronic acid and the neutral sugar being favoured. FAB-mass spectrometry showed the presence of (GlcA-Man)9 in a hydrolysis product of the least-substituted polysaccharide.
Australian Journal of Botany, 2013
Gethyllis multifolia L.Bolus and G. villosa Thunb. (Family: Amaryllidaceae) are deciduous and bul... more Gethyllis multifolia L.Bolus and G. villosa Thunb. (Family: Amaryllidaceae) are deciduous and bulbous geophytes that occur in the succulent Karoo biome of South Africa. Both species occupy the same natural habitat, but G. multifolia is threatened and G. villosa not. Both G. multifolia and G. villosa require seasonal bulb reserves for initial vegetative and reproductive growth. In spite of G. villosa having smaller bulbs than G. multifolia, both species produce similar flower sizes and weights. The aim of the present study was to determine the carbon and nitrogen costs of vegetative and reproductive growth during the phases of growth, senescence, reproduction and dormancy of these bulbous species. The rates, costs and efficiencies of biomass production during various growth phases of the two species were determined in a comparative experiment. The results show that in spite of a significantly smaller bulb, G. villosa produced more leaves per unit bulb mass and invested more carbon an...
Nigerian Journal of Natural Products and Medicine, 2012
ABSTRACT Dennettia tripetala a Nigerian medicinal plant widely employed in the management of oxid... more ABSTRACT Dennettia tripetala a Nigerian medicinal plant widely employed in the management of oxidative stress related diseases and infections was investigated for its active constituents. A DPPH (1,1-diphenyl-2-picrylhydrazine) guided fractionation was used to target and isolate the antioxidant constituents of the ethyl acetate solvent fraction of a 20% aqueous methanol leaf extract. Two flavonoid glycosides were isolated and identified by spectral data (1H, and 13C NMR, along with ESI-TOF-MS spectrometry) as: quercetin-3-O-arabinofuranoside, avicularin (1) and vitexin-2'’-O-rhamnoside (2). In the qualitative antioxidant assay, the compounds instantly bleached the DPPH purple colour indicating free radical scavenging potential (antioxidant activity). In the micro-well dilution assay, Compound (1) was the most active with MIC values of 0.081 mg/mL against Staphylococcus aureus NCTC 6571 and 2.50 mg/mL against Escherichia coli NCTC 8196 compared to the standard drug streptomycin which had MICs of 0.039 mg/mL and 0.156 mg/mL respectively against the two organisms. None of the compounds was able to inhibit the growth of the fungi strain used at the tested concentrations. Isolation of these antioxidant and antimicrobial compounds could provide rationale for the ethnomedicinal use of this plant in traditional medicine in the management of the oxidative stress related diseases and infections.
Journal of Medicinal Plants Research, Jan 10, 2015
Following the screening of several plant species from an inventory of common medicinal plants fro... more Following the screening of several plant species from an inventory of common medicinal plants from South Africa for medicinal properties, Cissampelos capensis was selected for further investigation due to its interesting and useful ethnomedicinal properties. This study attempts to relate specific constituents present in this plant with its widespread ethnomedicinal uses. Six compounds were isolated and their structures were unambiguously established by spectroscopic methods.
Plants
The global management of diabetes mellitus (DM) involves the administration of recommended anti-d... more The global management of diabetes mellitus (DM) involves the administration of recommended anti-diabetic drugs in addition to a non-sedentary lifestyle upon diagnosis. Despite the success recorded from these synthetic drugs, the traditional method of treatment using medicinal plants is increasingly accepted by the locals due to its low cost and the perceived no side effects. Helichrysum species are used in folk medicine and are documented for the treatment of DM in different regions of the world. This study reviews Helichrysum species and its compounds’ activities in the management of DM. An extensive literature search was carried out, utilizing several scientific databases, ethnobotanical books, theses, and dissertations. About twenty-two Helichrysum species were reported for the treatment of diabetes in different regions of the world. Among these Helichrysum species, only fifteen have been scientifically investigated for their antidiabetic activities, and twelve compounds were ide...
Plants
Protea cynaroides (king protea) is a flowering plant that belongs to the Proteaceae family. This ... more Protea cynaroides (king protea) is a flowering plant that belongs to the Proteaceae family. This multi-stemmed shrub is the national flower of South Africa and has important economic and medicinal values. Traditionally, the main therapeutic benefits of this plant species include the treatment of cancer, bladder, and kidney ailments. There are very limited reports on the isolation of phytochemicals and their biological evaluation from P. cynaroides. In this study, the leaves of P. cynaroides were air-dried at room temperature, powdered, and extracted with 80% methanol followed by solvent fractionation (hexane, dichloromethane, ethyl acetate, and butanol). The ethyl acetate and butanol extracts were chromatographed and afforded four new (1–4) and four known (5–8) compounds, whose structures were characterized accordingly as 3,4-bis(4-hydroxybenzoyl)-1,5-anhydro-D-glucitol (1), 4-hydroxybenzoyl-1,5-anhydro-D-glucitol (2), 2-(hydroxymethyl)-4-oxo-4H-pyran-3-yl-6-O-benzoate-β-D-glucopyra...
Interdisciplinary Journal of Chemistry
Volume 2(2): 1-6 biological activities, stimulating even more studies. Among these are fucoidans ... more Volume 2(2): 1-6 biological activities, stimulating even more studies. Among these are fucoidans (sulfated polymers of fucose) which are well known for a wide range of applications, from medicinal, nutraceutical, to cosmeceutical. In the present study, some compounds were isolated from Ecklonia maxima and characterized by spectroscopic methods. The compound s were tested for their biological activities on limited assays. Materials and methods Nuclear magnetic resonance (NMR) spectra were measured on a Varian-600 instrument using CD 3 OD as solvent (600 MHz for 1 H and 150 MHz for 13 C). MS spectra were obtained from a Waters Synapt G2 spectrometer. For TLC, aluminium pre-coated Si gel 60 F254 plates were used and spots detected under ultraviolet (UV) light (254 and 365 nm) and further visualized by spraying with vanillin-H 2 SO 4 followed by heating at ±120°C until spots were revealed. Preparative TLC was performed on a 0.5 mm thick Si gel layer coated on 20×20 cm glass plates. Column chromatography was carried out on Si gel 60 (0.040 to 0.063 mm) (230-400 Mesh ASTM, Merck) as well as Sephadex ® LH-20 (Pharmacia). Phlorotannins were determined by a HPLC (Agilent 1200, system equipped with two pumps, degasser, auto-sampler, and a
South African Carpobrotus species have been found to contain hydrolyzable tannins, various flavon... more South African Carpobrotus species have been found to contain hydrolyzable tannins, various flavonoids e.g. rutin and hyperoside, phytosterols and aromatic acids which have a diverse range of pharmacological properties; including antimicrobial and antioxidant activities. In this paper we described the identification and quantification of catechin in C. mellei and C. quadrifidus using cyclic and square wave voltammetry. The oxidation potential of catechin ranges from +171.0 mV to +631.6 mV. The oxidation mechanism proceeds in sequential steps, related to the catechol moiety and 3hydroxyl group. The oxidation of the catechol electron donating group occurs first at low potential and is a reversible reaction. The 3-hydroxyl group oxidises after and undergoes an irreversible reaction. The limit of detection (LOD) of catechin is 0.84 ppm and limit of quantification (LOQ) is 2.79 ppm with R.S.D. equal to 2.5%. The oxidation potentials of the ethyl acetate extracts of C. mellei and C. quadrifidus correspond with that of catechin. The content of catechin in C. mellei and C. quadrifidus was 5.0 ppm and 4.7 ppm, respectively. Other analytical techniques such as HPLC, UV-VIS, NMR, and FTIR were also used to validate the presence of catechin in the plant extracts.
Journal of Medicinal Plants Research, Mar 10, 2013
Phytochemical studies on Rhus natalensis root bark collected from Kenya led to the isolation and ... more Phytochemical studies on Rhus natalensis root bark collected from Kenya led to the isolation and identification of a new biflavonoid (3-(1-(2,4-dihydroxyphenyl)-3,3-bis(4-hydroxyphenyl)-1-oxopropan-2yl)-7-methoxy-4H-chromone-4-one (1), named rhuschromone, in addition to two other known compounds; 2',4'-dihydroxychalcone-(4-O-5''')-4'',2''',4'''-trihydroxychalcone (2) and 3-((Z)-heptadec-13enyl) benzene-1,2-diol (3). The chemical structures of the isolated compounds were established using spectroscopic techniques including high field nuclear magnetic resonance (NMR). The total extracts and the isolated compounds were tested for their antimicrobial activities against different strains of bacteria.
Natural Products Chemistry & Research, 2015
Ranunculus arvensis, belongs to family Ranunculacea, have 2500 species throughout the world. Due ... more Ranunculus arvensis, belongs to family Ranunculacea, have 2500 species throughout the world. Due to their local importance for various diseases and great biological potentials the plant was selected for further studies. Antioxidant activity was determined by DPPH scavenging method while phytotoxcicity was carried out through autoclaved petriplates growth inhibition. Antibacterial activity analysis was carried out by using microplates alamar blue assay. The Antioxidan, phytotoxic and antimicrobial results showed that this plant need detail phytochemical screening to isolate active chemical constituents which could be of scientific values.
The University of Cepe Town has been given the right to reprocluc9 this thesis In whole
Natural products chemistry & research, Nov 30, 2015
Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summerblooming, deciduous... more Gethyllis multifolia L. Bolus and G. villosa Thunb. are winter-growing, summerblooming, deciduous and bulbous geophytes that grow naturally in the semi-arid succulent Karoo biome of South Africa. Both species grow under full sun conditions and have four distinctive growth phases: a winter (cold and wet) growing phase, leaf senescence phase towards spring, flowering phase during the hot and dry summer months, and fruit and leaf formation phase in autumn. The medicinal uses of this genus (including G. multifolia "Kukumakranka" and G. villosa "hairy kukumakranka") range from cures for colic, digestive disturbances, teething problems, fatigue, boils, bruises and insect bites, to being used as an aphrodisiac. Gethyllis multifolia is threatened in its natural habitat and is listed in the 'Vulnerable' category of the 'Red Data List of Southern African Plants' and the 'IUCN-World Conservation Union List of Plants'. The literature indicate that the habitats of both species are being exposed to drier conditions and is further xii
Tuberculosis, 2009
Artemisia afra [Jacq] (Asteraceae) phytotherapy is widely used for its medicinal properties in tr... more Artemisia afra [Jacq] (Asteraceae) phytotherapy is widely used for its medicinal properties in traditional practices. In this study we investigated whether extracts of A. afra are capable of controlling mycobacterial replication. For Mycobacterium aurum cultured in the presence of aqueous-, methanol-and dichloromethane (DCM) extracts of A. afra we found that bacterial replication was inhibited by the dichloromethane extract only. Activity of the DCM extract was confirmed in dose-dependent studies against both M. aurum and M. tuberculosis with an IC 50 = 270 μg/ml and IC 50 = 290 μg/ml, respectively. Fractionation of the DCM extract and evaluation of its efficacy in vitro found that most of the antimycobacterial activity was associated with isolate fraction C8 that contained several sesquiterpene lactones, the most prominent of which are Artemin and Arsubin. Evaluation of the bactericidal efficacy in vitro showed that isolate fraction C8 reduced replication of M. aurum and M. tuberculosis in a dose-dependent manner with IC 50 = 1.9 μg/ml and IC 50 = 2.0 μg/ml, respectively, and an MIC = 10 μg/ml. Further, isolate fraction C8 and the DCM extract was administered to M. tuberculosis-infected mice at a tolerated dose of 1000 mg/kg for up to 26 weeks and mycobacterial burdens compared to untreated-, INH/RIF treated-and aqueous-extract-treated animals to assess its bactericidal activity in vivo. Bacterial replication remained unaffected during treatment with either isolate fraction C8 or the DCM extract resulting in pulmonary and splenic bacilli burdens comparable to that of untreated mice. In contrast, INH/RIF treatment cleared M. tuberculosis infection after only 8 weeks to undetectable levels. Interestingly, treatment of M. tuberculosis-infected mice with aqueous extract of A. afra regulated pulmonary inflammation during early infection notwithstanding its inability to inhibit
Global and Planetary Change, 2005
The effects of elevated atmospheric CO 2 concentrations on plant polyphenolic, tannin, nitrogen, ... more The effects of elevated atmospheric CO 2 concentrations on plant polyphenolic, tannin, nitrogen, phosphorus and total nonstructural carbohydrate concentrations were investigated in leaves of subtropical grass and fynbos shrub species. The hypothesis tested was that carbon-based secondary compounds would increase when carbon gain is in excess of growth requirements. This premise was tested in two ecosystems involving plants with different photosynthetic mechanisms and growth strategies. The first ecosystem comprised grasses from a C 4-dominated, subtropical grassland, where three plots were subjected to three different free air CO 2 enrichment treatments, i.e., elevated (600 to 800 Amol mol À1), intermediate (400 Amol mol À1) and ambient atmospheric CO 2. One of the seven grass species, Alloteropsis semialata, had a C 3 photosynthetic pathway while the other grasses were all C 4. The second ecosystem was simulated in a microcosm experiment where three fynbos species were grown in open-top chambers at ambient and 700 Amol mol À1 atmospheric CO 2 in low nutrient acid sands typical of south western coastal and mountain fynbos ecosystems. Results showed that polyphenolics and tannins did not increase in the grass species under elevated CO 2 and only in Leucadendron laureolum among the fynbos species. Similarly, foliar nitrogen content of grasses was largely unaffected by elevated CO 2 , and among the fynbos species, only L. laureolum and Leucadendron xanthoconus showed changes in foliar nitrogen content under elevated CO 2 , but these were of different magnitude. The overall decrease in nitrogen and phosphorus and consequent increase in C:N and C:P ratio in both ecosystems, along with the increase in polyphenolics and tannins in L. laureolum in the fynbos ecosystem, may negatively affect forage quality and decomposition rates. It is concluded that fast growing grasses do not experience sink limitation and invest extra carbon into growth rather than polyphenolics and
Food Hydrocolloids, 1991
Abstract A comparison is made between the molecular structures of three polysaccharides of plant ... more Abstract A comparison is made between the molecular structures of three polysaccharides of plant origin, all of which contain alternating sequences of D -glucuronic acid and D -mannose. They vary considerably in the degree of substitution of OH groups in the core structure, O-3 of both the uronic acid and the neutral sugar being favoured. FAB-mass spectrometry showed the presence of (GlcA-Man)9 in a hydrolysis product of the least-substituted polysaccharide.
Australian Journal of Botany, 2013
Gethyllis multifolia L.Bolus and G. villosa Thunb. (Family: Amaryllidaceae) are deciduous and bul... more Gethyllis multifolia L.Bolus and G. villosa Thunb. (Family: Amaryllidaceae) are deciduous and bulbous geophytes that occur in the succulent Karoo biome of South Africa. Both species occupy the same natural habitat, but G. multifolia is threatened and G. villosa not. Both G. multifolia and G. villosa require seasonal bulb reserves for initial vegetative and reproductive growth. In spite of G. villosa having smaller bulbs than G. multifolia, both species produce similar flower sizes and weights. The aim of the present study was to determine the carbon and nitrogen costs of vegetative and reproductive growth during the phases of growth, senescence, reproduction and dormancy of these bulbous species. The rates, costs and efficiencies of biomass production during various growth phases of the two species were determined in a comparative experiment. The results show that in spite of a significantly smaller bulb, G. villosa produced more leaves per unit bulb mass and invested more carbon an...
Nigerian Journal of Natural Products and Medicine, 2012
ABSTRACT Dennettia tripetala a Nigerian medicinal plant widely employed in the management of oxid... more ABSTRACT Dennettia tripetala a Nigerian medicinal plant widely employed in the management of oxidative stress related diseases and infections was investigated for its active constituents. A DPPH (1,1-diphenyl-2-picrylhydrazine) guided fractionation was used to target and isolate the antioxidant constituents of the ethyl acetate solvent fraction of a 20% aqueous methanol leaf extract. Two flavonoid glycosides were isolated and identified by spectral data (1H, and 13C NMR, along with ESI-TOF-MS spectrometry) as: quercetin-3-O-arabinofuranoside, avicularin (1) and vitexin-2'’-O-rhamnoside (2). In the qualitative antioxidant assay, the compounds instantly bleached the DPPH purple colour indicating free radical scavenging potential (antioxidant activity). In the micro-well dilution assay, Compound (1) was the most active with MIC values of 0.081 mg/mL against Staphylococcus aureus NCTC 6571 and 2.50 mg/mL against Escherichia coli NCTC 8196 compared to the standard drug streptomycin which had MICs of 0.039 mg/mL and 0.156 mg/mL respectively against the two organisms. None of the compounds was able to inhibit the growth of the fungi strain used at the tested concentrations. Isolation of these antioxidant and antimicrobial compounds could provide rationale for the ethnomedicinal use of this plant in traditional medicine in the management of the oxidative stress related diseases and infections.
Journal of Medicinal Plants Research, Jan 10, 2015
Following the screening of several plant species from an inventory of common medicinal plants fro... more Following the screening of several plant species from an inventory of common medicinal plants from South Africa for medicinal properties, Cissampelos capensis was selected for further investigation due to its interesting and useful ethnomedicinal properties. This study attempts to relate specific constituents present in this plant with its widespread ethnomedicinal uses. Six compounds were isolated and their structures were unambiguously established by spectroscopic methods.
Plants
The global management of diabetes mellitus (DM) involves the administration of recommended anti-d... more The global management of diabetes mellitus (DM) involves the administration of recommended anti-diabetic drugs in addition to a non-sedentary lifestyle upon diagnosis. Despite the success recorded from these synthetic drugs, the traditional method of treatment using medicinal plants is increasingly accepted by the locals due to its low cost and the perceived no side effects. Helichrysum species are used in folk medicine and are documented for the treatment of DM in different regions of the world. This study reviews Helichrysum species and its compounds’ activities in the management of DM. An extensive literature search was carried out, utilizing several scientific databases, ethnobotanical books, theses, and dissertations. About twenty-two Helichrysum species were reported for the treatment of diabetes in different regions of the world. Among these Helichrysum species, only fifteen have been scientifically investigated for their antidiabetic activities, and twelve compounds were ide...
Plants
Protea cynaroides (king protea) is a flowering plant that belongs to the Proteaceae family. This ... more Protea cynaroides (king protea) is a flowering plant that belongs to the Proteaceae family. This multi-stemmed shrub is the national flower of South Africa and has important economic and medicinal values. Traditionally, the main therapeutic benefits of this plant species include the treatment of cancer, bladder, and kidney ailments. There are very limited reports on the isolation of phytochemicals and their biological evaluation from P. cynaroides. In this study, the leaves of P. cynaroides were air-dried at room temperature, powdered, and extracted with 80% methanol followed by solvent fractionation (hexane, dichloromethane, ethyl acetate, and butanol). The ethyl acetate and butanol extracts were chromatographed and afforded four new (1–4) and four known (5–8) compounds, whose structures were characterized accordingly as 3,4-bis(4-hydroxybenzoyl)-1,5-anhydro-D-glucitol (1), 4-hydroxybenzoyl-1,5-anhydro-D-glucitol (2), 2-(hydroxymethyl)-4-oxo-4H-pyran-3-yl-6-O-benzoate-β-D-glucopyra...
Interdisciplinary Journal of Chemistry
Volume 2(2): 1-6 biological activities, stimulating even more studies. Among these are fucoidans ... more Volume 2(2): 1-6 biological activities, stimulating even more studies. Among these are fucoidans (sulfated polymers of fucose) which are well known for a wide range of applications, from medicinal, nutraceutical, to cosmeceutical. In the present study, some compounds were isolated from Ecklonia maxima and characterized by spectroscopic methods. The compound s were tested for their biological activities on limited assays. Materials and methods Nuclear magnetic resonance (NMR) spectra were measured on a Varian-600 instrument using CD 3 OD as solvent (600 MHz for 1 H and 150 MHz for 13 C). MS spectra were obtained from a Waters Synapt G2 spectrometer. For TLC, aluminium pre-coated Si gel 60 F254 plates were used and spots detected under ultraviolet (UV) light (254 and 365 nm) and further visualized by spraying with vanillin-H 2 SO 4 followed by heating at ±120°C until spots were revealed. Preparative TLC was performed on a 0.5 mm thick Si gel layer coated on 20×20 cm glass plates. Column chromatography was carried out on Si gel 60 (0.040 to 0.063 mm) (230-400 Mesh ASTM, Merck) as well as Sephadex ® LH-20 (Pharmacia). Phlorotannins were determined by a HPLC (Agilent 1200, system equipped with two pumps, degasser, auto-sampler, and a
South African Carpobrotus species have been found to contain hydrolyzable tannins, various flavon... more South African Carpobrotus species have been found to contain hydrolyzable tannins, various flavonoids e.g. rutin and hyperoside, phytosterols and aromatic acids which have a diverse range of pharmacological properties; including antimicrobial and antioxidant activities. In this paper we described the identification and quantification of catechin in C. mellei and C. quadrifidus using cyclic and square wave voltammetry. The oxidation potential of catechin ranges from +171.0 mV to +631.6 mV. The oxidation mechanism proceeds in sequential steps, related to the catechol moiety and 3hydroxyl group. The oxidation of the catechol electron donating group occurs first at low potential and is a reversible reaction. The 3-hydroxyl group oxidises after and undergoes an irreversible reaction. The limit of detection (LOD) of catechin is 0.84 ppm and limit of quantification (LOQ) is 2.79 ppm with R.S.D. equal to 2.5%. The oxidation potentials of the ethyl acetate extracts of C. mellei and C. quadrifidus correspond with that of catechin. The content of catechin in C. mellei and C. quadrifidus was 5.0 ppm and 4.7 ppm, respectively. Other analytical techniques such as HPLC, UV-VIS, NMR, and FTIR were also used to validate the presence of catechin in the plant extracts.
Journal of Medicinal Plants Research, Mar 10, 2013
Phytochemical studies on Rhus natalensis root bark collected from Kenya led to the isolation and ... more Phytochemical studies on Rhus natalensis root bark collected from Kenya led to the isolation and identification of a new biflavonoid (3-(1-(2,4-dihydroxyphenyl)-3,3-bis(4-hydroxyphenyl)-1-oxopropan-2yl)-7-methoxy-4H-chromone-4-one (1), named rhuschromone, in addition to two other known compounds; 2',4'-dihydroxychalcone-(4-O-5''')-4'',2''',4'''-trihydroxychalcone (2) and 3-((Z)-heptadec-13enyl) benzene-1,2-diol (3). The chemical structures of the isolated compounds were established using spectroscopic techniques including high field nuclear magnetic resonance (NMR). The total extracts and the isolated compounds were tested for their antimicrobial activities against different strains of bacteria.
Natural Products Chemistry & Research, 2015
Ranunculus arvensis, belongs to family Ranunculacea, have 2500 species throughout the world. Due ... more Ranunculus arvensis, belongs to family Ranunculacea, have 2500 species throughout the world. Due to their local importance for various diseases and great biological potentials the plant was selected for further studies. Antioxidant activity was determined by DPPH scavenging method while phytotoxcicity was carried out through autoclaved petriplates growth inhibition. Antibacterial activity analysis was carried out by using microplates alamar blue assay. The Antioxidan, phytotoxic and antimicrobial results showed that this plant need detail phytochemical screening to isolate active chemical constituents which could be of scientific values.