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A phytochemical investigation of Acridocarpus Natalitius and Typha Capensis.
Get PDFThesis (M.Sc.)-University of Durban-Westville, 2001.In the present study, a phytochemical investigation of two medicinal plants, namely,
Acridocarpus natalitius and Typha capensis is presented.
The roots of A. natalitius afforded a variety of pentacyclic triterpenoids, namely,
friedelin [41], epi-friedelinol [42], lupeol [43] and oleanolic acid [44], including
stigmasterol [45] from the hexane extract, whilst the methanolic extract produced a
flavonoid, (-)-epicatechin [4] and carbohydrates which included glucose [64] and
sucrose [65].
Two new bibenzyls were isolated from the hexane extract of the rhizhomes of T.
capensis, namely, typharin [47] and typhaphthalide [48]. β-Sitosterol [49] was also
isolated. The acetone extract afforded several flavan-3-ols which were isolated in
their free phenolic form. These include, afzelechin [10], epiafzelechin [23], (+)catechin
[11] and (-)-epicatechin [4]. A biological survey was carried out on the
crude methanolic extract in an independent survey and a brief discussion is presented
here.
All the compounds were isolated using a series of chromatographic techniques and
structures were elucidated by means of NMR spectroscopy, infrared spectroscopy and
mass spectrometry
Chemical prospecting of medicinal plants for drug discovery.
No full textThesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.African traditional medicine relies largely on the abundant African flora estimated at several tens
of thousands of species. These plants, like other living organisms, produce natural products
which are organic molecules exhibiting a remarkable wide range of chemical diversity and a
multiplicity of biological properties.
Over the past 20 years, interest in drugs of plants origin has been reviving and growing steadily.
Among the broad spectrum of natural products that are showing promise as possible leads to
useful therapeutic agents are the terpenoids. In the present study, selected African medicinal
plants were investigated for the presence of extractable and exploitable terpenoids as leads or
raw materials for producing more potent bioactive compounds for pre-clinical drugs discovery
programme for chemoprotective agents against cancer, HIV/AIDS, diabetes, hypertension,
malaria and other chronic diseases.
The plants investigated in this study included Callistemon salignus, C. viminalis, Melaleuca
bracteata var. revolution gold, M. bracteata var. revolution green, M. trichostachya var.
compata, Syzygium aromaticum and Tectona grandis.
These plants were subjected to two separate regimes of phytochemical extraction protocols
namely volatile and non-volatile-extraction protocol. The Callistemon species and Melaleuca
species upon hydrodistillation afforded essential oils. The gas chromatographic and mass
spectrometric (GC-MS) analysis of these essential oils reveals that 1,8-cineole was the major
constituent of the Callistemon oils. Similarly, 1,8-cineole was the major constituents of the
essential oil of M. trichostachya var. compata, while methyl eugenol was the predominant
constituent of the oils of Melaleuca bracteata var. revolution gold, and M. bracteata var.
revolution green.
Antibacterial investigation of the essential oils showed that they possess strong to moderate
inhibitory effect against selected bacteria.
In the non-volatile extraction protocol, various parts of the plants were sequentially extracted
with organic solvents to obtain crude extracts which were subjected to fractionation and
purification protocols (chromatographic techniques and re-crystallization). The crude extracts
from the leaves of the Callistemon and Melaleuca species gave a crystalline mixture of betulinic
acid and oleanolic acid in an appreciable yield. The crude extract from the cloves of Syzygium
aromaticum yielded oleanolic acid as the major extractive and maslinic acid as minor extractive.
The crude extracts from Tectona grandis afforded betulinic acid in an appreciable yield. The
elucidation of the structures of the pure extractives was achieved by extensive 1D and 2D
nuclear magnetic resonance (NMR) spectroscopy as well as infra-red spectroscopy (FT-IR) and
mass spectrometry (MS).
Betulinic acid and oleanolic acid were chosen as seed molecules for making known and
unknown derivatives for lead optimization study. The semi-synthesized compounds were 3-
acetoxyoleanolic acid, 3-acetoxyoleanolic hydrazide, 3-acetoxyloleanolic hydrazone, 3-succinyl
oleanolic acid, 3-acetoxybetulinic acid, 3-succinylbetulinic acid and maslinic acid di-acetate
Ethnopharmacology and phytochemistry of some selected medicinal plants in KwaZulu Natal.
Get PDFThesis (M.Sc.)-University of KwaZulu-Natal, 2006.In this ethnopharmacological study to isolate, purify, identify and test crude and
isolated compounds from organic and aqueous extracts from stem and leaves of
Protorhus longifolia and Sclerocarya birrea, stem bark of Hibiscus cannabinus and
Heteropyxis natalensis, leaves of Acokanthera venenata, Carissa marcrocarpa and
Syzygium cordatum, seeds of Chiononthus foveolatus and calyces of Hibiscus
sabdariffa were tested against seven pathogenic microorganisms which included six
bacterial species [Klebsiella pneumoniae (ATCC 12265), Bacillus cereus (ATCC 11778), Salmonella typhimurium (ATCC 13311), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 35219), Staphylococcus aureus (ATCC 29213)) and fungal yeast Candida albicans (ATCC 10231)]. Both organic and aqueous extracts from these medicinal plants exhibited antimicrobial properties against one or more mlcroorgamsms. The extracts of stem bark and leaves were tested for antimicrobial properties. Crude extracts that showed the highest activity were analysed through chromatographic and spectroscopic techniques to isolate, purify and characterise their active components. The highly active antimicrobial extracts were further tested for antimicrobial activity. Chromatographic (TLC and CC) spectroscopic (IR, 13C, 1HNMR) analyses of Syzygium cordatum leaf extract in ethyl acetate revealed the presence of C-30 triterpenes, ursolic (3B-hydroxyurs-12-en-28-oic acid) (UA) and oleanolic (3-hydroxylean-12-en-28-oic acid) (OA) acids; a mixture of methyl maslinate (2a, 3B-dihydroxyolean-12-en-28-oic acid methyl ester) (MM) and methyl corosolate (MC). Analyses of Protorhus longifolia leaf extract in hexane and ethylacetate revealed the presence of the alkaloid lupeol (lup-20(29)-en-3pB-ol), lupenone [lup - 20 (29) - en - 3 - one or lup - 20 ( 30 ) - en - 3 - one], lupinine (octahydro-2H-quinolizine-lmethanol),
lupulon (3 ,5-dihydroxy-2,6,6-tris(3-methyl-2-butenyl)-4-(3-methy1-1-oxobutyl)-2,4-yclohexadien-1-one) or (3,5-dihdroxy-4-isovaleryl-2,6,6-tris(3-methyl-2-butenyl)-2, 4-cyclohexadien-1-one) and luteolin [(2-(3, 4-dihydroxyphenyl)-5, 7-dihydroxy-4H -1-benzopyran-4-one), 3',4', 5,7 -tetrahydroxyflavone or 5,7,3' 4' -
tetrahydroxyflavone] and other compounds to be characterised in future studies.
Sclerocarya birrea bark extract in methanol was found to contain mixtures of
compounds that could not be separated due to solvent complications. Heteropyxis
natalensis stem bark in ethyl acetate gave betunilic acid (3B-hydroxy-20(29)-lupaene-
28-oic acid) as a major compound
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The mechanism of the selective inotropic and hypotensive effects of triterpenoids of plant origin.
Get PDFThesis (Ph.D.)--University of KwaZulu-Natal, 2004.Abstract available in PDF file
Phytochemical and anti-drepanocytosis studies of Cajanus cajan, Callistemon viminalis, Melaleuca bracteata var. Revolution Gold and Syzygium guineense.
No full textThesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2010.All over Africa, traditional healers use medicinal plants to prepare medicines to treat a
wide range of illnesses. One of these illnesses is sickle cell anaemia or drepanocytosis
or sicklemia. This disease is particularly common among sub-Saharan Africans with a
clear predominance in equatorial Africa. However, it also exists in North Africa,
Greece, Turkey, Saudi Arabia and India. An estimated 50 million people are affected
worldwide. A literature review on sickle cell anaemia revealed that a number of plants
have anti-drepanocytosic activity. The availability and frequency of ethnobotanic use of
plants were taken into account when selecting the plants investigated in this study.
Cajanus cajan, Callistemon viminalis, Melaleuca bracteata var. Revolution Gold and
Syzygium guineense (from DRC and South Africa) were selected for study. The selected
plants were subjected to modern phytochemical analysis. A total of 8 compounds were
isolated from the plants’ extracts and their structures determined by modern
spectroscopic techniques (1D and 2D NMR, FT-IR and MS). S. guineense from DRC
(Democratic Republic of Congo) yielded flavanonoid glycoside (A) as its major
chemical constituent. The South African S. guineense afforded 4 compounds namely
betulinic acid (B), sitosterol (C), friedelan-3-one (D) and a betulinic acid derivative (E).
Cajanus cajan showed the presence of fatty acids, one of them was characterized as an
unsaturated fatty acid (I). Callistemon viminalis afforded one compound, betulic acid
(F) and Melaleuca bracteata afforded two compounds which were characterized as
betulinic acid acetate (G) and ursolic acid acetate (H).
CH3-(CH2)n-CH2-CH=CH-CH2-CH=CH-(CH2)n-CH2-CH2-COOH
The investigation of the anti-drepanocytosis activities of the extractives and their crude
extracts showed in vitro antisickling activity.
Ethyl acetate crude extracts of Callistemon viminalis and Melaleuca bracteata; hexane,
dichloromethane and ethyl acetate crude extracts of Syzygium guineense of DRC,
betulinic acid, betulinic acid acetate and maslinic acid showed a high antisickling
activity, more than 70% of normalization. The compound BF4, a fatty acid, from
Melaleuca bracteata was found to have a medium activity, between 50 and 70% of
normalization and oleanolic acid showed the weakest activity, between 10 and 50 % of
normalization.
Maslinic acid and oleanolic acid which were used for anti-sickling bioassay were
isolated and characterized from Syzygium cordatum by my supervisor, Professor Shode.
Others crude extracts and pure isolated compounds were found to be non-active antisickling
agents. These included crude hexane and methanol extracts of Cajanus cajan;
crude dichloromethane extract of Callistemon viminalis; crude dichloromethane,
methanol and 80% aqueous methanol extracts of Melaleuca bracteata; crude hexane,
dichloromethane, ethyl acetate, and methanol extracts of Syzygium guineense (South
Africa); ursolic acid from Melaleuca bracteata and flavanone glycoside from Syzygium
guineense of DRC.
This is the first report of the in vitro anti-sickling activity of betunilic acid, betulinic
acid acetate, oleanolic acid, and maslinic acid
Quality and storage stability of yoghurt produced from pigeon pea milk supplemented with Propionibacterium freudenreichii
Get PDFSubmitted in fulfilment of the academic requirements for the Degree in Master's in Food Science and Technology, Durban University of Technology, Durban, South Africa, 2017.Pigeon pea (Cajanus Cajan) is consumed in many parts of Africa as a source of protein and carbohydrate. It is underutilised and mainly grown for subsistence. Researching on pigeon pea may enhance value addition and increase its utilization. In this study, a non-dairy probiotic yoghurt was prepared from pigeon pea milk. Yoghurt samples were prepared, using 100% pigeon pea milk, pigeon pea/soy milk in the ratio 50:50 and 100% soy bean milk. The yoghurts were inoculated with yoghurt starter cultures and divided into two equal parts. One part inoculated with Propionibacterium freudenreichii was referred to as probiotic yoghurt, while the other part served as the control. The nutritional, sensory and some functional properties of the yoghurt were determined. The microbiological quality of yoghurt samples stored at 4, 10 and 21°C, respectively, for 4 weeks, were monitored and analysed for aerobic spores’ formers, E. coli, total plate counts, mould and Propionibacterium freudenreichii weekly. The protein contents of the yoghurt samples varied from 4.54-5.85% for 100% soymilk and 100% pigeon pea yoghurt respectively. The probiotic yoghurt showed slightly lower protein content than pigeon pea yoghurt alone. All the yoghurt samples had considerably high total solids (16.04-17.41%) and were fairly good sources of amino acids. Essential amino acids in the yoghurt samples were comparable to the FAO/WHO (2007) recommended amino acid requirement for adults. Anti-nutritional factors of yoghurt samples were significantly lower (P≤0.05) than their milk counterparts, which may be attributed to the fermentation process. Probiotic yoghurt samples showed higher firmness than non-probiotic samples. Total plate counts (log 7.01- 7.46 CFU/ml) samples stored for 2 weeks at 4° C were similar. Predominant organisms were LAB and Propionibacterium freudenreichii. Storage temperature of yoghurt samples had an influence on the total plate count and LAB. Total plate count and LAB significant increased approximately by log 2 CFU/ml for the first two weeks of storage. However, moulds and E. coli were not detected in all samples. Beyond 2 weeks of storage, there was significant decline in total plate counts and LAB, while mould grew and increased. Aerobic spore formers and moulds were observed in the control yoghurt. However, E. coli was not found in all yoghurt samples throughout storage period. The pH of the milk in which yoghurt mixtures were formulated, ranged from pH 7 to 6.8 for pigeon pea and soymilk declined significantly as a result of acidification. Decline in pH at 4, 10 and 21°C was significant (p≤0.05) with the rate higher at 21, 10 than 4° C. Decline in pH resulted in increased TTA values over storage temperatures and periods. Samples stored at 21°C and 10°C had significantly higher TTA values than samples stored at 4° C. The colour values evaluated were recorded as L*, b*, a* and ∆E* during 4 weeks storage at 4, 10 and 21° C. Significantly high values (p≤0.05) were recorded for L* yoghurt samples with soymilk. The colour scale defines positive (red) and negative (green) for a* and b* positive (yellow) and negative (blue). All a* values both positive and negative were less than 3. There was no negative value recorded for b*. Colour difference ∆E* values trends increased as storage time and temperature increased. There were significant (p≤0.05) differences between samples stored at same and different storage temperatures and periods. Water holding capacity was significantly different (p≤0.05) in all the yoghurt samples stored at 4, 10 and 21°C for 4 weeks. Formulation with 100% soymilk recorded higher values. Soy yoghurt and probiotic yoghurts (100 %) showed higher water holding capacity compared to pigeon pea yoghurt and pigeon pea/soymilk yoghurt. The addition of Propionibacterium freudenreichii did not significantly affect sensory properties of the yoghurts. Acceptable yoghurt was produced from pigeon pea with comparable quality to soy which serves as control. Proximate composition was comparable to previous reports. Microbial quality and profile of all the yoghurt samples were similar. The absence of pathogenic bacteria in all the yoghurt samples confirm their safety. Soy yoghurt was most acceptable amongst the yoghurt samples but all the samples had comparable ratings, and these ratings are within commercially acceptable range (4 to 9) for yoghurt. Storage at 4oC should be the most acceptable, as storage at 21oC encourage proliferation of contaminant
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