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Bereiding en karakterisering van dikernige komplekse uitgaande van chroomheksakarboniel en groep 4 metalloseneVan Niekerk, Lizette 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT:
Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING:
Sien asb opsomming vir volteks
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Evaluation of pressure- and electrodriven separation techniques for the determination of phenolic compounds in wineDe Villiers, A. J. (Andre Joubert) 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: The phenolic content of wine is responsible for determining characteristics such as the
organoleptic qualities, colour stability, ageing properties and health-beneficial effects
associated with wine. The aim ofthis study was to investigate the possibilities offered by
capillary electrophoresis (CE) as an alternative separation technique to high performance
liquid chromatography (HPLC) for the analysis of polyphenols in wine. The complexity
of wine samples was the cause that neither technique was capable of a satisfactory singlestep
analysis of wine. Suitable sample preparation techniques such as Sephadex- and Sep-
Pak fractionation and ether extraction of wine polyphenols were investigated. These
techniques did not, however, prove to be universal. A novel form of sample preparation
namely a process analogous to lyophylization used to separate wine volatiles from nonvolatiles
was introduced.
The versatility of CE was further investigated in an attempt to eliminate the need for
sample preparation. The use of polyvinylalcohol (PVA) coated capillaries, micellar
electrokinetic chromatography (MEKC) and capillary gel electrophoresis (CGE) were
investigated in this regard. Although none of these techniques could offer conclusive
results, useful applications were forthcoming and routes for further investigation were
outlined. Liquid chromatography coupled to electro spray ionisation mass spectroscopy
(LC-ESI-MS) and capillary electrophoresis coupled to electro spray ionisation mass
spectroscopy (CE-ESI-MS) were compared for the analysis of polyphenols in wine.
While the latter technique could not produce sufficient separation compared to the
former, future development ofCE-ESI-MS should make it a powerful technique for these
analyses. / AFRIKAANSE OPSOMMING: Die fenoliese komponente in wyn speel 'n bepalende rol by eienskappe soos die
organoleptiese karakter, kleur stabiliteit, verouderingspotensiaal en gesondheids-voordele
wat met wyn geassosieër word. Die doel van hierdie projek was om ondersoek in te stel
na die potensiaal wat kapillêre elektroforese (CE, "capillary electrophoresis") as 'n
alternatiewe skeidingstegniek teenoor hoë druk vloeistof chromatografie (HDVC) vir die
analise van die polifenole in wyn bied. Die kompleksiteit van wyn monsters is van so 'n
aard dat 'n bevredigend enkelstap analise met geeneen van die tegnieke moontlik is nie.
Gepaste monster-voorbereidingstappe soos Sephadex- en Sep-Pak fraksionering asook
eter ekstraksie van die polifenole in wyn is ondersoek. Geeneen van die tegnieke was
egter universeel toepaslik nie. 'n Nuwe metode van monster-voorbereiding, naamlik 'n
proses analoog aan liofilisasie wat gebruik word om die wyn te skei in vlugtige en nievlugtige
komponente is gedemonstreer.
Die veelsydigheid van CE was gevolglik ondersoek in 'n poging om
monstervoorbereiding uit te skakel. Die gebruik van polyvinielalkohol-(pVA) bedekte
kapillêre, missellêre elektrokinetiese chromatografie (MEKC) en kapillêre gel
elektroforese (CGE, "capillary gel electrophoresis) is in hierdie verband ondersoek.
Alhoewel geeneen van hierdie tegnieke onweerlegbare resultate gelewer het nie, het
bruikbare toepassings hieruit voortgespruit en is die grondslag vir verdere navorsing gelê.
Vloeistof chromatografie gekoppel aan eIektrosproei ionisasie massaspektroskopie (LCESI-
MS) en kapillêre elektroforese gekoppel aan elektrosproei ionisasie massaspektroskopie
(CE-ESI-MS) is vergelyk vir die analise van polifenole in wyn. Alhoewel
laasgenoemde tegniek onvoldoende skeiding lewer vergeleke met eersgenoemde, behoort
toekomstige ontwikkelinge op die gebied van CE-ESI-MS dit 'n kragtige tegniek vir die
analise van hierdie monsters te maak.
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Chemiese karakterisering van die preorbitale afskeiding van die suni-ooi, Neotragus moschatusSpies, Anena 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT:
Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING:
Sien asb volteks vir opsomming
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New amino- and titanoxycarbene complexes of group 6 metalsHeydenrych, Greta 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2001. / ENGLISH ABSTRACT:
Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING:
Sien volteks vir opsomming
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A multinuclear (1H, 13C, 31P and 195Pt) magnetic resonance spectroscopy study of mixed ligand platinum(II) complexes with new N,N-dialkyl-N'-acyl(aroyl)thioureas as ligandsMtongana, Sibusiso 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT:
Please refer to fulltext for abstract / AFRIKAANSE OPSOMMING:
Sien asb volteks vir opsomming
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An Ab Initio density functional study of the structure and stability of transition metal ozone complexesVenter, Gerhard (Gerhard Abraham) 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: A thorough search through the literature as well as through the Cambridge Crystallographic
Structural Database resulted in no examples of a neutral ozone acting as ligand in a complex
with any metal. Ionic compounds containing ozonide as anionic species, however, are well
known throughout the literature and not surprisingly the only result for 0₃ and a metal in the
CCSD was an ionic rubidium ozonide compound.
What follows is a systematic study into the result of placing an ozone ligand within
complexing distance of a transition metal (the first transition row from titanium to copper). Due
to the novelty of the system, as first approximation four different orientations of the ozone ligand
relative to the metal (a metal cation in these calculations) were investigated. It was found that
coordination through the terminal oxygens resulted in energy minima for all the metal cations,
although not necessarily the absolute energy minimum on the potential energy surface for the
specific cation. A further structural study was done by adding carbonyl and hydrogen ligands to
the system, according to the 18-electron rule. For these calculations coordination through the
terminal oxygens was employed. In both series the dissociation energy was also calculated. The
dissociation energies for the M(CO)nHm(0₃) complexes were all positive, indicating that they are
theoretically stable structures.
The resulting wave functions were then analysed with the help of three techniques: Atoms
in Molecules (AIM), Charge Decomposition Analysis (CDA) and Natural Bond Orbital Analysis
(NBO). AIM showed that bonds were indeed formed between the ozone ligand and the transition
metal and hinted that the bonding model can be interpreted with the Dewar-Chatt-Duncanson
(DCD) model of σ-donation and л-back donation. CDA confirmed that this was the case. NBO
results proved erroneous due to the largely delocalized electronic structure of the complexes. / AFRIKAANSE OPSOMMING: 'n Deeglike soektog deur die literatuur en die Cambridge Crystallographic Structural Database
het geen resultate gelewer van komplekse waarin 'n neutrale osoonligand komplekseer met 'n
metaal nie. Ioniese verbindings waarin die osonied as anioon optree, is wel bekend deur die
literatuur en die enigste resultaat in die CCSD - vir 'n soektog bevattende osoon en 'n metaal -
het 'n rubidiumosonied-verbinding opgelewer.
Wat volg is 'n stelselmatige studie om die effek te ondersoek indien 'n osoonligand naby
genoeg aan 'n oorgangsmetaal geplaas word om kompleksering te bevoordeel (metale wat
gebruik is, is die eerste oorgangsreeks vanaf titanium tot koper). As gevolg van die onbekendheid
van die sisteem is vier verskillende oriëntasies van die osoonligand relatied tot die metal ('n
metal katioon in die geval) as beginpunt ondersoek. Daar is gevind dat koordinasie deur die
terminale suurstowwe van die osoonligand vir al die metal katione lei tot energie minima,
alhoewel dié minima nie noodwendig die globale minima op die potensiële energie oppervlaktes
van die katione is nie. 'n Verdere studie is gedoen deur karboniel- en waterstofligande tot die
sisteem te voeg, gelei deur die 18-elektron reel. Vir hierdie berekeninge is koördinasie deur die
terminale suurstowwe gebruik. In beide reeks is dissosiasie-energieë bereken. Die dissosiasie energieë
van die M(CO)nHm(0₃) komplekse was deurgaan positief wat aandui dat die komplekse
teoreties stabiel is.
Die verkrygde golffunksies is hierna analiseer deur middel van drie tegnieke: Atoms in
Molecules (AIM), Charge Decomposition Analysis (CDA) en Natural Bond Orbital Analysis
(NBO). AIM het getoon dat bindings inderdaad gevorm word tussen die osoonligand en die metal
en bet die moontlikheid laat ontstaan dat die bindingsmodel volgens die Dewar-Chatt-Duncason
(DCD) model van σ-donasie en л-terugdonasie geïnterpreteer kan word. Hierdie waarneming is
bevestig deur CDA. NBO resultate kon nie suksesvol gebruik word nie as gevolg van die hoë
graad van electron delokalisasie van die komplekse.
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Amino acid analysis in wines by liquid chromatography : UV and fluorescence detection without sample enrichmentDouglas, C. A. (Claire Anne) 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: In this study, the analysis of ammo acids usmg High Performance Liquid
Chromatography (HPLC) with pre-column derivatisation was optimised. The
derivatisation reagents include o-phthaldialdehyde (OPA), 9-
fluorenylmethylchloroformate (FMOC) and iodoacetic acid (IDA). Detection was
performed using UV and fluorescence in series. The developed method was utilised
for the analysis and quantitation of amino acids in eighteen wines. The application of
chemometric data evaluation was initiated. / AFRIKAANSE OPSOMMING: Hierdie ondersoek behels die optimisering van die aminosuuranalise deur gebruik te
maak van Hoë Druk Vloeistof Chromatografie (HDVC) in kombinasie met pre-kolom
derivatisering. Die derivativatiserings reagense sluit in o-phthaldialdehied (OPA), 9-
fluorenielmetielchloroformaat (FMOC) en jodoasynsuur (IDA). Deteksie is gedoen
deur gebruik gemaak van 'n ultraviolet (UV) en 'n fluorosensie detektor in serie. Die
metode sodoende ontwikkel is gebruik vir die analise en kwantifisering van aminosure
in agtien wyne. Die toepassing van chemometriese data evaluasie is ook geïnisieer.
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Synthesis of chiral thiourea ligands and their transition metal complexesGhebregziabiher Berhe, Haile 12 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Modification of chitosan with benzoylisothiocyanate was attempted, however due to
solvent problem the study was left incomplete till appropriate solvent is designed.
N,N-diethyl-N -camphanoylthiourea (HL8), N-piperidyl-N '-camphanoylthiourea (HL9),
N-pyrrolidyl-N -camphanoylthiourea (HL10) and N,N-diethyl-N -adamantylcarbonyl
thiourea (HL11)have been synthesised and characterised for the first time. Two of
these ligands HL8 and HL11, were used to form a number of transition metal
complexes, namely H30+{fae-[Co(L8-S,Obn, cis-[Ni(L8-S,0)2], trans-[Cu(L8-S,0)2],
translcis-[Zn(L 8_S,0)2], translcis-[Pt(L 8_S,0)2], Ag2[(HL8-S)(L-J.1-S,O)]2, translcis-
[Ni(L11-S,O)2]and translcis-[Cu(L11_S,O)2]. The new products are fully characterised
by means of MS, IR spectroscopy, NMR spectroscopy, elemental (C, H, Nand S)
analysis and melting point determinations. The H30+{fae-[Co(L8-S,Obn, cis-[Ni(L8-
S,O)2], trans-[Cu(L8-S,O)2] and Ag2[(HL8-S)(L-J.1-S,O)]2 are also characterised by Xray
diffraction analysis.
The structure of the new chiral N,N-dialkyl-N' -camphanoylthiourea ligand (HL8) has a
significant effect on its coordination chemistry with transition metal ions. This ligand
forms H30+ {fae-[Co(L8-S,Obn, cis-[Ni(L8-S,0)2], trans-[Cu(L-S,O)2] and Ag2[(HL8-
S)(L8-J.1-S,O)]2 complexes with the Co(II), Ni(II), Cu(II) and Ag(I) metal ions
respectively. The spectroscopic and X-ray diffraction results of these complexes
indicate a bidentate mode of coordination of the ligand (with its Sand °donor
atoms) to the Co(II), Ni(II) and Cu(II) metal ions. The reaction of this ligand with
silver(I) however affords the formation of a binuclear silver(I) complex exhibiting
monodentate and bidentate modes of coordination within the same complex. The
exclusive formation of trans-[Cu(L8-S,0)2] is a new phenomenon for the HL type
thiourea ligands with Sand °donor atoms. Up to this point a maximum of 15 %
trans-isomer has been reported in ltterature."
All the transition metal complexes made with HL8and HL11are air stable in both the
liquid and solid states except the H30+{fae-[Co(L 8-S,Ob]} Interestingly the deep
green fae- H30+{fae-[Co(L8-S,Obn complex is air sensitive and the Co(II) oxidizes to
Co(III) in the complex by atmospheric O2. The oxidation of Co(II) to Co(III) in the
complex is confirmed by 1Hand 13CNMR spectra as well as by UV-Visible spectra of the complex. The NMR spectra of the complexes indicated the presence of one
isomer in each complex except for the NMR spectra of the platinum complex of the
HL8 ligand. The presence of the minor trans-[Pt(L8-S,Q)21 isomer in combination with
the major cis-[Pt(L8-S,Q)21 isomer in the platinum complex was indicated by the 1H,
13Cand 195ptNMR spectra of the complex. / AFRIKAANSE OPSOMMING: Pogings om chitosan met benzoylisothiocyanate te modifiseer is onvoltooid gelaat
weens die gebrek aan'n geskikte oplosmiddel.
N,N-diethyl-N -carnphanoylthiourea (HL8), N-piperidyl-N -camphanoylthiourea (HL9),
N-pyrrolidyl-N -camphanoylthlourea (HL10) en N,N-diethyl-N -adamantylcarbonyl
thiourea (HL11) is vir die eerste keer gesintetiseer en gekarakteriseer. Twee van die
ligande, HL8 en HL11, is gebruik om verskeie oorgangsmetaalkomplekse te berei, nl.
H30+{fac-[Co(L8-S,Ohn, cis-[Ni(L8-S,0)2], trans-[Cu(L8-S,0)2], trans/cis-[Zn(L8
-
S,0)2], trans/cis-[Pt(L8-S,0)2], Ag2[(HLB-S)(L-jl-S,0)]2, trans/cis-[Ni(L11-S,0)2] en
trans/cis-[Cu(L11_S,0)2]. Die nuwe produkte is volledig gekarakteriseer deur middel
van MS, IR spektroskopie, KMR spektrometrie, elemente (C, H, N en S) analise en
smeltpuntbepaling. Die komplekse H30+{fao-[Co(L8-S,0)3n, cis-[Ni(L8-S,0)2], trans-
[Cu(L8-S,0)2] en Ag2[(HLB-S)(L-jl-S,0)]2 is ook deur middel van X-straaldiffraksieanalise
gekarakteriseer.
Die struktuur van die nuwe chirale N,N-dialkyl-N'-camphanoylthiourea ligand (HL8)
het In beduidende invloed op die koordinasie van hierdie ligand met
oorgangsmetaalione. Die ligand vorm H30+{fac-[Co(L8-S,Ohn, cis-[Ni(L8-S,0)2],
trans-[Cu(L-S,0)2] en Ag2[(HL8-S)(L8-Il-S,0)]2 komplekse met Co(ll)-, Ni(II)-, Cu(II)-
en Ag(I)-ione respektiewelik. Spektroskopiese en X-straaldiffraksie-analise van die
komplekse toon dat die ligande op 'n bidentate wyse d.m.v. die S- en O-donoratome
met Co(II), Ni(lI) en Cu(lI) koordineer. Die reaksie van hierdie ligand met Ag(I)-ione
lei egter tot die vorming van 'n dikernige silwer(I)-kompleks waarin die ligande
monodentaat (S) en bidentaat (S en 0) aan die metaal gebind is. Die vorming van
uitsluitlik die trans-[Cu(L8-S,0)2] in die reaksie van HL8 met Cu(lI) is 'n besondere
fenomeen in die chemie van hierdie tipe ligande; in die literatuur word melding
gemaak van slegs een ander trans-kompleks met hierdie ligande, en dan wel met 'n
maksimum opbrengs van 15%.29
Alle oorgangsmetaalkomplekse met HLB en HL11 is stabiel indien blootgestel aan lug,
ongeag of die verbindings opgelos word of in die vastetoestand verkeer, behalwe
H30+{fao-[Co(L8-S,Ohn. Die diep-groen gekleurde H30+{fao-[Co(L8-S,Ohn)3]} kompleks is lugsensitief; Co(lI) word deur lugsuurstof na Co(lIl) ge-oksideer. Die
oksidasie in die kompleks kan deur middel van 1H en 13CKMR spektrometrie sowel
as UV-sigbare spektrofotometrie bevestig word. Die KMR spektra van alle komplekse
dui op die teenwoordigheid van slegs een isomeer in oplossing, behalwe in die geval
van die platinum(lI) kompleks met HL8. Die teenwoordigheid van lae konsentrasies
trans-[Pt(L8-S,0)2] isomeer tesame met veel hoër konsentrasies van die cis-[Pt(L8
-S,O)2] isomeer word deur 1H, 13Cen 195ptKMR spektroskopie aangedui.
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Chemical characterisation of the uropygial secretion of Rhinopomastus cyanomelasGhebrealfa Kahsai, Negassi 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The uropygial gland of most birds produces a variety of hydrocarbons,
lipids, waxes, fatty acids, alcohols and other organic compounds. These
compounds have two widely recognized functions, viz. they are considered
essential for the maintenance of a good plumage condition, and may be used
for fungicidal, bactericidal or other hygienic purposes.
Scimitar-billed woodhoopoes, Rhinopomastus cyanomelas, are groupterritorial
birds that live in groups comprising between two and twelve
individuals. Individuals enter the roost cavities shortly after sunset and exit the
following morning soon after sunrise. During the period that the birds are
inside the roost, they are vulnerable to a range of vertebrate predators,
including snakes, genets and rats. When disturbed while roosting,
woodhoopoes immediately face away from the threat hence presenting their
uropygial glands in the direction of the threat. Typically, a drop of brown, highly
pungent secretion is then formed at the tip of the papilla to the uropygial gland,
and kept in place by a few tuft-like feathers. This response pattern has led
some observers to believe that the secretion serves an anti-predatory role. It
has been found that the synthetic volatile constituents of the uropygial
secretion of the green woodhoopoe, P. purpureus, individually or as a mixture,
have potent defensive properties against feline and reptilian predators. In
addition, the compounds also showed activity against a range of bacteria.
The aim of the present study was to determine the chemical composition
of the uropygial secretion of the scimitar-billed woodhoopoe, Rhinopomastus
cyanomelas, as a first step towards the evaluation of, inter alia, the
semiochemical function of the secretion. Using gas chromatography-mass
spectrometry, 179 constituents of the uropygial secretion of the scimitar-billed
woodhoopoe have been identified. The majority of the constituents of the
secretion are branched and unbranched aldehydes (aliphatic and aromatic),
acids (aliphatic and aromatic), sulfides and ketones. This group of volatile
compounds is responsible for the obnoxious odour of the secretion and possibly also for its defensive action against predators. The secretion also
contains a large number of branched and unbranched alkanes and wax esters.
The chemical composition of the secretion was compared with the
secretion of P. purpureus as well as with that of the hoopoe, Upupa africana.
The uropygial gland secretion of the scimitar-billed woodhoopoe is quite
similar to that of the green woodhoopoe, although it is much more complex
than that of the green woodhoopoe. In contrast to the uropygial secretions of
the green and the scimitar-billed woodhoopoes, the secretion of Upupa
africana does not have a strongly obnoxious odour and it also does not contain
large quantities of alkanes and wax esters. / AFRIKAANSE OPSOMMING: Die uropigiale klier van die meeste voëls produseer 'n verskeidenheid
van koolwaterstowwe, lipiede, was-esters, vetsure, alkohole en ander
organiese verbindings. Hierdie verbindings het twee algemeen erkende
funksies, naamlik die instandhouding van die goeie kondisie van die vere, en
'n swam- en kiemdodende werking.
Swartbekkakelaars (Engels: scimitar-billed woodhoopoes ),
Rhinopomastus cyanomelas, is groep-territoriale voëls wat in groepe van
tussen twee en twaalf saam woon. Individue gaan hul neste net na sononder
binne en verlaat dit weer die volgende oggend net na sonsopkoms. Terwyl die
voëls binne die neste is, is hulle kwesbaar ten opsigte van aanval deur
verskeie gewerwelde roofdiere, insluitende slange, muskeljaatkatte en rotte.
Wanneer hulle in hul neste gesteur word, sal kakelaars onmiddellik wegdraai
van die bedreiging sodat die uropigiale klier in die rigting van die bedreiging
gekeer is. 'n Druppel bruin, uiters onwelriekende afskeiding vorm dan by die
punt van die papil na die uropigiale klier, en word in posisie gehou deur 'n
verekwassie. Hierdie gedragspatroon het aanleiding gegee tot die gedagte by
sommige waarnemers dat die afskeiding as afweerstof teen roofdiere dien.
Daar is gevind dat die sintetiese vlugtige komponente van die uropigiale
afskeiding van die groenkakelaar, P. purpureus, individueel of as 'n mengsel,
sterk afweer-eienskappe teen katte en reptiele toon. Daarbenewens het die
verbindings ook aktiwiteit getoon teen 'n reeks van bakterieë.
Die doel van die huidige studie was om die chemiese samestelling van
die uropigiale afskeiding van die swartbekkakelaar, Rhinopomastus
cyanomelas, te bepaal as 'n eerste stap met die oog op die evaluering van,
onder andere, die semiochemiese funksie van die afskeiding. Deur van
gaschromatografie-massaspektrometrie gebruik te maak, is 179 komponente
van die uropigiale afskeiding van die swartbekkakelaar geïdentifiseer. Die
meeste van die komponente is vertakte en onvertakte aldehiede (alifaties en
aromaties), sure (alifaties en aromaties), sulfiede en ketone. Hierdie groep
vlugtige verbindings is verantwoordelik vir die afstootlike reuk van die afskeiding en waarskynlik ook vir sy afweer-aksie teen roofdiere. Die
afskeiding bevat ook 'n groot aantal vertakte en onvertakte alkane en wasesters.
Die chemiese samestelling van die afskeiding is vergelyk met die van P.
purpureus sowel as dié van die hoepoe, Upupa africana. Die uropigiale
klierafskeiding van die swartbekkakelaar stem tot 'n groot mate ooreen met dié
van die groenkakelaar, alhoewel dit veel meer kompleks is as dié van die
groenkakelaar. In teenstelling met die uropigiale afskeidings van die groen- en
die swartbekkakelaars, het die afskeiding van Upupa africana nie 'n afstootlike
reuk nie en bevat dit ook nie groot hoeveelhede alkane en was-esters nie.
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The role of micro-organisms in the production of semiochemicals in the interdigital secretion of the bontebok, Damaliscus pygargus pygargusScott, Gary Terri 03 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Bontebok, Damaliscus pygargus pygargus, formerly classified as D. dorcas
dorcas, are territorial animals with interdigital glands between the toes of the
forelegs. Males regularly defecate on dung heaps, on which they often lie, to
communicate with other members of their species. They also communicate by
means of visual displays, scent marking and occasionally with scraping or
pawing of dung heaps. It is assumed that scent marking with the interdigital
secretion serves to define territories frequented by these antelope. These
glands secrete a complex mixture of volatile and non-volatile compounds and
the volatile compounds in the secretion serve as a chemical signal for other
bontebok.
It has been suggested that the interdigital secretion is not produced in its final
composition by the interdigital gland alone, but that microbial activity is
responsible for many of the compounds present in the secretion. In general,
many compounds can be attributed to the by-products of microbial hydrolysis
of triglycerides, a common characteristic of sebum. It is well documented that
micro-organisms inhabit the deep recesses of sebaceous glands and the
presence of micro-organisms has been found to be consistent in all antelope
exocrine glandular areas.
This study involved the chemical characterisation of the volatile metabolites
produced in vitro by micro-organisms from the interdigital cavity of the
bontebok.
Various comparative studies were made, one of which was comparison of the
metabolites produced by the individual microbial species as well as the total
community of bacteria incubated in different media. A comparison of the compounds identified in the interdigital secretion and the metabolites produced
by the micro-organisms in the different media was also made.
The volatile metabolite extracts of the individual bacterial species and of the
total community were chemically characterised by low-resolution gas
chromatography-mass spectroscopy. Classes of compounds identified from
the volatile metabolite extracts include:
• Acids - Aliphatic (saturated and unsaturated)
• Alcohols - Aliphatic (saturated and unsaturated)
• Aldehydes - Aliphatic (saturated and unsaturated)
• Aromatic compounds
• Ketones - Aliphatic (saturated and unsaturated)
• Pyrazines
• Dimethyldisulphide
• Squalene and cholesterol
Several qualitative differences were found between the compounds identified in
the volatile metabolite extracts of the micro-organisms when incubated in
tryptic soy broth (TSB) and minimal salt medium (MSM). In particular, when the
microbes were incubated in TSB medium a number of pyrazines were found
that were not present when utilising MSM as a medium.
Additional qualitative differences were found between the compounds identified
in the metabolite extracts of the individual bacterial species and the total
community of bacteria, when incubated in both TSB and MSM media.
A comparison of the interdigital secretion and the metabolite extracts of the
microbial communities incubated in TSB and MSM revealed that many compounds produced in MSM corresponded to the compounds identified in the
interdigital secretion. These corresponding compounds were found to be
saturated and unsaturated acids, aldehydes and squalene. Furthermore, there
was only one corresponding compound in the case of TSB as medium. / AFRIKAANSE OPSOMMING: Die bontebok, Damaliscus pygargus pygargus, voorheen geklassifiseer as D.
dorcas dorcas, is 'n territoriale dier met interdigitale kliere tussen die kloutjies
van die voorpote. Ramme ontlas gereeld op mishope, waarop hulle dikwels lê,
om met ander lede van die spesie te kommunikeer. Hulle kommunikeer ook
deur middel van visuele seine, reukmerking en soms deur mishope met die
voorpote te kap of te skraap. Reukmerking met die interdigitale afskeiding dien
klaarblyklik om gebiede wat deur hierdie diere bewoon word, af te baken. Die
interdigitale kliere skei 'n komplekse mengsel van vlugtige en nie-vlugtige
verbindings af en die vlugtige verbindings dien as chemiese sein vir ander
bontebokke.
Die vermoede bestaan dat die interdigitale klier nie alleen verantwoordelik is vir
die finale samestelling van die interdigitale afskeiding nie, maar dat
mikrobiese aktiwiteit bydra tot die produksie van baie van die verbindings wat
in die afskeiding aanwesig is. Sekere verbindings kan in die algemeen
toegeskryf word aan die vorming van die neweprodukte van mikrobiese
hidrolise van trigliseriede, 'n algemene eienskap van sebum. Dit is bekend dat
die diep holtes van vetkliere 'n goeie teelaarde is vir mikroorganismes en daar
is gevind dat mikroorganismes feitlik deurgaans voorkom in alle anteloop
eksokriene klierareas.
Hierdie studie behels die chemiese karakterisering van die vlugtige metaboliete
wat in vitro deur mikroorganismes van die interdigitale klierholte van die
bontebok geproduseer word.
Verskeie vergelykende studies is uitgevoer waarvan een die vergelyking was
van die metaboliete wat deur die individuele mikrobiese spesies sowel as die totale gemeenskap van bakterieë geproduseer word tydens inkubasie in
verskillende media. Vergelyking van die verbindings wat in die interdigitale
afskeiding geïdentifiseer is met die metaboliete wat in verskillende media
geproduseer is, het ook deel van die studie uitgemaak.
Die vlugtige metaboliet ekstrakte van die individuele bakteriese spesies en van
die totale gemeenskap is chemies gekarakteriseer deur middel van laeresolusie
gaschromatografie-massaspektrometrie. Die volgende groepe
verbindings is onder andere in die vlugtige metaboliet ekstrakte geïdentifiseer:
• Sure - Alifaties (versadig en onversadig)
• Alkohole - Alifaties (versadig en onversadig)
• Aldehiede - Alifaties (versadig en onversadig)
• Aromatiese verbindings
• Ketone - Alifaties (versadig en onversadig)
• Pirasiene
• Dimetieldisulfied
• Skwaleen en cholesterol
Verskeie kwalitatiewe verskille is gevind tussen die verbindings wat
geïdentifiseer is in die vlugtige metaboliet ekstrakte van die mikroorganismes
onderskeidelik in TSB medium en MSM geïnkubeer. Opvallend was
byvoorbeeld die voorkoms van pirasiene in gevalle waar mikroorganismes in
TSB medium geïnkubeer is, terwyl hierdie groep verbindings afwesig was
wanneer MSM gebruik is.
Onderlinge kwalitatiewe verskille is ook gevind tussen die verbindings wat
geïdentifiseer is in die metaboliet ekstrakte van die individuele bakteriese spesies en die totale gemeenskap van bakterieë, wanneer in TSB medium
sowel as in MSM geïnkubeer is.
Vergelyking van die verbindings in die interdigitale afskeiding en in die
metaboliet ekstrakte van die mikrobiese gemeenskappe, het getoon dat 'n
aantal verbindings wat in MSM geproduseer is, ooreenstem met verbindings
wat in die interdigitale afskeiding geïdentifiseer is. Daar is gevind dat hierdie
verbindings versadigde en onversadigde sure en aldehiede en skwaleen is.
Met TSB as medium was daar slegs een ooreenstemmende verbinding.
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