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The inhibitory effect of rooibos on cytochromes P450 and downstream in vitro modulation of steroid hormonesMugari, Mufaro Buhlebenkosi 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This study describes:
1. Substrate binding assays investigating the effects of methanolic extracts of
unfermented and fermented Rooibos on the binding of natural substrates to ovine
adrenal microsomal and mitochondrial P450 enzymes, demonstrating the interference
of substrate binding in the presence of the Rooibos extracts.
2. The effects of selected flavonoids (quercetin, rutin and aspalathin) on the binding of
natural substrates to ovine adrenal microsomal and mitochondrial P450 enzymes,
demonstrating interference of substrate binding in the presence of the flavonoid
compounds.
3. Substrate conversion assays in non-steroidogenic COS-1 cells to investigate the
effects of methanolic extracts of unfermented and fermented Rooibos on the activity
of key steroidogenic P450 enzymes (CYP17A1, CYP21A2, CYP11B1, and
CYP11B2), demonstrating inhibition of the catalytic activity in the presence of
Rooibos extracts.
4. The effects of selected flavonoids on the substrate conversion of the aforementioned
key steroidogenic enzymes expressed in COS-1 cells.
5. An investigation of the effect of methanolic extracts of unfermented and fermented
Rooibos on steroid hormone production in human adrenal H295R cells under basal
and stimulated conditions, demonstrating the modulating effects of unfermented and
fermented Rooibos extracts. Basal and stimulated steroid hormone production was
decreased in the presence of unfermented and fermented Rooibos. / AFRIKAANSE OPSOMMING: Hierdie studie beskryf:
1. Die gebruik van substraatbindings-essais om die effek van metanoliese ekstrakte, van
gefermenteerde- en ongefermenteerde Rooibos, op die binding van die natuurlike
substrate aan skaap adrenale mikrosomale en -mitochondriale P450 ensieme te bepaal.
Daar is getoon dat die ekstrakte 'n beduidende inhiberende effek op ensiemsubstraatinteraksie
gehad het.
2. Die die inhiberende effek van geselekteerde flavonoïede (kwersetien, rutien and
aspalatien) op die binding van die natuurlike substrate aan skaap adrenale
mikrosomale en -mitochondriale P450 ensieme.
3. Die gebruik van substraatomsettings-essais in nie-steroïedogeniese COS-1 selle, om
die effek van gefermenteerde- en ongefermenteerde Rooibos ekstrakte op die
aktiwiteit van die steroïedogeniese P450 ensieme (CYP17A1, CYP21A2, CYP11B1,
and CYP11B2) se katalitiese aktiwiteit te bepaal. Daar kon aangetoon word dat die
katalitise aktiwiteite van bg. ensieme beduidend beïnvloed word deur die Rooibos
ekstrakte.
4. Die gebruik van substraatomsettings-essais in nie-steroïedogeniese COS-1 selle, om
die effek van geselekteerde flavonoïede op die aktiwiteit van bogenoemde
steroïedogeniese P450 ensieme te bepaal.
5. 'n Ondersoek na die invloed van metanoliese ekstrakte van gefermenteerde- en
ongefermenteerde Rooibos op steroïedhormoon biosintese in die menslike adrenale
H295R-selmodel. Die ondersoek, onder basale en gestimuleerde toestande, het getoon
dat beide Rooibosekstrakte in bogenoemde toestande steroïedhormoon produksie
geinhibeer het.
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An investigation into the influence of rooibos (Aspalathus linearis) on androgen metabolism in normal and prostate cancer cellsDu Toit, Therina 04 1900 (has links)
Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: In this study, the influence of rooibos on the catalytic activity of enzymes 17β -hydroxysteroid dehydrogenase type 3 (17βHSD3), 17β-hydroxysteroid dehydrogenase type 5 (AKR1C3),
17β-hydroxysteroid dehydrogenase type 2 (17βHSD2), 5α-reductase type 1 (SRD5A1) and
5α-reductase type 2 (SRD5A2), which catalyse prostate androgen metabolism, was investigated.
The activities of both 17βHSD3 and AKR1C3 heterologously expressed in CHO-K1 and HEK293
cells were inhibited significantly by rooibos, with rooibos reducing the conversion of
androstenedione (A4) and 11keto-androstenedione (11KA4) to testosterone (T) and 11ketotestosterone
(11KT), respectively. The catalytic activity of 17βHSD2 towards T, 11hydroxytestosterone
(11OHT) and 11KT was also significantly inhibited by rooibos in transiently
transfected HEK293 cells. In transiently transfected HEK293 cells rooibos did not inhibit SRD5A1
while the rate of T conversion to dihydrotestosterone (DHT) by SRD5A2 was decreased. Analysis
of steroid metabolism in PNT2 cells also suggests that rooibos does not modulate the catalytic
activity of endogenously expressed SRD5A towards A4, however, the conversion of T to DHT was
reduced. In addition, reductive 17βHSD activity towards A4 was inhibited in the presence of
rooibos in both PNT2 and BPH-1 cells. In contrast, the conversion of 11KA4 to 11KT was inhibited
in BPH-1, PC-3 and LNCaP cells, with negligible conversion of 11KA4 in PNT2 cells. Interestingly,
data suggests inhibition of 3α-hydroxysteroid dehydrogenase type 3 (AKR1C2) activity in the
production of androsterone (AST) from 5α–androstenedione (5α-dione), as well as the dehydrogenase reaction of T to A4 in PNT2 cells by rooibos. Androgen metabolism pathways were
subsequently investigated in LNCaP cells to determine androgen metabolism by endogenous
enzymes. Rooibos resulted in the reduced conversion of A4 in LNCaP cells to the same extent as
indomethacin, a known AKR1C3 inhibitor. Rooibos also modulated T, DHT and AST metabolism in
LNCaP cells. Furthermore, uridine diphosphate glucuronosyltransferase (UGT) activity in LNCaP
cells was inhibited by rooibos, decreasing T-, DHT– and AST-glucuronide formation. These data
prompted subsequent investigations into the influence of rooibos at cellular level, and prostatespecific
antigen (PSA) levels were assayed in the presence of rooibos. PSA was significantly
inhibited by rooibos in the absence and presence of DHT, suggesting possible interaction of
rooibos with the mutated androgen receptor (AR) or estrogen receptor-β (ERβ) expressed in
LNCaP cells.
Taken together, rooibos inhibited the catalytic activity of key enzymes that catalyse the activation
of androgens in the prostate, as well as inhibiting enzymes involved in the conjugation of
androgens. At cellular level, PSA levels were also decreased by rooibos, possibly through AR or
ERβ interactions – clearly indicating a modulatory role for rooibos in active androgen production. / AFRIKAANSE OPSOMMING: In hierdie studie was die invloed van rooibos ten opsigte van die katalitiese aktiwiteite van die
ensieme 17β-hidroksi-steroïed-dehidrogenase tipe 2, tipe 3 en tipe 5 (17βHSD2, 17βHSD3,
AKR1C3), asook 5α-reduktase tipe 1 en tipe 2 (SRD5A1, SRD5A2) ondersoek. Hierdie ensieme is
betrokke in die produksie van androgene in die prostaat. Rooibos het die katalitiese aktiwiteit van
17βHSD3 en AKR1C3 in CHO-K1 en HEK293 selle beïnvloed en het vermindere omskakeling van
androstenedioon (A4) en 11keto-androstenedioon (11KA4) na testosteroon (T) en 11-ketotestosteroon
(11KT), afsonderlik, veroorsaak. Die katalitiese aktiwiteit van 17βHSD2 teenoor T,
11-hidroksie-testosteroon (11OHT) en 11KT was ook beïnvloed in die teenwoordigheid van rooibos
in HEK293 selle. Die katalitiese aktiwiteit van SRD5A1 teenoor A4 en T is nie beïnvloed deur
rooibos nie, alhoewel dit voorkom asof rooibos die omsettingstempo van T na dihidrotestosteroon
(DHT) deur SRD5A2, getransfekteer in HEK293 selle, verminder het. Verdere ondersoeke is in
normale prostaat epiteel selle, in die teenwoordigheid van rooibos uitgevoer. Rooibos het geen
invloed op die katalitiese aktiwiteit van SRD5A teenoor A4 gehad nie, alhoewel vermindere
omskakeling van T na DHT aangetoon kon word. Rooibos het ook die omskakeling van A4 na T in
beide PNT2 en BPH-1 selle tot „n mate geïnhibeer. Die omskakeling van 11KA4 na 11KT was ook
verminder in BPH-1, PC-3 en LNCaP selle. Die omskakeling van 11KA4 na 11KT was beduidend
laer in PNT2 selle en kon die invloed van rooibos nie aangetoon word nie. Bykomende data toon
dat rooibos ook die omskakeling van 5α-androstenedioon (5α-dione) na androsteroon (AST),
gekataliseer deur 3α-hidroksi-dehidrogenase tipe 3 (AKR1C2), verminder, gesamentlik met die
vermindere omskakeling van T na A4, deur 17βHSD2, in PNT2 selle. Hierdie studie het ook
ondersoek ingestel, na die metabolisme van androgene in LNCaP selle. Vermindere A4
metabolisme is in die teenwoordigheid van rooibos asook in die teenwoordigheid van
indometasien, „n bekende AKR1C3 inhibitor, gevind. Rooibos verminder dus die aktiwiteit van
reduktiewe 17βHSD in LNCaP selle. Verandering in die metabolisme van T, DHT en AST in
LNCaP selle, in die teenwoordigheid van rooibos, is ook gevind. Verdere ondersoek in LNCaP
selle het gewys dat rooibos „n vermindering in die produksie van gekonjugeerde T, DHT en AST
veroorsaak. Die studie het die invloed van rooibos op prostaat-spesifieke antigeen (PSA) ook
ondersoek. Daar is vasgestel dat rooibos die vlakke van PSA verminder in die afwesigheid en
teenwoordigheid van DHT in LNCaP selle. Hierdie resultaat dui op moontlike interaksie van
rooibos met die androgeen (AR) of estrogeen-reseptor-β (ERβ), teenwoordig in LNCaP selle.
Rooibos het die katalitiese aktiwiteit van ensieme, wat bydra tot androgeen produksie, geïnhibeer,
asook die konjugasie van androgene. Op „n sellulêre vlak, het rooibos die vlakke van PSA-sekresie
verminder, wat moontlike interaksie met die AR en ERβ aandui. Hierdie bevindings dui daarop dat
rooibos wel n rol het om te speel in die modulasie van aktiewe androgene in die prostaat.
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The inhibition of adrenal steroidogenic enzymes and modulation of glucocorticoid levels in vitro and in vivo by aspalathus linearis (rooibos)Schloms, Lindie 04 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This study describes:
• the influence of a methanolic extract of unfermented Rooibos and five major
Rooibos flavonoids, aspalathin, nothofagin, rutin, orientin and vitexin, on the
activities of key adrenal steroidogenic enzymes - cytochrome P450 17β-
hydroxylase/17,20-lyase (CYP17A1), 3β-hydroxysteroid dehydrogenase
• the development of a novel UPLC-MS/MS method for the separation and
quantification of 21 adrenal steroid metabolites;
• the influence of Rooibos and aforementioned flavonoids on adrenal steroid
hormone production in H295R cells - a human adrenal carcinoma cell line
expressing the enzymes catalysing the production of mineralocorticoids,
glucocorticoids and adrenal androgens, assayed under both basal (normal)
and forskolin-stimulated (stressed) conditions;
• the influence of Rooibos on the inter-conversion between cortisol and
cortisone by 11βHSD1 and 11βHSD2 expressed in CHO-K1 cells;
• the influence of Rooibos consumption on circulating steroid hormone levels
and ratios in male Wistar rats;
• the influence of Rooibos consumption on circulating steroid hormone levels
and ratios in male and female human test subjects at risk for developing
cardiovascular disease.
(3βHSD2), cytochrome P450 21-hydroxylase (CYP21A2) and cytochrome
P450 11β-hydroxylase (CYP11B1), expressed in non-steroidogenic COS-1
cells; / AFRIKAANSE OPSOMMING: Hierdie studie beskryf:
• die invloed van metanoliese ekstrakte van ongefermenteerde Rooibos en vyf
van die hoof flavonoïedverbindings in Rooibos, aspalatien, notofagien, rutien,
oriëntien en viteksien, op die aktiwiteite van ensieme wat steroïedbiosintese
in die bynier kataliseer – sitochroom P450 17α-hidroksilase/17,20-liase
(CYP17A1), 3β-hidroksisteroïed dehidrogenase (3βHSD2), sitochroom P450
21-hidroksilase (CYP21A2) en sitochroom P450 11β-hidroksilase (CYP11B1),
uitgedruk in nie-steroïed produserende COS-1 selle;
• die ontwikkeling van ‘n geskikte UPLC-MS/MS metode vir die skeiding en
kwantifisering van 21 steroïedmetaboliete in die bynier;
• die invloed van Rooibos en die bg. flavonoïede op steroïedproduksie in
H295R selle – ‘n menslike bynier kanker sellyn gekenmerk deur die
ekspressie van die steroidogeniese ensieme wat die produksie van
mineralokortikoïede, glukokortikoïede en bynierandrogene kataliseer, geanaliseer
onder beide basale (normale) en forskoliengestimuleerde
(gestresde) kondisies;
• die invloed van Rooibos op die omeenskakeling tussen kortisol en kortisoon
deur 11βHSD1 and 11βHSD2 in CHO-K1 selle;
• die invloed van Rooibosinname op vlakke van sirkulerende steroïed hormone
en relatiewe verhoudings in die bloed van manlike Wistarrotte;
• die invloed van Rooibosinname op sirkulerende steroïed hormoon vlakke en
relatiewe verhoudings in die bloed van mans en vrouens met ‘n hoë risiko vir
die ontwikkeling van kardiovaskulêre siektes.
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Development and evaluation of a food frequency questionnaire to assess daily total flavonoid intake using a rooibos intervention study modelVenter, Irma 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: A comprehensive food frequency questionnaire (FFQ) was developed to assess the daily total
flavonoid intake over the past fortnight within a 14-week intervention that consisted of four periods
to determine the effect of rooibos consumption on oxidative stress in adults (n=40) at intermediate
to high coronary heart disease (CHD) risk. Within the intervention the comprehensive FFQ validity
(against six estimated dietary records and biomarkers), reproducibility (on administrations in the
washout and control periods six weeks apart as these periods had similar flavonoid intake
restrictions) and responsiveness (across the four intervention periods of changed dietary
conditions) was evaluated. The baseline period dietary record and FFQ dietary sources found to
contribute most to the participants’ daily total flavonoid intake, considering the percentage
contribution, and the between-person variation in intake, considering the stepwise multiple
regression analysis, formed the food list of the resultant abbreviated FFQ. The validity,
reproducibility and responsiveness of the latter were also evaluated within the intervention and its
validity (against dietary records) and reproducibility (on re-administration two weeks apart) in an
additional group (n=90) being at low and intermediate CHD risk to evaluate its external strength.
The validity and reproducibility evaluations of the comprehensive and abbreviated FFQs in the
intervention and abbreviated FFQ within the additional group comprised paired difference tests (to
establish the ability to estimate group intakes), correlation coefficients (to establish the ability to
rank individual participants), category agreement and gross misclassification next to the weighted
kappa statistic (to establish the ability to classify the participants into tertiles and quintiles of intake)
and Bland-Altman plots (as representation of the limits of agreement between the two dietary
assessment methods). Correlation coefficients were also used for biomarker validity evaluations in
the baseline period. The repeated measures analysis of variance (ANOVA) (Bonferroni correction)
was used for the responsiveness evaluations of the comprehensive and abbreviated FFQs across
the intervention periods alongside that of the biomarkers as evidence for the changed dietary
conditions.
The study demonstrated that the comprehensive FFQ could be modified to a format with a brief
food list as few items contributed appreciably to the total flavonoid intake and of which most also
contributed to the between-person intake variability. The comprehensive and moreover the
abbreviated FFQ in the validity evaluations provided sufficiently accurate daily total flavonoid intake
estimates. They could determine the intake at group level in correspondence with that of the
dietary records. The participant intakes could additionally be categorized and in particular ranked
greatly alike to the dietary record intakes. The Bland-Altman plots revealed proportional bias
regarding overestimation at the higher intake level. The reproducibility also appeared to be greatly
satisfactory although seasonal fruit exclusions from the abbreviated FFQ food list may hamper its
repeated administration. Both FFQs also confirmed the changed total flavonoid intakes across the
intervention periods in relation to changes in the expected direction concerning the plasma total
polyphenol, conjugated diene and thiobarbituric acid reactive substance concentrations. / AFRIKAANSE OPSOMMING: ‘n Omvattende voedsel frekwensie vraelys (VFV) is ontwikkel om die daaglikse totale flavonoïed
inname oor twee agtereenvolgende weke te beraam te midde van ‘n 14-week intervensie. Die
intervensie het uit vier periodes bestaan wat die effek van rooibosinname op oksidatiewe stres in
volwassenes (n=40), met ‘n intermediêre tot hoë koronêre hartsiekte (KHS) risiko, bepaal het.
Binne die intervensie is die geldigheid (teen ses geskatte dieetrekords en biochemiese merkers),
herhaalbaarheid (op aanwending ses weke uitmekaar in die uitwas en kontrole intervensie
periodes met dieselfde flavonoïed inname bepalings) en waarneembaarheid (oor vier intervensie
periodes van veranderde dieet bepalings) van die omvattende VFV geëvalueer. Die dieetbronne in
die basislyn periode dieetrekords en vraelyste wat die meeste tot die deelnemers se daaglikse
totale flavonoïed inname (baseer op die persentasie bydrae) en die tussen-persoon variasie in
inname (baseer op die stapsgewyse meervuldige regressie analise) bygedra het, het die
voedsellys van die voortvloeiende verkorte VFV gevorm. Die geldigheid, herhaalbaarheid en
waarneembaarheid van dié VFV is binne die intervensie geëvalueer en die geldigheid (teen
dieetrekords) en herhaalbaarheid (heradministrasie twee weke later) daarvan in ‘n verdere groep
(n=90) met lae en intermediêre KHS risiko as evaluasie van die eksterne vermoë van die VFV.
Die geldigheid en herhaalbaarheid evaluasies van die omvattende en verkorte VFV in die
intervensie en die verkorte VFV in die verdere groep het bestaan uit gepaarde verskil toetse
(bepaling van die groepinname skattingsvermoë), korrelasie koëffisiënte (bepaling van individuele
deelnemer rangorde skattingsvermoë), kategorie ooreenstemming en erge wanklassifikasie naas
die aangepaste kappa statistiek (bepaling van die vermoë om die deelnemer innames in derdes en
vyfdes te klassifiseer) en die Bland-Altman karterings (verteenwoordiging van
ooreenstemmingslimiete tussen die twee dieetinname metodes). Korrelasie koëffisiënte is ook
gebruik vir biochemiese merker geldigheid evaluasies in die basislyn periode. Die herhaalde
metings analise van variansie (ANOVA) (Bonferroni regstelling) is gebruik om die
waarneembaarheid evaluasies van die omvattende en verkorte VFV oor die intervensie periodes
naas dit van die biochemiese merkers te evalueer as bewys van die veranderde dieet bepalings.
Die studie het aangedui dat die omvattende VFV gewysig kon word tot ‘n formaat met ‘n verkorte
voedsellys omdat slegs ‘n aantal items merkbaar tot die totale flavonoïed inname bygedra het en
die meeste hiervan ook tot die tussen-persoon variasie in inname. Die omvattende en die verkorte
VFV het in die geldigheid evaluasies daarvan voldoende akkurate daaglikse totale flavonoïed
inname skattings opgelewer omdat groep innames bepaal kon word in ooreenstemming met dit
verkry van die dieetrekords en die deelnemer innames bykomend kategoriseer en in besonder
grootliks eenders rangeer kon word as met hul dieetrekord innames. ‘n Proporsionele oorskatting
by die hoër inname vlakke is wel vir al twee getoon in die Bland-Altman karterings. Die
herhaalbaarheid was ook grootliks aanvaarbaar, alhoewel seisoenale vrugte uitsluitings in die
verkorte VFV voedsellys die heruitvoering kan bemoeilik. Al twee vraelyste kon ook die
veranderinge in die daaglikse totale flavonoïed inname oor die intervensie periodes bevestig in
ooreenstemming met veranderinge in die verwagte rigting van die plasma totale polifenool,
konjugaat diëne en tiobarbituursuur reaktiewe stof konsentrasies.
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Cancer modulating properties of unique South African herbal teas (rooibos and honeybush) in short term in vitro and in vivo carcinogenesis assaysMarnewick, Jeanine Lucasta 12 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: This thesis provides the first scientific evidence on the cancer modulating properties of
two unique South African herbal teas, rooibos (Aspalathus Iinearis) and honeybush
(Cyclopia intermedia) utilizing in vitro as well as in vivo carcinogenesis assays by:
• Demonstrating the in vitro antimutagenic activity of aqueous extracts of the
herbal teas against the metabolic activated mutagens, 2-acetylaminofluorene (2-
AAF) and the mycotoxin, aflatoxin B1 (AFB,) as well as, to a certain extent,
against the direct acting mutagen, hydrogen peroxide, utilizing the Salmonella
typhimurium mutagenicity assay.
• Increasing the activity of hepatic drug metabolizing enzymes, glutathione Stransferase
alpha and UPD-glucuronosyl transferase, and reduced the oxidative
stress by stabilizing the level of reduced glutathione (GSH) resulting in an
increased hepatic reduced to oxidized glutathione ratio (GSG:GSSG). No toxic
effects were noticed in rats consuming the herbal teas for 10 weeks as their sole
source of drinking fluid.
• Demonstrating the ex vivo modulation of 2-AAF- and AFB1-induced mutagenesis
by sub- cellular hepatic fractions of rats consuming the herbal teas in the
Salmonella mutagenicity assay. Hepatic cytosolic fractions protected against
mutagenesis of both mutagens, while the microsomal fractions exhibited a
reduced capacity to metabolize AFB1 to its active mutagenic metabolite.
• Providing evidence for the in vivo modulation of tumour promotion using the liver
as well as the two-stage skin carcinogenesis animal models. The unprocessed
herbal teas arrested proliferation of the placental form of glutathione-Stransferase
(GSTP+) altered cells as well as reduced the total number of enzyme
altered foci in the liver of rats. Topical application of polyphenolic fractions of the
various herbal teas prior to 12-0-tetra-decanoylphorbol-13-acetate (TPA) tumour
promotion, reduced tumour formation in mouse skin initiated with 7,12-dimethylbenz[
ajanthracene (DMBA). The protective effect was illustrated by a decreased
tumour incidence, a reduction in tumour volume as well as a delayed onset of tumour development. The f1avanol/proanthocyanidin content of the fractions
could playa major role in the protection against skin tumour promotion.
• Proposing possible mechanisms whereby rooibos and honeybush herbal teas
could exert their cancer modulating properties with respect to in vitro and ex vivo
antimutagenicity, in vivo oxidative status and reduced tumour promotion.
• Providing evidence that the herbal teas mimic the cancer modulating properties
of green and black teas although differences exist, presumably due to differences
in the polyphenolic constituents.
• Suggesting that rooibos and honeybush herbal teas may play an important role
as chemopreventive agents in the modulation of cancer. / AFRIKAANSE OPSOMMING: Hierdie tesis bevat die eerste ondersoek na die effek van waterige en polifenoliese
ekstrakte van rooibos (Aspalathus Iinearis) en heuningbos (Cyclopia intermedia) op
verskeie aspekte van kankerontwikkeling. Die twee kruietees is uniek aan Suid-Afrika
en kan 'n belangrike rol speel in die voorkoming van kanker. Verskillende in vitro so wei
as in vivo studies het die volgende getoon:
• Antimutageniese aktiwiteite teen die metabolies-geaktiveerde mutagene, 2-
asetielaminofluoreen (2-AAF) en die mikotoksien, aflatoksien B1 (AFB1) in die
Salmonella fyphimurium mutagenisiteitstoets. 'n Beperkte mate van beskerming
is ook verleen teen die oksidatiewe mutageen, waterstofperoksied, sonder
metaboliese aktivering.
• Verhoogde aktiwiteite van die fase II ensieme, glutatioon S-tranferase alfa en
UDP-glukuronidase, wat liggaamsvreemde verbindings metaboliseer. Die
kruietees verlaag die oksidasietoestand soos weerspieel word deur 'n toename
van gereduseerde glutatioon tot die geoksideerde vorm in die lewer van rotte wat
10 weke hierdie kruietees gedrink he!. Die kruietees het geen toksiese uitwerking
op die rotte gehad nie.
• Antimutageniese aktiwiteite van subselluiE~re fraksies van die lewer teenoor 2-
AAF en AFB1 in die Salmonella toets. Die sitosolfraksie van die rotlewer bied
beskerming teen die ge"induseerde mutagenese van beide mutagene, terwyl die
mikrosomale fraksie ook die metaboliese aktivering van AFB1 na die aktiewe
mutageniese metaboliet verminder.
• In vivo modulering van kankerpromosie met behulp van bekende rotlewer en
muisvel kankerontwikkelingsmodelle. In die lewermodel het die
ongeprosesseerde kruietees beide die ontwikkeling en getal van GSTP+ fokusse
onderskeidelik vertraag en verminder. In die geval van die velkankermodel het
aanwending van polifenoliese fraksies van die kruietees beskerming gebied teen
die ontwikkeling van velkankers by muise. Die aantal en grootte van die tumors
het afgeneem terwyl die verskyning daarvan ook vertraag is. • Verskeie meganismes waardeur rooibos- en heuningboslee moonllik kanker kan
moduleer word voorgeslel. Verskille in die polifenoliese sameslelling asook hul
onderskeie konsenlrasies kan 'n belangrike rol speel in die kankerveranderende
effekle van die lees.
• Oal gereelde inname van rooibos- en/of heuningboslee moonllik 'n belangrike rol
kan speel in die voorkoming van dieel- en omgewings-geYnduseerde kankers.
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